Arthroscopy of the subtalar joint.

The purpose of this study was to determine the position and relative safety of the anterior, posterior, and newly defined middle portals by measuring their distance from the neurovascular structures and tendons on the lateral side of the foot and ankle. Furthermore, this study demonstrates specific components of the posterior subtalar joint and arthroscopic access to each utilizing a technique that allows direct anatomic correlation. The 15 specimens were divided into three groups of five feet each, with one arthroscopic portal site and one instrumentation portal site per group. Group I used the anterior portal for the arthroscope and the posterior portal for the curette. Group II used the posterior portal for the arthroscope and the anterior portal for the curette. In group III, the arthroscope was inserted through the anterior portal and the curette through the middle portal. The sural nerve and small saphenous vein were at risk with posterior portal placement. The anterior portal presented a minor risk of injury to the dorsal intermediate cutaneous branch of the superficial peroneal nerve. The middle portal was without risk to surrounding structures. Group I provided the best access to the posterior facet of the subtalar joint. Group II provided excellent arthroscopic visualization of the posterior facet, but poor access for instrumentation via the anterior portal. Group III provided the best access to the sinus tarsi. No combination of portals allowed visualization or instrumentation of the middle or anterior facets.