Coaxial portals for posterior ankle arthroscopy: An anatomic study with clinical correlation on 29 patients

Purpose: The authors performed a cadaveric study on 10 ankles and retrospec tively reviewed 29 arthroscopic synovectomies to determine the trajectory, minimal safe distances, and complications using a new approach for posterio r ankle arthroscopy. Type of Study: Anatomic study and case series. Materia ls and Methods: A posterolateral portal was established Immediately posteri or to the peroneal tendon sheath. While staying within the posterior ankle capsule, an inside-out technique was then used to establish the posteromedi al portal directly behind the medial malleolus adjacent to the posterior ti bial tendon. The cadaveric ankles were frozen, sectioned, and photographed to measure the proximity of neurovascular structures to these coaxial porta ls. From 1988 to 1994, arthroscopic synovectomy was performed on 23 patient s (29 ankles) with hemophilia using these modified portals. Results: Result s of the anatomic study showed that the posterior tibial nerve and posterio r tibial artery were located a mean distance of 5.7 mm (SER I, 0.6 mm) and 6.4 mm (SEM, 0.7 mm) from the edge of the cannula, respectively. Neither pe netration nor contact of nerve or vessel was observed at either posterior p ortal. In the 29 clinical cases, posterior capsular synovectomy was achieve d arthroscopically with no detectable complications at an average 45-month follow-up, Conclusions: Our anatomic data show that the coaxial portals des cribed here are essentially equidistant to the neurovascular structures com pared with conventional portals. Our clinical results suggest that his tech nique for posteromedial and posterolateral portals is safe, effective, and reproducible.