[Efficacy of Hintermann calcaneal lengthening osteotomy for flexible flatfoot]

Objective: To investigate the clinical efficacy of Hintermann osteotomy (H-LCL) for flexible flatfoot. Methods: A follow-up study. Clinical data of 30 patients with flexible flatfoot treated with H-LCL operation from January 2020 to December 2021 in Sports Medical Center of the First Affiliated Hospital of Army Medical University were retrospectively analyzed. There were 8 males and 22 females, with a mean age of (39.0±15.2) years. The mean time from symptom onset to the diagnosis［M（Q₁，Q₃）］was 24.0 (5.5, 102.0) months. The functional and imaging scores of the patients before and after the last follow-up were compared to evaluate the clinical efficacy of the operation. The functional scores included American Orthopedic Foot and Ankle Society (AOFAS) score, visual analogue scale (VAS) of pain, pain interference (PI) and physical function (PF) index in Patient-Reported Outcomes Measurement Information System (PROMIS). And the imaging scores included Meary's angle, calcaneal pitch angle, calcaneal valgus angle and talonavicular coverage angle. Results: The mean operation time was (82.3±24.4) min, and the follow-up periods was (17.9±6.9) months. At the last follow-up, VAS of pain [M(Q₁, Q₃)] decreased from 5 (4, 6) to 2 (1, 2); PI decreased from 59.8±5.0 to 44.6±5.7; AOFAS increased from 65.2±10.0 to 85.8±3.3; PF increased from 50 (48.5,51.0) to 58.5 (54.0, 66.0); Meary's angle (antero-posterior image) decreased from 15.7° (10.1°, 29.2°) to 3.9° (2.6°, 5.3°); Meary's angle (lateral image) decreased from 13.5°±6.8° to 4.4°±2.6°; calcaneal pitch angle increased from 14.0°±3.3° to 18.6°±4.2°; calcaneal valgus angle decreased from 12.6°±7.3° to 4.3°±2.5°; and talonavicular coverage angle decreased from 20.9°±10.7° to 7.7°±5.2°. The up-mentioned parameters were all improved statistically significant at the last follow-up when compared with those before the operation (all P<0.05). Conclusion: H-LCL brings a significant improvement of clinical outcome scores and good radiological correction of flatfoot deformities in correcting flexible flatfoot, it conforms to the anatomical characteristics of the subtalar joint.