Scapulothoracic Motion in Normal Shoulders and Shoulders With Glenohumeral Instability and Impingement Syndrome

Abstract

Qualitative visual inspection and manual muscle testing are traditional methods of evaluation that may overlook subtle weakness of the axioscapular musculature. A modification of the standard technique of Moiré topographic analysis of spinal deformity was applied to assess axioscapular muscle function in 51 subjects: 22 asymptomatic individuals, 22 with shoulder instability, and seven with impingement syndrome. Static Moiré evaluation demonstrated scapulothoracic asymmetry or increased topography in 14% of asymptomatic subjects, compared with 32% and 57% in the instability and impingement groups, respectively. The dynamic Moiré test demonstrated an abnormal Moiré pattern in 18% of asymptomatic individuals, compared with 64% and 100% in the instability and impingement groups, respectively. Axioscapular muscle dysfunction is common with both instability and impingement syndrome of the shoulder, although it remains to be determined whether this represents a primary or secondary phenomenon.