Isolated Flexor Hallucis Longus Tendon Transfer for Chronic Achilles Tendon Rupture: Systematic Review and Meta-Analysis

Abstract

Background: Chronic Achilles tendon ruptures (CATRs) pose a clinical challenge because guidelines on optimal treatment modalities are lacking. This meta-analysis aims to investigate the use of Flexor Hallucis Longus (FHL) tendon transfer as a treatment option. Methods: A literature search was performed across multiple databases from inception until 31 July 2025. The databases searched included Ovid MEDLINE®, EMBASE (Elsevier), Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews. Included studies presented CATR patients of all ages, with no previous surgeries to the ankle, who were managed with an FHL tendon transfer (PROSPERO ID: CRD42023489724). Results: Sixteen studies met the eligibility criteria with 323 patients. For functionality, baseline AOFAS-AH (American Orthopaedic Foot & Ankle Society—Ankle Hindfoot) scores were 56.85 (95% CI: 51.03–62.68, I2 = 96%). At ≥12 months post-operative follow-up, AOFAS-AH scores were 91.46 (95% CI: 88.45, 94.48, I2 = 93%). ATRS (Achilles Tendon Rupture Score) at baseline was reported as 31.04 (95% CI: 5.80, 56.28, I2 = 99%). At ≥12 months post-operative follow-up, ATRS amounted to 90.73 (95% CI: 83.69, 97.77, I2 = 89%). Overall complication rates were 7.5% (CI: 0.04,0.11, I2 = 40%), consisting of superficial infections at 4.2% (95% CI: 0.01, 0.07, I2 = 0%), activity limitations at 4% (95% CI: 0.01, 0.08, I2 = 0%) and disturbed wound healing at 3.8% (95% CI: 0.01, 0.06, I2 = 0%). The minimum clinically important difference (MCID) for ATRS was achieved at 12 months onwards. Conclusions: Surgical management of CATR patients with FHL tendon transfer appears to improve functionality and subjective outcomes, supporting its use amongst the treatment modalities available.