Magnetic resonance imaging of posterior cruciate ligament injuries: a new classification of traumatic tears.

PURPOSE: The aim of our study was to propose a new classification of acute posterior ligament (PCL) injuries based on magnetic resonance imaging (MRI).

MATERIALS AND METHODS: Using MRI, we reviewed 220 patients presenting an acute posterior ligament injury. The MRI exam was performed on a 0.2-Tesla (T) magnet and a 1.5-T magnet using T1-weighted spin echo (SE), T2-weighted SE and fat-suppression scans [short-tau inversion recovery (STIR)] in axial, sagittal and coronal planes. In no case was paramagnetic contrast agent injected.

RESULTS: Twenty-five per cent of patients were identified as having type I lesions and another 30% as having type II lesions according to the Gross classification. Out of 77 patients, 35% of the whole sample, 37 had a tear of the posteromedial fascicle (type II lesion), and the remaining 40 had anterolateral fascicle tears (type III). In 10% of cases, the ligaments appeared completely interrupted, and these were classified as type IV lesions.

CONCLUSIONS: T1-weighted SE sequences need to be integrated with T2-weighted and STIR sequences to detect the real extent of the remaining fascicle. The MRI exam could thus be able to provide a qualitative evaluation of PCL injuries and establish how the injury compromises joint stability.