Clinical test for anterolateral rotary instability of the knee

A simplified test for anterolateral rotary subluxation of the knee is largely based on the concepts described by Galway and McIntosh although performed in a different manner. The examiner places the right hand gently on the lateral side of the knee with the thumb overlying the posterior aspect of the fibula and the index finger palpating the anterolateral aspect of the joint line to determine the the tibiofemoral relationship. The left hand embraces the lateral side of the distal end of the femur with the thumb over the posterior aspect of the lateral femoral condyle. With equal pressure on the lateral femoral condyle and fibular head the knee is pushed gently forward into flexion. When anterointernal tibial luxation is present, a reduction phenomenon is felt as the knee passes into the 25 to 40 degree flexion range. This may occur as a sudden palpable and occasionally audible repositioning which is responsible for such terminology as a "pivot shift" or "jerk sign." We have experienced many instances where the reduction phenomenon is more subtle and is determined by palpation alone. The pathologic mechanics are determined by observations at surgery in 45 patients with a positive test. This test has improved our diagnositc ability and is easly taught to those unfamiliar with knee joint disorders.