Return to Sport and Functional Outcomes After Minimally Invasive Zadek Osteotomy for Insertional Achilles Tendinopathy in Young Athletes: A Retrospective Case Series

Abstract

Background:

Insertional Achilles tendinopathy (IAT) is a common cause of posterior heel pain in active individuals and athletes. Traditional open surgical techniques are effective but associated with notable morbidity and prolonged rehabilitation. Minimally invasive Zadek osteotomy (MIS Zadek) has emerged as a tendon-preserving alternative aimed at reducing soft tissue disruption and facilitating early recovery. This study evaluated clinical and functional outcomes of MIS Zadek in young, athletic patients with IAT.

Methods:

This retrospective single-centre case series included patients younger than 55 years who underwent MIS Zadek for symptomatic IAT between 2022 and 2024, with a minimum follow-up of 18 months. All patients were physically active before symptom onset. Procedures were performed according to the technique described by Kaplan et al. Primary outcomes included return-to-sport time, Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF), and PROMIS Pain Interference (PI). Secondary outcomes included visual analogue scale (VAS) pain scores, radiographic union, and complications. PROMIS outcomes were evaluated against established minimal clinically important difference thresholds.

Results:

Fifteen athletic patients (mean age, 37.2 ± 9.1 years; 10 males, 5 females) with no relevant comorbidities were included with a minimum 18-month follow-up. All patients returned to their preinjury level of sport at a mean of 4.2 ± 1.1 months. Radiographic union was achieved in all cases at a mean of 10.2 ± 2.1 weeks. PROMIS Physical Function improved from 39.6 ± 5.8 preoperatively to 52.4 ± 6.1 at 3 months and 59.1 ± 5.0 at final follow-up (P < .001), whereas PROMIS Pain Interference decreased from 63.9 ± 6.4 to 51.2 ± 6.0 and 45.1 ± 5.0, respectively (P < .001). VAS pain scores improved from 7.1 ± 1.2 to 1.8 ± 1.1 at final follow-up (mean change −5.3, 95% CI −6.0 to −4.6; P < .001). Two minor complications (13%) were observed.

Conclusion:

MIS Zadek was associated with meaningful pain relief, functional improvement, and return to sport in athletic patients with IAT in this cohort. These findings suggest that it may represent a viable tendon-preserving surgical option. Prospective comparative studies are needed to further evaluate its role relative to alternative treatments.

Level of Evidence:

Level IV, therapeutic case series.

Introduction

Insertional Achilles tendinopathy (IAT) is a frequent cause of posterior heel pain in active individuals and athletes and remains a challenging condition for foot and ankle surgeons. It is commonly associated with a Haglund deformity, and together these pathologies form the clinical spectrum of Haglund syndrome. ¹ Approximately 6% to 8% of the general population experiences Achilles tendon pain, and nearly one-third of these cases involve the insertional portion of the tendon. Among patients presenting with IAT, up to 25% demonstrate concomitant Haglund deformity, which contributes to ongoing mechanical irritation, retrocalcaneal bursitis, and progressive tendon degeneration.^2,3

Initial management of IAT is nonoperative and typically includes activity modification, physical therapy, footwear modification, and eccentric strengthening. Despite appropriate conservative treatment, up to 40% of patients fail to achieve adequate symptom relief and ultimately require surgical intervention. Traditional surgical treatment has historically relied on open midline or slightly medial Achilles tendon splitting approaches, allowing debridement of degenerative tendon tissue and resection of the Haglund prominence, followed by tendon reattachment to the calcaneus. ⁴ Although effective, open techniques are associated with notable morbidity, including wound complications, prolonged immobilization, delayed return to sport, and risk of tendon weakness or rerupture.^5-7

The Zadek osteotomy was developed as a surgical strategy for the treatment of insertional Achilles pathology and Haglund syndrome. It was first described by an American orthopaedic surgeon, Zadek, in 1939, later popularized by Keck and Kelly in 1965.^8,9 This procedure involves a dorsal closing-wedge calcaneal osteotomy, which reorients the Achilles tendon insertion away from the posterior superior calcaneal prominence, thereby reducing mechanical impingement, decreasing tendon compression, and unloading the diseased insertion without requiring detachment of the tendon. By altering the biomechanical environment of the Achilles insertion, the Zadek osteotomy addresses the pathophysiology of IAT while preserving the integrity of the tendon bone interface.^8-11

Recent advances in minimally invasive surgery have led to the development of the minimally invasive Zadek osteotomy (MIS Zadek). This procedure uses percutaneous approach combined with fluoroscopic guidance to perform the calcaneal osteotomy with minimal soft tissue disruption. Compared with traditional open techniques, MIS Zadek aims to reduce wound complications, minimize postoperative pain, preserve tendon integrity, and allow for earlier rehabilitation and faster return to athletic activity outcomes that are particularly important in younger, high-demand patients.

