AOFAS Winter Meeting Abstracts 2024

Abstract

3D Weight-Bearing CT Imaging Analysis of Foot Mechanics: Bridging High Heels and Hallux Valgus

Kepler A.M. Carvalho, MD; Tania Szejnfeld Mann, MD, PhD; Aly Fayed, MD; Grayson M. Talaski, BA; Emily Joan Luo, BS; Antoine Acker, MD; Nacime Salomao Barbachan Mansur, MD, PhD; Jonathan Kaplan, MD; Bopha Chrea, MD; Cesar de Cesar Netto, MD, PhD

Keywords: hallux valgus, high heels

Introduction/Purpose: Evidence in the literature suggests the negative effects of using High Heels (HH), becoming a challenge for clinicians and researchers since they are welcomed by women worldwide, mainly due to the subjective power of attractiveness given to them. Although some people blame HH as one of the causes of Hallux Valgus (HV), until now, there are no studies in the literature that effectively prove a cause-effect relationship between HH and HV. The objectives of this study are: (1) to analyze whether the increase in heel height can lead to HV and (2) to evaluate whether HV can increase in severity with increasing heels. We hypothesized that an increase in heel height could cause and increase the severity of HV deformity.

Methods: Comparative cross-sectional study. Forty-one feet from twenty-one participants (11 males and 10 females, aged 30.8 ± 8.9 years, and with Body Mass Index 25.5 ± 2.0 m kg2) were recruited. HH shoes were designed for this study with three heights for each participant: 3, 6, and 9 cm. The inclusion criteria were: no regular wearing of heels. The exclusion criteria were: Hallux Valgus diagnosis and/or any orthopedic conditions that affect the Foot and Ankle joints.

Hallux Valgus Angle (HVA), Intermetatarsal Angle (IMA), First-Metatarsal Phalangeal Angle, 1st-to-5th Intermetatarsal Angle, First Tarsometatarsal Angle (axial), Second tarsometatarsal angle (axial), Hindfoot Moment Arm (HMA) (mm), Saltzman 45 angle and, Foot Ankle Offset (FAO) were measurement using semiautomated software analysis. Multiple comparisons were performed (Bonferroni’s for normal distributions and Wilcoxon test for no normal distributions) when there was a main effect on an outcome (p < 0.05).

Results: With the increase in HH, we noticed a progressive increase in HVA (p < 0.001), IMA (p < 0.001), First-Metatarsal Phalangeal Angle (p < 0.001), First Tarsometatarsal Angle (axial) (p < 0.001), and the Second tarsometatarsal angle (axial) (p < 0.001). The Hindfoot Moment Arm (HMA) (mm), Saltzman 45 angle, and Foot Ankle Offset (FAO) had hindfoot varization behavior. When we stratified the groups and compared them, we noticed that an increase of 3 cm in heels slightly increased HVA and IMA (p > 0.05). However, heel increases above 6 cm significantly increased HVA and IMA (p > 0.001). Based on Coughlin’s classification, a 3 cm heel increase promoted a mild HV and increases above 6 cm caused a moderate HV.

Conclusion: Based on data from our study with patients without Hallux Valgus through analysis with WBCT versus high heels, we conclude that increasing heel height can lead to Hallux Valgus and can progressively increase the severity with increasing high heels. High heels above 6 cm can lead to moderate Hallux Valgus. These findings may be an essential step toward a better understanding of the effects of increasing high heels on Hallux Valgus pathology.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00001

A Comparative Analysis of Outcomes using PROMIS after Operative vs Non-operative Treatment of Achilles Rupture

Philomena Burger, BA; Mina Botros, MD; Zein S. El-Zein, MD; David J. Ciufo, MD

Introduction/Purpose: Achilles tendon rupture is a common injury in the adult population. The role of operative and non- operative management remains controversial with the development of functional rehabilitation programs. The purpose of this study is to evaluate and compare the patient-reported outcomes using Patient-Reported Outcomes Measurement Information System (PROMIS) after operative and non-operative treatment of acute Achilles rupture. PROMIS is a valid, reliable, and effective tool to evaluate patient outcomes after treatment for Achilles ruptures. Our hypothesis is that there is no significant difference in PROMIS scores between patients undergoing operative compared to non-operative treatment of Achilles rupture.

Methods: Under an IRB-approved protocol, Achilles rupture was identified using ICD 9 and ICD10 codes of 727.67 and S86.0. Patients who underwent Achilles tendon primary repair were identified using CPT code 27650 (Repair, primary open or percutaneous, ruptured Achilles tendon). Revision Achilles repair and chronic Achilles ruptures were excluded. All patients treated non-operative underwent a strict functional rehabilitation protocol. We included patients treated between 1/1/2015 and 11/30/2022. PROMIS physical function (PF), pain interference (PI), and depression scores were routinely collected prospectively during the initial office visit and follow-up appointments. A distribution-based method used to determine the minimal clinically important difference (MCID), which was 1/2 standard deviation of each PROMIS domain. A medical records review was performed to collect patient demographic data. Statistical analysis was used to compare preoperative and postoperative scores and significance was indicated when P < 0.05.

Results: 216 patients with Achilles tendon ruptured were included (115 Nonoperative versus 101 Operative). Patients treated non-operatively were older than those treated surgically (mean age: 45.1 vs 35.6; p < 0.001). The operative group had a lower BMI compared to non-operative group (27.8 vs. 29.5; p = 0.004). There is no statistical difference in the Achilles tendon re-rupture rate between both groups (operative: 2% vs. 4.3%; p = 0.344). Both groups are effective in improving PROMIS PF, PI, and depression scores (p < 0.001). The mean PROMIS PF change (pre- to post-treatment) is significantly greater in the operative, compared to the non-operative group (13.2 vs. 9.5; p = 0.042). Both treatments had similar mean PROMIS PI change, mean PROMIS depression change, and rates of meeting MCID for all 3 PROMIS domains at 6 months.

Conclusion: In patients with Achilles tendon rupture, operative management may lead to statistically significant higher improvements in physical function compared to non-operative management. However, non-operative management was associated with similar overall rates of re-rupture, PROMIS PI and depression outcomes, and chances of meeting MCID as those who underwent operative intervention. Nonoperative management of Achilles tendon rupture, similar to operative treatment, is a successful treatment option and leads to significant improvement in physical function, pain interference, and depression PROMIS scores.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00002

A Comparison of Post-Operative Patient Reported Outcome Measurements Following Bunion Surgery: Modified Lapidus vs Minimally Invasive Techniques

Madeline Bhend, BSc(Med), BS; Chase Gauthier, MD; Tyler Gonzalez, MD, MBA; J. Benjamin Jackson, MD, MBA

Keywords: Hallux Valgus, Bunion, Lapiplasty, Minimally Invasive Technique, Time-to-Weight-Bear, Revision, Patient Reported Outcomes

Introduction/Purpose: The modified Lapidus procedure (MLP) or a minimally invasive surgery distal transverse osteotomy (MISDTO) are acceptable surgical treatment options for hallux valgus. The current literature is evolving when comparing the effects of each procedure on patient reported outcomes and post-operative complications. The purpose of this study is to compare postoperative outcomes, time to weight bear, and patient reported outcomes using the Patient Reported Outcome Instrumentation System (PROMIS) for the MLP and MISDTO.

Methods: This study retrospectively reviewed patients who underwent a MLP or MISDTO for hallux valgus correction at Prisma Health Midlands between February 2020 and February 2022. Data collected included: demographic data, postoperative outcomes, time to weight bear, and PROMIS scores, including Pain Interference (PI), Physical Function (PF), and Mobility scores. Paired Student’s T-Test and Wilcoxon Rank Sum test were used to compare continuous variables and Chi-Squared test for categorical variables.

Results: A total of 81 patients undergoing MLP and 78 undergoing MISDTO were included in the study. Average follow-up for MLP and MISDTO patients was 53.7 and 43.4 weeks, respectively. MLP demonstrated significant improvement in PI (52.5 vs 56.8, P < 0.001) and Mobility (46.3 vs 43.4, P = 0.044) scores, while MISDTO demonstrated a significant improvement in PI (48.8 vs 57.1, P < 0.001), PF (50.2 vs 44.9, P < 0.001), and Mobility (49 vs 42.8, P < 0.001) scores. MISDTO patients had significantly larger improvements in PI (7.6 vs 4.5, P = 0.008), PF (5.3 vs 2.2, P = 0.026), and Mobility (5.5 vs 2.9, P = 0.02) compared to MLP patients. MISDTO patients had a significantly lower non-union rate (13.6% vs 2.6%, P = 0.025), hardware failure rate (0% vs 9.9%, P = 0.007), and time to weight-bear (2.2 vs 7.8 weeks, P < 0.001).

Conclusion: Both MLP and MISDTO procedures are effective treatments for improving the pain and mobility issues associated with hallux valgus while maintaining patients’ function. MISDTO was found to improve patient reported outcomes significantly more than MLP, with a lower non-union rate, lower hardware failure rate, and shorter time to weight-bear. These findings suggest MISDTO is superior to MLP in improving patient reported outcomes and postoperative outcomes in the treatment of hallux valgus. Further study multicenter and long term outcome studies could be useful further evaluate these short term findings.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00003

A Comparison of PROMIS Scores in Patients Treated with First Metatarsophalangeal Joint Arthrodesis and Polyvinyl Alcohol Hydrogel Implant Hemiarthroplasty for Hallux Rigidus

Seif El Masry, BS; Allison L. Boden, MD; Grace DiGiovanni, BA; Agnes Cororaton, MSc; Scott J. Ellis, MD

Keywords: First Metatarsophalangeal Joint Arthrodesis, Synthetic Cartilage Implant, PROMIS score, hallux rigidus

Introduction/Purpose: Current literature shows similar clinical outcomes between first metatarsophalangeal joint arthrodesis and polyvinyl alcohol hydrogel (synthetic cartilage implant or SCI) hemiarthroplasty in the treatment of hallux rigidus; however, prior studies have not reported validated patient-reported outcome measures. To our knowledge, this is the first study to compare patient-reported outcome measures using the validated Patient Reported Outcomes Measurement Information System (PROMIS) in patients treated for hallux rigidus with metatarsophalangeal joint arthrodesis and SCI hemiarthroplasty. In addition, this novel study provides comparative data of the complication and revision rates for each procedure.

Methods: A retrospective review of prospectively collected data within an institutional registry identified 101 patients who underwent metatarsophalangeal joint arthrodesis and 82 patients who underwent SCI hemiarthroplasty for treatment of hallux rigidus between January 2016 and June 2022. Chart review was performed to obtain demographic information, complications, and revision rates. Preoperative, 1-year, and 2-year PROMIS scores were obtained from the registry and confirmed via chart review. Equivalence testing was performed using two one sided t-tests (TOST) and setting a ±5 unit margin of difference as the clinically meaningful difference to determine if there was a difference in PROMIS scores between groups. Linear regression models were also utilized to compare adjusted postoperative PROMIS scores between the two cohorts. For the equivalence testing, a p-value > 0.05 indicated a statistically significant result.

Results: Demographic information and preoperative hallux rigidus severity between the cohorts showed no statistically significant difference (Table 1). The SCI cohort had no intra-operative or post-operative wound complications, but one patient within the MTP fusion cohort was treated for a superficial wound infection. The SCI group had six patients revised to MTP fusions within 3- years due to continued pain and/or implant subsidence. The MTP fusion group had 2 patients revised due to non-union and 13 patients that had symptomatic hardware requiring removal. Equivalence comparison of PROMIS scores showed the SCI cohort had significantly worse pain intensity scores at 2 years and significantly less improvement in pain intensity scores from pre- operative to 1-year post-op (Table 2). There were no differences found between cohorts for other PROMIS domains.

Conclusion: For the treatment of hallux rigidus, the SCI hemiarthroplasty and metatarsophalangeal joint arthrodesis have equivalent outcomes for all PROMIS domains except the pain intensity domain. While patients in both cohorts had improvement in pain from pre-operative to post-operative time points, SCI was not as effective as first MTP fusion at relieving pain intensity at a follow-up of 2 years. While SCI is a motion-sparing procedure, patients with a primary goal of improving pain may be better suited for first MTP joint arthrodesis.

Tables demonstrating the comparisons of both the preoperative demographic data as well as demonstrating the PROMIS scores across different time periods (preoperative, 1 year and 2 years).

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00004

Agreement Analysis on Postoperative Care Between ChatGPT and a High-Volume Foot and Ankle Surgeon

Ben Efrima, MD; Agustin Barbero, MD; Cristian Indino, MD; Camilla Maccario, MD; Federico Giuseppe Usuelli, MD

Keywords: ChatGPT, Artificial Intelligence, Foot and Ankle Surgeon, Orthopedic Surgeon

Introduction/Purpose: ChatGPT is an Artificial intelligence (AI) algorithm based on a user-friendly interface that does not requires advanced programming skills. Since its release to the public, it has made AI more accessible. As a result, the patient refers to chat GTP for medical inquiries. This study compares the postoperative (PO) information provided by chatGPT to those of a high- volume foot and ankle orthopedic surgeon.

Methods: The study includes 251 patients treated for end-stage osteoarthritis with total ankle arthroplasty. Postoperative emails containing inquiries about their PO status were uploaded to chatGTP. We then evaluated the agreement in simple (SA) and complex (CA) answers. The SA abbreviated the answer provided into “yes” or “no” Its agreement analysis was made using Cohens Kappa. In contrast, CA contained detailed information, and answers were classified into complete agreement, partial agreement, or complete disagreement. Additionally, in partial agreement answers, we calculated the percentage of agreement. Finally, we measured the cases where the surgeon added additional information unrelated to the inquiry.

