Foot & Ankle International

As total ankle arthroplasty (TAA) use evolves, understanding implant longevity and survivorship expectations has become critical for patient counseling and decision making. The purpose of this study was to determine the long-term survivorship of the INBONE II TAA.

Patients enrolled in a prospective single-institution TAA registry with minimum 10-year follow-up after INBONE II TAA were retrospectively identified. Chart review captured operative data, prior and concomitant surgeries, reoperations, and revision details. Pre- and postoperative radiographs were measured to assess alignment and periprosthetic lucency or osteolysis. Survivorship was determined by incidence and timing of metal component revision (MCR). Data were stratified by those who failed (MCR) and those who did not. Of 180 TAAs, 74 ankles (71 patients) met inclusion criteria.

Mean age at surgery was 60.9 years (38.7-78.4), with median 10.4 years of follow-up (IQR 9.8, 11.1). Survivorship at minimum 10 years was 93.2% (95% CI: 87.1%-99.3%). Overall reoperation rate was 16.9%. Peri-implant lucency was found in 28.4% of tibias (21) and 13.5% of taluses (10); cysts were noted in 21.6% of tibias and 12.2% of taluses. The MCR rate was 6.8% (3 talus, 2 both components), secondary to failure of ingrowth (2), osteolysis/polyethylene wear (2), and infection (1). Patients who underwent MCR exhibited numerically greater preoperative varus talar tilt (9.6 vs 2.9 degrees) and varus tibiocalcaneal angle (−5.6 vs 9.1 degrees), although these differences were not statistically significant (P = .25 and .07, respectively). They also showed larger changes from pre- to postoperative alignment in tibiotalar and distal tibial angles compared with nonfailures (−16.2 vs 0.2 degrees, P = .11; −7.3 vs −0.2 degrees, P = .07), which likewise were not statistically significant.

Ten-year survivorship of INBONE II TAA was 93% in this cohort. Despite periprosthetic osteolysis and/or peri-implant lucency, the reoperation rate was low. Although the small number of failures prevented statistically significant conclusions, radiographic patterns suggest possible higher risk of failure in those with greater varus deformity.

The optimal amputation level along the first ray in diabetic foot disorders remains disputed, particularly the choice between transmetatarsal first ray amputation and hallux amputation. This study aimed to compare mid- to long-term outcomes between these surgical approaches, focusing on ulcer recurrence and revision rates.

A retrospective analysis was conducted at a tertiary care center, examining 112 patients who underwent first ray amputations between 2000 and 2023. The study compared outcomes over 5 years between transmetatarsal first ray amputation (n = 28) and hallux amputation (n = 84), which was defined as any amputation at the hallux. The primary outcome was ulcer recurrence; secondary outcomes were needed for revision surgery and revision-free survival. Multivariable Cox regression analysis was performed, adjusting for age, sex, chronic kidney disease, peripheral arterial disease, coronary heart disease, and history of contralateral amputation. Additionally, a propensity score matched analysis was conducted to control for significant baseline age differences.

After a maximum follow-up of 48 months, no statistically significant difference was found in ulcer recurrence between the 2 procedures in the unmatched cohort (HR = 0.56, P = .078, 95% CI: 0.30-1.07). Similarly, no significant difference was observed in revision surgery rates (HR = 0.680, P = .189, 95% CI: 0.35-1.31). In the propensity-matched analysis, transmetatarsal amputation was associated with a significantly lower risk of ulcer recurrence (HR = 0.33, 95% CI: 0.14-0.78; P = .011). Age emerged as a significant predictor of ulcer recurrence, with each additional year associated with reduced risk (HR = 0.977, P = .001, 95% CI: 0.96-0.99). Higher stage of PAD (stage III or higher) showed lower risk of ulcer recurrence compared with lower stage (HR = 0.34, P = .01, 95% CI: 0.15-0.78). Chronic kidney disease was associated with an increase of revision (HR = 2.067, P = .018, 95% CI: 1.13-3.77 ), a history of minor amputation or conservative surgery on the contralateral side significantly increased revision risk (HR = 5.798, P = .021, 95% CI: 1.30-26.03).