Kiriluk et al ¹² compared percutaneous Zadek osteotomy with open Haglund resection and demonstrated comparable early improvements in pain and function between groups. The percutaneous cohort showed lower rates of wound-related complications and faster early recovery, while maintaining reliable symptom relief. The authors concluded that MIS Zadek osteotomy represents a safe and effective alternative to traditional open resection in appropriately selected patients. Bakaes et al ¹³ performed a systematic review comparing percutaneous and open Zadek osteotomy for insertional Achilles tendinopathy and Haglund’s deformity. The authors reported comparable improvements in pain and functional outcomes between approaches, with a trend toward lower wound-related complications and faster recovery following percutaneous techniques. However, they emphasized substantial heterogeneity among included studies and limited high-quality comparative data, underscoring the need for standardized reporting and prospective trials.

Despite increasing interest in these techniques, clinical outcome data for MIS ZADEK in young, athletic patients with IAT remain limited. Most existing studies have focused on mixed or older populations, in whom functional goals, rehabilitation expectations, and return-to-sport demands differ substantially from those of active athletes.

Therefore, the purpose of this study was to evaluate the clinical and functional outcomes of 15 athletic patients younger than 55 years who underwent MIS ZADEK osteotomy for symptomatic insertional Achilles tendinopathy. The primary endpoints were time to return to sport, Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function, PROMIS Pain Interference, and procedure-related complications. By focusing on a young, highly active cohort, this study uniquely examines whether minimally invasive Zadek techniques can restore high-level function and enable a reliable return to sport while maintaining a favourable safety profile in a demanding patient population.

Study Design and Setting

This was a single-centre retrospective consecutive case series evaluating clinical and functional outcomes following minimally invasive Zadek osteotomy (MIS Zadek) for the treatment of insertional Achilles tendinopathy. The study was conducted at a high-volume foot and ankle surgery centre specializing in minimally invasive hindfoot procedures. Institutional review board approval was obtained before data collection (AMC 0008-26).

Patient Selection

Medical records were reviewed for all patients who underwent MIS Zadek osteotomy between January 2022 and December 2024. Inclusion criteria were (1) age <55 years at the time of surgery; (2) clinical and radiographic diagnosis of insertional Achilles tendinopathy with or without Haglund deformity; (3) persistent symptoms despite a minimum of 6 months of structured nonoperative treatment including physical therapy, activity modification, footwear modification, and antiinflammatory measures; and (4) participation in regular athletic or recreational sports before symptom onset. Only active and athletic patients were enrolled in this study. For the purpose of eligibility, athletic activity was defined as participation in structured or recreational sports or physical exercise more than 3 times per week, with each session lasting at least 60 minutes. This criterion was used to ensure a homogeneous cohort of physically active individuals with clinically relevant functional demands on the Achilles tendon.

Exclusion criteria included prior surgery to the affected Achilles tendon or calcaneus, systemic inflammatory arthropathy, neuropathic disorders, acute Achilles rupture, or less than 18 months of postoperative follow-up.

Surgical Technique

All procedures were performed by fellowship-trained foot and ankle surgeons experienced in minimally invasive hindfoot surgery. The MIS Zadek osteotomy was performed under general anaesthesia with an adjunctive ankle block. All minimally invasive Zadek osteotomies in this study were performed in accordance with the surgical technique described by Kaplan et al, ¹⁴ ensuring standardized operative execution and consistency with previously published methodology. Patients were positioned in a lateral decubitus position with the operative side supported on a radiolucent bump. The procedure was carried out under continuous fluoroscopic guidance. Through small percutaneous stab incisions, a high-speed burr was introduced to create an approximately 1-cm dorsal closing-wedge osteotomy in the posterior calcaneus. The osteotomy was gradually closed by dorsiflexing the ankle under fluoroscopic control and was then stabilized using two 7-mm cannulated screws placed percutaneously (Figures 1 and 2). The Achilles tendon was not detached or violated, and no routine tendon debridement or direct resection of the Haglund prominence was performed.

