Clinical and radiographic changes within 24-month follow-up after reverse total shoulder arthroplasty – which follow-up do we need?

Introduction Reverse total shoulder arthroplasty (rTSA) is an established procedure, yet the optimal timing of postoperative follow-up (FU) remains controversial. Although guidelines and clinical studies frequently define a two-year FU to assess short-term outcomes, there is little evidence to support this practice. This study investigates longitudinal changes in patient-reported outcomes (PROMs), range of motion (ROM) and radiographic findings over a 24-month period after primary rTSA. Methods This retrospective study included 66 primary rTSA patients (62% female; mean age 72.4 years; cuff tear arthropathy 50.0 %, primary osteoarthritis 31.8 %) with three implant designs at a single high-volume center. Assessments were performed preoperatively and at 6, 12, and 24 months postoperatively. At each timepoint, the Constant Score (CS) as well as various PROMs, including the Subjective Shoulder Value (SSV), Visual Analog Scale (VAS), EQ-5D-5L and the Shoulder Pain and Disability Index (SPADI) were assessed. ROM was measured, and standardized radiographic evaluations were performed. Longitudinal changes were analyzed using the Friedman test with post-hoc correction. Additionally, mixed-effect models and Bayesian logistic regression were applied to evaluate time and group effects for both PROMs/ROM and radiographic outcomes. Results All PROMs improved significantly within the first 6 months; smaller gains in CS, SSV, and SPADI occurred up to 12 months, while pain and EQ-5D-5L improvement plateaued earlier. No further PROM changes occurred beyond the first year. ROM in flexion and abduction improved markedly within the first 6 months, with only minor additional gains in flexion at 12 months and stabilization thereafter; external rotation improved more slowly, reaching significance only at 12 months, before plateauing. Model-based analysis showed no interactions between time and implant groups for any of the PROMs and only minor differences for ROM. Radiographic evaluation revealed low rates of implant loosening, scapular notching, and periprosthetic fractures, with most events occurring in the first postoperative year. Discussion RTSA leads to significant clinical and functional improvement within the first 6 to 12 months, followed by a plateau with no further changes up to 2 years. Radiographic findings and complication rates remained largely stable, with most events occurring in the first postoperative year; implant differences were minimal. These findings suggest that routine two-year FU provides limited additional information for short-term assessment, though monitoring remains important for potential late complication. Awareness of the early plateau phase is essential for realistic patient counseling, evidence-based decision-making, and efficient resource allocation.