Treatment of Chronic Achilles Tendon Ruptures by Endoscopic Flexor Hallucis Longus Transfer with Double Fixation: Results in 36 Patients at a mean follow-up of 38 Months (range, 12-58 Months).

BACKGROUND

Endoscopic flexor hallucis longus (FHL) tendon transfer is now a common technique for the treatment of chronic Achilles tendon ruptures. In most cases, the FHL is harvested in zones 1-2 and fixed using an interference screw within a vertical calcaneal tunnel. To enhance fixation we developed an original technique involving fixation of the FHL by tenodesis in a horizontal calcaneal tunnel combined with tendon-to-tendon suturing. The aim of this study was to evaluate the outcomes of endoscopic FHL transfer with fixation using a tenodesis screw in a horizontal calcaneal tunnel combined with tendon-to-tendon suturing regarding: (1) iterative rupture and complications, (2) Pain and function according to European Foot and Ankle Society (EFAS) score, (3) return to work and participation is sports.

HYPOTHESIS: This method of FHL transfer would provide satisfactory functional results and enable early return to activities.

MATERIAL AND

METHODS

Thirty-six patients operated between January 2019 and June 2023 were assessed retrospectively after a mean follow-up of 38 months (range, 12-58 months). The cohort consisted of 30 men and 6 women, with a mean age of 53.6 years (range, 16-76 years) at the time of surgery. Seven cases (19.4%) involved iterative ruptures, and 29 cases (80.6%) involved chronic ruptures. All procedures were performed by the same surgeon using the same FHL transfer technique. The Visual Analog Scale (VAS) for pain and the European Foot and Ankle Society (EFAS) score were used as primary outcome measures.

RESULTS

At the final follow-up, the median VAS decreased from 7 (Inter Quartile Range (IQR), 6-8) preoperatively to 0 (IQR, 0-1.3) (p < 0.001), and the EFAS score improved from 8 (IQR, 4.8-10) to 32 (IQR, 29.5-35,3) (p < 0.001). Three surgical revisions were required for infection (8.3%). Two patients (5.6%) developed complex regional pain syndrome type 1, and three patients (8.3%) reported disabling plantar dysesthesias. No secondary graft rupture was observed. The return-to-work rate among active patients was 100%, with a median time of 3 months. Among athletes, 75.9% (22/29) resumed sports activity, with a mean postoperative Victorian Institute of Sport Assessment - Achilles (VISA-A) score of 69.2/100 (range, 44-100). Only one patient reported dissatisfaction with the surgical outcome.

DISCUSSION: Endoscopic FHL transfer with double fixation appears to be a safe and reliable technique, allowing rapid return to work and sports activities.

LEVEL OF EVIDENCE: IV; retrospective cohort study.