Characterization of tissue resistance during a dorsally directed translational mobilization of the glenohumeral joint.

Abstract

To quantify forces applied by therapists during dorsal glide translational mobilization of the glenohumeral joint, to determine the relationship of tissue resistance to the load-displacement relation of the glenohumeral joint, and to determine the safety of the forces applied by the therapists during dorsal glide translational mobilization. A fresh cadaver shoulder specimen mounted on a 6-axis load cell was used to register forces applied by therapists during dorsal glide translational mobilization of the glenohumeral joint in a test-retest pattern. Biomechanics laboratory. Twelve experienced orthopedic physical therapists. Not applicable. Forces exerted by therapists during passive dorsal glide translational mobilization in the loose-packed position and in the end range of abduction, with different grades of movements. The movements did not include any manipulation or thrust-type procedures. Simulated dorsal glide procedures were performed by the material testing system to construct the load-displacement curve of the glenohumeral specimen. The corresponding locations of the forces applied by therapists were interpolated and plotted on the load-displacement curve. The peak force values measured during mobilization were characterized by large intertherapist variability: coefficients of variation ranged from 40.97% to 77.49%. Test-retest reliability for intrasession measures was high (ICC(2,1) range,.90-.94); intersession reliability was poor (ICC(2,1) range,.01-.54). The mean forces ranged from 18.36 to 38.76N. When interpolated to the load-displacement curve, the mean peak forces obtained fell mostly in the toe and the linear elastic regions of the load-displacement curve. Force parameters measured during dorsal glide mobilization were characterized by large intertherapist variability with high intrasession and poor intersession test-retest reliability. The mobilization forces applied by experienced orthopedic physical therapists fall safely in the toe and the linear elastic regions of the load-displacement curve.