Results: There was only a slight agreement in the SA category (K = 0.08). In the CA category, we found 27 percent of complete agreement; in 52 percent, we found complete disagreement; in 20 percent, we found only partial agreement. In 50% of the cases, the surgeon added information unrelated to the question.

Conclusion: We found limited agreement between chat GPT and the primary surgeon regarding postoperative information. Indicating that chat, GPT is currently an unreliable source for postoperative management.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00005

Anatomical Structures at Risk in Percutaneous Distal Bunionette Correction

Shrey Nihalani, BS, BA; Mila Scheinberg, MD, MS; Ashish Shah, MD

Keywords: Bunionette, Cadaver, Percutaneous, Shannon burr

Introduction/Purpose: Bunionette deformity affects 23% of the population and has numerous surgical options, including a minimally invasive approach (MIA) to decrease complications. Percutaneous surgery is favored by patients as it decreases pain, inflammation, and noticeable incision sites. Three possible osteotomy sites have been identified: proximal, diaphyseal, and distal. The study investigates the anatomic structures at risk during distal osteotomy of bunionette deformity using a Shannon burr. The distal osteotomy site was on average greater than 8 mm from the extensor digitorum longus and adductor digiti minimi while it was 1.64 mm from the lateral dorsal cutaneous nerve. The study highlighted the challenges posed by minimally invasive approaches to treating bunionette deformity and the need for cautious consideration when utilizing percutaneous methods.

Methods: Eleven fresh frozen below-knee amputated foot and ankle cadavers were used for this study. Cadavers were allowed to thaw for 12 hours at room temperature before performing any tissue handling. All cadavers were visually inspected for evidence of gross pathology. Fluoroscopic radiographs were used to inspect for evidence of preexisting pathology of the fifth metatarsal. All cadavers with gross pathology or radiographic fifth metatarsal pathology were excluded from the study. All procedures were performed by a fellowship trained orthopaedic foot and ankle surgeon.

Results: All eleven cadavers met the inclusion criteria for this study. The average age of the patients was 66.6 ± 20.1 years. There were five female feet and six male feet. There were seven right feet and four left feet. Distance from the percutaneous access site was measured to structures at potential risk. The closest structure at risk was the lateral dorsal cutaneous nerve (LDCN) (1.64 mm), which was contacted 2/11 times and transected both times. The extensor digitorum longus (EDL) and abductor digiti minimi (ADM) had no instances of contact during the procedure. Dissection allowed for the identification of structures at risk and the assessment of osteotomy. All procedures resulted in a complete osteotomy.

Conclusion: Overall, distal percutaneous bunionette osteotomy is largely safe. Structures pertinent to the surgery were identified with ease and were intact after osteotomy with a Shannon burr. Anatomic variations of LDCN can present challenges to the procedure. Meticulous dissection and judicious use of fluoroscopy can help prevent further damage. Surgeons should be aware of anatomic variations in order to proceed safely.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00006

Anterior Talo-Fibular Ligament Tensile Properties Compared to Suture Tape, Allograft, and Copolymer Augmentation Elements: An Isolated Biomechanical Study

Sarah June Ingwer, BS; Ryan Rigby, DPM; Andrew Rosenbaum, MD; Oliver Hauck, MS; Anthony N. Khoury, PhD; David I. Pedowitz, MD

Keywords: ATFL, internal brace, artelon, ankle instability, augmentation

Introduction/Purpose: The modified Brostrom-Gould (MB) technique incorporates the inferior extensor retinaculum for added strength of anatomic Anterior Talo-Fibular Ligament (ATFL) repair. A major limitation of the MB technique is the inability to restore native ATFL biomechanics. Surgical augmentation methods have been introduced to address the MB insufficiency. The purpose of this study is to investigate the isolated biomechanical performance of common MB augmentation elements including suture tape, allograft, and copolymer compared to that of native ATFL.

Methods: A total of 24 samples were tested in this study, n = 6 in each group. An electromechanical testing system (Instron, Norwood, MA) was used to investigate the biomechanical performance of native ATFL, UHMW-PE suture tape (FiberTape™, Arthrex, Inc., Naples, FL), allograft (Semitendinosus Graft), and copolymer (FlexBand™, Artelon, Marietta, GA). Native ATFL ligaments were isolated from cadaver specimens (mean age: 63 years; range: 45-80), semitendinosus allografts were obtained from LifeNet Health (Jacksonville, FL). Samples measured 20 mm between rigid fixtures and oriented parallel with the long axis of the load cell to simulate worse-case loading. Samples were loaded to failure at 305 mm/min. Biomechanical outcomes included elongation, stiffness, and ultimate load to failure. One-way ANOVA was used to evaluate significant effects of all biomechanical variables. If significance was observed, post-hoc comparisons of augment element and native ATFL were performed with either Tukey or Holm-Sidak test (SigmaPlot, 14.0, Systat).

Results: Stiffness was greatest for the suture tape group (246.4 ± 52.1 N/mm) and least for the copolymer (9.4 ± 2.9 N/mm). Significant differences were observed between all augment elements except when comparing ATFL to allograft (p = 0.086). Ultimate load was greatest for the suture tape group (544.1 ± 59.7 N) and least for the copolymer (146.7 ± 8.9 N). Analysis revealed that suture tape ultimate load was statistically greater than copolymer (p < 0.001, Figure 1). Elongation at ultimate failure was greatest for the copolymer group (30.0 ± 8.7 mm) and least for suture tape (2.6 ± 0.5 mm). Significant interactions were detected for all ultimate load comparisons except for allograft and ATFL (p = 0.691), allograft and suture tape (p = 0.537), and ATFL and suture tape (p = 0.436). See Figure 1 for all data and statistical outcomes.

Conclusion: ATFL augmentation elements require thorough evaluation for clinical adoption. Copolymer was 79% weaker in ultimate load and elongated 131% more than the native ATFL. Conversely, suture tape group exhibited 47% greater ultimate load and 82% less elongation at failure compared to ATFL. Clinically, these results suggest the copolymer maintains elastic properties incapable of supporting ATFL ligament healing under load. ATFL augmentation with suture tape offers advantageous post- operative load-sharing support and may allow return to preinjury level activity sooner, as has been seen clinically.1 These results provide insight into how these augmentation elements perform in a static model.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00007

Arthroscopic Assisted Reduction of Talus Fractures Leads to Improved Clinical Outcomes at Mid- Term Follow-Up

Hayden Hartman, BS; Haley N. Tornberg, BS; Paul Fine-Lease, BA; Arianna Gianakos, DO

Keywords: talus, calcaneus, minimally invasive, arthroscopic, trauma

Introduction/Purpose: Talus fracture is an uncommon and challenging pathology to treat due to its relationship with articular cartilage, ligamentous network, and avascular nature. The purpose of this systematic review was to evaluate the clinical outcomes after arthroscopic talar fracture fixation, compare to conventional open reduction and internal fixation (ORIF), and analyze the quality and level of evidence of the included studies.

Methods: A systematic review of the MEDLINE, EMBASE, and Cochrane Library databases was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in June 2023. Articles were included if they evaluated outcomes following arthroscopic treatment of talus fractures, were written in English, were peer-reviewed, had a minimum of 2 patients per cohort, had human patients, and had a minimum 6-month follow-up. Inclusion criteria consisted of: Studies reporting clinical data following arthroscopy for the treatment of talus fractures were included and assessed.

Results: Seven studies were analyzed, including 4 case series, 1 retrospective cohort, and 2 retrospective comparative studies. 237 patients treated with arthroscopic assisted reduction were compared to 76 patients treated with ORIF. Amongst arthroscopically treated patients, the AOFAS score improved from 71.2 ± 5.2 preoperatively to 89.9 ± 4.3 postoperatively. The SF-36 score improved from 73.2 ± 30.3 preoperatively to 104.5 ± 19.3 postoperatively. In total, 6 complications (3.0%) were observed in arthroscopically treated patients, of which the most common was peri-talar osteoarthritis in 2 patients (0.84%). In comparative cohorts, ORIF patients experienced a 13.0% complication rate in 6 patients (talar necrosis, malunion, nonunion, infection, and post-traumatic arthritis), compared to 2.2% in 1 patient (malunion) in the arthroscopic cohort.

Conclusion: This study demonstrates that arthroscopic assisted reduction of talar fractures results in good clinical outcomes with lower complication rates. This minimally invasive approach had lower complications than ORIF, with no cases of talar necrosis and decreased postoperative traumatic arthritis. This technique provides adequate exposure without additional osteotomy, while decreasing trauma to local anatomical trauma, minimizing the risk of postoperative complications, and improving fracture healing assessment of concomitant lesions. These findings indicate arthroscopic treatment of talus fractures is an efficacious and safe procedure with comparable or improved clinical and postoperative outcomes as compared to conventional ORIF.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00008

Axial Rotation Analysis in Total Ankle Arthroplasty Using Weight-Bearing Computer Tomography and Three-Dimensional Modeling

Ben Efrima, MD; Agustin Barbero, MD; Joshua Ovadia, MD; Cristian Indino, MD; Camilla Maccario, MD; Federico Giuseppe Usuelli, MD

Keywords: Total Ankle Arthroplasty, Axial Rotation, Weightbearing Computed Tomography, 3 Dimensional Models

Introduction/Purpose: Post-operative alignment is the most critical indicator for a successful total ankle arthroplasty (TAA). Total ankle malrotation is associated with an increased risk for polyethylene wear and medial gutter pain. Currently, there is no consensus on the correct way to measure the alignment of the tibial and talar component rotations in the axial plane. In the current study, the post-operative analysis system was assessed using weight-bearing computer tomography and a three- dimensional (3D) model. The purpose of the study was to assess the inter-observer and intra-observer agreement of this system.

Methods: Four angles were measured by two raters independently in two separate readings: posterior tibial component rotation angle (PTIRA), posterior talar component rotation angle (PTARA), tibia talar component axial angle (TTAM), and tibial component to the second metatarsal angle (TMRA). Agreement analysis was quantified according to the interclass coefficient.

Results: Sixty TAAs across 60 patients were evaluated. A good inter-observer agreement and intra-observer agreement when measuring the PTIRA, PTARA, and TTAM angles was observed along with an excellent inter-observer agreement and intra- observer agreement when measuring the TMRA angle.

Conclusion: In conclusion, the current 3D model-based measurement system demonstrates good to excellent inter and intra- agreement. According to these results, 3D modelling can be reliably used to measure and assess the axial rotation of TAA components.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00009

Classification of the Os Calcis Subtalar Morphology in Symptomatic Flexible Pediatric Pes Planus Deformity Using Weightbearing CT and Distance Mapping

Agustin Barbero, MD; Ben Efrima, MD; Joshua Ovadia, MD; Cristian Indino, MD; Camilla Maccario, MD; Federico Giuseppe Usuelli, MD

Keywords: weightbearing computed tomography, distance mapping, os calcis subtalar joint, pes planus, morphology, pediatrics, PCFD, progressive collapsing foot deformity

Introduction/Purpose: The etiology of symptomatic pediatric pes planus (PP) deformity is unclear. Reduced os calcis subtalar joint (OCST) anterior facet morphology has been suggested to result in less support to the talar head and a higher propensity to develop PP deformity. Weightbearing computed tomography (WBCT) and distance mapping (DM) offer new opportunities to investigate PP deformity in general and the OCST specifically. The purpose of this study is to investigate the OCST morphology using DM and to classify PP subtalar subtypes with DM using Bruckner’s A-D classification system.

Methods: Forty feet in 25 patients in a national referral center were evaluated for symptomatic PP deformity that failed nonoperative treatment. A WBCT scan was performed as part of the preoperative evaluation. Visualization of the distance distribution between the articulating surfaces of the subtalar joint was based on a DM technique. Intra- and interobserver agreement of the subtalar morphology was assessed using Bruckner’s classification system.

Results: The mean age was 10.7 ± 1.4 years. The following mean ± SD and median ± ranges were semiautomatically measured for this group: Meary angle −21 ± 8, calcaneal inclination 15 ± 4 degrees, talar coverage angle 39 (range 32.6-49) degrees, and hindfoot moment-arm 16 ± 5 mm. Classifying subtalar morphology using DM yielded an excellent intra- and interobserver agreement. The individual percentages of each individual subtype were calculated: type A 5%, type B 48%, type C 4%, and type D in 44%.

Conclusion: This study demonstrated excellent intraobserver and interobserver agreement in classifying the OCST using DM. A higher prevalence of types B and D was observed compared to types A and C in this PP cohort.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00010

Clubfoot Correction with Ponseti Technique: Three-Dimensional Alignment Analysis and Residual Adult Deformity Effects on Patient-Reported Outcomes

Ryan Jasper, BS; Kepler A.M. Carvalho, MD; Aly Fayed, MD; Antoine Acker, MD; Vineel Mallavarapu, BS; Grayson M. Talaski, BA; Nacime Salomao Barbachan Mansur, MD, PhD; Bopha Chrea, MD; Cesar de Cesar Netto, MD, PhD

Keywords: Weightbearing CT, Clubfoot, Patient-reported outcomes

Introduction/Purpose: Few studies have assessed the long-term outcomes of the Ponseti technique and none have utilized 3- dimensional weightbearing analysis. The goal of this study was to understand how potential residual 3D deformities and abnormalities influence patient reported outcomes (PROs). This was accomplished by assessing anatomical foot and ankle alignment in adult clubfoot patients treated with the Ponseti method using 3D weightbearing CT (WBCT) imaging and then correlating residual foot and ankle malalignment with PROs.

