Bilateral Simultaneous Chronic Achilles Tendon Rupture Treated With Open and Endoscopic Flexor Hallucis Longus Tendon Transfer: A Case Report

Bilateral chronic Achilles tendon rupture is an exceptionally rare condition with limited evidence guiding optimal management. We present a unique within-patient comparison of two reconstructive techniques: endoscopic flexor hallucis longus (FHL) tendon transfer on one side and open FHL transfer on the contralateral side. This design eliminates interpatient variability and allows direct comparison of operative time, surgical exposure, cosmetic outcomes, and functional recovery. Functional outcomes were assessed at 12 months and confirmed at the 24-month follow-up. Both techniques resulted in excellent restoration of plantar flexion strength and high patient satisfaction. The endoscopic approach required longer operative time but appeared to offer better cosmetic outcomes based on wound appearance. This case suggests that both open and endoscopic FHL tendon transfer may be effective options for chronic Achilles tendon rupture; however, further studies are needed to validate these findings.