Chronically injured posterior cruciate ligament: magnetic resonance imaging.

Magnetic resonance imaging has been said to be highly reliable for diagnosis of acute posterior cruciate ligament insufficiency. In the present study, 13 patients whose posterior cruciate ligament insufficiency had been documented by magnetic resonance imaging within 10 weeks of the acute injury were recalled for a followup examination and magnetic resonance imaging. The followup interval ranged from 5 months to 4 years. In only 23% of the cases did the posterior cruciate ligament still appear discontinuous on followup magnetic resonance imaging. In the remaining 77%, the posterior cruciate ligament was continuous from tibia to femur, although it appeared abnormally arcuate or hyperbuckled. Conventional interpretation of these magnetic resonance images would suggest that the posterior cruciate ligament had healed. Nevertheless, by clinical examination results, these same patients all were judged to have posterior cruciate ligament insufficiency. Thus, it was concluded that although magnetic resonance imaging may be reliable for evaluation of acute posterior cruciate ligament injury, magnetic resonance imaging findings should not be used to infer functional status in chronic cases.