2091264 Manual Application of Inferior Glenohumeral Mobilizations: An Ultrasound Investigation of The Effect of Shoulder Position on Movement and Force

Abstract

displacement, its quantification can assist clinicians in identifying joint hypomobility or hypermobility. Historically, stiffness measurements have been determined using expensive and often complicated motion analysis systems along with wired load cells and force transducers. Ultrasound imaging (USI), can monitor joint surfaces providing displacement measurements while handheld dynamometry (HHD) can reliably measure forces used during the application of manual translational forces. Stiffness can then be calculated and compared to uninvolved joints to assist with differential diagnosis. The purpose of this study was to determine the intratester reliability of posterior glenohumeral stiffness utilizing ultrasound imaging and hand held dynamometry. Methods: 28 healthy adults consented to participate. With the subject supine, the shoulder was positioned in 55 degrees of abduction and 30 degrees of horizontal adduction. The ultrasound transducer was placed over the anterior glenohumeral joint and a posterior translatory force applied through a hand held dynamometer. The maximum force was recorded. This process was repeated three times on each shoulder. End range stiffness was calculated as the amount of movement per unit of force. Descriptive statistics and an intraclass correlation coefficient (ICC) were calculated for stiffness. An ANOVA was used to determine the association between dominance and stiffness. Results: Mean posterior stiffness of the glenohumeral joint was .06 mm/ N (SD5.02) with the standard error of the mean 5 .002mm/N. Intratester reliability was excellent with the ICC for stiffness 5 .905. Stiffness was significantly greater in the dominant arm with less movement per unit force as compared to the nondominant arm.Conclusions: This study provides support for the utilization of ultrasound imaging and hand-held dynamometry to reliably measure posterior stiffness of the glenohumeral joint. Incorporating stiffness measurements into examinations of individuals with shoulder dysfunctions may assist in identifying potential underlying etiology and increase efficacy of treatment.Objectives: Abnormal elevation of the scapula during overhead movement of the arm is often associated with shoulder dysfunction. This increase in elevation, referred to as a shrug sign, is thought to alter scapular mechanics by increasing activation of the upper trapezius muscle and inhibiting contraction of the lower trapezius (LT). By comparing the thickness of the LT during normal overhead motion and during motion that occurs with scapular elevation, patterns of abnormal muscle firing can be identified, information that will assist with differential diagnosis. The purpose of this study was to determine the pattern of LT thickness during a laboratory induced shrug sign. Methods: 18 healthy adults consented to participate. With the subject sitting, an ultrasound transducer was placed over T7 and the fibers of the LT identified. As the subject actively elevated the arm from 0 to 90 degrees of flexion, a continuous video of the LT wa...