Comparison of Dynamic Ultrasound to Stress Radiography for assessing Inferior Glenohumeral Laxity

Authors: D. Hulse, S. C. Cheng, K. J. Fairbairn, M. Clarke, W. A. Wallace

References: British Journal of Sports Medicine 2007;41:118-124. 2007

Abstract
Aims: To determine the level of agreement between dynamic ultrasound imaging and stress radiography for measurement of inferior glenohumeral laxity in asymptomatic shoulders; and to determine the repeatability of the dynamic ultrasound technique.

Methods: Using a custom-made stress device to apply an inferior displacement force of 95N, 20 asymptomatic male subjects were assessed for inferior glenohumeral laxity using conventional stress radiography and dynamic ultrasound. Paired differences between the two methods were evaluated using the 95% limits of agreement method.1 At a separate session, 19 male subjects had inferior glenohumeral laxity assessed by two observers, using dynamic ultrasound. Inter- and intraobserver repeatability was determined for the ultrasound technique.

Results: The mean (SD) inferior translation was 4.74 (4.10) mm using stress radiography and 4.42 (2.28) mm using dynamic ultrasound. The mean (SD) paired difference between the two methods was –0.31 (2.33) mm. Dynamic ultrasound overestimated glenohumeral translation for lower measurements and underestimated translation at higher measurements (p<0.001). A regression method was used to determine the 95% upper and lower limits of agreement,1 which were (3.02–0.19 x average translation) and (1.87–1.01 x average translation), respectively. Intra- and interobserver repeatability of dynamic ultrasound is shown in the table

Conclusions: Repeatability coefficients demonstrated excellent consistency of measurement between sessions and good consistency between observers. The SEM indicated a high level of precision when measuring inferior translation. Repeatability of dynamic ultrasound was consistent with that observed previously for anterior and inferior translation.2 Dynamic ultrasound compares favourably with stress radiography, though technical factors may account for the observed variation of difference between the two methods with magnitude of measurement. Dynamic ultrasound is a valid and repeatable method for assessing inferior glenohumeral laxity. It has advantages over stress radiography in terms of portability and lack of ionising radiation.

Abstract 004 Intra- and interobserver repeatability