The study found no clear advantage of either transmetatarsal or hallux amputation regarding risk of revision surgery, whereas the risk of ulcer recurrence was significantly lower in the propensity-matched transmetatarsal amputation group.

Acute lateral ankle sprains are among the most common musculoskeletal injuries, accounting for up to 20% of all sports-related injuries and a leading cause of time lost from athletic participation. Although most cases respond to conservative care, 20% to 40% of athletes develop persistent pain, recurrent sprains, or chronic instability. Biologic therapies such as platelet-rich plasma (PRP) have gained interest for their potential to accelerate ligament healing, but evidence in acute athletic ankle sprains remains limited.

This study was designed as a nonmasked randomized controlled trial of consecutively recruited patients presenting with acute lateral ankle sprain. This prospective comparative study enrolled 40 athletic patients (mean age 33.1 years; 50% male) who sustained an acute lateral ankle sprain and presented within 2 weeks of injury. All patients engaged in ≥3 sports sessions weekly, including 8 professional athletes. Participants were randomized to conventional treatment with rest, ice, compression, elevation (RICE) and physiotherapy (n = 20) or the same regimen plus 3 leukocyte-poor PRP injections administered at weekly intervals (n = 20). Primary outcomes were functional and pain assessment using Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) and Pain Interference (PI) computer adaptive tests at baseline, 6, and 12 months. The secondary outcome was time to return to unrestricted sport.

Baseline PROMIS scores were similar between groups. PROMIS PF improved from 42.6 to 69.8 in the control group and from 43.0 to 71.4 in the PRP group by 12 months, whereas PROMIS PI decreased from 61.2 to 38.4 and 60.8 to 37.4, respectively. Both groups exceeded established minimal clinically important differences by 6 months, with no significant between-group differences at 6 or 12 months (PF, P = .68; PI, P = .74). Median time to unrestricted sports return was significantly shorter with PRP (14.5 weeks, 95% CI 13.1-15.9) compared to controls (17.8 weeks, 95% CI 16.2-19.4; P = .042). At 12 months, 3 PRP patients (15%) and 5 controls (25%) underwent surgery for persistent instability, consistent with published rates of failed conservative management.

Leukocyte-poor PRP did not improve PROMIS Pain Interference, PROMIS Physical Function, or overall return to sport rates compared with conventional care. Although a statistically significant and clinically meaningful acceleration in time to return to sport with a moderate effect size was observed, this outcome was exploratory and underpowered, and larger prospective trials are required for confirmation.

Autologous osteoperiosteal transplantation (AOPT) is a promising treatment for large cystic osteochondral lesions of the talus (OLTs), but the influence of lesion laterality remains unclear. The purpose of this study was to compare the clinical and radiologic outcomes of lateral vs medial large cystic OLTs treated with AOPT.

Patients with lateral or medial large cystic OLTs who underwent AOPT between 2010 and 2023 were retrospectively reviewed. Patients were propensity matched in 1:1 ratio on sex, age, body mass index, affected side, and lesion profiles (area, depth, volume). Clinical outcomes were assessed using the visual analog scale for pain (VAS), the Foot Ankle Outcome Score (FAOS), and the ankle activity score (AAS). The final FAOS score was designated as the primary outcome measure. Radiologic outcomes were evaluated using the MOCART (magnetic resonance observation of cartilage repair tissue) 2.0 ankle score.

