The Effect of Preoperative X/Y Ratio on Clinical Outcomes following Percutaneous Zadek Osteotomy for Insertional Achilles Tendinopathy

Background: The percutaneous dorsal closing wedge calcaneal Zadek osteotomy (ZO) is an effective treatment for patients with insertional Achilles tendinopathy (IAT), although consensus is lacking on ideal patient selection. Tourné et al proposed that a preoperative calcaneal X/Y ratio <2.5 defines surgical candidacy, but this criterion remains controversial. This study evaluated whether patients with IAT benefit from percutaneous ZO regardless of preoperative X/Y ratio. Methods: A retrospective comparative study of 27 patients undergoing percutaneous ZO was performed. Patients were stratified into 2 cohorts based on preoperative X/Y ratio (<2.5 vs ≥2.5). Primary outcomes were PROMIS scores for pain, function, and mobility at 3, 6, and 12 months. Secondary outcomes included complication rates and radiographic parameters. Minimal clinically important differences were used to assess clinical significance. Results: Between May 2022 and May 2024, 27 cases were included in the current analyses. Seventeen cases had an X/Y <2.5; 10 had an X/Y ≥2.5. Both cohorts demonstrated significant improvement in PROMIS pain, function, mobility scores ( P < .05). Patients with X/Y ≥2.5 demonstrated statistically greater improvement in pain scores than patients with X/Y <2.5 ( P = .049) at 1-year follow-up. Ninety-eight percent of patients were satisfied following ZO intervention. Conclusion: Percutaneous ZO demonstrated meaningful improvement in patients’ function, pain, and mobility regardless of preoperative X/Y ratio. These findings challenge the use of the <2.5 X/Y threshold as a strict selection criterion. Percutaneous ZO may be a viable option for a broader population of IAT patients than previously considered.