Sonographic evaluation of ACL rupture signs compared to arthroscopic findings in acutely injured knees.

Evaluation of ultrasound (US) examination for the diagnosis of an acute anterior cruciate ligament (ACL) rupture. We performed a prospective examination of 193 patients to analyze the three indirect criteria of ACL rupture: echo-poor space at the femoral insertion of the ACL, S-shaped course and thickening of the posterior cruciate ligament (PCL) and protrusion of the posterior fibrous capsule. The assumption that the echo-poor space at the femoral insertion has a great significance was confirmed in this study. Sensitivity for ACL rupture was 0.91 and specificity was 0.80, protrusion of the posterior fibrous capsule had a specificity of 0.77 and a sensitivity of 0.68. The use of both criteria increased the sensitivity of sonography to 0.98, but the specificity decreased to less than 0.50. We conclude that the US examination with its three indirect signs of ACL rupture has a high predictive value in the acute traumatized knee joint.