A total of 22 matched patients per group were included, with a mean follow-up of 84.6 ± 45.9 months. The lateral group comprised 20 males and 2 females (mean age, 40.4 ± 11.2 years), whereas the medial group included 18 males and 4 females (mean age, 38.0 ± 8.4 years). Both groups demonstrated significant improvements in total FAOS scores (lateral: 53.4 ± 13.8 to 87.2 ± 10.1, P < .001; medial: 51.1 ± 12.6 to 89.7 ± 8.4, P < .001) and in all secondary clinical outcomes at final follow-up (all P < .001), with no intergroup differences (all P > .05). Similarly, there were no significant differences in the total MOCART 2.0 ankle score (73.8 ± 10.7 vs 73.0 ± 9.9; nonsignificant) or in any of its individual subcomponents.

This cohort study demonstrated that AOPT yields comparable mid‑ to long‑term clinical and radiologic outcomes for medial and lateral large cystic OLTs, and that radiologic results were not significantly associated with clinical outcomes.

Tarsometatarsal (TMT) joint arthrodesis is essential for managing surgical management of severe bunion deformities, complex midfoot trauma, and osteoarthritis. Various fixation methods and bone grafting types have been described, but the impact of the number of joints fused on union rates remains unclear. This study aimed to evaluate whether fusing multiple joints affects arthrodesis rates and to compare union outcomes among different fixation constructs and grafting techniques.

We conducted a single-center retrospective cohort study of 582 TMT fusions, comparing single- vs multiple-joint fusions involving medial and central columns. The average follow-up was 15.5 months. Two fellowship-trained foot and ankle surgeons assessed radiographs and computed tomographic (CT) scans. Radiographic union was evaluated at 8 and 12 weeks as well as the specific fixation constructs and bone graft used across each joint.

Single-TMT-joint surgeries had a significantly greater proportion of fusions occurring by 12 weeks than the multiple-TMT-joint surgeries, 74.9% vs 67.0%, respectively, P = .0002. Ultimate union rates were similar for single-joint fusions (80.3%) and multiple-joint fusions (82.6%. Many nonunions were asymptomatic; the combined asymptomatic nonunion and union rate was 95.4%. The revision rate for all nonunions was 25.5%. Staple fixation was associated with higher nonunion rates in the second (46.15%) and third (37.5%) TMT joints, whereas screw fixation showed the highest nonunion at the first TMT joint (54.6%). The lowest nonunion rates were observed with combined interfragmentary screw fixation and plating across all joints. Diabetic patients and current smokers experienced higher complication and nonunion rates.

Although the radiographic nonunion rate (18.2%) exceeded prior reports, symptomatic nonunion was rare (4.6%). Multiple-TMT-joint surgeries required more time to confirm radiographic union than single joint surgeries. Among the modifiable factors, implant and graft choice were associated with differences in union rates.

Periprosthetic joint infection (PJI) remains an uncommon but devastating complication after total ankle arthroplasty (TAA). Literature investigating treatment of PJI in TAA is limited, demonstrating poor patient-reported outcomes and high rates of complications and reoperations. Therefore, continued investigation of PJI treatment following TAA is necessary. This exploratory study describes clinical, microbiological, and patient-reported outcomes for PJI treatment following TAA at minimum 2-year follow-up.

Retrospective chart review was conducted for a single-institution registry of primary TAA patients between January 2015 and December 2021 with at least 1 follow-up appointment. Patients with PJI were identified using Musculoskeletal Infection Society (MSIS) criteria. Acute vs chronic PJI was defined as infectious symptom duration of <4 weeks and ≥4 weeks, respectively. Clinical, radiographic, microbiologic, and patient-reported outcomes were collected for PJI patients. The primary outcome was maintenance of a functioning TAA implant at the most recent follow-up; the secondary outcome was successful limb salvage.

