Posterior portals for arthroscopic surgery of the knee.

Posterolateral and posteromedial portals are necessary for certain arthroscopic procedures of the knee. Many surgeons hesitate to use portals. A cadaveric study was performed to identify the structures at risk in establishing these portals. These include the saphenous vein and nerve, popliteal vessels, lateral superior and inferior genicular arteries, and peroneal nerve. Two basic techniques can be used to visualize the posterior compartments--from the same side or diagonally across the intracondylar notch. A clinical review of 179 patients in which posterior portals were used showed no serious complications. In three cases there was residual numbness in the distribution of the saphenous nerve and in two cases the saphenous vein was punctured. In three cases, the posterior compartments could not be safely visualized. In 87 cases the posterior compartment was visualized from the ipsilateral side; in the remaining 92 cases we used the contralateral technique placing the arthroscope diagonally across the intracondylar notch.