Arthroscopy of the posterior knee compartments: neurovascular anatomic relationships during arthroscopic transverse capsulotomy.

PURPOSE: To clearly define the anatomic relations that exist in the posterior knee under arthroscopic conditions in a cadaveric model and to describe a technique for an all-arthroscopic posterior capsule release.

METHODS: Seven cadaveric knees were examined under arthroscopic conditions. After a routine diagnostic arthroscopy of the anterior compartment, posteromedial and posterolateral portals were created, the posterior capsule and septum were released, and the distance from the posterior border of the tibial insertion of the posterior cruciate ligament (PCL) to the popliteal artery was measured under direct arthroscopic visualization after capsulotomy. The distances from the posteromedial arthroscopic portal and lateral arthroscopic portal to the saphenous neurovascular bundle and peroneal nerve, respectively, were evaluated.

RESULTS: The mean distance between the PCL and popliteal artery was 19.3 mm (range, 15 to 28 mm; SD, 4.27 mm); between the posteromedial portal and saphenous vein, 22.6 mm (range, 16 to 35 mm; SD, 6.7 mm); and between the posterolateral portal and peroneal nerve, 40 mm (range, 30 to 52 mm; SD, 7.94 mm).

CONCLUSIONS: When arthroscopic posterior transverse capsulotomy is performed via the author's technique and with the knee flexed to 90 degrees , there is an adequate safe zone between the popliteal neurovascular structures, peroneal nerve, saphenous neurovascular structures and the posterior capsule, posterolateral and posteromedial portals, respectively (minimum, 15 mm).

CLINICAL RELEVANCE: With a mean distance of 19.3 mm between the PCL and the popliteal artery after capsulotomy, surgeons can feel confident that a safe zone is present for posterior knee arthroscopy. In addition, they can be reassured that posterior portals are safe if created with the knee in the proper position.