抄録
The relationships between an infraspinatus insertion injury and the functional A-P instability in the throwing motion were evaluated.82 shoulders of 82 men with shoulder pain during throwing motion, aged between 15 and 35 years, were examined.
The subjects consisted of 37 shoulders with abnormal findings of the infraspinatus insertion (Group I)and 45 shoulders without an abnormality (Group N).
In the cinearthrography, the joint kinetics on axial views were recorded. Using an image analyzing system, the center of the humerl head was measured, and the rotation of the glenohumeral joint was calculated in each position.
Group I: The maximum external rotation glenohumeral joint could be seen in 0 degrees of horizontal abduction. The center of the humeral head showed the centripetal motion through to the throwing motion.
Group N: MER of GH joint occurred in 10 degrees of HRZ. ABD. Concerning the motion of the humeral head, it could be translated anteriorly in the external rotation and posteriorly in the following internal rotation.
The infraspinatus insertion injury was associated with functional anterior-posterior instability of the glenohumeral joint in the throwing motion.
We considered that excessive anterior translation occurring with an external rotation might cause stress of the infraspinatus insertion in the following phase.
