Intercondylar Roof Inclination Angle: Is It a Risk Factor for ACL Tears or Tibial Spine Fractures?

Background: The relationship between the angle of inclination of the intercondylar roof [roof inclination angle (RIA)] and likelihood of knee injury has not been previously investigated in children. Methods: Twenty-five skeletally immature patients with a tibial spine fracture were age matched (+/- 1 y) and sex matched with 25 patients with an anterior cruciate ligament (ACL) tear and with 50 control knees (2 for each patient). Demographic and diagnostic information was collected, and radiographic measurements were performed on notch and lateral radiographs of the knee. Results: Patients with a tibial spine fracture had an increased RIA compared with controls and patients with an ACL tear. Patients with ACL tears had a steeper notch roof, as indicated by a decreased RIA when compared with controls and patients with tibial spine fractures. Conclusions: Our results demonstrated that a decreased RIA was associated with ACL tear and that an increased RIA was associated with tibial spine fracture.