Abstract
Background:
Calcific insertional Achilles tendinopathy (CIAT) may remain symptomatic despite prolonged nonoperative treatment. Minimally invasive (MIS) Zadek osteotomy unloads the Achilles insertion biomechanically, but whether calcific deposits require excision remains unclear.
Methods:
This exploratory comparative case series included 20 consecutive patients undergoing MIS Zadek osteotomy. Patients were grouped based on the presence (n = 10) or absence (n = 10) of calcification. Outcomes included visual analog scale (VAS) and European Foot & Ankle Society (EFAS) scores. Non-parametric statistical analysis was performed.
Results:
Both groups demonstrated substantial improvement, with median VAS decreasing from 7 (IQR 2) to 0 (IQR 1) at 1 year. EFAS scores improved from 12 (IQR 6) preoperatively to 24 (IQR 2) at final follow-up. With the numbers available, no significant between-group difference could be detected in VAS (P = .349), EFAS at 6 months (P = .939), or EFAS at 1 year (P = .932).
Conclusion:
MIS Zadek osteotomy was associated with substantial clinical improvement regardless of calcification. Excision of calcific deposits may not be necessary in all cases, although larger studies are required.
Level of Evidence:
Level IV, case series.
Introduction
Insertional Achilles tendinopathy (IAT) is a common cause of posterior heel pain. Calcific insertional Achilles tendinopathy (CIAT) represents a subset characterized by intratendinous or retrocalcaneal calcification and often a posterosuperior calcaneal prominence.1-5 These structural abnormalities may contribute to mechanical impingement at the Achilles insertion.
Although most cases respond to nonoperative treatment, a proportion remain symptomatic and require surgical intervention.3,6-10 Traditional techniques often involve debridement and excision of calcific deposits with partial detachment of the Achilles tendon.3,11
The Zadek dorsal closing-wedge calcaneal osteotomy alters calcaneal morphology and reduces mechanical load at the Achilles insertion.12-16 Recent studies suggest that mechanical decompression alone may be sufficient, even without excision of calcification.17,18
This study evaluated whether clinically meaningful differences exist between patients with and without calcification when the calcific deposit is intentionally left unexcised during MIS Zadek osteotomy.
Methods
This exploratory comparative case series was conducted at a tertiary referral center with institutional review board approval. Twenty consecutive patients undergoing MIS Zadek osteotomy for recalcitrant insertional Achilles tendinopathy between January 2023 and December 2024 were included. Patients were classified based on the presence (CIAT group, n = 10) or absence (control group, n = 10) of calcification on weightbearing radiographs. Patients were not randomized or matched.
A percutaneous dorsal closing-wedge calcaneal osteotomy was performed under fluoroscopic guidance using Kirschner wires to guide osteotomy trajectory, and a high-speed burr was used to complete the osteotomy. The osteotomy gap was closed with ankle dorsiflexion and stabilized using headless compression screws. Calcific deposits were intentionally left unexcised in the CIAT group (Figure 1).
Side-by-side comparison of pre- and postoperative lateral ankle radiograph. (A) Pre-operative radiograph demonstrating the posteriorly orientated bony spur. (B) Post-operative radiograph demonstrating the change in orientation of the retrocalcaneal calcification, which becomes more vertical and no longer projects posteriorly.
Perioperative antibiotic prophylaxis consisted of a single preoperative dose of intravenous cefazolin administered within 30 minutes prior to incision, followed by 2 postoperative doses in accordance with institutional protocol.
Postoperatively, patients were placed in a postoperative shoe with partial weightbearing for 2 weeks, followed by progressive weightbearing in a controlled ankle motion (CAM) boot for 4 weeks, and then transitioned to regular footwear.
Outcome measures included visual analog scale (VAS) and European Foot & Ankle Society (EFAS) functional scores recorded preoperatively and at follow-up.
Given the small sample size and non-normal distribution of variables, non-parametric statistical analysis was performed. Between-group comparisons were conducted using Mann-Whitney U tests, and changes over time were evaluated using Friedman tests for related samples. Continuous variables are presented as medians with interquartile ranges. Statistical analyses were conducted on an exploratory basis, and P values are reported descriptively.
