Motion analysis and surgical results of anterior transfer of flexor hallucis longus for equinovarus gait in children with hemiplegia

Background: Rigid equinovarus foot deformities are seen in patients with cerebral palsy (CP). This retrospective study was undertaken to evaluate flexor hallucis longus tendon (FHL) transfer with gastrocsoleus recession (GSR) using motion analyses and quantitative measurement, and to investigate postoperative complications. Methods: This study included 10 hemiplegic CP patients who underwent FHL transfer with GSR, and were evaluated by motion analyses consisting of weight distribution in static standing position and three-dimensional gait analysis, both pre and post-operatively. They were assessed in terms of kinematic data, Gait Variable Scores (GVS), and Gait Profile Score (GPS). Results: The mean age at operation was 7.3 years (range, 4-13 years), and mean follow-up duration was 35 months (range, 25-64 months) post-operatively. Weight distribution at surgical site significantly rose from 34.3% pre-operatively to 47.3% post-operatively, and abnormal asymmetry of weight distribution between surgical site and contralateral site disappeared post-operatively. Maximum ankle dorsiflexion (ADF) at initial contact rose from -20.9 degrees to -6.28 degrees. Similarly, Maximum ADF at both stance and swing phase rose from -13.8 degrees to 17.7 degrees (P = 0.0003), and from -19.5 degrees to 1.35 degrees (P = 0.001), respectively. Although mean GPS decreased from 15.6 degrees pre-operatively to 11.8 degrees, which corresponded to 2.38 times the minimal clinically important difference (MCID = 1.6 degrees), three cases manifested talipes calcaneus at final follow-up. Conclusion: Although quantitative assessment showed that the potential value of FHL transfer with GSR was to obtain initial heel contact and maintain sufficient clearance from the ground in swing, it also revealed a risk of leading to talipes calcaneus. In the near future, we should establish accurate criteria for determination of transfer site, and consider the possibility of modification of this procedure in order to balance between recurrent equinus and significant talipes calcaneus. Study design: Clinical comparison between preoperative and postoperative. (C) 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.