Topographical anatomy of the intercondylar roof. A pilot study.

Anatomical features of the intercondylar roof with respect to the native anterior cruciate ligament and proposed substitute ligament attachment sites in anterior cruciate ligament reconstructive surgery were investigated. Using cadaveric knees and K wires, radiographs were obtained with markers placed on the roof and the tibial and femoral attachment sites. In the knees studied, the intercondylar roof was V shaped with distinct anterior and posterior limbs. The posterior limb corresponded to the radiographic line commonly called Blumensaat's line. The anterior limb was oriented 25 degrees more vertical than the posterior limb and impinged on the anterior cruciate ligament in extension. In this pilot study, estimates of the degree of impingement in full extension were made by drawing lines representative of 10-mm grafts at selected sites on lateral radiographs. A graft placed at the central portion of the native femoral site to the normal tibial site did not impinge, while a graft placed at the traditional femoral site to an anteromedial tibial site impinged as much as 8 mm throughout its entire extent. This pilot study presents preliminary, provocative information suggesting that the intercondylar roof is actually V shaped and that substitute ligaments placed at attachment sites commonly used today may impinge over most of their length.