Posterolateral and posteromedial portals are necessary for certain art
hroscopic procedures of the knee. Many surgeons hesitate to use portal
s. A cadaveric study was performed to identify the structures at risk
in establishing these portals. These include the saphenous vein and ne
rve, popliteal vessels, lateral superior and inferior genicular arteri
es, 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 poste
rior portals were used showed no serious complications. In three cases
there was residual numbness in the distribution of the saphenous nerv
e and in two cases the saphenous vein was punctured. In three cases, t
he 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 th
e arthroscope diagonally across the intracondylar notch.