Surgical Treatment of Insertional Achilles Tendinopathy With or Without Flexor Hallucis Longus Tendon Transfer

Abstract

Background: Chronic insertional Achilles tendinopathy is a common pathology that can be difficult to manage. Some experts have advocated augmentation with the flexor hallucis longus (FHL) tendon in patients over age 50 and those with more severe tendon disease. We hypothesized that FHL augmentation would be associated with superior clinical outcome scores and greater ankle plantar flexion strength compared with Achilles debridement alone. Methods: Consecutive patients older than 50 years who had failed nonoperative treatment for chronic insertional Achilles tendinopathy were randomly assigned to Achilles decompression and debridement alone (control group) or Achilles decompression and debridement augmented with FHL transfer (FHL group). Outcome measures included American Orthopaedic Foot & Ankle Society (AOFAS) ankle/hindfoot score, visual analog scale (VAS) for pain, ankle and hallux plantar flexion strength, and a patient satisfaction survey. A total of 39 enrolled patients had a minimum 1-year follow-up, 18 in the control group and 21 in the FHL transfer group. The average patient age was 60.5 years. Results: AOFAS and VAS scores improved in both groups at 6 months and 1 year with no difference between groups. There was greater ankle plantar flexion strength in the FHL group at 6 months and at 1 year compared with the control group ( P < .05). There was no difference between the 2 groups in hallux plantar flexion strength preoperatively and at 1 year after surgery. Some 87% of patients were satisfied with the outcome of their procedure. There was no significant increase in wound complications in the FHL group ( P < .05). Conclusion: We found no differences in pain, functional outcome (as measured by the AOFAS ankle/hindfoot scale), and patient satisfaction when comparing patients treated with Achilles debridement alone versus FHL augmentation for chronic Achilles tendinopathy. Ankle plantar flexion strength appeared to be improved with FHL transfer, with no loss of hallux plantar flexion strength. Although FHL transfer was a safe adjunct to tendon debridement and partial ostectomy for insertional Achilles tendinopathy in older patients with little compromise in function, it may not be necessary for primary cases. Level of Evidence: Level 1, prospective randomized trial.