Of the 955 patients included in this analysis, 12 (1.3%) underwent reoperation for PJI at median 5.7-year follow-up, with 5 acute and 7 chronic PJI patients. The PJI incidence rate was 5.4 per 1000 person-years at risk (95% CI: 2.8, 9.5). Implant retention rate was 50% across all PJI patients, including 4 of 5 acute and 2 of 7 chronic PJI patients. One acute PJI patient underwent explant with permanent cement spacer. Chronic PJI patients without functioning TAA implant at final follow-up had undergone permanent cement spacer with washouts (n = 1), tibiotalocalcaneal arthrodesis (n = 1), ankle arthrodesis (n = 1), and below-knee amputation (n = 2).

Debridement, antibiotics, and implant retention (DAIR) appears to be a viable option for acute PJI treatment. However, DAIR and explant with staged revision may be insufficient for complete eradication of chronic PJI. Infection recurrence may result in permanent loss of function because of limited secondary treatment options after failed revision.

Additional trans-syndesmotic screws (TSS) are used in “fibula pro-tibia” approach for unstable ankle fractures applied to high-risk patients (diabetes, smoking, osteoporosis, obesity). These patients are at higher risk of complications. The peroneal artery (PA) may be at risk with additional TSS fixation. Iatrogenic vascular compromise may explain these postoperative complications. Therefore, this study investigates the range in which the PA and its deep perforating branch (dPA) are at risk with TSS fixation and identifies safe zones to avoid iatrogenic injury in this vulnerable population.

A retrospective analysis of lower extremity computed tomography angiograms (CTAs) was performed (2021-2022) in specified patients with comorbidities who might benefit from multiple syndesmotic screw fixation. CTAs were reformatted in the syndesmotic plane, and the PA was deemed at risk if a templated 3.5-mm syndesmotic screw intersected its course. Measurements were taken from both the tibial plafond and fibular tip and included the level where the PA and dPA branch entered and exited this danger zone.

Ninety-eight CTAs (196 limbs) were analyzed. Seventy-two patients were age ≥ 65 (mean 75, SD 8), 52 had diabetes, 16 were active nicotine users, and 16 had BMI ≥35. The PA was at risk in 98.5% (n = 195) limbs. The danger zone began 7.5 cm (SD 1.5 cm) proximal to the tibial plafond and 10 cm (SD 1.5 cm) proximal to the fibular tip. The dPA branch perforated the syndesmotic plane at 3.6 cm (SD 0.8 cm) proximal from the plafond and 6 cm (SD 0.9 cm) from the fibular tip. Finally, the PA and dPA were out of the danger zone at 2.5 cm (SD 0.4 cm) proximal from the tibial plafond and 5 cm (SD 0.6 cm) from the fibular tip. No difference was found between inclusion subgroups nor between individual patients’ contralateral legs.

PA and dPA are at risk with TSS, notably in the distal fifth of the limb, ending ~2.5 cm proximal to the plafond. Knowledge of this zone aids in planning for TSS fixation, especially for high-risk patients.

The medial malleolar osteotomy is required in some cases of osteochondral lesions, bone tumors, and fractures of the medial talar dome for surgical access. The literature is uncertain about which type of osteotomy and fixation is best. The objective of this study was to compare, in cadaveric specimens, the oblique and chevron medial malleolar osteotomies and their fixation with either 2 or 3 screws, evaluating the possibility of articular displacement. We hypothesize that the chevron osteotomy results in a lower chance of articular displacement at the end of the procedure than the oblique osteotomy. Our second hypothesis is that fixation with 3 screws also reduces the risk of articular displacement compared with 2 screws.

Forty anatomical fresh‑frozen specimens were analyzed and divided into 4 groups (10 per group): oblique osteotomy fixed with 2 or 3 screws and chevron osteotomy fixed with 2 or 3 screws. One fracture occurred in the chevron osteotomy group with 3 screws, leaving 39 specimens for analysis. After osteotomies and fixation, the talus was removed, and articular displacement (step‑off) of the distal tibia was assessed using a digital caliper.