Figure 1.

The MIS Zadek Procedure. (A) The figure schematically illustrates the dorsal-based closing-wedge resection performed percutaneously in the posterior calcaneus. The excised wedge has an approximately 10-mm dorsal base with a plantar apex, consistent with the planned minimally invasive osteotomy geometry. (B) The figure schematically demonstrates the postoperative configuration following close wedge resection and osteotomy closure. After removal of the dorsal-based wedge, the calcaneus is realigned to reduce posterior prominence and unload the Achilles insertion. The osteotomy is stabilized with 2 percutaneously placed cannulated screws, providing secure fixation and promoting reliable bone healing.

Figure 2.

Preoperative and postoperative radiographic appearance following minimally invasive Zadek osteotomy. (A) The preoperative image demonstrates a prominent Haglund deformity and coarse calcific degeneration at the Achilles tendon insertion on the calcaneus. (B) The postoperative image illustrates anterior translation of the posterior calcaneal tuberosity following resection of a dorsal-based wedge and fixation with 2 cannulated screws, resulting in unloading of the Achilles tendon insertion.

Postoperative Protocol

All patients were placed in a controlled ankle motion (CAM) boot immediately postoperatively. Partial weightbearing was initiated at 2 weeks, progressing to full weightbearing in the boot by 4 weeks. At 8 weeks, patients transitioned to athletic footwear. Formal physiotherapy focusing on range of motion, progressive strengthening, and gradual return to impact activity started 2 weeks after surgery. Physiotherapy was conducted according to a standardized rehabilitation protocol developed jointly by the primary author and the participating physiotherapists. This protocol was consistently applied across all patients in order to ensure uniformity of management after surgical intervention. Return to sport was allowed once patients demonstrated pain-free walking, adequate calf strength, and functional stability. The decision was made by the treating surgeon together with the physiotherapy team.

Outcome Measures

The primary outcome measures were return-to-sport time, PROMIS Physical Function, and PROMIS Pain Interference. PROMIS questionnaires were administered preoperatively and at 3, 6, 12, and 18 months postoperatively using validated electronic versions. To facilitate clinical interpretation, established minimal clinically important difference (MCID) thresholds were applied: 5 to 8 points for PROMIS Physical Function and 8 to 10 points for PROMIS Pain Interference. Improvements equal to or greater than these thresholds were considered to represent clinically meaningful change in addition to statistical significance. Secondary outcomes included visual analogue scale (VAS) pain scores, and procedure-related complications including wound problems, non-union, mal-union, nerve symptoms, infection, and reoperation. Return to sport was defined as resumption of the patient’s preinjury athletic or recreational activity at or near their prior level of participation. No loss to follow-up was described in this study.

Radiographic Assessment

Weightbearing ankle and hindfoot alignment radiographs were obtained preoperatively and at routine postoperative intervals (6 weeks, 3, 6, and 12 months) to confirm osteotomy healing and alignment. Union was defined radiographically by bridging trabeculae across the osteotomy site and clinically by absence of pain with weightbearing. MRI was obtained in every case prior to surgery to assess tendon integrity, bone marrow edema, and other pathologies.

Sample Size and Power

An a priori power analysis was performed to estimate the sample size required to detect a clinically meaningful change in patient-reported outcomes following minimally invasive Zadek osteotomy. Because the primary analyses were based on within-patient comparisons over time, the calculation was based on paired measurements. Using established MCID thresholds for PROMIS Physical Function (5-8 points), the study was powered to detect a conservative clinically meaningful improvement of 8 points. Assuming an SD of change of approximately 10 points (Cohen d = 0.8), a 2-tailed paired t test with an α level of .05 required 15 patients to achieve approximately 80% power. Similar assumptions for PROMIS Pain Interference yielded comparable power estimates. Accordingly, inclusion of 15 consecutive patients with complete preoperative and postoperative PROMIS data was considered sufficient to support the primary study endpoints and to characterize functional recovery and return-to-sport outcomes in this athletic cohort.

