1. Early and thorough examination is essential for exact diagnosis, which forms the basis for rational treatment in all injuries to the collateral and cruciate ligaments of the knee joint.
2. In addition to a careful history and examination, the authors advocate the use of certain tests which are helpful in diagnosis.
3. Abduction rocking to a moderate degree may indicate an isolated lesion of the tibial collateral ligament. Abduction rocking to a marked degree is indicative of combined injury to tibial collateral and anterior cruciate ligaments. Verification of abduction rock ing is obtained by anteroposterior roentgenograms of both knees, held in abduction to show the relative degree of separation of the joint surfaces on their medial aspects. In the presence of muscle spasm, this test may require general anaesthesia. If this test is positive, an operation for repair of the injured ligament should be performed.