Instrumented measurement of glenohumeral joint laxity and its relationshipto passive range of motion and generalized joint laxity

The purpose of this study was to objectively characterize in vivo glenohume ral joint laxity using an instrumented shoulder arthrometer. Secondary obje ctives were to examine the relationship of glenohumeral joint laxity with p assive 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 d ata were obtained at displacement forces of 67, 89, 111, and 134 N. Bilater al passive shoulder range of motion measures were obtained, and a modified Beighton Mobility Score was used to quantify generalized joint laxity. Ther e were no significant differences in glenohumeral joint laxity between the right and left shoulders (P values = 0.14 to 0.73). No significant differen ces in laxity were seen between directions (F-(1,F-4000) = 1.35, P = 0.25). However, significant differences were observed between force levels (F-(3, F-400) = 27.17, P < 0.0001). No moderate or stronger correlations between l axity, passive range of motion, and generalized joint laxity were seen. The se data confirm the presence of a wide spectrum of symmetric laxity in subj ects that fails to correlate strongly with passive range of motion or gener alized joint laxity.