Biomechanical Study For Static Posterior Stability Function Of Glenohumeral Ligament Of Shoulder Joint

Objective: It's on prove that the glenohumeral ligament especial inferior glenohumeral ligament exerts important roles to the posterior stability of shoulder joint, and supply for diagnosing and treating of posterior shoulder instability.Material and Methods: 15 fresh cadaver shoulder joints are made into bone-ligament-bone modes for selective amputation experimentation. Under 22N central pressure, applying INSTRON8874 mechanical monitoring system gives 50N front & rear load to shoulder bones, and draw a load-displacement curve, and then measure the shoulder bones displacement after resection of the following body planes, (1). Integrity. (2). SGHLcut, (3).SGHL+MGHLcut. (4). SGHL+MGHL+IGHL cut. (5). MGH cut. (6). MGHL+IGHL cut. (7). IGHL-AB cut. (8). IGHL-PB cut. (9). IGHL cut. Make variance analyses by employing software SPSS10.0.Results: After simplex cut SGHL, front & rear displacements have no obvious difference compare to integrity. After SGHL+MGHL cut and abduction 90°, the front displacement increase slightly, the average displacement reaches around 19.59±2.38mm(p<0.05), but no obvious increase of rear displacement. The front and rear displacements of all the angles of SGHL+MGHL+IGHL cut have increased, and the shoulder joints are extremely unstable. IGHL-AB amputate 45°and 90°, it displaces 19.90mm (p<0.05) averagely, the displacement is very obvious, that means shoulder joins are of hemipelvic dislocation or dislocation. There exists displacements after simplex IGHL-PB amputate 45°, it's increased obviously and its average speed at 10.74mm (p<0.05), there is no obvious difference between abduction 90°and integrity. After IGHL full cut 45°and 90°, the displacement increased (p<0.05) averagely.Conclusion: The glenohumeral ligament is composed of an upper, middle and lower part, which are the major structures of shoulder joint static stability. When shoulder joint abduction 45°-90°, the glenohumeral ligaments and inferior glenohumeral ligaments anterior bundle are the main front stable structure; and inferior ligament rear bundle is the main rear stable structure, the main reason for clinic recurrent anterior & rear dislocation of shoulder joint perhaps is the tendon allografts injury. There is some significance to the diagnoses of checking shoulder joint instability by the glenohumeral ligament function of the shoulder joint abduction body position. It's of some effects to the rebuilding stability of shoulder joint of remedying the inferior and superior glenohumeral ligaments. Moreover, the selective cut experimentation is an effective way for studying biomechanics of shoulder joint.