Statistical Analysis

Descriptive statistics were used to summarize demographic characteristics, baseline pathology, clinical outcomes, return-to-sport timelines, radiographic healing, and complications. Continuous variables are reported as mean ± SD when normally distributed and as median with IQR when non-normally distributed; categorical variables are presented as counts and percentages. Normality was assessed using the Shapiro-Wilk test. Changes in PROMIS Physical Function, PROMIS Pain Interference, and VAS pain scores from baseline to postoperative time points (3, 6, 12, and 18 months) were evaluated using paired testing (paired t test for normally distributed data or Wilcoxon signed-rank test for non-normally distributed data). A 2-sided P value <.05 was considered statistically significant. Given the single-arm retrospective design and the evaluation of multiple outcomes across repeated time points, these analyses were considered exploratory. No formal adjustment for multiple comparisons (eg, Bonferroni or false discovery rate correction) was applied; therefore, P values should be interpreted descriptively and in the context of clinical relevance. Analyses were conducted using R (version 4.5.0; R Foundation for Statistical Computing). No loss to follow-up occurred.

Results

Fifteen consecutive athletic patients met the inclusion criteria and were available for a minimum of 18-month follow-up. The mean age was 37.2 ± 9.1 years (range 22-53). The cohort consisted predominantly of males (10 males, 5 females). No patient had relevant medical comorbidities, none were active smokers, and none were receiving systemic corticosteroids or fluoroquinolone therapy. All participants were engaged in regular athletic activity prior to symptom onset, most commonly running (n = 9), tennis (n = 4), and soccer (n = 3), with 10 patients participating in more than 1 sport. In accordance with the study definition, all patients performed structured physical activity more than 3 times per week for at least 60 minutes per session. (Tables 1 and 2). All patients underwent a standardized course of nonoperative management prior to surgery, including physiotherapy, accommodative orthoses/inserts, nonsteroidal anti-inflammatory drugs (NSAIDs), and usage of braces. The mean duration from symptom onset to surgery was 6.7 ± 2.6 months.

Table 1.

Patient Demographics (N = 15). ^a

Characteristic	Value
Age, y, mean ± SD	37.2 ± 9.1
Sex: male/female, n	10/5
Comorbidities, n	0
Smoking status, n	0

a

Table 1 summarizes the baseline demographic characteristics of the study cohort. The study included 15 patients with a mean age of 37.2 ± 9.1 years, reflecting a relatively young and active population. The majority of patients were male (10 males, 5 females). Notably, no patients reported relevant medical comorbidities or smoking history, indicating a generally healthy cohort and minimizing the potential influence of systemic risk factors on surgical outcomes.

Table 2.

Presurgery Athletic Activities of Study Participants (N = 15). ^a

Sport b	Number of Participants (n)	Percentage (%)
Running	9	60.0
Tennis	4	26.7
Soccer	3	20.0
Multiple sports participation	10	66.7

a

Table 2 summarizes the preinjury athletic activities of the study cohort. Running was the most common sport, reported by 9 patients (60%), followed by tennis in 4 patients (26.7%) and soccer in 3 patients (20%). Notably, 10 patients (66.7%) participated in more than 1 sport, reflecting a highly active and multidimensional athletic population.

b

Ten patients participated in more than 1 sport; therefore, percentages exceed 100%.

All patients returned to their preinjury level of athletic participation. The mean time to return to sport was 4.2 ± 1.1 months (95% CI 3.6-4.8). No patient required secondary procedures to facilitate return to activity. Radiographic assessment demonstrated union of all osteotomies at a mean of 10.2 ± 2.1 weeks (range 8-19), with no cases of non-union, mal-union, fracture or hardware failure.

Substantial improvement was observed in both PROMIS domains, with the majority of recovery occurring by 3 months and maintenance of gains through 18 months. PROMIS Physical Function (PF) improved from a preoperative mean of 39.6 ± 5.8 to 52.4 ± 6.1 at 3 months, 56.1 ± 5.7 at 6 months, 58.3 ± 5.2 at 12 months, and 59.1 ± 5.0 at 18 months. Using paired 2-tailed t tests, the mean improvement at 3 months was +12.8 points (95% CI +9.4 to +16.2, P < .001), exceeding the accepted MCID for PROMIS PF (5-8 points). Further gains were observed at 18 months with a total improvement of +19.5 points (95% CI +15.8 to +23.1, P < .001), confirming both statistical and clinical significance. (Table 3, Figure 3).

