The Dynamic Apprehension Test: A Valid Measure of Shoulder Function following Surgical Stabilization
2Orthopaedic Surgery, Souraski Medical Center, Israel
3Sackler Medical School, Tel-Aviv University, Israel
Background:
Readiness to return to unrestricted activity following surgical stabilization of the shoulder is often determined based on non-validated and somewhat arbitrary criteria. The “dynamic apprehension test” (DAT) is a novel measure of patient’s ability to control stresses to anterior shoulder stability. The test is performed in a supine position by alternatingly extending the arm overhead to 135° and 180° of shoulder abduction as many times as possible over a 1-minute period while holding a 2-3 kg dumbbell. Reliability and validity of the DAT are assessed herein.
Methods:
Twenty-two patients (1 female) with an average age, height and weight of 24.0 ± 5.2 years,177.7 cm ± 6.9, 76.1 ± 12.7 kg, respectively, were assessed before and 6 months after surgical stabilization of their shoulder using the Western Ontario Shoulder Instability Index (WOSI), Subjective Shoulder Value (SSV) and the DAT. Difference between pre- and post-operative DAT scores were assessed via repeated measures analysis of variance, while correlation between the DAT, WOSI and SSV were determined using Spearman Rho correlation coefficient.
Results:
Inter-rater reliability of the DAT was excellent (intraclass correlation coefficient 0.98). Pre-operatively, the average score of the DAT was 4.4 and 12.7 repetitions on the operated- and non-operated side, respectively. Fourteen of 22 patients (63.6%) were unable to perform the DAT pre-operatively on the operated side. Post-operatively, improvement in DAT score was significantly greater on the operated versus non-operated side (11.7 versus 7.6 repetitions, P=0.04) and only 6/22 patients (27.2%) were still unable to perform the test. A high correlation was found between the post-operative DAT and WOSI scores (r=-0.74, P<0.001), and a moderate correlation was found between the post-operative DAT and SSV scores (r=0.58, P=0.007).
Discussion:
The DAT is a reliable and valid measure of shoulder function following surgical stabilization and may assist in determining readiness to return to full unrestricted activity following surgery. Further research is needed to determine the predictive validity of the DAT is identifying patients at risk for persistent instability following surgical stabilization of the shoulder.