On the basis of the experimental data presented, it seems logical to conclude that fracture of the lateral tibial plateau and rupture of the medial collateral ligament may occur simultaneously. In such circumstances, the medial collateral ligament injury may be demonstrated by gentle abduction stress testing of both knees and comparing the medial clear space of both the normal and the involved knees. Using this test, an increase of more than 1.0 millimeter in the medial clear space is presumptive evidence of either partial or complete rupture of the medial collateral ligament.