Preoperative Shoulder Strength Is Associated with Postoperative Primary Anatomic Total Shoulder Arthroplasty Outcomes and Improvement.

Abstract Background While numerous preoperative factors that influence postoperative outcomes after anatomic total shoulder arthroplasty (aTSA) have been identified, preoperative shoulder strength has not been studied. The purpose of this study was to determine if preoperative shoulder strength is predictive of postoperative outcomes and improvement after primary aTSA. Methods A retrospective review was conducted of prospectively-collected data from 160 shoulders with minimum 2-year follow-up after primary aTSA. Preoperative external rotation (ER) strength, supraspinatus strength, and abduction strength score were analyzed to determine their correlation with postoperative outcomes and improvement in shoulder strength, range of motion (ROM), and outcome scores. Multiple linear regression models were subsequently used to adjust for covariates and determine the preoperative measures of shoulder strength that most influenced postoperative outcomes and improvement. Results Preoperative ER strength, supraspinatus strength, and abduction strength score were each moderately correlated with their respective postoperative values and improvement (P Conclusion Preoperative shoulder strength is moderately associated with postoperative outcomes and improvements in shoulder strength, ROM, and outcome scores after primary aTSA. Importantly, we identified preoperative strength values that led to a decrease in strength postoperatively, but not ROM or outcome scores. The results from our study demonstrate abduction strength may be a useful indicator of patient outcomes after aTSA. Our findings will provide surgeons with useful prognostic insight to aid in guiding patient expectations.