Anatomical Variation of the Posterior Tibial Neurovascular Bundle During Posterior Ankle Arthroscopy for Posterior Ankle Impingement Syndrome: A Case Report.

We report the case of a 32-year-old male professional soccer player presenting with a one-year history of posterior ankle pain due to posterior ankle impingement syndrome secondary to an elongated Stieda process and loose bodies. Preoperative review of MRI revealed an anatomical variation of the posterior neurovascular bundle in relation to the flexor hallucis longus (FHL) tendon at the level of the ankle joint. In this case, the neurovascular bundle was situated posterior and lateral to the FHL tendon, as opposed to medial to the FHL tendon, as seen in typical anatomy. This finding is significant because posterior ankle arthroscopy relies on the FHL tendon as an anatomical landmark to protect the posterior neurovascular bundle by always working lateral and posterior to the tendon. An arthroscopic approach would have posed a high risk of iatrogenic injury to the tibial nerve and posterior tibial vessels. The originally planned arthroscopic ankle debridement was therefore changed to an open approach using a posteromedial incision. Postoperative recovery was uncomplicated, and the patient returned to soccer within seven weeks with little swelling and no pain.