Methods: There were 37 consecutive patients (57 feet) included and 14 volunteers healthy controls (28 feet) included in this study. Every participant was evaluated using a WBCT (HiRise©) in a bipedal standing position. From these scans Cavus, Adductus, and Varus components were evaluated using multiple 3D measurements calculated using the semi-automatic segmentation software Bonelogic^®. Specific Cavus related measurements included sagittal talus-first metatarsal angle and the calcaneal inclination angle. Varus related measurements included talocalcaneal angle in both the sagittal and axial planes as well as the hindfoot moment arm and the hindfoot alignment angle. Adductus deformity was evaluated using talonavicular coverage angle. These measurements were then correlated with patient reported outcome surveys, which included Visual Acuity Scale for pain, PROMIS general health, PROMIS physical function, PROMIS pain interference, pain catastrophic scale, and European foot and ankle society score.

Results: There was no significant overall residual 3D-deformity observed in clubfoot patients when compared to controls, with similar FAO measurements observed between the groups, clubfoot = 2.63% (95%CI = 1.41%-3.85%) and control = 3.2% (CI = 1.6%-4.8%,P = 0.58). The sagittal talus-first-metatarsal in the clubfoot-patients had a mean-value of −0.12° compared to the controls, −5.2°. Clubfoot patients also had a decreased calcaneal-inclination-angle relative to the controls, 13.01° and 21.5° respectively. Talocalcaneal-angle for clubfoot patients in both the sagittal-plane,44.28°, and axial-plane, 17.74°, were reduced compared to the controls, 57.51° and 25.78°. Talonavicular-coverage-angle in the clubfoot-group (18.63°) was less than the controls (29.19°). Talus-first-metatarsal-angle in the sagittal-plane was significantly correlated with VAS-scores (RSquare = 0.19, P = 0.0118) and the EFAS-Score (RSquare = 0.27, P = 0.0025). Talocalcaneal-angle in the sagittal plane was also significantly correlated with the PROMIS-Pain-Interference-score (P = 0.038) and PROMIS-Physical-Function-score (RSquare = 0.32, P = 0.0007).

Conclusion: The Ponseti technique is an effective nonsurgical treatment for the overall three-dimensional foot and ankle alignment of Clubfoot. While mild, but statistically significant residual Varus and Adductus deformities were observed in adult clubfoot patients, the overall 3D alignment (FAO) was found to be similar between clubfoot patients and controls. These findings highlight the efficacy of the Ponseti technique and potentially explain the overall good PROs. The results of this study could potentially provide insight into treatment targets that may be applied to help optimize patient outcomes when treating children with Clubfoot in the future.

The Ponseti technique is an effective nonsurgical treatment for Clubfoot’s overall three-dimensional foot and ankle alignment. While mild, but statistically significant residual Varus and Adductus deformities were observed in adult clubfoot patients, the overall 3D alignment (FAO) was found to be similar between clubfoot patients and controls. These findings highlight the efficacy of the Ponseti technique and potentially explain the overall good PROs. The results of this study could potentially provide insight into treatment targets that may be applied to help optimize patient outcomes when treating children with Clubfoot in the future.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00011

Comparison of Complication Rates and Surgical Costs for Total Ankle Replacements Performed in the Outpatient vs Inpatient Setting

Devon Nixon, MD; Hyunkyu Ko, PhD; Brook Martin, PhD

Keywords: surgical costs, total ankle replacement

Introduction/Purpose: Increasing data has highlighted the safety and cost-effectiveness of outpatient hip, knee, and shoulder arthroplasty. However, limited evidence – mainly small, single institution case series – has explored complication rates and costs between outpatient and inpatient total ankle arthroplasty (TAA) surgeries.

Methods: Utilizing Medicare claims from 2016 to 2019, we retrospectively identified patients ≥65 years of age who underwent TAA based on CPT coding. Patients on Medicare HMO, under age 65, and dual-eligible patients were excluded. Within this dataset, we compared surgeries performed in the outpatient versus inpatient setting. We compared groups based on readmission, all-complication, and infection rates within 1-year of TAA using logistic regressions controlling for age, sex, race, and comorbidity. To help mitigate bias, we also performed a propensity matched model with the same variables. Data were reported as percentage point (PPT) differences (95% CI) between groups, with a positive number indicating higher complication rates and costs among patients treated in the inpatient setting.

Results: In total, 8,281 total ankle arthroplasty cases were identified (outpatient: 5,524 and inpatient: 2,757. Compared to inpatient cases, outpatient TAA surgeries were performed on younger, healthier (as assessed by Charlson Comorbidity Index (CCI) scores) patients who were more likely to be female (p < 0.001). In logistic regression analyses, outpatient TAA cases had lower readmission, all-complication, infection, mortality, and device-associated complication rates (p < 0.001) as compared to inpatient surgeries. Further, outpatient surgeries had sizable cost reductions compared to inpatient surgeries (p < 0.001).

Conclusion: TAA performed in the outpatient setting appears to have less complications and decreased cost compared to inpatient procedures – though inpatient surgeries were presumably riskier as they were performed on older patients with increased co-morbidities. When clinically appropriate, though, TAA as an outpatient procedure appears to provide substantial reductions in cost with notable reductions in surgical risk.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00012

Congruency of the TN Joint and Subtalar Joint Middle Facet Under With and Without Weightbearing: A Preliminary Report

Stephen Wittels, MD; Mingjie Zhu, DAOM MPH; Mark Myerson, MD; Shuyuan Li, MD, PhD

Keywords: Peritalar subluxation, Weightbearing CT, 3D remodeling

Introduction/Purpose: Peritalar subluxation is a key feature of both flatfoot and cavovarus deformities. Our preliminary studies have found that on WBCT there is 20% subluxation of the middle facet of the subtalar joint in normal controls, and >35% in patients with flexible flatfoot deformities; In the spherical talonavicular joint there is physiological uncovering of the talar head regardless of whether the joint is bearing weight or not, since the articular area of the talar head is 1.2 times of the navicular. We hypothesize that there may be a tendency to overestimate the pathological peritalar subluxation on both XR and WBCT. This study aimed to investigate the congruency of each peritalar joint using a weightbearing 3D CT scan remodeling technique.

Methods: Five below-knee-amputated fresh frozen cadaveric feet were used (no history of surgery, trauma, arthritis, and deformities). Each specimen was CT scanned using both non-weightbearing and weightbearing protocols. Segmentation on Materialise Mimics software was used to remodel each peritalar bone three dimensionally. Congruency of the restored talonavicular joint and subtalar middle facet was evaluated in the GeoMagic. The total articular surface area for each bone was reconstructed, calculated and recorded. The articulation of each joint with or without weightbearing was restored for analyzing joint uncoverage. Paired t-test (P value ≤ 0.05) was used to compare the coverage % differences.

Results: In the anterior and middle facets of the subtalar joint, There was 16.40% uncoverage of the calcaneus under non- weightbearing, and 30.68% of uncoverage under weightbearing; 17.94% uncoverage of the talus under non-weightbearing, and 24.89% of uncoverage under weightbearing. In the posterior facet of the subtalar joint, the total articular surface on the talus side (683.96 ± 112.07 mm²) was 1.13 times larger than the calcaneus side (606.78 ± 107.23 mm²). In the talonavicular joint, the total articular surface on the talus side (714.18 ± 124.97 mm²) was 1.28 times larger than the navicular side (556.76 ± 97.65 mm²).

Conclusion: Our preliminary study in this group of normal cadaver feet has found that in both the talonavicular and middle facet of the subtalar joints, there is physiological uncovering or subluxation regardless of whether the joint is bearing weight or not.

Further investigation with a larger sample size is in process.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00013

Defining the Patient Acceptable Symptom State (PASS) for PROMIS After Hallux Rigidus Correction Surgery

Allison L. Boden, MD; Stone R. Streeter, BS; Seif El Masry, BS; Grace DiGiovanni, BA; Agnes Cororaton, MSc; Matthew S. Conti, MD; Scott J. Ellis, MD

Keywords: hallux rigidus, first MTP fusion, MTP arthritis, cheilectomy

Introduction/Purpose: In an ever-changing healthcare landscape, patient-reported outcomes (PROs) are becoming more important for reimbursement and evaluating the success of surgical procedures. Unfortunately, it is unclear which PROs correlate best with clinical improvement. The patient acceptable symptom state (PASS) asks the patient whether or not their outcome is acceptable at a particular post-operative time point. Recently, the use of this metric has gained traction within the foot and ankle literature. To our knowledge, this is the first study that aims to establish PASS thresholds for Patient-Reported Outcome Measurement Information System (PROMIS) scores in patients who underwent operative intervention for hallux rigidus.

Methods: A retrospective review of prospectively collected data within an institutional registry was performed. We identified 174 patients treated for hallux rigidus between February 2019 and March 2021 with at least 2-year post-operative PROMIS scores.

Chart review was performed to obtain demographic information and to confirm the surgical procedures that were completed. Two-years post-operatively, patients answered two PASS anchor questions (Satisfaction, Delighted-Terrible scale) with Likert- scale responses, which was collected along with pre-operative and 2-year post-operative PROMIS scores via the registry. After patient’s answers to the Satisfaction and Delighted-Terrible scales were recategorized into binary responses, PASS thresholds were determined using the maximum Youden Index and a 95% confidence interval was quantified using 2000 bootstrapped iterations. Differences in patient and surgical characteristics between patients who met or did not meet the PASS threshold were compared using independent samples t-test and Pearson chi square. Statistical significance was established at an alpha of 0.05.

Results: There was excellent association between PASS thresholds and the PROMIS domains of Physical Function (48.6, AUC = 0.82) and Pain Interference (52.1, AUC = 0.86). Overall, 125/174 (71.8%) and 105/174 (60.3%) patients met the threshold for Physical Function (PF) and Pain Interference (PI), respectively. For the PF and PI domains, age, BMI, method of cheilectomy and use of Akin/Moberg osteotomy did not impact a patient’s likelihood of meeting the PASS threshold. For the PF domain and the PI domain stratified by the Delighted-Terrible scale, women were more likely to meet the PASS threshold than men (63.2% vs. 36.8%, p = 0.057 and 73% vs. 45%, p = 0.023, respectively). Lastly, patients with a higher pre-operative PF score had a higher chance of meeting the PASS threshold (p < 0.001).

Conclusion: Following operative intervention to treat hallux rigidus, pre-operative PROMIS scores were strongly associated with a patient’s likelihood of meeting the PASS threshold. After surgical intervention for hallux rigidus, less than 75% of the patients felt their outcome was acceptable; however, the PASS threshold for PF was lower than population average, so it may not be necessary for patients to reach normal physical function levels post-operatively in order to have an acceptable outcome.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00014

Defining the Patient Acceptable Symptom State (PASS) for PROMIS After Hallux Valgus Correction Surgery

Allison L. Boden, MD; Stone R. Streeter, BS; Seif El Masry, BS; Grace DiGiovanni, BA; Agnes Cororaton, MSc; Matthew S. Conti, MD; Scott J. Ellis, MD

Keywords: hallux valgus, bunion, lapidus

Introduction/Purpose: Surgical interventions to correct hallux valgus have been shown to improve patient reported outcomes (PROs); however, many of these instruments do not measure a patient’s subjective outcome experience. The patient acceptable symptom state (PASS) is defined as the symptom threshold that a patient must reach to be satisfied with the outcome of their surgery. PASS thresholds have been defined for hallux valgus correction using American Orthopaedic Foot & Ankle Society (AOFAS) scores; however, no studies have used a validated PRO metric. This is the first study that aims to establish PASS thresholds for Patient-Reported Outcome Measurement Information System (PROMIS) scores in patients following operative intervention for hallux valgus.

Methods: A retrospective review of prospectively collected data within an institutional registry was performed. We identified 291 patients treated for hallux valgus with or without second hammertoe correction between February 2019 and March 2021 with at least 2-year post-operative PROMIS scores. Chart review was performed to obtain demographic information and to confirm the surgical procedures completed. Two-years post-operatively, patients answered two PASS anchor questions (Satisfaction, Delighted-Terrible scale) with Likert-scale responses, which was collected along with pre-operative and 2-year post-operative PROMIS scores via the registry. After patient’s answers to the Satisfaction and Delighted-Terrible scales were recategorized into binary responses; PASS thresholds were determined using the maximum Youden Index and a 95% confidence interval was quantified using 2000 bootstrapped iterations. Differences in patient and surgical characteristics between patients who met or did not meet the PASS threshold were compared using independent samples t-test and Pearson chi square.

Results: There was excellent association between PASS thresholds and the PROMIS domains of Physical Function (50.3, AUC = 0.86) and Pain Interference (51.5, AUC = 0.86). Overall, 204/291 and 205/291 patients met the threshold for Physical Function (PF) and Pain Interference (PI), respectively. For both PROMIS domains, a lower BMI was associated with a higher likelihood of meeting the PASS threshold (p = 0.002 for PF, p = 0.032 for PI). For the PF domain, Lapidus patients were more likely to meet the PASS threshold (p = 0.05), and patients with first MTP fusion were less likely to meet the PASS threshold (p = 0.004). Meeting the PASS threshold wasn’t impacted by the concomitant correction of a second hammertoe. Lastly, patients with a higher pre-operative PF score had a greater chance of meeting the PASS threshold (p < 0.001).