The results indicated a lower incidence of articular displacement in chevron osteotomy (21.1%) compared with oblique osteotomy (50%). Fixation with 3 screws showed a lower rate of incongruence (21.1%) compared with 2 screws (50%). When the type of osteotomy and fixation were combined the chevron osteotomy fixed with 3 screws had no measurable articular displacement in this cadaveric model.

In this cadaveric surgical technique model, a chevron medial malleolar osteotomy fixed with 3 screws showed no measurable articular displacement and overall had a lower risk of articular step‑off compared with oblique osteotomy and 2‑screw fixation.

Minimally invasive surgery (MIS) for hallux valgus correction has demonstrated excellent clinical and radiographic outcomes. However, there are occasions where there is limited bone formation and remodelling despite successful union. This study investigated whether demineralised bone matrix fibre allograft augmentation could be associated with greater radiographic bone formation compared with standard percutaneous technique.

A retrospective comparative study of patients undergoing fourth-generation percutaneous hallux valgus correction with demineralised bone matrix fibre allograft augmentation (DBM group) or without (NDBM group). Primary outcome was radiographic healing assessed at 6 weeks, 3 months, and 6 months using a validated classification system. Secondary outcomes included patient-reported outcome measures (Manchester-Oxford Foot Questionnaire [MOXFQ], EuroQol 5-dimension, 5-level [EQ-5D-5L], visual analogue scale [VAS] Pain), and radiographic parameters (intermetatarsal angle, hallux valgus angle).

Between September 2022 and July 2024, a total of 215 patients (191 female; 24 male; 316 feet) underwent fourth-generation percutaneous metatarsal extra-capsular transverse osteotomy for hallux valgus correction. Patients were divided into 2 groups: DBM, 222 feet; and NDBM, 94 feet. Radiographic follow-up was available for 75.2% (167 feet) of DBM and 79.8% (75 feet) of NDBM cases. The DBM group showed significantly improved radiographic union scores at 3 and 6 months (P = .005-.027) but not 6 weeks (P = .06). There were no significant differences between groups in terms of final patient-reported outcome measures or radiographic deformity correction (P > .05). Multivariable regression analysis adjusting for baseline confounders found that DBM was associated with a statistically but not clinically significant improvement in patient-reported outcome measures (PROMs; based on the minimal clinically important difference); however, PROM findings should be interpreted cautiously, given baseline imbalance and approximately 50% loss to follow-up. The additional cost of bone graft augmentation was USD$1780 per procedure.

The addition of demineralised bone matrix fibre allograft to the lateral healing zone, was associated with higher radiographic healing scores and a greater proportion classified radiographically as united at scheduled time points following percutaneous hallux valgus surgery. Future studies should investigate whether other biological adjuncts could further optimize healing in specific patient populations or identify those that may not demonstrate bony remodelling.

Modern percutaneous hallux valgus surgery, including the minimally invasive chevron and Akin (MICA) technique, is considered to cause less pain than traditional methods because of reduced soft tissue morbidity. Nevertheless, opioids are often prescribed postoperatively. This study investigates whether mild to moderate analgesics (World Health Organization [WHO] level 1 and 2) are sufficient for pain control following modern percutaneous hallux valgus correction.

This prospective single-surgeon case series includes 125 consecutive feet that underwent MICA surgery between May 2018 and May 2023; 95 feet (76%) were included with ≥12-month follow-up. Data on pre- and postoperative analgesic consumption and radiologic parameters were recorded. Patient-reported analgesic consumption was collected at prespecified visits via electronic questionnaires; no pill counts were performed. The primary endpoint was the proportion of patients using any opioid by the end of postoperative week 2. Secondary outcomes included radiologic parameters and complication rates.

The mean follow-up period was 1.6 years (±0.5). Fourteen percent (95% CI 0.08-0.22) required any opioids within the first two postoperative weeks, with a mean of 23.3 morphine milligram equivalents (MME; 95% CI 9.7-37.0). Two percent (95% CI 0.01-0.07) required WHO level 3 opioids. Seventy-five percent of patients stopped taking analgesics within 3 weeks (95% CI 0.65-0.82). Significant improvements were observed in hallux valgus angle (HVA), intermetatarsal angle (IMA), and distal metatarsal articular angle (DMAA).

