Associations between patient-reported scores, strength and physical performance tests following shoulder stabilisation surgery

Abstract

Introduction and Aims: Shoulder stabilisation surgery results in substantial time loss from participation in sport. Following surgery, most athletes desire to return to pre-injury sporting activity at their pre-injury level. However, high rates of re-injury have been reported and strength and functional performance tests may provide valuable insight into an athlete’s upper body function and readiness to return to sport following stabilisation surgery. The aim of this research was to investigate and compare (to the unaffected limb) post-operative measures of strength and performance, in patients after stabilisation surgery for shoulder instability. Methods: We evaluated a pilot group of 17 athletic males at 4 to 6 months following shoulder stabilisation surgery. Peak isometric external and internal rotation force using a handheld dynamometer was assessed, together with the Athletic Shoulder (ASH) test involving three long-lever isometric tests in an I, Y and T position on a force plate. Limb symmetry indices (LSIs) were calculated for the operated limb, as a percentage of the non-operated limb for rotator strength, as well as the peak force and rate of force development (RFD) over 100ms for each of the individual ASH tests. Western Ontario Shoulder Instability (WOSI) and Shoulder Instability Return to Sport after Injury (SIRSI) questionnaires were also assessed. Correlation coefficients were undertaken to assess the relationship between rotator strength, performance tests and patient-reported outcomes. Results: Only 35%, 59%, and 77% patients demonstrated an LSI >90% for peak force in the I, Y and T test positions, respectively, while only 47%, 35%, and 53% patients demonstrated an LSI >90% for RFD in these same positions. No associations were observed between patient-reported scores and isometric internal and external rotator strength (p>0.05). Moderate, negative associations were observed for WOSI scores and LSIs of peak force in the I test (r = -0.601; p = 0.018) and Y-test (r = -0.611; p = 0.016), positions of the ASH test, as well as the LSI in RFD in the I position (r = -0.517; p = 0.049). No associations were observed between patient-reported scores and isometric internal and external rotator strength (p>0.05). Discussion: In this early pilot trial of athletes, long-lever isometric tests, for both peak force and RFD, appeared to better relate to self-reported function and quality of life than isometric strength measures using an HHD. Future research investigating performance-related factors, and their association with re-injury and return to sport, are required. Conflict of interest statement: My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.