With variations in joint destruction, patient expectations and health status, it can be difficult to interpret outcomes following arthroplasty. The purpose of this study was to determine the relationships between different outcome indicators in 44 patients followed for two years after a reverse shoulder arthroplasty.
Prospectively collected outcomes included the Constant-Murley score, Simple Shoulder Test (SST), range of motion (ROM), strength, patient satisfaction with their care and independent clinician case-review to determine global clinical outcome. Continuous outcomes were divided in two subgroups according to definitions of functional outcomes. Cohen’s kappa was used to evaluate agreement between outcomes. Pearson correlations were used to quantify interrelationships.
Although 93% of patients were substantially satisfied, fewer had good results on the other outcomes: 68% on global clinical outcome, 46% on SST and 73% on Constant-Murley score. The SST demonstrated better than chance agreement with Constant-Murley score, ROM in flexion, abduction and external rotation, and strength in external rotation. No agreement between satisfaction and other outcomes were observed. Significant correlations were observed between Constant-Murley score and SST (
r= 0.78). The Constant-Murley score and SST demonstrated variable correlation with ROM and strength in flexion, abduction, internal and external rotation (0.38 < r< 0.73); the highest correlations being observed with shoulder elevation ROM ( r> 0.50). Conclusions:
Results show that outcome varies according to patient perspective and assessment methods. Patient satisfaction with their care was related to neither self-reported nor physical impairment outcomes. Positive patient ratings of satisfaction may not necessarily be evidence of positive outcomes.