Internal impingement of the shoulder in the overhead athlete

Internal impingement of the shoulder refers to a constellation of pathologic conditions, including, but not limited to, articular-sided rotator cuff tears, labral tears, biceps tendinitis, anterior instability, internal rotation deficit, and scapular dysfunction. Physiologic adaptations to throwing include increased external rotation, increased humeral and glenoid retroversion, and anterior laxity, all of which may predispose an individual to internal impingement. Nonoperative treatment should always be attempted first, with a focus on increasing the range of motion and improving scapular function. When an operative intervention is chosen, it is important to address microinstability in order to have a good outcome and prevent failure.

Computed tomography measurement of humeral head retroversion: influence of patient positioning

For accurate humeral head arthroplasty, the surgeon needs to know some geometric data, such as, for example, the retroversion angle of the humeral head. Only a few reports have described and evaluated the use of computed tomography (CT) to measure humeral head retroversion. The humerus position relative to the roentgen beam is variable from one subject to another depending on the patients' morphology. It could influence the retroversion measurement and has not been investigated previously. This study analyzes in 9 cadaver humeri the variability of retroversion angle measurements with different humerus positioning relative to the roentgen beam during CT examination. The truest retroversion angle can be obtained when true axial slices, perpendicular to the humeral diaphysis, are obtained. Our study tries to clarify technical problems that occur during CT examination. Geometric considerations that can modify the measurements are presented. A reliable method of humeral head retroversion angle measurement is recommended, which could be useful to the shoulder surgeon.