A post hoc power analysis demonstrated that approximately 30 to 40 patients per group would be required to detect a clinically meaningful difference in VAS scores, confirming that this study is underpowered to detect small to moderate between-group differences.
Results
Baseline Characteristics
Twenty patients were included, with comparable baseline characteristics between groups (Table 1). There were no significant differences in age (P = .272), BMI (P = .820), preoperative VAS (P = .263), or EFAS scores (P = .676).
Demographic Characteristics of Patients Included in the Study.
Abbreviations: BMI, body mass index; CIAT, calcific insertional Achilles tendinopathy.
Pain improved substantially following surgery, with median VAS decreasing from 7 (IQR 2) preoperatively to 0 (IQR 1) at 1 year. With the numbers available, no significant difference between groups could be detected at 1 year (P = .349).
Functional outcomes improved, with EFAS scores increasing from a median of 12 (IQR 6) preoperatively to 19.5 (IQR 4) at 6 months and 24 (IQR 2) at 1 year across all 20 patients. With the numbers available, no significant between-group differences were observed at 6 months (P = .939) or 1 year (P = .932). Friedman analysis demonstrated significant improvement (χ² = 56.7, P < .001) (Table 2).
Comparison of Clinical and Functional Outcomes Following Minimally Invasive Zadek Osteotomy in Patients With and Without Radiographic Deformity.
Abbreviations: CIAT, calcific insertional Achilles tendinopathy; EFAS, European Foot & Ankle Society score.
Discussion
This exploratory case series suggests that minimally invasive Zadek osteotomy is associated with substantial improvement in pain and functional outcomes in patients with insertional Achilles tendinopathy regardless of whether calcific deposits are present.
Traditional surgical techniques for CIAT frequently require partial detachment of the Achilles tendon to allow excision of calcific deposits or posterior calcaneal prominence.3,11 These procedures involve direct surgical intervention at the Achilles insertion and subsequent tendon repair. In contrast, Zadek osteotomy alters calcaneal morphology and reduces mechanical compression at the tendon insertion without disrupting the Achilles tendon.12-14
Recent studies evaluating modified Zadek osteotomy have reported favorable outcomes even when intratendinous calcification is not excised.17,18 These reports support the concept that mechanical decompression of the Achilles insertion may be sufficient to alleviate symptoms in CIAT.
In the present study, both groups experienced substantial improvement in pain and function following surgery. Median VAS scores improved from severe preoperative pain to minimal pain at 1 year. Functional recovery was similarly marked, with EFAS scores approaching the maximum value of the scale at final follow-up.
However, several limitations must be acknowledged. The small sample size limits statistical power to detect between-group differences. Power analysis suggests that approximately 30 to 40 patients per group would be required to detect clinically meaningful differences in VAS scores. Additionally, the retrospective design may introduce selection bias, and EFAS scores approached the maximum value at final follow-up, suggesting a potential ceiling effect.
Despite these limitations, the consistent improvement observed in both cohorts suggests that calcific deposits may not necessarily require direct surgical excision when mechanical impingement is addressed through calcaneal osteotomy.
Conclusion
MIS Zadek osteotomy was associated with substantial clinical improvement in insertional Achilles tendinopathy. In this exploratory series, patients with calcific deposits left unexcised achieved outcomes comparable to those without calcification. Excision of calcific deposits may not be necessary in all cases, although further study is required.
Supplemental Material
sj-pdf-1-fao-10.1177_24730114261445097 – Supplemental material for Percutaneous Zadek Osteotomy for Calcific Insertional Achilles Tendinopathy: An Exploratory Comparison of Outcomes With and Without Retrocalcaneal Calcification
Supplemental material, sj-pdf-1-fao-10.1177_24730114261445097 for Percutaneous Zadek Osteotomy for Calcific Insertional Achilles Tendinopathy: An Exploratory Comparison of Outcomes With and Without Retrocalcaneal Calcification by Dhivakaran Gengatharan, Inderjeet Singh Rikhraj, Hon Keng Pui Bryan, Eric Wei Liang Cher and Wen Xian Png in Foot & Ankle Orthopaedics
Footnotes
Ethical Considerations
Ethical approval for this study was obtained from SingHealth Institutional Review Board 2020-2381
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.
References
Supplementary Material
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