Conclusion: This is the first study to define a PASS threshold for hallux valgus correction using PROMIS scores, a validated outcomes measure. Pre-operative PROMIS scores, patient BMI, and the type of procedure performed impacted a patient’s likelihood of meeting the PASS threshold. These results may be helpful in counseling and educating patients on their chances of obtaining a satisfactory result following hallux valgus correction.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00015

Defining the Patient Acceptable Symptom State Using PROMIS Following Reconstruction of the Progressive Collapsing Foot Deformity

Stone R. Streeter, BS; Sophie Kush, BS; Agnes Cororaton, MSc; Jensen Henry, MD; Scott J. Ellis, MD; Matthew S. Conti, MD

Keywords: Progressive collapsing foot deformity, Patient-reported outcomes, PROMIS, PASS

Introduction/Purpose: Although reconstruction of the flexible progressive collapsing foot deformity (PCFD) has been shown to improve patient-reported outcomes (PROs), there is limited data describing postoperative success as defined by patient satisfaction following surgery. Distinct from the minimal clinically important difference (MCID), the patient acceptable symptom state (PASS) is a novel PRO measurement that represents the symptom threshold beyond which patients are satisfied with their postoperative outcome. The primary aim of this study was to use Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) and Pain Interference (PI) scores in combination with anchor questions to define PASS thresholds following reconstruction of the flexible PCFD. A secondary aim was to analyze how patient-specific variables and certain PCFD reconstruction procedures may impact the probability of reaching PASS thresholds.

Methods: Using data collected from a foot and ankle orthopedic registry at a large academic institution, 109 patients who underwent reconstruction of a flexible PCFD between February 2019 and March 2021, had preoperative and 2-year postoperative PROMIS PF and PI scores, and 2-year postoperative responses to two PASS anchor questions (the delighted-terrible scale and the satisfied scale) were included in the study. Patients who underwent either a double or triple arthrodesis were excluded. Patient responses to the anchor questions were dichotomized and receiver operating characteristic (ROC) curve analyses were performed. Using the Youden Index to balance sensitivity and specificity and maximize the area under the curve (AUC), PASS thresholds with 95% confidence intervals were quantified using 2000 bootstrapped iterations. Lastly, multivariable logistic regressions were performed to analyze the influence of patient demographics, preoperative PROMIS scores, and certain PCFD reconstruction procedures on the probability of reaching the PASS thresholds.

Results: The PASS threshold for PROMIS PF was found to be 42.6 using both the delighted-terrible and the satisfied scale and 73.4% of patients (80/109) reached the threshold (both AUCs: 0.91) (Table 1). The PASS thresholds for PROMIS PI defined using the delighted-terrible scale and the satisfied scale were 54.5 (AUC: 0.90) and 57.5 (AUC: 0.91), respectively, with 72.5% of patients (79/109) and 81.7% of patients (89/109) meeting the respective thresholds. Neither patient demographics nor specific PCFD reconstruction procedures affected the probability of meeting the PASS thresholds. However, a lower preoperative PROMIS PF score or a higher preoperative PROMIS PI score significantly decreased the probability of achieving the PASS thresholds.

Conclusion: Following reconstruction of the flexible PCFD, PASS thresholds for the PROMIS PF and PI domains were found to be lower and higher, respectively, than population norms. This suggests that patients may be satisfied with the outcome of their surgery despite not returning to the population mean. The probability of achieving the PASS thresholds was influenced by both preoperative PROMIS PF and PI scores but not by patient demographics or certain PCFD reconstruction procedures. In addition to guiding future outcomes research, these results may help foot and ankle surgeons optimize treatment for the flexible PCFD and better manage patient expectations.

PASS Thresholds for Flexible PCFD.

PASS thresholds defined for reconstruction of the flexible PCFD using PROMIS Physical Function and Pain Interference scores in combination with two anchor questions, the delighted-terrible scale and the satisfied scale. The PASS thresholds were calculated using the Youden Index which maximizes the area under the curve (AUC) and uncertainty is represented by 95% confidence intervals (CI). PASS Anchor Question #1 (Delighted-Terrible Scale): “If you were to spend the rest of your life with your foot or ankle symptoms just the way they have been in the last twenty-four hours, how would you feel?” Response options: (1) Delighted, (2) Pleased, (3) Mostly satisfied, (4) Equally satisfied and Dissatisfied, (5) Mostly dissatisfied, (6) Unhappy, or (7) Terrible. PASS Anchor Question #2 (Satisfied Scale): “Are you satisfied with the results of your surgery?” Response options: (1) Very satisfied, (2) Satisfied, (3) Neither satisfied nor dissatisfied, (4) Dissatisfied, or (5) Very dissatisfied.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00016

Does Timing of Subtalar Arthrodesis Affect Reoperation or Revision Rates for Total Ankle Arthroplasty?

Pradip Ramamurti, MD; Joshua Schwartz, MD; M. Truitt Cooper, MD; Joseph Park, MD

Keywords: Total ankle arthroplasty, Hindfoot arthrodesis, Ankle arthritis, Subtalar arthritis, Triple Arthrodesis

Introduction/Purpose: The incidence of primary total ankle arthroplasty (TAA) in the treatment of end-stage ankle arthritis has increased substantially over the last decade. TAA may be performed alone or in conjunction with additional procedures including subtalar (ST) or triple arthrodesis as end-stage ankle arthritis is often associated with degenerative disease affecting neighboring joints. Prior literature has demonstrated that the ipsilateral hindfoot arthrodesis may increase the risk for revision after TAA and that simultaneous ST arthrodesis with TAA could result in significant short term clinical and radiologic improvements. However, there is limited research comparing staged versus simultaneous hindfoot arthrodesis with concomitant TAA. The purpose of this study is to compare the reoperation rates after TAA with simultaneous hindfoot arthrodesis versus staged hindfoot arthrodesis followed by TAA.

Methods: Patients who underwent primary TAA from 2015 to 2022 were identified in the PearlDiver database using international classification of diseases (ICD) and current procedural (CPT) codes. Patients were only selected if they contained 1-year database follow-up after the index TAA. Patients were sorted into three cohorts: (1) primary TAA without any history of hindfoot arthrodesis (control), (2) those with staged hindfoot arthrodesis prior to TAA, and (3) those with hindfoot arthrodesis at the same time as TAA. Demographic characteristics including age, gender, and Charlson Comorbidity Index (CCI) were assessed for each cohort. The 1-year rate of reoperation and revision were the primary outcomes of this study. Univariate analysis using chi- square tests and student T-tests were performed to analyze any differences in patient demographics, comorbidities, and complications. Multivariate analysis using logistic regression was subsequently conducted to account for any confounding variables and covariates.

Results: 9,912 patients underwent TAA without prior hindfoot arthrodesis, 297 patients underwent TAA with prior hindfoot arthrodesis and 174 with hindfoot arthrodesis concurrently with TAA. The incidences of reoperation (OR 3.52, 12.6% vs. 3.9%, P < 0.001) and revision (OR 3.66, 4.0% vs. 1.1%, P = 0.001) were higher in the simultaneous cohort when compared to the control. However, there were no statistically significant differences in rates of reoperation (OR 0.96, 4.0% vs. 3.9%, P = 0.891) or revision (OR 1.94, 2.4% vs. 1.1 %, P = 0.095) when comparing staged hindfoot arthrodesis to the control.

Conclusion: Patients undergoing concurrent hindfoot arthrodesis with TAA had a 3.5 times higher odds of reoperation and revision when compared to the control. Patients undergoing staged procedures did not demonstrate a difference in revision or reoperation rates when compared to the control. Staged hindfoot arthrodesis and TAA may be an effective option in treating complex end-stage ankle and hindfoot arthritis whereas a simultaneous approach may lead to higher rates of complications.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00017

Evaluation of ChatGPT’s Response to Common Patient Questions for Total Ankle Arthroplasty

Chase Gauthier, MD; Justin Kung, MD; Yianni Bakaes, BSc(Med); Tyler Gonzalez, MD, MBA; Nicholas L. Strasser, MD; Joseph Park, MD; J. Benjamin Jackson, MD, MBA

Keywords: Artificial Intelligence, Total Ankle Arthroplasty, Patient Education, Accuracy, Patient Questions

Introduction/Purpose: Many patients use the internet as a source for medical information regarding their medical condition. However, the accuracy and reliability of the information is variable. The recent release of general population facing artificial intelligence (AI) chatbot programs has created a potential alternative medical information source for patients. Our study examined the accuracy of the information provided by ChatGPT for total ankle arthroplasty (TAA), as determined by four fellowship-trained foot and ankle orthopedic surgeons.

Methods: GPT-4, the latest ChatGPT model, was asked the 12 of the most common questions patients have regarding TAA. Its responses were recorded and evaluated by four fellowship-trained foot and ankle orthopedic surgeons on a scale of 1 to 4, with 1 representing an excellent response not requiring clarification and 4 representing an unsatisfactory response requiring significant clarification. Averages of scores for each question were recorded and an average of every score was used to develop an overall accuracy score.

Results: The overall accuracy score of GPT-4 was 1.35. The responses by GPT-4 received a score of 1 for 32 of 48 (66.7%) responses. There was found to be no significant difference in scores for any of GPT-4’s responses.

Conclusion: Our study found that GPT-4 performed well in providing accurate and near complete information to commonly questions asked to physicians by patients regarding TAA. Our results suggest that AI models, like GPT-4, may be an effective alternative source of medical information for patients. Further study with subsequent AI models and direct patient interaction may shed further light on the utility of this potential patient education modality.

ChatGPT Response Accuracy Score.

Accuracy scores for ChatGPT, as determined by four foot and ankle fellowship-trained orthopedic surgeons.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00018

Evaluation of Surgical Costs in Acute Achilles Repairs

Kade Wagers, BSc(Med), MSc; Devon Nixon, MD; Blessing S. Ofori-Atta, MS; Angela Presson, PhD; William Tucker, MD

Keywords: Surgical Costs, Achilles Tendon Repair

Introduction/Purpose: Increasing attention is being paid to the costs associated with various orthopedic surgeries. Here, we studied the factors that influence costs associated with surgically treated acute Achilles tendon tears.

Methods: We retrospectively identified patients with surgically repaired acute Achilles tendon tears, excluding insertional ruptures or chronic tendon issues. Using the Value Driven Outcome (VDO) tool from our institution, we assessed total direct costs as well as facility costs. Briefly, the VDO tool includes an item-level database that can capture granular-level cost data – costs are then reported as relative mean data. Cost variables were adjusted to 2022 US dollars, and total direct cost was compared with patient characteristics using gamma regressions to report cost ratios with 95% confidence intervals (CIs).

Results: Our cohort consisted of 224 patients with Achilles tendon tears surgically repaired by one of four fellowship-trained orthopedic foot and ankle surgeons. There were no differences in demographics, total direct costs, or facility costs based on positioning (prone N = 156, supine N = 68). Total direct costs were 9% higher in males (N = 182) compared to females (N = 42) (p = 0.023, 95% CI: 1.01-1.17) in an unadjusted analysis. Mini-open repairs (N = 215), compared to percutaneous techniques (N = 9), had 32% less total direct costs (p < 0.001; 95% CI: 0.60-0.78). Compared to surgery at a main academic hospital (N = 15), procedures at an ambulatory care center (N = 207) had 25% lower total direct costs (p < 0.001; 95% CI: 0.67-0.83) and 44% lower reduced facility costs (p < 0.001; 95% CI: 0.51-0.61). Significance was maintained in multivariable analysis except for sex.

Conclusion: Improving cost-effective orthopedic care remains an increasingly important goal. Patient positioning for Achilles tendon repair does not appear to have meaningful effects on cost. Surgery at an ambulatory center was significantly less costly than repairs performed at an academic hospital. When clinically appropriate, considering surgery location at an ambulatory center appears to reduce surgical costs.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00019

First Tarsometatarsal Instability Corrects Itself After Triple Arthrodesis in Progressive Collapsing Foot Deformity

Clifford L. Jeng, MD; Morgan Motsay, BS; Kenneth Rowe, BA; Maggie K. Manchester, BS; Michael Cotton, MD; John T. Campbell, MD

Keywords: triple arthrodesis, progressive collapsing foot deformity, flatfoot, PCFD, first tarsometatarsal instability, 1st TMT instability

Introduction/Purpose: Triple arthrodesis is commonly used to correct severe or rigid progressive collapsing foot deformity (PCFD). In many cases of PCFD, patients have associated first tarsometatarsal instability demonstrated by plantar gapping or dorsal subluxation on the lateral weight-bearing radiographs. During flatfoot reconstruction this is usually addressed with a first tarsometatarsal fusion to realign the joint and to restore the medial column height. However in the setting of triple arthrodesis it has not been well established if it is necessary to add a first tarsometatarsal fusion to the procedure in order to adequately correct the overall deformity. This study retrospectively examined pre- and post-operative radiographs of patients that had first tarsometatarsal instability as a component of their PCFD and who were managed by triple arthrodesis alone.

Methods: All triple arthrodesis cases were searched for a single surgeon between 2013 and 2021. Inclusion criteria were patients who had a diagnosis of PCFD and had an isolated triple arthrodesis without first tarsometatarsal joint fusion. Pre-operative radiographs were then examined for the presence of first tarsometatarsal joint instability on the lateral weight-bearing view only. This was demonstrated by either plantar gapping or first metatarsal dorsal subluxation at the tarsometatarsal joint. Those patients who were a minimum of 21 months post-op were called to obtain current radiographs. Measurement of the sagittal first metatarsal-medial cuneiform angle as well as the first metatarsal lift as described by King and Toolan (FAI 2004) was performed.

Results: Twenty patients satisfied the inclusion criteria and were included in the study. Of these patients, five had no correction of their first tarsometatarsal joint instability postoperatively and were considered failures. The remaining fifteen patients demonstrated early correction of their first tarsometatarsal joint instability and were called back for longer term follow-up radiographs. Average follow-up was 4.8 years (range 1.8-9.4 years). The sagittal first metatarsal-medial cuneiform angle (plantar gapping) improved significantly from 3.8 degrees to 1.0 degrees (p = 0.00002). The first metatarsal lift (dorsal subluxation) corrected from 4.0 mm to 1.5 mm (p = 0.000001). Only one patient showed radiographic evidence of arthritis in the first tarsometatarsal joint at final follow-up.

