Analysis of the intercondylar notch by computed tomography

The purposes of this study were to document the dimensions and configuration of the intercondylar notch in the normal knee; to compare normal knee intercondylar notches to those of knees with unilateral and bilateral ACL tears to determine if there is a relationship between intercondylar notch stenosis and ACL tears; and to determine if generalized ligamentous laxity is associated with intercondylar notch stenosis and ACL tears. Three groups were compared: Group I, bilateral ACL tears; Group II, unilateral tears; and Group III, normal knees. Notch dimensions were computer-generated from CT scans. All patients were examined for ligamentous laxity. Statistically significant differences were found between normal and ACL-injured knees in regard to opening notch angle, ratio of notch width at two-thirds of the notch length to condylar width, and ratio of maximum notch width to condylar width, suggesting a significant association between anterior outlet stenosis and unilateral and bilateral ACL tears. The shapes of the notches were determined from tracings of the distal CT scan. Shapes ranged from inverted U to cresting wave. Narrow notches tended to be waveshaped, but more study is needed in this area. Notch-plasty is recommended for those with documented stenosis. The ratio of maximum notch width at two-thirds of the notch height to maximum condyle width should not be much less than 0.2, and the opening notch angle should be at least 50 degrees.