Glenohumeral ligaments (GHLs) play important roles in stabilizing the shoulder joint. However, it is impossible to assess the kinematics of the GHLs in vivo. Here we estimated the length of GHLs using an in vivo motion analysis system and visualized the kinematics of each GHL. Firstly, 3D-CT data were collected from 10 enbalmed cadaver shoulders with marker pins inserted into the sites of attachment of superior, middle, anterior band of inferior GHL (SGHL, MGHL, AIGHL). The average positional data of each ligament was determined, based on the data related to the size of the humerus and glenoid.Secondly, 3D-MRI data of shoulder were collected from 10 healthy volunteers, in the position of every 30 degrees between maximal internal and external rotation at 90 degrees of abduction. Those data were matched to the cadaveric data and the pathways of each GHL during shoulder internal-external rotation were visualized with our motion analysing system.The estimated pathway of each GHL was visualized as quasi-dynamic motions by our system. The mean maximum length of SGHL was 26.2mm at 30 degrees of external rotation. The mean maximum length of MGHL and AIGHL were 40.3mm and 42.7mm, respectively, at maximal external rotation. We established a new visualization system of GHLs. The length of each GHL at various shoulder positions can be calculated by this system. We believe that this system has a potential to provide useful information to understand the kinematics of the shoulder joint.