Conclusion: First tarsometatarsal joint fusion to correct medial column instability is well established in flatfoot reconstruction cases. However less is known about whether this is required when performing a triple arthrodesis for PCFD. In this study, 75% of patients had their first tarsometatarsal joint instability correct itself after isolated triple arthrodesis and maintained this correction at 4.8 year follow-up. In many cases of PCFD with medial column instability, triple arthrodesis alone may be adequate to restore overall alignment thereby avoiding the additional operative time and risk for complication associated with a first tarsometatarsal joint fusion.

First tarsometatarsal joint instability correction following isolated triple arthrodesis.

Pre-operative radiographs demonstrate plantar gapping and dorsal subluxation at the first tarsometatarsal joint consistent with medial column instability. At 2.8 year post-operative follow up after isolated triple arthrodesis, radiographs show maintained correction of the instability.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00020

Fusion Rates in Tibiotalocalcaneal Arthrodesis with Tantalum Coated Metal Cup Augmentation

Erik Freeland, DO; Aine Gallahue, BS; Adel Mahjoub, MD; Pietro M. Gentile, BS; Nicholas D'Antonio, MD; Vineeth Romiyo, BS

Keywords: TTC, Ankle arthrodesis, Ankle fusion, Subtalar fusion, tibiotalocalcaneal arthrodesis, tantalum, tantalum coated metal spacer, intramedullary nail

Introduction/Purpose: Tantalum coated metal spacers (TCMS) have recently been utilized to fill and provide structure to large bony defects in the hindfoot. Tantalum is an appealing material due to its biocompatibility, lack of immune response generation, and structural integrity. Compared to custom printed spacers and bulk allografts, TCMS are readily available off-the-shelf implants with significantly less cost. There is currently a paucity of literature assessing the use and outcomes of TCMS in foot and ankle surgery, specifically in tibiotalocalcaneal (TTC) arthrodesis. This study serves to assess clinical outcomes and fusion rates of patients who underwent TTC arthrodesis utilizing intramedullary nailing with TCMS augmentation for large bony defects.

Methods: We retrospectively identified all patients > 18 years of age who underwent TTC arthrodesis with TCMS augmentation at our tertiary care center between 2015 and 2021. We also identified all patients who underwent TTC arthrodesis without augmentation within that time frame. The computed tomography (CT) scans at the six-month postoperative point were reviewed by one board-certified orthopaedic foot and ankle surgeon to determine fusion status, which was defined as having at least 50% fusion mass. Patient-reported outcomes measures (PROMs) including the modified foot function index (FFI) and PROMIS Global Mental Health Score were collected for patients in both groups. Patient demographics, clinical outcomes, and PROMs were compared between groups. A multivariate logistic regression model measured the effect of TCMS augmentation on the likelihood of achieving fusion.

Results: Of the 65 patients included, 21 patients (32.3%) underwent TTC with TCMS augmentation. There were no significant differences in demographics between the two groups. Patients in the TCMS group had significantly higher modified FFI (91.1 + 47.6 vs 26.3 + 48.8, p < 0.001) and PROMIS Global Mental Health (12.2 + 4.82 vs. 5.59 + 6.76, p < 0.001) scores in the postoperative period. Overall, the fusion rate was higher for the TCMS group, however the difference was not significant between groups (90.5% vs. 80.5%, p = 0.472). Multivariate logistic regression identified that TCMS augmentation was a nonsignificant predictor of increased odds of fusion at the six-month postoperative point (OR = 2.87, p = 0.232).

Conclusion: This study is the largest to date to present 6-month postoperative CT scans demonstrating successful TTC fusion with TCMS augmentation, contributing to our understanding of its utility. Given the severity of disease and bone loss in the TCMS group, it is not surprising that post-operative patient reported outcome scores differed significantly compared to the control group. TCMS augmentation can be utilized as cost effective spacers to fill large defects in TTC arthrodesis with successful union rates. Further studies are needed to evaluate the efficacy of TCMS augmented fusions as a viable substitute to custom printed cages.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00021

Gender Representation Among Foot & Ankle Conference Presenters and Research Authors: A 10-Year Analysis (2012-2022)

Marguerite Anne Mullen, BA; Emmanuel Budis, BS; Arianna Gianakos, DO; Soheil Ashkani Esfahani, MD; Christopher W. DiGiovanni, MD; Daniel Guss, MD, MBA

Keywords: Gender diversity, national meetings, research publications

Introduction/Purpose: Today women are over 50% of medical school matriculants but remain underrepresented in orthopaedic surgery (~15% of residents and <6% of practicing surgeons). Moreover, despite different and sometimes controversial reports, the rate of female society memberships and national and international meeting speakers as well as their contribution to leadership positions including moderating sessions, podiums, and symposiums are believed to be low. The objective of this study was to assess whether there is a gap in female representation among invited speakers at American Orthopaedic Foot & Ankle Society (AOFAS) national meetings relative to research productivity as reflected by article authorship in Foot & Ankle International journal (FAI).

Methods: Programs for AOFAS specialty days and annual meetings and FAI articles from January 2012 to December 2022 were obtained. Industry-hosted programs were excluded. Gender was identified through personal acquaintance or online search on the biographies of the authors. Presentations and articles were categorized as “technical” or “non-technical”, where technical was defined as relating to basic science or the clinical practice of orthopaedics. Comparisons were done using the Chi-Square Test (significance level = p < 0.05).

Results: 1,020 AOFAS presentations and 2,230 FAI articles were analyzed. Gender was unavailable for 0.19% of AOFAS speakers, 4.48% of FAI first authors and 4.13% of FAI senior authors. 11.08% of AOFAS invited national meeting speakers, 15.18% of FAI first authors and 7.40% of FAI senior authors were female. Overall, the proportion of female speakers was significantly lower than female first authors (p = 0.0036), and significantly higher than female senior authors (p < 0.001). In 2018 and 2019, women were more likely to have given “non-technical” AOFAS presentations. There was no significant difference in other years or among FAI articles. The average annual change was +2.00% female AOFAS presenters, +0.31% FAI female first authors and −0.37% FAI female senior authors per year.

Conclusion: Women represented 15.16% of first authors in FAI between 2012 and 2022 but 11.08% of invited speakers at AOFAS meetings. Meanwhile, the percentage of female AOFAS membership in the organization as a whole increased from 7.5% to 13%. Thus, despite historically low rates of representation, female Foot & Ankle surgeons were proportionally represented in 2021 and 2022 among invited national conference presentations and research compared to female society membership and female research publications in FAI. There is still room to increase representation of deserving historically under-represented groups, however the increase in female AOFAS presenters demonstrates a positive trend.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00022

Impact of Surgeon Type on Total Ankle Arthroplasty Readmission, Complication, and Infection Rates

Devon Nixon, MD; Hyunkyu Ko, PhD; Brook Martin, PhD

Keywords: surgeon type, total ankle arthroplasty

Introduction/Purpose: Total ankle arthroplasty (TAA) remains an attractive surgical option to address end-stage ankle pathology in appropriately selected patients. When successful, TAA can yield high patient satisfaction and marked improvements in patient- reported outcomes. However, surgical complications can lead to significant clinical impairment. TAA can be performed by both orthopedic surgeons and non-orthopedic surgeons – however, no prior study has compared TAA outcomes based on surgeon type.

Methods: Utilizing Medicare claims from 2016 to 2019, we retrospectively identified patients ≥65 years of age who underwent TAA based on CPT coding. Patients on Medicare HMO, under age 65, and dual-eligible patients were excluded. Within this dataset, provider type was identified, allowing for comparisons between orthopedic and non-orthopedic surgeons. We compared groups based on readmission, all-complication, and infection rates within 1-year of TAA using logistic regressions controlling for age, sex, race, and comorbidity. To help mitigate bias, we also performed a propensity matched model with the same variables. Data were reported as percentage point (PPT) differences (95% CI) between groups, with a positive number indicating higher rate of complications among patients treated by non-orthopedic surgeons.

Results: During our timeframe, 8,244 Medicare patients underwent TAA – 6,928 performed by orthopedic surgeons and 1,316 performed by non-orthopedic surgeons. There were no differences between groups based on age, sex, or race. Readmission rates were similar between groups (p = 0.058). TAA performed by non-orthopedic surgeons had higher all-complication rates (43.4% vs. 36.7%, p < 0.001) and infection rates (8.9% vs. 4.7%, p < 0.001) compared to non-orthopedic surgeons. These differences in all- complication risk in non-orthopedic surgeons were further seen in logistic regression analyses (5.8 ppt (95% CI: 2.3, 9.4), p < 0.001) and propensity matched analyses (5.6 ppt (95% CI: 2.1, 9.2), p < 0.001). Group-differences were also revealed in infection risk through logistic regression analyses (3.9 ppt (95% CI: 2.0, 5.9), p < 0.001) and propensity matched analyses (3.8 ppt (95% CI: 1.8, 5.8), p < 0.001).

Conclusion: TAA performed by non-orthopedic surgeons had greater all-complication and infection rates as compared to TAA done by orthopedic surgeons.

Analyses of complications between orthopedic surgeons and non-orthopedic surgeons performing total ankle arthroplasty.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00023

Improved Survival Rates with Fixed Bearing Total Ankle Arthroplasty

Elizabeth K. Nadeau, MD; Trevor D. Ottofaro, MD; Joshua L. Morningstar, BS; Christopher E. Gross, MD; Daniel Scott, MD, MBA

Keywords: Total Ankle Arthroplasty, Fixed Bearing, Mobile Bearing, Outcomes

Introduction/Purpose: With increasing total ankle arthroplasty (TAA) being performed and a plethora of new survivorship data available, an updated literature review is needed to better understand the impact of different types of implants on the outcomes of TAA. The purpose of this study is to compare the outcomes of fixed vs mobile bearing TAAs in the literature.

Methods: A comprehensive search of MEDLINE for all articles published between 2004 and 2023 was conducted with a minimum two-year mean follow-up. Two reviewers evaluated each study to determine whether it was eligible for inclusion and abstracted the data of interest. Meta-analytic pooling of group results across studies was performed, examining implant survival and component failure. Seventy-three implant groups met inclusion criteria (only 3rd and 4th generation implants), composed of STAR (20), Salto (mobile bearing) (10), Salto Talaris (11), Hintegra (8), Zimmer (6), INBONE II (6), INBONE I (4), Infinity (4), Cadence (4). 41 groups (56.2%) were implanted with mobile bearing devices, and 32 (43.8%) with fixed bearing implants. In total, 6498 subjects were included, with a mean age of 61.77 years and a mean BMI of 28.5 kg/m². At a mean follow-up of 62.2 months, the overall reoperation rate was 21.13% and the metal component revision rate was 10.16%.

Results: The mean follow-up of mobile bearing TAA studies (N = 41) was 77.8 (range 24-188.4) months, and that of fixed bearing studies (N = 32) was 45.3 (range 24-85.2) months. Multivariate analysis of bearing type, controlling for follow-up duration, found fixed bearing implants had statistically significantly higher metal component survival rates (fixed = 96.1%, mobile = 87.9%, p = .001); however, there were no statistically significant differences in rates of reoperation (fixed = 17.0%, mobile = 24.8%, p = .768). When examining specifically tibial and talar component failure rates, there was no statistically significant difference between bearing type (fixed tibial = 1.46%, mobile tibial = 2.95%, p = .472) (fixed talar = 2.19%, mobile talar = 2.79%, p = .966). Overall implant survival rates at one, two, five, and ten years were 96.4%, 96.0%, 92.7%, and 79.4%, respectively, and did not differ by bearing type (Table 1).

Conclusion: Implant survival was statistically significantly better for 3rd and 4th generation fixed bearing TAAs as compared to mobile bearing TAAs, controlling for length of follow-up. There was no statistically significant difference in total reoperation rate. This suggests that fixed bearing implants may offer improved implant survival compared to mobile bearing implants, though further research is needed to confirm these findings.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00024

Is Fibular Fixation Necessary with Increasing Proximity in Ankle Fractures: A Survey of OTA and AOFAS Surgeons

Zachary P. Herzwurm, MD; Evan Loewy, MD; Spencer Albertson, MD

Keywords: Fibula, fixation, proximity, OTA, AOFAS

Introduction/Purpose: Ankle fractures are one of the most common fractures encountered in orthopedics. The Maisonneuve fracture pattern is described as a pronation, external rotation injury involving the medial ankle structures, the syndesmosis, and the proximal third of the fibula. However, the actual distance from the proximal fibula has not been defined in what distinguishes a Maisonneuve fracture. With Weber C fractures, most surgeons tend to provide fixation to the fibula and reassess the syndesmosis afterwards. When dealing with the proximal fibula “Maisonneuve” fracture pattern, most surgeons would tend to ignore the fibula fracture and focus on syndesmotic reduction.

Orthopaedic Trauma Association and American Orthopaedic Foot & Ankle Society provided their opinion via survey in treating increasing proximity of fibula fractures associated with unstable ankle fracture patterns.

Methods: A survey was provided to eight OTA and AOFAS orthopedic surgeons. A powerpoint was provided to the surgeons that contained non-weightbearing injury films of eighteen patients. A questionnaire was provided giving two answer choices, address the fibular or syndesmosis primarily.

The eighteen ankle fractures were selected based on increasing proximity of the fibula fracture, which ranged from 4.5 cm to 32.3 cm. The ankle fractures were grouped into four categories to include the Maisonneuve variant based on distance. These fracture radiographs were randomized in order to not influence the surgeon’s opinion during the study.

The four groups were as follows:

1. 4.5 cm to 7.4 cm to include six ankle fracture radiographs

2. 8 cm to 10.4 cm to include four ankle fracture radiographs

3. 14.6 cm to 23.3 cm to include five ankle fracture radiographs

4. 30.7 cm to 32.3 cm to include three Maisonneuve variant ankle fracture radiographs

Results: Regarding section 1, the majority of surgeons responded with open reduction, internal fixation of the fibula as their initial reduction.

