KNEE EXTENSION AND ITS RELATIONSHIP TO THE SLOPE OF THE INTERCONDYLARROOF - IMPLICATIONS FOR POSITIONING THE TIBIAL TUNNEL IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTIONS

This study determined that knee extension (range, -30 degrees to 2 deg rees) and the slope of the intercondylar roof (range, 26 degrees to 46 degrees) vary widely between knees in both men and women. We found a weak relationship between knee extension and the slope of the intercon dylar roof (r(2) = 0.207); therefore, roof angle cannot be predicted b y clinically measuring knee extension. Clinical relevance: A knee with a given degree of extension can have a variety of different slopes to the intercondylar roof. Knees with the combination of hyperextension and a vertically oriented slope to the intercondylar roof are ''unforg iving'' because they require a more posterior position for the tibial tunnel to avoid roof impingement and an extensive roofplasty. If the s urgical objective is to minimize the extent of the roofplasty and avoi d roof impingement, then consideration should be given to customizing the placement of the tibial tunnel to account for variability in knee extension and roof angle when reconstructing the anterior cruciate lig ament. Studies have shown that isometric graft placement can be achiev ed with this surgical approach.