Abstract:

Objective To study the  length changes of the inferior glenohumeral ligament(IGHL) during shoulder abduction with MRI and 3D software.Methods Fourteen  right shoulder joints of 14 healthy volunteers were evaluated in 7 isometric abduction positions (0°,30°,60°,90°,120°,150°,and 180°) using MRI scanning.3D shoulder models were reconstructed and the attachment points of the ligaments were located.The shortest ligament lengths were calculated between each origin and insertion in 3D space for each abduction position.Results During shoulder abduction,the 3D distance of AIGHL was found to elongate and attained the maximal length at 120° abduction(54.5 mm±3.0 mm) (P< 0.05).Pouch and PIGHL reached the maximal lengths at 180° abduction(54.5 mm±3.0 mm,50.6 mm±3.1 mm) (P< 0.05).Conclusion AIGHL prevents anterior dislocation of the humeral head at 120°  abduction.In 180° abduction,pouch can maintain the anterior stability and PIGHL has the contribution to the inferior stability.

Key words: shoulder joint, abduction, inferior glenohumeral ligaments, magnetic resonance imaging