Section 2, the responses remained consistent with a majority of surgeons choosing to address fibular fixation followed by syndesmotic evaluation. The total number of responses in this section scored 43 answer A selections to 5 answer B selections.

Section 3 (14.6-23.3 cm) provided the most variability in the responses provided. With 60 possible answer choices, the polled surgeons responded with answer choice A seventeen times and answer choice B 43 times.

Section 4 (30.7-32.2 cm) or the Maisonneuve produced a steady response of answer choice B. Syndesmotic reduction was performed 34 times compared to only two fibular fixation choices – or answer choice A.

Conclusion: The purpose of this study was to evaluate expert opinion on differing treatment as the proximity of the fibular fracture increased in connection with an unstable ankle fracture pattern. General consensus under 10,4 cm was to address fibular fixation. However, once the fibular fracture exceeded 14 cm, significant variability was noted. These results prove that further biomechanical studies are needed to determine the effect fibular stability in increasing proximity has on the syndesmosis.

Chart 1 shows answer selections across the four categories. Chart 2 shows answer selections across the highest variability group 3.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00025

Is There Still a Learning Curve for Primary TAA After Completing a High Volume Ankle Replacement Fellowship? A Multicentered Study

Margaret Higgins, MD; Elizabeth A. Cody, MD; Grace DiGiovanni, BA; Jonathan McKeeman, MD; Samantha N. Weiss, MD; James R. Lachman, MD

Keywords: ankle, arthroplasty, outcomes, learning curve

Introduction/Purpose: The learning curve in Total ankle arthroplasty (TAA) has long been reported. Surgeon experience of five to twenty-five ankle replacements have been show to decrease various perioperative and long term complications in this complex surgery. Fellowship programs with high-volume ankle arthroplasty experiences have been suggested to mitigate this learning curve and provide benefit to early career surgeons with TAA outcomes. The purpose of this study was to evaluate the learning curve for TAA in two high-volume surgeons practices through the first three years of practice. Both surgeons completed fellowships and participated in more than 100 ankle replacements each. We hypothesized that experience during fellowship will help minimize complications and negate any learning curve previously established in the literature.

Methods: Prospectively collected data was retrospectively reviewed on all patients who underwent primary TAA surgery during the first three years of clinical practice after fellowship in this IRB approved, multi-centered study. Patient demographics and clinical data, radiographic outcomes, and patient reported outcomes were collected on all patients. Patients undergoing revision TAA (as a first surgery), patients without a minimum of 2 years follow-up, and patients undergoing arthrodesis conversion to TAA were all excluded. The data was analyzed using Chi Squared test and the Moving Average Method where appropriate. All statistical analysis was performed by someone with an expertise in biostatistics.

Results: Eighty-seven patients (67.8% male, avg. age 64) met inclusion criteria for the study. Average tourniquet time (111.9 min) and fluoroscopy time (106.3 secs) decreased as surgeon experience increased, with the trend stabilizing after patient 20.

Complication rate (wound complication, infection, return to OR, intraoperative fracture, etc.) was similar throughout the study period. No differences were seen in component positioning (postop AP TT angle, Postop Lateral TT angle), PROMIS Pain interference, PROMIS Depression, or PROMIS Physical function with regards to time during the study. Statistically significant differences (improvements) were seen in in the following postoperative measurements when compared to preoperative values: AP TT angle, Lateral TT angle, and PROMIS Pain Interference/Depression/Physical function.

Conclusion: Learning curve as it relates to intraoperative fluoroscopy time and intraoperative tourniquet time remained even after completing a high volume TAA fellowship but clinical and PROs did not show this same trend. Radiographic measurements, complications (both intraop and postop), and patient reported outcomes did not show a time sensitive change after fellowship. Though some variables did show the maintenance of a learning curve, this multi-centered study suggests that completion of a high volume TAA fellowship can mitigate some variables in the learning curve.

Study Data Summary.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00026

Lessons from Revision Total Ankle Replacement: Tibias Fail Early, and Taluses Fail Late (And Fail Again)

Jensen Henry, MD; Emily Teehan, MS; Scott J. Ellis, MD; Jonathan Deland, MD; Constantine Demetracopoulos, MD

Keywords: total ankle replacement, total ankle arthroplasty, revision ankle replacement revision ankle arthroplasty, aseptic loosening

Introduction/Purpose: With the last decade’s surge in total ankle replacement (TAR), there is an anticipated commensurate increase in the number of revisions that orthopaedic foot and ankle surgeons will encounter. The salvage and implant options to deal with a failed primary TAR are expanding. However, the literature on survivorship and outcomes after revision TAR in the modern era is relatively limited. What’s more, little is known about the risk factors for further revision or failure of revision TAR. This study aimed to describe the timing to and survivorship after revision TAR. We hypothesized that tibial-sided failures would occur earlier after the index surgery, and secondary revisions after failure of revision TAR would occur more due to talar-sided failures than tibial-sided failures.

Methods: This is a single-institution retrospective cohort study of TAR patients (2012-2022) with minimum 2-year follow-up. Revision TARs (defined as exchange of tibial and/or talar components) with any implant (Cadence, Inbone, Invision, Infinity, Salto, STAR, Vantage, Zimmer; or custom total talus replacement [TTR]) were included. Five surgeons contributed patients.

Demographics, primary and revision surgical data, and postoperative complications were recorded. Etiology of failure necessitating revision (tibial failure, talus failure, combined failure) and ultimate outcomes after revision (revision TAR survived, additional revisions, conversion to fusion, below-knee-amputation [BKA]) were recorded. Revisions for periprosthetic joint infection (PJI) and conversions to fusion were excluded. There were 59 ankles that underwent revision for any cause. Excluding 9 2-stage revisions for PJI and 3 conversions to ankle or tibiotalocalcaneal fusion, there were 47 ankles that underwent revision TAR that were included for analysis. Chi-square and ANOVA tests were used to compare risk factors and timing for failure.

Results: There were 47 revision TARs, with mean age 60.6 (range: 31-77) years, mean BMI 29.5 kg/m², 19 (40.4%) females, and mean 3.5 years follow-up. Revisions for tibial failure (n = 22) occurred significantly earlier (1.3 ± 0.5 years) than those for talus failure (n = 19, 2.3 ± 1.7 years) or combined tibial/talus failure (n = 6, 2.9 ± 3.3 years) (P = 0.048). Revisions for tibial-only failure had significantly better survivorship (95.5%) than revisions for talus or combined tibia/talus failures: 26% of talus failures and 33% of combined tibia/talus failures underwent at least one more revision (P = 0.033). Of the 7 failures after revision talus, 2 ultimately underwent BKA, 2 were converted to TTR, 2 were revised to modular stemmed talus implants, and 1 was treated with explant and cement spacer for PJI.

Conclusion: This study demonstrates that TAR tibial failures occur earlier than talus failures or combined tibial/talus failures. When patients with isolated tibial failure undergo revision of both tibial and talar components, they usually do well with good survivorship post-revision. However, revisions for talar failures and combined tibial/talar failures occur later but are more devastating: nearly 1/3 go on to a second revision. This is important given the consequences of talar implant subsidence, bone necrosis, loss of bone stock, and limited salvage options. As TAR utilization expands, it is imperative to develop implants and surgical strategies to maximize success for revision surgery.

Flowchart of failures after revision TAR.

PJI = periprosthetic joint infection. TTC = tibiotalocalcaneal. BKA = below-knee amputation. Tibial implant geometry included: Low-pro = low- profile tibial implant. Stem = stemmed tibial implant. Keel = keeled tibial implant. Talus implant geometry included: chamfer/round and flat-cut talus.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00027

Micro CT Analysis and 3D Modelling of Fluid Permeability of Talar Subchondral Bone After Marrow Stimulation Techniques Demonstrates Superiority of Nanofracture Over Microfracture and Fine Wire Drilling

James P. Warren, PhD, MChem, BSc; Ahranee Canden, MSc, BSc; Claire L. Brockett, PhD; Mark A. Farndon, FRCS (Tr&Orth)

Keywords: Nanofracture, subchondral bone, permeability, bone marrow stimulation

Introduction/Purpose: The aim was to compare different bone marrow stimulation techniques and consequent fluid permeability of subchondral bone by assessing flow of radiopaque contrast agent using μCT image analysis and 3D modelling.

Methods: Donated human tali specimens (n = 12) were prepared by creating separate matched 10 mm diameter chondral defects in each. Each defect underwent one of three surgical techniques: fine wire drilling, nanofracture or microfracture, addition of radiopaque contrast agent and imaged using a clinical μCT scanner. Using Slicer 3D software each μCT scan was segmented for bone and contrast agent regions in each surgical site of each sample. Each site was resolved into a cylinder and the ratio of segmented pixels of contrast agent against bone calculated.

Results: μCT analysis indicated that 8/12 nanofracture regions demonstrated enhanced flow of contrast to at least the depth of the fracture site, with some additional lateral flow also observed. 8/12 microfracture regions demonstrated flow of contrast agent localised to the fracture site and preferential flow laterally. Only 1/12 samples with fine wire drilling demonstrated any fluid flow. In 11/12 samples that showed no permeation of contrast agent, a residual layer of contrast agent on the chondral surface was seen. Segmentation of each sample site showed a significant increase (n = 12, p < 0.05) in fluid flow of the contrast agent in the nanofracture sites (11%) compared to microfracture (5%) and fine wire drilling (2%).

Conclusion: Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling. Microfracture allowed some fluid flow, but only confined to the immediate area around the fracture site, while fine wire drilling allows very little fluid flow at all. This study suggests that nanofracture should perhaps be the preferred mode of subchondral bone preparation for osteochondral lesions of the talus.

Quantitative measurement of contrast permeability into talar subchondral bone by technique.

Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00028

Minimally Invasive Dorsal Cheilectomy and Hallux Metatarsal Phalangeal Joint Arthroscopy for the Treatment of Hallux Rigidus

Chase Gauthier, MD; Thomas L. Lewis, MB ChB, MRCS, BSc, FRCS(Tr&Orth); John O'Keefe, MD; Yianni Bakaes, BSc(Med); Vikram Vignaraja, MBBS; J. Benjamin Jackson, MD, MBA; Jonathan Kaplan, MD; Robbie Ray, MD, MBChB, FRCS(Ed), ChM, FEBOT; Tyler Gonzalez, MD, MBA

Keywords: Arthroscopy, Minimally invasive, hallux rigidus, dorsal cheilectomy, hallux

Introduction/Purpose: Minimally invasive dorsal cheilectomy (MIDC) has become a popular alternative to an open approach for treating Hallux Rigidus, although the current literature is divided on its effectiveness regarding complications and patient reported outcomes. To combat a portion of the complications related to the MIDC approach, a first metatarsophalangeal (MTP) joint arthroscopy can often be added to the procedure. The combined procedure has been demonstrated to be effective at improving patient reported outcomes without increasing the complication rate relative to an open procedure. This study looks to examine the effectiveness of the MIDC with first MTP arthroscopy procedure in patients with hallux rigidus with minimum 1 year follow up.

Methods: This was a multicenter retrospective review was conducted for adult patients treated with MIDC and first MTP arthroscopy between 3/1/2020 and 8/1/2022, with at least one year of postoperative follow-up data. Patient charts were reviewed for demographic information, operative time, pre and postoperative first MTP range of motion (ROM), visual analog scale (VAS), Manchester-Oxford Foot Questionnaire (MOXFQ), and EQ5DLD scores. Continuous data was expressed as a mean and standard deviation, categorical data was expressed as a percentage. Wilcoxon Rank Sum test was used to compare continuous variables. All P < 0.05 was considered significant.

Results: A total of 31 patients were included in the study with an average follow-up time of 16.5 months (range: 12-26.2). There was 1 (3.2%) complication of an underservice EHL tendon tear, 2 (6.5%) patients were converted to a MTP fusion, and 1 (3.2%) patient underwent revision cheilectomy and capsular release for MTP joint contracture. There was a significant improvement in patient’s ROM in dorsiflexion (50 vs 89.6 degrees, P = 0.002), but not in plantarflexion (11.3 vs 18.6 degrees, P = 0.07). There was a significant improvement in patient’s postoperative VAS pain scores (6.4 vs 2.1, P < 0.001), MOXFQ pain scores (58.1 vs 30.7, P = 0.001), MOXFQ Walking/Standing scores (56.6 vs 20.6, P = 0.001), MOXFQ Social Interaction scores (47.3 vs 19.36, P = 0.002), and MOXFQ Index scores (54.7 vs 22.4, P < 0.001).

Conclusion: We found that MIDC with first MTP arthroscopy was effective at improving patient reported outcomes, specifically patient’s pain scores, at one year with low complication and revision rates. These results demonstrate MIDC and first MTP arthroscopy’s is an effective treatment for early-stage hallux rigidus and may be considered as an alternative to an open approach.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00029

Outcomes Following Extracellular Matrix Cartilage Allograft for the Management of Osteochondral Lesions of the Talus: A Systematic Review

James J. Butler, MBBCh; Hayden Hartman, BS; Luilly Vargas, MD; Ravneet Dhillon, MD; Grace W. Randall, BS; Taylor Wingo, MD; John G. Kennedy, MD, FRCS(Orth)

Keywords: Extracellular matrix cartilage allograft, biocartilage, osteochondral lesion of the talus

Introduction/Purpose: The purpose of this systematic review was to evaluate the clinical and radiographic outcomes in patients who received extracellular matrix cartilage allograft (EMCA) during surgical intervention for osteochondral lesions of the talus (OLT).