Table 3.

Clinical Outcomes. ^a

Outcome	3 mo	6 mo	12 mo	18 mo
PROMIS Physical Function	52.4 ± 6.1	56.1 ± 5.7	58.3 ± 5.2	59.1 ± 5.0
PROMIS Pain Interference	51.2 ± 6.0	47.8 ± 5.6	45.9 ± 5.1	45.1 ± 5.0
VAS Pain	2.6 ± 1.3	2.1 ± 1.5	1.8 ± 1.1	1.8 ± 1.1
Return to sport, mo	4.2 ± 1.1	—	—	—

Abbreviations: PROMIS, Patient-Reported Outcomes Measurement Information System; VAS, visual analogue scale.

a

Table 3 presents longitudinal clinical outcomes following surgery. PROMIS Physical Function improved from 52.4 ± 6.1 at 3 months to 56.1 ± 5.7 at 6 months and 59.1 ± 5.0 at 18 months. PROMIS Pain Interference decreased from 51.2 ± 6.0 at 3 months to 47.8 ± 5.6 at 6 months and 45.1 ± 5.0 at final follow-up. VAS pain improved from 2.6 ± 1.3 at 3 months to 2.1 ± 1.5 at 6 months and stabilized at 1.8 ± 1.1 at 12 and 18 months. Return to sport occurred at a mean of 4.2 ± 1.1 months, indicating early functional recovery with sustained improvements thereafter. Collectively, these findings demonstrate significant and sustained improvements in pain and function following intervention, consistent with the statistically significant changes reported in the Results (all P < .001).

Figure 3.

Patient-Reported Outcomes Measurement Information System (PROMIS) outcome trends following surgery. Longitudinal changes in PROMIS Physical Function (PF) and PROMIS Pain Interference (PI) scores from preoperative assessment to 18-month follow-up. PROMIS PF demonstrated progressive improvement, whereas PROMIS PI showed sustained reduction, indicating durable functional recovery and pain relief. (All measures exceed MCID.)

PROMIS Pain Interference (PI) decreased from 63.9 ± 6.4 preoperatively to 51.2 ± 6.0 at 3 months, 47.8 ± 5.6 at 6 months, 45.9 ± 5.1 at 12 months, and 45.1 ± 5.0 at 18 months. The reduction at 3 months was −12.7 points (95% CI −16.0 to −9.3, P < .001), surpassing the MCID threshold for PROMIS PI (8–10 points), with sustained improvement of −18.8 points at 18 months (95% CI −22.4 to −15.2, P < .001). (Table 3, Figure 3).

VAS pain scores followed a trajectory similar to PROMIS PI. Mean VAS improved from 7.1 ± 1.2 preoperatively to 2.6 ± 1.3 at 3 months (mean change −4.5, 95% CI −5.3 to −3.7; P < .001) to 2.1 ± 1.5 at 6 months (mean change −4.8, 95% CI −5.8 to −3.7; P < .001) and to 1.8 ± 1.1 at 12 and 18 months (mean change −5.3, 95% CI −6.0 to −4.6; P < .001). These changes were consistent with clinically meaningful improvement and paralleled the PROMIS pain trajectory. (Table 3).

Two minor complications (13%) occurred. One patient experienced a transient sural nerve neuropraxia, which fully resolved without intervention by 6 months postoperatively. One patient developed a superficial wound infection, successfully treated with topical therapy without the need for oral antibiotics or surgical intervention. No deep infections, thromboembolic events, Achilles tendon injuries, fractures, removal of hardware, or reoperations were recorded.

