MRI Measurements of the Cartilage Contact Pattern, Contact Area, and Contact Centroid of the Glenohumeral Joint During Abduction Under Static Conditions In Vivo

PurposeThis study aimed to determine the changes in the cartilage contact pattern, contact area, and contact centroid between the humeral head and glenoid during abduction using magnetic resonance imaging (MRI) under static conditions in vivo. We hypothesized that as the glenohumeral abduction angle increases, the cartilage contact area increases and the contact pattern and contact centroid shift superiorly and anteriorly. MethodsThe present study comprised 14 Japanese men with no history of shoulder injury or disorders. MRI was performed in the following four postures: neutral posture with arms at the side of the trunk and postures at 30 degrees, 60 degrees, and 120 degrees of thoracohumeral abduction, which corresponded to 18.6 degrees +/- 5.7 degrees, 27.8 degrees +/- 7.0 degrees, and 66.8 degrees +/- 13.1 degrees of glenohumeral abduction, respectively. The cartilage contact pattern was determined from the signal intensity profiles of MR images using image analysis software. ResultsWe observed that the contact area was independent of the thoracohumeral abduction angle. The contact area at 120 degrees of thoracohumeral abduction was approximately 10% smaller than at other angles, although this difference was not statistically significant. The contact centroid was significantly shifted superiorly as the thoracohumeral abduction angle increased (p < 0.01), with a trend toward anterior movement. ConclusionThese results confirmed that the contact pattern and contact centroid shifted superiorly and anteriorly. We believe that determining the contact pattern and contact area of the glenohumeral joint is useful for detecting abnormal shoulder joint movements and can guide the diagnosis, treatment, and rehabilitation of patients with shoulder disorders.