Methods: During January 2023, the PubMed, Embase and Cochrane library databases were systematically reviewed to identify clinical studies evaluating outcomes in patients who received EMCA during surgical intervention for osteochondral lesions of the talus. Data regarding lesion characteristics, surgical characteristics, subjective clinical outcomes, radiographic outcomes, complication rates, failure rates and secondary surgical procedure rates were extracted and analysed. In total, 5 clinical studies were included in this review.

Results: In total, 162 patients received EMCA during surgical intervention for OLT at a weighted mean follow-up of 23.8 ± 4.2 months. The weighted mean lesion area was 77.9 ± 42.6 mm². Overall, 111 (68.5%) of OLTs were located medially, 45 (27.8%) of OLTs were located laterally and 6 (3.7%) OLTs were located centrally. Four studies performed arthroscopic debridement and bone marrow stimulation with ECMA, 3 studies utilized concentrated bone marrow aspirate and 1 study performed autologous osteochondral transplantation. Improvements were noted in AOFAS, FAOS and VAS scores following surgical intervention. The weighted mean post-operative MOCART score was 76.3 ± 2.9. In total, 17 (10.5%) complications were reported across the 5 studies. Twelve failures (7.4%) were recorded, all of which required further surgical intervention.

Conclusion: This systematic review demonstrated improvements in subjective clinical outcomes and radiological outcomes at short-term follow-up following surgical intervention for OLTs augmented with ECMA. A low failure rate and moderate complication rate was noted. However, there was marked heterogeneity between the included studies with regards to surgical technique utilized, lesion size and patient cohort size. Further research is warranted to determine the optimal role of ECMA in the management of OLT.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00030

Outcomes of Percutaneous Zadek Osteotomy for Insertional Achilles Tendinopathy with Two-Year Minimum Follow-Up: A Retrospective Study

SarahRose Hall, BA; Oliver Schipper, MD; Jonathan Kaplan, MD; Anne Holly Johnson, MD; Tyler Gonzalez, MD, MBA; Ettore Vulcano, MD

Keywords: Zadek osteotomy, insertional Achilles tendinopathy, Haglund deformity, MIS, percutaneous, minimally invasive, outcomes

Introduction/Purpose: Insertional Achilles tendinopathy (IAT) is a common source of posterior heel pain treated by orthopaedic foot and ankle surgeons. Traditional surgical treatment consists of an open Achilles tendon debridement with re-attachment as well as excision of the posterosuperior calcaneal prominence with or without a gastrocnemius recession. However, frequent complications include wound healing issue, scar pain, weakness and sural nerve injury. Accordingly, the percutaneous ZO is gaining popularity in the field as an alternative to an open midline splitting approach. Limited literature exists describing outcomes of the percutaneous ZO using a larger sample size. The purpose of this study was to analyze patient reported outcomes and complications after percutaneous ZO with a minimum two-year follow-up period.

Methods: One hundred and eight cases treated with percutaneous ZO were retrospectively reviewed across October 2017 to July 2021 and outcomes data was available for 104 cases with a minimum two-year follow-up. Patient sex, age, and pertinent comorbidities were recorded. Postoperative complications and patient satisfaction following intervention were evaluated. Foot Function Index score (FFI) was utilized to measure patients’ pain and functional outcomes. Visual Analyzing Scale score (VAS) was also utilized to evaluate pain. These measurements were taken at preoperative and final follow-up. Statistical comparisons were performed using two-tailed, paired t-test with p < 0.05.

Results: Mean follow-up time was 41.2 ± 13.1 months (range 24-65 months). The mean FFI score improved from 56.1 ± 5.9 (range 47-88) preoperatively to 11.0 ± 5.1 (range 7-59) postoperatively (p < 0.001). Average VAS score improved in patients receiving percutaneous ZO from 7.6 ± 1.3 (range 5-10) to 0.4 ± 0.9 (range 0-7) postoperatively (p < 0.001). The overall complication rate was 3.8% (N = 4). Of 104 cases, 98.1% of patients were satisfied with their procedure (102/104).

Conclusion: The percutaneous ZO is a safe and highly effective intervention for treatment of IAT. At a minimum of two-years follow-up, this intervention is associated with minimal complications, improved functional outcomes, reduced pain, and high patient satisfaction.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00031

Prediction of Short-Term Postoperative Complications Following Open Reduction Internal Fixation of Acute Ankle Fractures

Avinesh Agarwalla, MD; Anirudh Gowd, MD; Elizabeth A. Cody, MD; Alexander Peterson, MD; Eric W. Tan, MD; Joseph Liu, MD

Keywords: Open reduction internal fixation; ankle fractures; complication rate; machine learning; neural networks; risk assessment

Introduction/Purpose: Acute ankle fractures are a common injury and represent a significant financial burden to the healthcare system. Reimbursement following ankle fractures is complicated by bundled payments within the 90-day global period which do not account for unpredictable complications. Comorbidity indices, such as the American Society of Anesthesiologists (ASA) classification, are often correlated with complications; however, the positive predictive value of these metrics have not been investigated. As insurers continue to transition towards bundled reimbursements, greater attentiveness towards providing efficient care is paramount. The purpose of this investigation is to develop a machine learning (ML) model that is predictive of complications following operative management of acute ankle fractures. This study will also compare ML algorithms to legacy indices to assess the predictive value in predicting complications.

Methods: The American College of Surgeons-National Surgical Quality Improvement Program database was queried via Current Procedural Terminology (CPT) from 2015 to 2018 for open reduction internal fixation (ORIF) cases for ankle fractures, including ORIF of the medial malleolus, posterior malleolus, lateral malleolus, bimalleolar, trimalleolar, syndesmosis. Training and validation sets were created by randomly assigning 80% and 20% of the data set. Included variables were age, body mass index (BMI), operative time, smoking status, comorbidities, diagnosis, and preoperative hematocrit and albumin. Complications included any adverse event, transfusion, surgical site infection, return to the operating room, deep vein thrombosis or pulmonary embolism, pneumonia, urinary tract infection, cerebrovascular accident, cardiac arrest, myocardial infarction. Each ML algorithm was compared with one another and to a baseline model using American Society of Anesthesiologists (ASA) classification. Model strength was evaluated by calculating the area under the curve (AUC) for receiver operating characteristic (ROC) of any adverse event.

Results: We identified a total of 28,736 ORIF cases. Mean age and BMI were 32.2 ± 18.6 years, 30.8 ± 7.6 kg/m^2, respectively. The overall incidence of any medical complication was 3.4% (n = 975) with surgical site infection (1.3%, n = 386) and return to operating room (1.3%, n = 367) being the most common. Percentage hematocrit, BMI, operative time, and age were of highest importance in outcome prediction. Logistic regression (AUC: 72%) and gradient boosting (AUC: 72%) ML algorithms outperformed ASA classification (AUC: 69%) for predicting any adverse event following ORIF of ankle fractures.

Conclusion: Legacy comorbidity indices are simple metrics that can be easily constructed from patient demographic variables and past medical history. However, the predictive power is limited as they have shown a low positive predictive value for predicting complications. Machine learning algorithms can calculate patient-specific risk for postoperative complications which may adjust perioperative care and site of surgery. These models have the capability to optimize utilization of healthcare resources and minimize excessive expenditure by providing patient-specific care.

Receiver Operating Curve-Area under the Curve Analysis for Adverse Events Following ORIF of Ankle Fractures.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00032

Preoperative Degenerative Changes at the Medial Sesamoid-Metatarsal Joint Is Associated with Postoperative Patient-Reported Outcomes in Hallux Valgus

Sophie Kush, BS; Stone R. Streeter, BS; Brett D. Steineman, PhD; Scott J. Ellis, MD; Matthew S. Conti, MD

Keywords: Hallux Valgus, Osteoarthritis, PROMIS Scores

Introduction/Purpose: While hallux valgus (HV) is understood to be a triplanar deformity of the first metatarsal, less is known about the contribution of the sesamoid-metatarsal joint (SMJ) to pain and function. Osteoarthritis of the SMJ is frequently present in HV feet, with an incidence rate ranging from 32% to 81%. Following surgical correction, approximately 10% of HV patients remain dissatisfied, but factors affecting postoperative outcomes are poorly understood. The primary aim of our study was to describe the relationship between degenerative changes at the SMJ as measured on weightbearing CT (WBCT) scans and 1-year patient-reported outcome scores following a modified Lapidus procedure for correction of HV. We hypothesized that decreased joint space at the SMJ would affect postoperative patient-reported outcomes.

Methods: This study included 48 consecutive patients who underwent a modified Lapidus procedure for HV, had preoperative and at least 5-month postoperative WBCT scans, and had preoperative PROMIS scores and at least 1-year postoperative PROMIS Physical Function (PF), Pain Interference, and Pain Intensity scores. For each patient, the first metatarsal and sesamoids on pre- and postoperative WBCT scans were segmented using Disior Bonelogic software and uploaded to Geomagic Design X to perform distancing mapping. The minimum and average distances between the first metatarsal head and medial sesamoid (medial-SMJ) for each patient pre- and postoperatively were calculated. Sesamoid subluxation was measured on WBCT scans using the grading system from 0 to 3 (Yildirim et al). A simple linear regression model was used to investigate the correlations between minimum preoperative and postoperative medial-SMJ distances and 1-year postoperative PROMIS scores in patients with postoperative reduction of the sesamoids (grade 0).

Results: Preoperatively, the mean minimum and average medial-SMJ distances were 0.76 ± 0.37 mm and 1.54 ± 0.33 mm, respectively. Postoperatively, the mean minimum and average medial-SMJ distances were 1.08 ± 0.25 mm and 1.73 ± 0.24 mm, respectively. Thirty-five of 48 patients had a complete reduction of the sesamoids. Lower preoperative minimum distances at the medial-SMJ were significantly correlated with worse 1-year PROMIS PF scores (r = 0.405, P = 0.016) (Figure 1). Similarly, lower preoperative minimum distances at the medial-SMJ were significantly correlated with worse 1-year PROMIS Pain Intensity scores (r = −0.350, P = 0.039) but did not reach significance for 1-year PROMIS Pain Interference scores (r = −0.286, P = 0.095). The postoperative minimum medial-SMJ distance was not correlated with 1-year PROMIS PF, Pain Interference, and Pain Intensity scores.

Conclusion: In HV patients undergoing a modified Lapidus procedure with postoperatively reduced sesamoids, decreased joint space at the medial sesamoid-metatarsal head articulation was associated with worse 1-year postoperative function as measured by PROMIS PF scores and worse 1-year postoperative pain as measured by PROMIS Pain Intensity scores. In contrast, postoperative degenerative changes at the SMJ were not found to be associated with patient-reported outcomes. Our results suggest that pre-existing SMJ arthritic changes may affect postoperative outcomes and may be a source of dissatisfaction following HV surgery despite appropriate correction of the deformity.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00033

Preservation of 1st Metatarsal Head Blood Supply with Minimally Invasive Chevron vs Transverse Osteotomy

Derrick E. Wendler, MD; Gary W. Stewart, MD; Erroll Bailey, MD

Keywords: Minimally Invasive Surgery, Hallux Valgus, Vascular Injury, Bunion

Introduction/Purpose: The purpose of this study is to evaluate damage to the first dorsal metatarsal artery, first plantar metatarsal artery, and the superficial branch of the medial plantar artery after different types of minimally invasive osteotomies are performed on cadaveric specimen.

Methods: 10 cadaveric feet were injected with methylene blue dye to aid in visualizing the vessels. We then randomly divided the samples into 2 groups of 5. Group A received a chevron osteotomy and group B received a transverse cut osteotomy. We then dissected the specimen and studied the damage to the first metatarsal head vascular plexus and recorded the distance of our cuts from the center of the metatarsal head.

We plan to take 6 additional cadaveric feet and inject them with silicone based dye prior to performing osteotomies on these additional specimen; 3 chevron and 3 transverse. We will then dissect these specimen in a similar manner to evaluate for vascular plexus damage. We believe this will improve our scientific process.

Results: After careful dissection we did not find major damage to the vascular plexus in any of the specimen. Please note: we will be continuing this project with additional cadaveric specimen and improved dye techniques.

Conclusion: We did not find a difference in vascular risk between MIS transverse and chevron osteotomy techniques. If the primary safe zone guidelines are respected and care is taken to avoid common pitfalls, surgeons can confidently choose between the two constructs without accommodating further AVN risk.

Gross Dissection Displaying First Dorsal Metatarsal Artery.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00034

Progressive First Metatarsal Shortening Is Observed Following Allograft Interpositional Arthroplasty in Hallux Rigidus

Aly Fayed, MD; Kepler A.M. Carvalho, MD; Matthew T. Jones, BS; Eli Schmidt, BS; Antoine Acker, MD; Emily Joan Luo, BS; Grayson M. Talaski, BA; Albert O. Anastasio, MD; Nacime Salomao Barbachan Mansur, MD, PhD; Cesar de Cesar Netto, MD, PhD

Keywords: Hallux rigidus, interpositional arthroplasty, acellular dermal allograft, transfer metatarsalgia.

Introduction/Purpose: Interpositional arthroplasty (IPA) is a motion-preserving surgery in patients with advanced hallux rigidus. Literature displays several complications after the procedure including transfer metatarsalgia, cock-updeformity and infection. In a finite element model, shortening of the first metatarsal was associated with increased plantar pressure on lateral rays during gait. Additionally, there are reports of a positive correlation between first metatarsal shortening after hallux valgus surgery and transfer metatarsalgia of the second, third and fourth metatarsophalangeal joints. The goals of this study were to report the outcomes and complications of IPA using acellular dermal allograft (IPA-ADA) as well as study the changes in the length of the proximal phalanx of the hallux (P1) and the first metatarsal (M1) following the procedure.

