PARTIAL TEARS OF THE ANTERIOR CRUCIATE LIGAMENT - ARE THEY CLINICALLYDETECTABLE

Eight cadaveric lower extremities were examined by three experienced k nee surgeons in blinded fashion. The knees were examined with intact a nterior cruciate ligaments, sectioned anteromedial bundles, and comple tely sectioned anterior cruciate ligaments to evaluate detectable laxi ty changes. Lachman, anterior drawer, lateral pivot shift, and KT-1000 arthrometer testing were performed. Optimized biplanar radiography us ing a defined spatial coordinate reference system was performed with a 30-pound anterior force at 30 degrees of flexion to confirm clinical findings. Physical examination and arthrometer testing detected no dif ference between intact and partially sectioned anterior cruciate ligam ents; these ligaments were significantly different than completely sec tioned ligaments, with the Lachman test being the most sensitive. Desp ite consistent clinical detection of complete sectioning of the anteri or cruciate ligament by both physical examination and arthrometer test ing, neither method proved accurate in the diagnosis of isolated tears of the anteromedial bundle, but both did show that partially sectione d anterior cruciate ligament closely resembled intact ligament and dif fered significantly from completely sectioned ligament, as confirmed b y radiologic data. Clinically diagnosed ''partial tear'' is likely to be complete rupture of the anterior cruciate ligament. Historically, c linically diagnosed partial tears of the anterior cruciate ligament ha ve tended to ''progress'' to symptomatic instability. Our data imply t hese patients may have had functionally incompetent ligaments from tim e of injury and, in fact, were demonstrating the expected natural hist ory of an anterior cruciate ligament-deficient knee.