All-inside endoscopic treatment of ganglion cyst of the flexor hallucis longus tendon sheath: surgical technique and short-term outcomes

Hallucal ganglion cysts (HGCs) are often symptomatic and recurrent. We aimed to evaluate the feasibility and clinical outcomes of all-inside endoscopic partial excision of the flexor hallucis longus (FHL) tendon sheath combined with wider resection of the posterior ankle capsule for the treatment of ankle-derived HGCs. Twenty-four patients with HGCs who underwent surgical intervention between February 2021 and February 2024 were included. Thirteen patients had known recurrences, and twelve developed ulcerations. All patients underwent preoperative ankle arthrography to confirm communication between the cyst and ankle joint, followed by arthroscopic surgery. The cystic nature of the hallux mass was confirmed preoperatively by either ultrasound or magnetic resonance imaging (MRI). Clinical evaluations included the American Orthopaedic Foot & Ankle Society (AOFAS) score, visual analog scale (VAS), and the Short-From-36 Health Survey (SF-36). Complications were assessed postoperatively and during follow-up. Twenty-four patients were followed up, with a mean follow-up period of 27.92 ± 2.81 months (range: 24–35 months). The VAS score decreased from 3 (1.25, 4) to 0 (0, 1), the AOFAS score improved from 79.58 ± 6.92 to 94.46 ± 3.74, and the SF-36 score improved from 55.17 ± 11.06 to 89.71 ± 5.44 at the last follow-up. All differences were statistically significant ( P < 0.001). Two minor complications were observed: one patient developed scar‑related pain, and another reported transient tibial‑nerve‑distribution numbness; both resolved with symptomatic conservative management. In selected patients with ankle-communicating HGCs, all-inside endoscopic partial excision of the flexor hallucis longus (FHL) tendon sheath combined with wider resection of the posterior ankle joint capsule achieved favorable short-term clinical outcomes. Ankle arthrography is helpful for the preoperative identification of ankle–joint communication. The ankle-origin pathogenesis remains a working hypothesis that requires further validation. Level IV, retrospective case series.