[Proton spin and computerized tomography in ligament injuries of the knee joint]

In a prospective study we evaluated the use of cat-scan an MRI in 106 patients with chronic complaints and acute injuries of the knee joint. All patients went to surgery afterwards. A total of 30 patients suffered from acute or chronic ligament ruptures. There were 20 ACL ruptures, 2 PCL ruptures, 3 MCL ruptures, and 2 LCL ruptures. In patients with ACL ruptures the MRI had a sensitivity of 80%, a specificity value of 80%, and a negative predictive value of 95%; whereas cat-scan had a sensitivity of 90%, a specificity of 95%, an accuracy of 94%, a positive predictive value of 82%, and a negative predictive value of 98%. All complete ACL ruptures we correctly diagnosed. However, 4 partial ACL ruptures were missed by MRI and 2 partial ruptures were missed by cat-scan. All other ligament ruptures (PCL, MCL, LCL) except one MCL rupture were correctly diagnosed by MRI as well as by cat-scan.

In this study cat-scan and MRI proved to have a very high negative predictive value. Having a negative result in one of these imaging techniques means that a rupture of a ligament is highly unlikely. This may have influence on the number of unnecessary invasive arthroscopic procedures.