Quantifying Range-of-Motion Changes Across 4 Simulated Measurements of the Glenohumeral Joint Posterior Capsule: An Exploratory Cadaver Study.

Abstract

Study Design Repeated-measures controlled laboratory cadaveric study. Background There is a lack of information about the most sensitive measure of glenohumeral joint posterior capsule length. Although maximum strains on the glenohumeral joint posterior capsule are observed in measurements combining glenohumeral joint flexion and internal rotation (IR), the range-of-motion (ROM) change after experimental contracture has never been compared across commonly used posterior capsular measurements. Objectives To evaluate the IR ROM change across 4 glenohumeral joint posterior capsule measurements after experimental capsule shrinkage using radiofrequency thermal energy. Methods Repeated measures of ROM across 4 test positions were compared after progressive experimental contracture of the posterior capsule in 12 cadaver shoulders. The ROM data were collected with a 3-D motion-capture device and evaluated using repeated-measures analysis of variance. Results Overall, ROM decreased after experimental capsular contracture. There was a significant interaction effect between test and condition (F = 4.26, P = .01). Two of the 4 tests, those that combined humeral flexion and IR, detected significant reductions in the ROM following experimental capsular contracture. Conclusion Greater ROM change was observed in tests combining flexion and IR of the glenohumeral joint after experimental posterior capsular contracture. These tests appear more responsive to capsular-length change. J Orthop Sports Phys Ther 2016;46(12):1080-1085. Epub 29 Oct 2016. doi:10.2519/jospt.2016.6440.