Thresholds For Diminishing Returns In Postoperative Range Of Motion After Total Shoulder Arthroplasty

Abstract

BackgroundSatisfaction following shoulder arthroplasty (TSA), which is commonly reported using patient-reported outcome measures (PROMs), is partially dependent upon restoring shoulder range of motion (ROM). We hypothesized there exists a minimum amount of ROM necessary to perform functional tasks queried in PROM questionnaires, beyond which further ROM may provide no further improvement in PROMs. MethodsA retrospective review of a multicenter international shoulder arthroplasty database was performed between 2004-2020 for patients undergoing anatomic or reverse TSA (aTSA, rTSA) with minimum 2-year follow-up. Our primary outcome was to determine the threshold in postoperative active ROM (abduction, forward elevation [FE], external rotation [ER], and internal rotation [IR] score) whereby additional improvement was not associated with additional improvement in PROMs (Simple Shoulder Test [SST], American Shoulder and Elbow Surgeons [ASES] score, and the Shoulder Pain and Disability Index [SPADI]). For comparison, we also evaluated the Shoulder Arthroplasty Smart (SAS) score, which is not subject to the ceiling effect. ResultsWe included 4,459 TSAs (1,802 aTSAs, 2,657 rTSAs) with minimum 2-year follow-up (mean, 56±32 months). The threshold in postoperative ROM that were associated with no further improvement were: active abduction, 107-113° for PROMs versus 163° for the SAS score; active FE, 149-162° for PROMs versus 176° for the SAS score; active ER, 50-52° for PROMs versus 72° for the SAS score; IR score, 4-5 points for all PROMs versus 6 points for the SAS score. Out of 3,508 TSAs with complete postoperative ROM data, 8.5% achieved or exceeded all ROM thresholds (14.5% aTSAs, 4.8% rTSAs). ConclusionsOur findings demonstrate that postoperative ROM exceeding 113° of abduction, 162° of FE, 52° of ER, and IR to L1 is associated with minimal additional improvement in PROMs. While individual patient needs vary, the thresholds may provide helpful targets for patients undergoing postoperative rehabilitation.