Instrumented Measurement of Glenohumeral Joint Laxity and its Relationship to Passive Range of Motion and Generalized Joint Laxity

The purpose of this study was to objectively characterize in vivo glenohumeral joint laxity using an instrumented shoulder arthrometer. Secondary objectives were to examine the relationship of glenohumeral joint laxity with passive range of motion and generalized joint laxity. Fifty-one recreational athletes with no history of shoulder injury or long-term participation in overhead sports participated in this study. Anterior and posterior laxity data were obtained at displacement forces of 67, 89, 111, and 134 N. Bilateral passive shoulder range of motion measures were obtained, and a modified Beighton Mobility Score was used to quantify generalized joint laxity. There were no significant differences in glenohumeral joint laxity between the right and left shoulders ( P values = 0.14 to 0.73). No significant differences in laxity were seen between directions (F (1,400) = 1.35, P = 0.25). However, significant differences were observed between force levels (F (3,400) = 27.17, P < 0.0001). No moderate or stronger correlations between laxity, passive range of motion, and generalized joint laxity were seen. These data confirm the presence of a wide spectrum of symmetric laxity in subjects that fails to correlate strongly with passive range of motion or generalized joint laxity.