In this prospective case series within a standardized care pathway, most patients did not require opioids, and high-potency opioids were rarely used. Routine prescription of high-potency opioids after third/fourth-generation percutaneous hallux valgus correction may be unnecessary for most patients in similar settings. Hardware-related findings should be interpreted cautiously because the screw design and osteotomy technique changed during the study period, which may have confounded comparisons.

Osteoarthritis (OA) of the ankle is a disabling and understudied disease, most commonly emerging posttraumatically after ankle fractures (PTOA). Despite its prevalence, the molecular mechanisms linking joint trauma to ankle OA are not well defined, limiting opportunities for early intervention. This study characterized synovial transcriptional changes to identify early molecular drivers of disease onset in fracture-induced ankle PTOA.

Synovium was collected under an institutional review board–approved protocol from patients undergoing ankle fracture fixation, and ankle arthroplasty for end-stage PTOA after a prior ankle fracture, or nontraumatic OA (NTOA). Synovium from patients with no or minimal OA served as controls. Bulk RNA sequencing was performed, followed by differential gene expression analysis and Gene Ontology (GO) enrichment. Machine learning clustering (k-means and hierarchical) and classification (logistic regression) models were employed to distinguish transcriptomic signatures of synovial subtypes.

RNA-seq and unsupervised clustering revealed distinct synovial transcriptional profiles separating NTOA and PTOA, with a uniquely shared signature between Fracture and PTOA synovium. WNT signaling was enriched across all groups compared to controls, with particularly broad activation in PTOA. WNT7B showed the strongest upregulation in Fracture and PTOA, with a smaller increase in NTOA. Logistic regression classified synovial subtypes based on gene expression profiles with high accuracy.

These findings support the hypothesis that ankle OA following fracture represents a molecularly distinct subtype. Although WNT pathway activation has been known in OA, its broader activation in PTOA suggests that joint trauma initiates a pathologic synovial cascade, with WNT pathway activation playing a central role. The clear timing of most ankle fractures offers a unique opportunity for early therapeutic intervention. Focused research on the synovial molecular link between ankle fractures and PTOA could underpin the development of targeted, disease-modifying strategies in the immediate postinjury period.

Charcot-Marie-Tooth (CMT) disease is the most common cause of neurogenic cavus foot. This study aimed to identify key morphologic differences between pes cavus in individuals with CMT, idiopathic cavus, and healthy controls.

This single-site, case-control study included individuals 18-65 years old without prior foot and ankle surgery. Participants were grouped based on disease state; all patients with CMT had clinical or genetic confirmation of the diagnosis. Morphologic assessment was completed using HiRise weightbearing computed tomography (WBCT). Statistical analysis involved using generalized linear models for repeated measures and pairwise comparisons between groups or Wilcoxon rank sum tests.

120 total WBCT scans (n = 40 each of CMT, idiopathic cavovarus, controls) from 73 participants were analyzed. Six measurements evaluating medial column height were assessed: Meary angle, calcaneal pitch, cuneiform to floor and skin distances, and navicular to skin and floor distances. Forefoot adduction/midfoot supination was assessed (axial talar–first metatarsal angle and forefoot arch angle). The transverse tarsal arch was assessed using the transverse arch plantar (TAP) angle. All measures of medial longitudinal height were greater in CMT vs controls (P < .05). Forefoot adduction was 3 times greater in CMT cavus compared with controls. The TAP angle differed significantly between CMT (94.2 ± 13.4), idiopathic (100.5 ± 9.4; P = .02), and controls (102.7 ± 7.8; P < .001).

