Movement analysis of asymptomatic normal shoulders: a preliminary study.

The dynamic pattern of scapulothoracic rhythm during arm forward flexion in the scapular plane has been studied radiographically. The technique involves dynamic radiographic screening of shoulder movement in elevation. It has low levels of radiation compared with plane x-ray examination techniques of scapular movement analysis, and the results are comparable to those of previously published studies. We analyzed real-time video images of shoulder movement in 10 young male volunteers (group I; mean age, 35 years) and 9 older male volunteers (group II; mean age, 70 years) with the use of computer-aided software. Group I showed mean arm elevation of 154 degrees, glenohumeral movement of 107 degrees, and total scapular movement of 55 degrees. Group II showed mean arm elevation of 118 degrees, glenohumeral movement of 77 degrees, and total scapular movement of 40 degrees. No statistically significant difference was found in the glenohumeral-scapular or glenohumeral-arm movement ratios of these 2 groups. We conclude that although the total range of arm elevation reduces with increasing age, the glenohumeral-to-scapular movement ratio does not change. The technique of movement analysis described is dynamic, safe, and applicable to clinical studies of shoulder movement.