Methods: In this IRB-approved retrospective study, we assessed patients who underwent IPA-ADA in a single academic institute from 2019 to 2022. All patients’ demographic data, surgical details, complications, and patient-reported outcomes (PROs) were extracted. On standing conventional anteroposterior (AP) foot views, we measured the lengths of the first metatarsal (M1), the second metatarsal (M2), the proximal phalanx of the big toe (P1), and the entire length of the hallux (HX). The ratio of M1/M2 and P1/HX were calculated. The first metatarsophalangeal joint space was measured at the medial and lateral aspects of the joint on the APview. All measurements were recorded pre-operatively, at six weeks follow-up, and at the final follow-up. Descriptive statistics were performed, and comparison between groups was performed using analysis of variance (ANOVA) or Kruskal Wallis test according to data normality. The Dunn-Bonferroni test was then performed for pairwise group comparisons. A p-value < 0.05 was considered significant.

Results: Eleven patients were included, 9 being females (81.81%). Six were hallux rigidus Coughlin grade III (54.55%), and 5 were grade IV (45.45%). The average age was 59 years (SD ± 6.78), and the body mass index (BMI) was 26 (SD ± 4.79). At the final follow- up, there was significant shortening of the first ray in comparison to the pre-operative length evidenced by lower M1/M2 (82.63 SD ± 2.29 versus 75.42 SD ± 5.1; p = 0.001) and P1/HX ratio53.38 ± 2.29 versus 48.98 SD ± 7.92; p = 0.001). Although there was no significant difference between M1/M2 at 6 weeks and at the final follow-up (p = 0.716), there was a significant negative correlation between follow-up length and M1/M2 (r = −0.76, p = 0.003). Follow-up was (19.95 months; range 3-39). Complications and PROs are listed in Figure 1.

Conclusion: Interposition arthroplasty using dermal allograft for HR is associated with progressive shortening of the first ray at the level of the first metatarsal as well as the proximal phalanx. Although the study did show shortening of the first ray, the small sample size didn’t allow for a correlation between this shortening and complications such as transfer metatarsalgia and cock-up toe deformity. The potential shortening should be considered in the selection of patients, particularly in the setting of an already short first metatarsal or when simultaneous Akin/Moberg osteotomy is planned.

Interposition arthroplasty using dermal allograft for HR is associated with progressive shortening of the first ray at the level of the first metatarsal as well as the proximal phalanx. Although the study did show shortening of the first ray, the small sample size didn’t allow for a correlation between this shortening and complications such as transfer metatarsalgia and cock-up toe deformity. The potential shortening should be considered in the selection of patients, particularly in the setting of an already short first metatarsal or when simultaneous Akin/Moberg osteotomy is planned.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00035

Single-Center, Early Experience with the First 3D-Printed Surface, Fixed Bearing, Total Ankle Arthroplasty: A Minimum of 2-Year Follow-Up

Jesse F. Doty, MD; Jordan Dunson, MD; Joseph R. Duff, MD

Keywords: total ankle arthroplasty, 3-D printed design, implant survivorship

Introduction/Purpose: As the fourth generation of total ankle arthroplasty (TAA) implants evolve, treatment solutions for end- stage ankle arthritis continue to improve. Technological advancements in CT guided planning and 3-D printing offers surgeons the ability to perform TAA with patient specific instrumentation and implants. 3-D printed components are designed to act as scaffold in hopes to facilitate early in-growth, to increase implant stability, to support long-term survivorship, and ultimately to improve the quality of life our patients. We present our early experience at a single academic center with a minimum of 2-year follow up data on the first 3-D printed, fixed bearing, TAA in the United States. We hypothesize that 3-D printed technology will demonstrate improved long-term survival and increased bony in-growth on the implant-bone interface.

Methods: A retrospective review was performed on patients who underwent TAA with a minimum of 2-year clinical and radiographic data in which this 3-D printed TAA was utilized at our single academic center. Patient demographic, radiographic, and functional outcome scores were collected preoperatively, at 6 months, 1 year, and 2 years. The severity of ankle arthritis and associated deformities in patients were stratified using the COFAS classification. The primary outcomes of this study were implant survivorship, comparative analysis of preoperative and postoperative Patient Reported Outcomes Measurement Information System (PROMIS) physical function scores, VAS pain scores, radiographic development of linear radiolucency > 2 mm, cystic radiolucency > 5 mm, subsidence, and adverse events within 2 years of surgery.

Results: Thirty patients were included with a median follow-up of 26 months (range, 24-36 months). Implant survival rate was 90%. One patient was revised to a stemmed TAA secondary to tibial subsidence. One patient required a TTC fusion secondary to Charcot collapse. One patient was revised to a staged ankle fusion secondary to periprosthetic joint infection. Two patients (6.7%) experienced linear radiolucency > 2 mm with tibial subsidence in which one patient required a revision TAA (mentioned above) and another who was asymptomatic. No significant cystic radiolucency > 5 mm were identified. Five patients required re-operation from complications unrelated to the implant. VAS scores decreased significantly from 6 (IQR, 4-8) to 1 (IQR, 2-4) (P <.001; r = 0.55). PROMIS Physical scores increased significantly from 43.6 (IQR, 33-47.7) to 50.8 (44.8-57.7) (P <.001; r = 0.60).

Conclusion: The utilization of this new 3-D printed, fixed bearing TAA demonstrated a ninety percent overall implant survival rate in our small cohort of patients. Further data will be required to determine the long term efficacy of this new 3-D printed implant on patient outcomes. Our early experience and complications presented in our study demonstrate that this 3-D printed TAA implant is safe and effective in the treatment of end-stage ankle arthritis.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00036

The Effect of First Metatarsal Shortening and Sagittal Displacement on Forefoot Pressure in MIS Hallux Valgus Correction

Andres Lopez, MD; Edward T. Haupt, MD; Giselle M. Porter, BSc(Med), BSc; Yianni Bakaes, BSc(Med); Glenn Shi, MD; J. Benjamin Jackson, MD, MBA; Paisley Myers, PhD; Tyler Gonzalez, MD, MBA

Keywords: Hallux Valgus, Minimally Invasive Surgery, Metatarsal Shortening, Transfer Metatarsalgia, Plantar Displacement, Dorsal Displacement, Forefoot Pressure, Sagittal Plane Displacement

Introduction/Purpose: Minimally invasive surgical (MIS) treatment of hallux valgus (HV) deformity is increasing in popularity. A 2 mm-diameter burr is used to create a distal first metatarsal osteotomy prior to capital fragment translation and fixation. The metatarsal will shorten by the burr’s diameter (2 mm). Plantar or dorsal capital fragment displacement may also cause load transference and possibly transfer metatarsalgia. In this study, we examine the effect of MIS HV on forefoot loading mechanics with respect to metatarsal shortening and sagittal plane displacement.

Methods: Four lower-limb cadaveric specimens were studied. A pedobarography pressure-sensing mat was used to record forefoot plantar pressure in a controlled weightbearing stance position.10 Control and post-osteotomy measurements were obtained with the capital fragment fixated in 3 possible positions: 0 mm, 5 mm dorsal, and 5 mm plantar displacement. Pedobarography data yielded pressure data within measurable graphical depictions. Raw mean contact pressure measurements were taken under the first and fifth metatarsal heads to establish medial and lateral forefoot loading pressure ratios. A priori power analysis was performed based on previous peer-reviewed pedobarographic data and our study was adequately powered.

Results: 40 measurements were recorded and ratios of medial-to-lateral forefoot loading were constructed. Medial forefoot pressure change control versus 0 mm displacement, and control versus dorsal displacement was not found to be statistically significant (p = 0.525, p = 0.55 respectively). Significant medial pressure increase was identified comparing control versus plantar displacement (p = 0.006). Lateral pressure increased significantly with dorsal displacement of the osteotomy (p = 0.013).

Conclusion: MIS hallux valgus correction does not appear to cause increase in lateral forefoot pressure loading when sagittal plane displacements are controlled. Plantar displacement increases medial loading, and dorsal displacement increases lateral loading. The clinician must consider metatarsal head position post-osteotomy, as decrease in medial loading and subsequent increase in lateral loading may lead to lateral forefoot pain and transfer metatarsalgia.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00037

The Effect of Operative Time on Short-Term Total Ankle Arthroplasty Outcomes

Solangel Rodriguez-Materon, MD; Samantha Trynz, MS, BS; Dev Patel, BA; Joshua L. Morningstar, BS; Christopher E. Gross, MD; Daniel Scott, MD, MBA

Keywords: Total Ankle Arthroplasty, Operative Time, Outcomes

Introduction/Purpose: There is a paucity of literature investigating the association of operative time and postoperative outcomes following total ankle arthroplasty (TAA). Thus, this study seeks to evaluate the relationship between total operative time and postoperative outcomes following TAA.

Methods: The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database was queried from 2007 to 2020 to identify 2133 TAA patients. Demographics, medical comorbidities, concomitant procedures, hospital length of stay (LOS), and 30-day complication, readmission, and reoperation rates were compared between groups. Patients were excluded based on an operative time greater than 290 minutes to limit the influence of extreme outliers. The cohort was predominantly male (53.8%) and mean patient age was 64.10 (range 19-87) years with a mean BMI of 31.00 (range 17.14-57.78) m/kg2. The mean operative time of the cohort was 149.56 (standard deviation [SD] = 49.60) minutes.

Results: Demographic characteristics associated with increased operative time were decreased age (p 1 SD above the mean), independently predicted were readmission (OR = 2.817; 95%CI = 1.334-5.951; p = 0.007), urinary tract infection (OR = 6.410; 95%CI = 1.384-29.6866; p = 0.018), wound dehiscence (OR = 5.127; 95%CI = 1.282-20.508; p = 0.021), and bleeding requiring transfusion (OR = 18.364; 95%CI = 1.846-182.682; p = 0.013).

Conclusion: The study found longer operative time during TAA is associated with a statistically significant increase in wound dehiscence, urinary tract infection, readmission, reoperation, and increased length of stay. Therefore, surgeons should prioritize measures to reduce operative time when appropriate while optimizing implant placement, deformity correction, and implant stability in TAA.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00038

Total Ankle Arthroplasty Polyethylene Wear Varies with Implant Type and Mode of Failure

Emily Teehan, MS; Isabel Shaffrey, BS; Joseph T. Nguyen, MPH; Mark Wishman, BS; Joaquin Palma Munita, MD; Jensen Henry, MD; Constantine Demetracopoulos, MD

Keywords: Ankle arthroplasty, Polyethylene damage, Retrieval, Revision arthroplasty, Ankle arthritis

Introduction/Purpose: Polyethylene wear is a concern for failure of any joint replacement, including total ankle arthroplasty (TAA). Heterogeneity in bearing surface design among current TAA systems show no clear solution to the competing objectives of function (constraint and kinematics) and wear (contact stresses). Literature has begun to investigate polyethylene wear and damage; however, a comprehensive understanding of polyethylene wear patterns in vivo and location remains unknown. This study aims to quantify the type and severity of differing damage modes on the polyethylene insert from retrieved TAA prostheses following reoperation or revision. We hypothesized that polyethylene wear amount will be greater in TAAs that underwent revisions rather than reoperation, and that wear would vary between implants based on extent of constraint.

Methods: This is a retrospective study of TAA patients (2007-2021) who underwent revision (removal of polyethylene and tibial and/or talar components) or reoperation (removal of polyethylene only) following primary TAA with a symmetric bicondylar (SB) implant with more constraint or an asymmetric bicondylar (AB) implant with less constraint. Demographics and surgical data were recorded. Retrieved polyethylene inserts were examined microscopically to characterize wear patterns according to a standardized protocol. Polyethylenes were divided into four regions on both the articular and backside surfaces: 1) lateral anterior, 2) lateral posterior, 3) medial anterior, and 4) medial posterior. Each region was graded by two independent raters on a scale of 0 to 3 based on severity for each of the following damage modes: 1) burnishing, 2) pitting, 3) scratching, 4) third body debris, 5) abrasion, 6) surface deformation, and 7) delamination. We assessed associations between polyethylene wear pattern and severity with implant type, revision, and reoperation.

Results: 55 TAAs underwent revision (n = 28) or reoperation (n = 27). 30 (55%) ankles had primary TAA with AB implants (Salto Talaris) and 25 (45%) with SB implants (Inbone/Infinity) (Table 1). SB cohort had a shorter mean in-body duration (time from polyethylene implant to polyethylene explant) versus AB cohort (P = 0.011). SB cohort had significantly greater overall polyethylene damage severity (P = 0.007) and greater damage severity in all articular regions versus AB (P ≤ 0.035 for all). Burnishing was significantly greater in SB versus AB (P < 0.001). TAAs that underwent revision had significantly greater overall damage severity versus reoperation (P = 0.005), with significantly greater damage severity on articular medial posterior (P = 0.003), lateral anterior (P = 0.001), and lateral posterior (P = 0.004) regions. Scratching (P = 0.005), pitting (P < 0.001), and third body debris (P = 0.036) were significantly greater in revision TAAs.

Conclusion: While damage modes between SB and AB total ankle implants were similar, ankles with primary SB implants exhibited greater overall polyethylene damage severity in comparison to AB implants, despite being in-body for a shorter duration. In accordance with existing literature for total knee arthroplasty, this may suggest increased polyethylene damage severity with increased constraint. Irrespective of time in-body, failure for revision was associated with greater polyethylene damage than reoperation. This study provides the foundation for additional analyses to investigate radiographic alignment, mode of failure, and, ultimately, the association between polyethylene wear, peri-implant cysts and lucency, and TAA failure.

Foot & Ankle Orthopaedics, 9(1S)

DOI: 10.1177/2473011424S00039