Flexor Hallucis Longus Tendon Impingement Syndrome: All-inside Arthroscopic Treatment and Long-term Follow-up

This study aimed to evaluate the surgical technique and long-term clinical outcomes of all-inside arthroscopic treatment for flexor hallucis longus (FHL) tendon impingement syndrome. We retrospectively evaluated 34 FHL tendon impingement syndrome patients with complete follow-up data who were admitted from June 2015 to August 2018 and underwent the all-inside arthroscopy technique. The subjects consisted of 20 (58.82%) males and 14 (41.18%) females, with a mean age of 32.7 ± 10.2 (range 21-52) years. The cases consisted of 19 (55.88%) right and 15 (44.12%) left feet. The mean disease duration was 18.5 ± 9.1 (range 10-43) months. The visual analogue scale (VAS), American Orthopaedic Foot & Ankle Society (AOFAS), Karlsson Ankle Functional Score (KAFS), and 36-item Short Form Health Survey questionnaire (SF-36) scores for pain were 3.6 ± 1.2, 84.1 ± 9.6, 86.3 ± 10.7, and 94.7 ± 9.3, respectively. All patients were treated with all-inside posterior arthroscopy for the debridement of the FHL tendon sheath combined with partial muscle belly resection. Post-operative follow-up and observation of the patients' pain and ankle movement were evaluated using VAS, AOFAS, KAFS, and SF-36. All incisions were healed in the first stage, and no complications such as nerve, blood vessel, or tendon injuries occurred. The hospital stays were 3 to 5 days, with a mean of 3.7 ± 1.3 days. All patients were followed up for 12 to 36 months, with a mean follow-up time of 25.4 ± 8.5 months. By the last follow-up, the ankle joint and hallux movement were normal and returned to the pre-pain state for these patients. The VAS score decreased to 0.2 ± 0.1, while the AOFAS, KAFS, and SF-36 scores increased to 97.7 ± 8.5, 97.9 ± 8.2, and 118.2 ± 8.4, respectively. Advantages of all-inside posterior arthroscopic partial muscle belly resection for the treatment of FHL tendon impingement syndrome include small surgical trauma, fast functional recovery, and reliable outcomes. This procedure is therefore worthy of clinical attention and promotion.