Our results indicate that forefoot adduction/midfoot supination are more pronounced in CMT pes cavus compared with idiopathic and controls, reflecting the severity of muscular imbalances characterizing the progression of CMT. The transverse and medial longitudinal arch are more severely affected in CMT compared with controls. Prior flatfoot studies have identified maximal collapse between the plantar medial cuneiform and the second and third metatarsals; our TAP angle findings demonstrate the opposite in CMT-associated cavus with significant exaggeration of transverse tarsal arch curvature. This exaggerated curvature likely contributes to the intrinsic stiffness characteristic of this foot morphology.

Middle facet subluxation (MFS) of the subtalar joint is a key indicator of peritalar subluxation in progressive collapsing foot deformity (PCFD). Although its assessment relies on weightbearing computed tomography (WBCT), it remains unclear which weightbearing radiographic (WBR) measurements correlate with MFS. We hypothesize that radiographic parameters assessing hindfoot alignment are correlated with MFS.

Seventy-three feet diagnosed with PCFD were evaluated using WBR and WBCT. Five parameters were measured in both modalities: talonavicular coverage (TNC) angle, hindfoot moment arm (HMA), talo–first metatarsal angle, calcaneal pitch angle, and sinus tarsi impingement. MFS was then measured on WBCT. Multivariate and bivariate regression analyses were used to identify which WBR measurements predict or correlate with MFS. Partition analysis was used to identify cutoff values for WBR measurements linked with MFS.

Multivariate regression identified TNC angle and HMA as combined MFS predictors (R² = 0.524, P < .0001). In the bivariate analysis, TNC angle demonstrated a moderate individual correlation with MFS (r = 0.68), whereas HMA showed a weak individual correlation (r = 0.39). Partition analysis identified practical radiographic thresholds (TNC angle ≥ 38 degrees, HMA ≥ 11.4 mm) for MFS ≥18% yet these thresholds explained only 27.3% of variability (R² = 0.273).

TNC angle and HMA are the most useful WBR measurements for identifying MFS in PCFD. In settings without WBCT access, these offer a practical assessment tool, associated with MFS ≥18%; however, these cutoffs accounted for only 27.3% of variance (R² = 0.273), underscoring residual unexplained factors.

Os intermetatarseum (OI) is an accessory ossicle situated between the first and second metatarsals. While often asymptomatic, its presence can occasionally lead to development of painful syndrome that require a clinical intervention or even surgical excision. However, the data on its prevalence and clinical relevance is limited. Aim of this study is to determine the prevalence of OI and systematically synthesize available data on its clinical characteristics.

Three major databases (PubMed/MEDLINE, Embase, and ScienceDirect) were searched for original studies reporting on OI until July 2025. The study was pre-registered on PROSPERO (ID: CRD420251132172) and strictly followed PRISMA guidelines. Heterogeneity was assessed via the 95% prediction intervals, I² statistic, and χ² test.

A total of 21 studies encompassing 22 157 feet met the inclusion criteria for quantitative analysis. The pooled prevalence estimate (PPE; per foot) of OI in the general population was 1.16% (95% CI 0.75%-1.80%) in the general population. The PPE was comparable between males (0.79%, 95% CI 0.21%-2.90%) and females (0.41%, 95% CI 0.07%-2.35%). Regionally, North America demonstrated a significantly higher PPE (3.11%, 95% CI 2.28%-4.23%) than Asia (0.39%, 95% CI 0.13%-1.21%) but not Europe (1.84%, 95% CI 0.96%-3.51%). No significant difference was found between cadaveric studies (2.68%, 95% CI 1.04%-6.77%) and radiographic studies (0.90%, 95% CI 0.53%-1.52%).

OI is a relatively rare anatomical finding that is present in approximately 1 in 100 feet. High heterogeneity and significant publication bias mean the pooled values are approximate. Nevertheless, its awareness and proper identification are essential, as it may occasionally present with symptoms and mimic other pathologies such as fractures, which require different management strategies.