Characterization of spontaneous healing of chronic posterior cruciate ligament injury: Analysis of instability and magnetic resonance imaging.

PURPOSE: To explore the healing process of the injured posterior cruciate ligament (PCL) by evaluating instability measurements and magnetic resonance imaging (MRI) findings.

MATERIALS AND METHODS: A retrospective cross-sectional study of 46 cases of complete PCL tear who obtained MRI more than two months after injury.

RESULTS: A total of 13 cases (28%) showed nearly normal PCL contour, 20 cases (44%) showed continuity but deformed PCL contour, and 13 cases (28%) showed discontinuity. The duration from injury to MRI was not directly correlated with continuity. However, the group that obtained MRI more than six months after injury showed more continuity than the group that obtained MRI within six months of the injury (P < 0.01). The group with nearly normal continuity showed better stability results in the KT-1000 arthrometer and stress radiographs than the group with discontinuity (P < 0.05). The presence of other combined ligament injuries had a negative effect on regaining PCL continuity (P <0.05).

CONCLUSION: More than two-thirds (72%) of chronic PCL injury cases showed ligamentous continuity on MRI, especially when the injury had occurred more than six months before. Stability may improve as continuity is regained. The presence of other combined ligament injuries appears to prohibit spontaneous PCL healing.