Discussion

The principal finding of this study is that minimally invasive Zadek osteotomy (MIS Zadek) was associated with reliable pain relief, substantial functional improvement, and consistent return to sport in a young, athletic cohort with insertional Achilles tendinopathy. All patients resumed their preinjury level of athletic participation at a mean of 4.2 ± 1.1 months (95% CI 3.6-4.8), without the need for secondary procedures. PROMIS Physical Function improved from a preoperative mean of 39.6 ± 5.8 to 52.4 ± 6.1 at 3 months and 59.1 ± 5.0 at 18 months, representing a mean increase of +12.8 points at 3 months (95% CI +9.4 to +16.2; P < .001) and +19.5 points at final follow-up (95% CI +15.8 to +23.1; P < .001), exceeding established minimal clinically important difference thresholds. PROMIS Pain Interference decreased from 63.9 ± 6.4 preoperatively to 51.2 ± 6.0 at 3 months and 45.1 ± 5.0 at 18 months, corresponding to mean reductions of −12.7 points (95% CI −16.0 to −9.3; P < .001) and −18.8 points (95% CI −22.4 to −15.2; P < .001), respectively. Consistent with these findings, mean VAS pain scores improved from 7.1 ± 1.2 preoperatively to 1.8 ± 1.1 at 18 months, reflecting mean decreases of −5.3 points (95% CI −6.0 to −4.6; P < .001). Radiographic union was achieved in all patients at a mean of 10.2 ± 2.1 weeks, and only 2 minor complications (13%) were observed, both resolving without surgical intervention.

Traditional surgical management of IAT has primarily relied on open Achilles-splitting approaches with tendon debridement and reattachment.^15,16 Although these techniques demonstrate satisfactory long-term pain relief, reported complication rates range from 8% to 30%, with wound complications, delayed healing, and prolonged immobilization remaining major concerns, particularly in active patients.^15-17 Furthermore, return-to-sport timelines following open procedures are often prolonged, ranging from 6 to 12 months.^16,17

With increasing interest in minimally invasive strategies, percutaneous Zadek osteotomy has gained attention as a less disruptive alternative. Early studies by Nordio et al ¹⁸ and Hall et al ¹⁹ demonstrated significant improvements in pain and function, alongside low rates of wound complications and expedited rehabilitation. Subsequent comparative investigations have further evaluated the relative merits of MIS and open techniques. A systematic review by Bakaes et al ¹³ found comparable clinical outcomes between approaches, while highlighting a trend toward reduced soft tissue morbidity and faster recovery following percutaneous procedures. Similarly, Kiriluk et al ¹² reported favourable early outcomes and lower wound-related complication rates after MIS Zadek osteotomy compared with open Haglund resection. More recently, Gengatharan et al ²⁰ directly compared open and minimally invasive Zadek osteotomy and demonstrated equivalent improvements in patient-reported outcomes and radiographic union, with MIS associated with shorter operative times and reduced postoperative morbidity. Collectively, current evidence suggests that both open and percutaneous Zadek osteotomy provide effective symptom relief and reliable union for insertional Achilles tendinopathy. ²¹ Minimally invasive techniques may offer advantages in soft tissue preservation and early recovery; however, longer-term comparative data and standardized outcome reporting remain necessary to define optimal patient selection and surgical indications.

To date, most available studies have focused on mixed-age cohorts or non-athletic populations, with limited emphasis on return-to-sport metrics. The present study specifically evaluated young, athletic patients with high functional demands. The observed mean return-to-sport time of 4.2 months shows favourable results for MIS Zadek osteotomy.^15-17 Additionally, the magnitude and durability of PROMIS improvements in our cohort were numerically higher than those reported in several prior studies evaluating open techniques, though direct comparison is limited by differences in study design, population, and outcome instruments.^15,16 These findings suggest that MIS Zadek may offer distinct advantages for physically active individuals by combining biomechanical unloading with minimal soft tissue disruption.

The favourable outcomes observed in this cohort may be associated with several biomechanical and technical factors. By reorienting the calcaneal tuberosity, MIS Zadek reduces posterior impingement and compressive forces at the Achilles insertion while preserving the native tendon-bone interface. This contrasts with tendon-detaching procedures, which may compromise the tendon and prolong rehabilitation. Furthermore, the percutaneous approach minimizes disruption of surrounding soft tissues, thereby reducing wound complications and postoperative stiffness. The early initiation of controlled weightbearing, 2 weeks after surgery, and early physiotherapy in our protocol likely contributed to the rapid functional recovery and consistent return to sport observed in this series. Importantly, the absence of routine tendon debridement or Haglund resection in this cohort underscores the potential of biomechanical unloading alone to achieve symptomatic relief in selected patients, aligning with emerging concepts emphasizing load modification rather than aggressive tendon excision.

