[Biomechanical evaluation of glenohumeral ligament in holding anterior stability of shoulder joint].

ABSTRACT

OBJECTIVE: To investigate the effect of glenohumeral ligament (GHL) in static stabilizing structure of shoulder joint. METHODS: Fifteen upper limbs specimen from fresh adult corpse were made shoulder joint-bone ligament specimen and divided in 5 groups (n=3). The load-shift curve of the following specimen was measured respectively at the shoulder joint in abductive angles of 0 degrees, 45 degrees and 90 degrees, influenced by 50 N posterior-anterior load to evaluate anterior stability of shoulder joint. According to different selective-cutting test, 5 groups were divided subgroups group A (A1-A4), respectively normal group, superior GHL (SGHL) injury group; SGHL/middle GHL (MGHL) injury group and SGHL/MGHL/inferior GHL (IGHL) injury group; group B (B1-B3), respectively normal group, MGHL injury group, MGHL/IGHL injury group; group C (C1-C2), respectively normal group, IGHL-anterior band (IGHL-AB) injury group; group D D1-D2), respectively normal group, IGHL-posterior band (IGHL-PB) injury group; and group E (E1-E2), respectively normal group, IGHL injury group. RESULTS: For complete shoulder joint (A1 group), there was very small average shift (15.00+/-4.99 mm), for A4 group, there was the worst stability of shoulder joint, the average shift was 22.34+/-5.70 mm. For B2 group, the stability of shoulder joint had no obvious decrease. For B3 group, the stability of shoulder joint was worst at abduction angle of 45 degrees and 90 degrees. For C2 group, the stability of shoulder joint at abduction angle of 45 degrees (23.19+/-4.58 mm) and 90 degrees (15.32+/-1.30 mm) was worse than that of A1 group (P<0.05); half-dislocation or dislocation could be seen. For D2 group (17.30+/-4.93 mm), there was less effect on anterior stability of shoulder joint than that of A1 group (P<0.05). For E2 group (20.26+/-4.75 mm), the effect on anterior stability was similar to C2 group. CONCLUSION: GHL is a key static stabilizing structure of shoulder joint. SGHL has no obvious effect on anterior stability of shoulder joint. MGHL and IGHL together holds anterior stability of shoulder joint, and IGHL plays the most important role.