Transfer of the Flexor Hallucis Longus Tendon for Neglected and Degenerative Tendo Achillis Rupture: A Prospective Clinical Study

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Introduction. The Achilles tendon is one of the most frequently ruptured tendons in the human body. Surgical management commonly includes end to end repairs in acute tears, and chronic ruptures require autologous tendon transfer with Flexor hallucis longus or Flexor digitorum longus. Methods. A longitudinal observational study was done on 22 confirmed cases of chronic Achilles tendon rupture. Two incision technique of FHL tendon transfer with no exposure/debridement of the Tendoachilles was incorporated and functional outcome with American Orthopaedic Foot and Ankle Society Ankle-Hindfoot score, modified RUPP and Achilles Tendon Total Rupture (ATRS) scores both pre- and post-operatively were evaluated. Wound healing time and complications, heel-floor distance, calf circumference, hallux function and morbidity, graft characteristics and anatomic variation of master Knot of Henry were evaluated. Patients were followed up and assessed at 6 weeks, 3 months, and 6 months post-operatively. Results. The mean length of the FHL graft obtained from 2 incision technique was 8.09 cm. There was significant improvement in the Heel Rise Height Index from 7 to 63% (p < 0.0001), mean AOFAS ankle-hindfoot score from 43.9 to 89.6 (p < 0.001), mean ATRS Score from 19.6 to 79 (p < 0.0001) and mean Hallux MTP-IP scores to 96.3 (p < 0.0001) at 6th month follow up was found. 13 (59%) had “Excellent” modified RUPP scores. 20 (90.9%) had Type I variation while 2 (9.1%) had Type II variation in MKH. Mean length of the graft obtained was 8.09 cm. Mean wound healing time was about 13 days and only one had wound complication. Conclusions. FHL tendon transfer has advantages of requiring minimal dissection, being stronger than FDL and PB and it is an in-phase transfer with the same axis of contraction.