Lachman test evaluated. Quantification of a clinical observation.

The Lachman test has become recognized as the most reliable noninvasive clinical method for determining the integrity of the anterior cruciate ligament. The original description provided for the test is reported as either positive or negative. The purpose of this study is to present a clinical grading system for positive examinations. The criteria are as follows: Grade I, proprioceptive appreciation of a positive test; Grade II, visible anterior translation of the tibia; Grade III, passive subluxation of the tibia with the patient supine; and Grade IV, ability of the patient with a cruciate-deficient knee to actively sublux the proximal tibia. Seventy-five patients with arthroscopically documented complete anterior cruciate ligament tears were examined clinically and graded using the above criteria. In addition, all patients had arthrometric examinations to measure the amount of anterior subluxation of the tibia in millimeters. A one-way analysis of variance followed by Scheffe multiple comparisons demonstrated the mean measurements of anterior displacement of the tibia in each laxity group to be significantly different.