Tibiofemoral joint positioning for the valgus stress test

Abstract

Context: Recommendations on the positioning of the tibiofemoral joint during a valgus stress test to optimize isolation of the medial collateral ligament (MCL) from other medial joint structures vary in the literature. If a specific amount of flexion could be identified as optimally isolating the MCL, teaching and using the technique would be more consistent in clinical application. Objective: To determine the angle of tibiofemoral joint flexion between 0° and 20° that causes a difference in the slope of the force-strain line when measuring the resistance to a valgus force applied to the joint. Design: Cross-sectional study. Setting: University research laboratory. Patients or Other Participants: Twelve healthy volunteers (6 men, 6 women: age = 26.4 ± 5.6 years, height = 170.9 ± 8.4 cm, mass = 75.01 ± 14.6 kg). Intervention(s): Using an arthrometer, we applied a valgus force, over a range of 60 N, to the tibiofemoral joint in 0°, 5°, 10°, 15°, and 20° of flexion. Main Outcome Measure(s): Force-strain measurements were obtained for 5 positions of tibiofemoral joint flexion. Results: As knee flexion angle increased, slope values decreased (F4,44 = 17.6, P < .001). The slope at full extension was not different from that at 56 of flexion, but it was different from the slopes at angles greater than 106 of flexion. Similarly, the slope at 56 of flexion was not different from that at 10° of flexion, but it was different from the slopes at 15° and 20° of flexion. Further, the slope at 106 of flexion was not different from that at 15° or 20° of flexion. Finally, the slope at 15° of flexion was not different from that at 20° of flexion. Conclusions: When performing the manual valgus stress test, the clinician should fully extend the tibiofemoral joint or flex it to 5° to assess all resisting medial tibiofemoral joint structures and again at 15° to 20° of joint flexion to further assess the MCL. © by the National Athletic Trainers' Association, Inc.