This study offers several methodological and clinical strengths. First, it focuses on a homogeneous cohort of young, athletic patients, addressing an important gap in the existing literature. Prior studies have largely included older or sedentary individuals, limiting the applicability of their findings to high-demand populations.^1,2,16,17 Second, standardized outcome assessment using validated PROMIS instruments at multiple time points allowed for precise evaluation of both functional recovery and pain reduction. The use of MCID thresholds further enhanced the clinical interpretability of the results. Third, all procedures were performed by fellowship-trained surgeons experienced in minimally invasive hindfoot techniques, reducing technical variability and enhancing internal validity. In addition, a consistent rehabilitation protocol was applied across all patients, limiting confounding related to postoperative management. Finally, comprehensive radiographic follow-up and routine preoperative MRI ensured accurate diagnosis, assessment of union, and exclusion of alternative pain generators, strengthening the reliability of the reported outcomes.

Several limitations should be acknowledged. First, the retrospective design introduces inherent risks of selection and information bias. Although all eligible consecutive patients were included, unmeasured confounders may have influenced outcomes. Second, the sample size was relatively small, reflecting the strict inclusion criteria and focus on a specific athletic population. Although statistically and clinically meaningful improvements were observed, the limited cohort restricts the generalizability of the findings and precludes multivariate analysis of prognostic factors. Third, the absence of a comparative control group treated with open Zadek osteotomy or traditional debridement limits the ability to draw definitive conclusions regarding the superiority of MIS Zadek. Future randomized or matched comparative studies are required to confirm these findings. Fourth, return to sport was based on patient-reported activity resumption rather than objective performance metrics. Although this approach reflects real-world clinical practice, subtle differences in performance level may not have been captured. Fifth, several minimally invasive techniques for insertional Achilles tendinopathy are currently emerging, including approaches that involve tendon debridement and partial detachment. The present study focused exclusively on minimally invasive Zadek osteotomy and did not evaluate these evolving MIS insertional Achilles procedures. Consequently, the relative effectiveness and potential superiority of different minimally invasive techniques cannot be determined. Future comparative studies are required to establish the optimal surgical approach and define procedure-specific indications. Finally, although follow-up exceeded 18 months in all cases, longer-term data are needed to evaluate durability, late complications, and potential progression of tendon degeneration.

Future investigations should focus on prospective, multicentre comparative studies evaluating MIS Zadek against open and MIS debridement and open Zadek osteotomy in athletic populations. Larger sample sizes would allow identification of predictors of outcome, including age, sport type, tendon degeneration severity, and alignment parameters. Integration of objective functional testing and sport-specific performance metrics may further refine return-to-play assessments. Additionally, longer-term follow-up is warranted to determine whether biomechanical unloading alone provides durable protection against recurrent symptoms and progressive tendon degeneration.

Conclusion

Minimally invasive Zadek osteotomy was associated with pain relief, functional improvement, and return to sport in young, athletic patients with insertional Achilles tendinopathy. In this consecutive case series, all patients returned to their preinjury activity level within an expected time frame, accompanied by clinical improvements in PROMIS Physical Function and Pain Interference scores, consistent radiographic union, and a low complication rate. By unloading the Achilles insertion while preserving soft tissue, MIS Zadek may represent a tendon-sparing surgical option in high-demand populations. However, given the retrospective design, absence of a control group, and limited sample size, these findings are descriptive and do not allow conclusions regarding comparative effectiveness. Further prospective comparative studies with larger cohorts and longer follow-up are warranted to better define its role and durability.

Supplemental Material

sj-pdf-1-fao-10.1177_24730114261446302 – Supplemental material for Return to Sport and Functional Outcomes After Minimally Invasive Zadek Osteotomy for Insertional Achilles Tendinopathy in Young Athletes: A Retrospective Case Series

Supplemental material, sj-pdf-1-fao-10.1177_24730114261446302 for Return to Sport and Functional Outcomes After Minimally Invasive Zadek Osteotomy for Insertional Achilles Tendinopathy in Young Athletes: A Retrospective Case Series by Gil Genuth, Peter Stavrou, Chris Brown and Lukas D. Iselin in Foot & Ankle Orthopaedics