COPYRIGHT © 2002 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED Posterior Ankle Arthroscopy AN ANATOMIC STUDY

Background: Ankle arthroscopy has generally been performed with use of anterior portals with the patient in the supine position. Little has been published on ankle arthroscopy performed with use of posterior portals, particularly with the patient in the prone position. The purpose of the present study was to evaluate the relative safety and efficacy of ankle arthroscopy with use of posterior portals with the limb in the prone position. Methods: Thirteen fresh-frozen cadaver specimens were used. Posterolateral and posteromedial portals were established. Arthroscopy was performed, and the extent of the talar dome that could be visualized was marked. Four-millimeter plastic cannulae were filled with oil and were placed in the portals for use as reference land-marks on magnetic resonance imaging studies. The proximity of the portal cannulae to the adjacent structures was measured on standard magnetic resonance images and then during careful dissection. The distances mea-sured by dissection were compared with the measurements made on magnetic resonance images. Results: An average of 54 % (range, 42 % to 73%) of the talar dome could be visualized. The average distance between a cannula and adjacent anatomic structures after dissection was 3.2 mm (range, 0 to 8.9 mm) to the sural nerve, 4.8 mm (range, 0 to 11.0 mm) to the small saphenous vein, 6.4 mm (range, 0 to 16.2 mm) to the tibial nerve, 9.6 mm (range, 2.4 to 20.1 mm) to the posterior tibial artery, 17 mm (range, 19 to 31 mm) to the medial calcaneal nerve, and 2.7 mm (range, 0 to 11.2 mm) to the flexor hallucis longus tendon. The magneti