Transfer of the flexor hallucis longus to replace the Achilles tendon. Indications, technique and results

Background. Transfer of the flexor hallucis longus (FHL) tendon is a therapeutic option to replace a dysfunctional Achilles tendon in cases of rerupture with large defects, loss of the Achilles tendon after postoperative infection or severe tendinosis. Materials and methods. Between January 1994 and December 2005, 35 patients (5 female and 30 male, average age 47 years) were treated with 36 FHL transfers and 25 patients with 26 FHL transfers could be re-evaluated at a mean follow-up time of 79 months (range 20-133 months) after surgery. Results. Of the 25 patients, 18 (72%) subjectively rated the result as excellent, 5 (20%) as good, and 1 patient (4%) each as fair and poor. According to the criteria of Trillat and Mournier-Kuhn, 18 patients (72%) were rated excellent, 4 (16%) good and 3 (12%) fair. The AOFAS ankle/hindfoot score at follow-up averaged 91 (range 13-100), the AOFAS forefoot score averaged 95 (range 24-100). Conclusions. FHL transfer to the Achilles tendon provides favorable results in cases of complicated cases with defects, infections or severe tendinosis after Achilles tendon rupture.