Abstract
From 1986 to 1995, 256 patients who had an ACL injury were operated on in our hospital. We investigated ACL injury mechanism in these patients. We examined the relationship between the position of the knee joint and the derection of force when the ACL was torn. Valgus stress to the knee and external rotation of the tibia on the femur was thought to be the most common injury mechanism.
Forty-four patients with an acute complete ACL tear were examined by Magnetic Resonance Imaging (MRI). Among them, 64% showed signs of “bone bruise” located at both the lateral femoral terminal sulcus and the postero-lateral part of the tibial plateau. These findings suggest that the common injury mechanism of the ACL involves severe anterior subluxation with impact of the posterior part of the tibia on to the femur. Particularly in a non-contact type of ACL injury, we think that contraction of the quadriceps exerts an anterior drawing force onto the tibial tubercle when the patient lands from a jump. This was thought to be the cause of the anterior tibial dislocation tibia, even if the tibia was rotated externally.
