Comparative Study on Postoperative Immobilization in Reverse Total Shoulder Arthroplasty: 4 Weeks vs. 6 Weeks of Immobilization Yields Similar Clinical and Functional Outcomes

<b>Background/Objectives</b>: To investigate clinical and functional outcomes of patients undergoing reverse total shoulder arthroplasty (RTSA) using a rehabilitation protocol of either 4 or 6 weeks of immobilization. <b>Methods</b>: This comparative study analyzed a consecutive patient cohort that underwent RTSA in a single institute from January 2021-February 2023. Patients were assigned to groups according to the duration of postoperative immobilization and were followed up for a minimum of one year. Patient demographics, range of motion (ROM), functional outcomes using the Simple Shoulder Test (SST) and the American Shoulder and Elbow Score (ASES) as well as postoperative complications were recorded. The minimum clinically important difference (MCID) was used to assess whether the differences between the groups in SST, ASES, SWB, and VAS were clinically relevant. <b>Results</b>: Sixty patients met the inclusion criteria (35 patients in the 6-week immobilization group (6 WG) and 25 patients in the 4-week immobilization group (4 WG)) and were available for the total follow-up period. Similar baseline demographics were observed between the groups. Active ROM significantly improved for both groups, with abduction and forward flexion improving the most. In terms of functional outcomes, significant improvement (<i>p</i> < 0.001) was demonstrated for both groups (ASES, SST, VAS, and SWB). However, patients in the 4 WG reached significantly better results in VAS and SWB at 6 weeks and 3 months, as well as in ASES 3 months postoperatively, whereas both groups leveled off at the end of the follow-up period after 1 year. Taking into account the MCID, these differences for ASES at 3 months, as well as VAS and SWB at 6 weeks and 3 months postoperatively, were significant. Surprisingly, there were no differences between the groups over the entire follow-up period in terms of the SST. <b>Conclusions</b>: The author's findings suggest faster clinical recovery at 6 weeks and 3 months in patients undergoing postoperative immobilization of 4 weeks compared to 6 weeks following RTSA. However, clinical and functional outcomes were equal for 4 WG and 6 WG at one year follow up.