An objective measurement technique for posterior scapular displacement

Contemporary shoulder rehabilitation programs emphasize scapular control in the treatment of shoulder pathology. In addition, scapular winging and scapular tipping are often cited as key components to both the evaluative and rehabilitative phase of treatment. However, the lack of objective measurement procedures makes clinical evaluation of these phenomena difficult. The purpose of this project was to develop a reliable technique to quantify posterior scapular displacement (direction of scapular movement for winging and/or tipping). Forty healthy subjects (21 males, 19 females) who reported no current shoulder pain participated in this study. A measurement instrument was designed to quantify, to the nearest whole degree of motion, the posterior displacement of the inferior angle of the scapula from the posterior thorax. Subjects' scapulae were each measured two times without holding weight (unweighted position) and two times while the subjects held 10% of their body weight (weighted position). During all trials, two testers were blinded from the measurement readings. Intraclass correlation coefficients (ICC) were calculated based on a repeated measure analysis of variance to determine intertester and intratester reliability. The standard error of measurement (SEM) was used to determine the measurement error. Intratester within-day reliability ICCs ranged from 0.97 to 0.98, and SEM ranged from 0.6 to 1.1 degrees. Intertester within-day reliability ICCs ranged from 0.92 to 0.97, and SEM ranged between 1.1 and 1.7 degrees. None of the calculated p values for intratester and intertester reliability were statistically significant (p < 0.05). We conclude that this measurement technique is a reliable method to quantify posterior scapular displacement. Further research utilizing this measurement technique is recommended.