Reliability analysis of shoulder balance measures: Comparison of the 4 available methods

STUDY DESIGN.: Observational study with 3 examiners. OBJECTIVE.: To compare the reliability of shoulder balance measurement methods. SUMMARY OF BACKGROUND DATA.: There are several measurement methods for shoulder balance. No reliability analysis has been performed despite the clinical importance of this measurement. METHODS.: Whole spine posteroanterior radiographs (n = 270) were collected to compare the reliability of the 4 shoulder balance measures in patients with adolescent idiopathic scoliosis. Each radiograph was measured twice by each of the 3 examiners using 4 measurement methods. The data were analyzed statistically to determine the inter-and intraobserver reliability. RESULTS.: Overall, the 4 radiographical methods showed an excellent intraclass correlation coefficient regardless of severity in intraobserver comparisons (>0.904). In addition, the mean absolute difference values in all methods were low and were comparatively similar (<1.73). However, in interobserver comparisons, reliabilities were significantly decreased in the less severe radiographs, firstly on radiographical shoulder height measures (intraclass correlation coefficients >0.445, mean absolute difference <3.91). However, the intraclass correlation coefficients in the coracoid height difference and clavicular angle methods were in the excellent range (>0.810 and >0.787, respectively) regardless of severity. In addition, the mean absolute difference values in the clavicular angle method were lower (<0.62) than others. CONCLUSION.: The higher reliability of the clavicular angle and coracoid height difference methods indicate the clinical usefulness of these methods. Physicians should selectively use the shoulder balance measurement method clinically.