Reverse Total Shoulder Arthroplasty: 14-Year Clinical Experience with 496 Performed Arthroplasties

PURPOSE OF THE STUDY Reverse total shoulder arthroplasty (RSA) can be considered a proven method for the treatment of the most severe shoulder joint affections. In this study, we present 14-year experiences of the authors with the LimaCorporate SMR® RSA system in 496 cases. MATERIAL AND METHODS Included in the study are 496 RSAs performed between 2007 and 2020. We successfully followed up 368 shoulders in 358 patients. This was a prospective study with function being evaluated preoperatively and at the last follow-up in 2020. We evaluated the range of motion in active elevation and the classic Constant Score (CS). According to this score, the pain level was also evaluated. Standard statistical methods were used with a paired t-test used for comparisons of values. RESULTS The mean follow-up in our group was 5.5 years (0.7-13.6, SD 3.22, median 4.96). Indications were: primary osteoarthritis (84), acute trauma (69), posttraumatic sequelae (79), cuff tear arthropathy (37), RA (29), chronic dislocations (18), final treatment of infectious complications (7), avascular necrosis (6), tumours (4) and TSA revisions (9). The mean post-operative CS of all patients was 71.9 (2-94, SD 11.26, median 73). The mean post-operative active elevation was 127.35° (30°-180°, SD 28.36, median 130°). The mean pain level at final follow-up was 0.65 (0-3, SD 0.65, median 1). There was a statistically significant improvement In the CS (26.9 to 71) and the final achieved elevation (48.5° to 127.35°) in all groups except acute traumas for obvious reasons. A significant decrease in pain (2.8 to 0.65) was observed in all groups. We saw no implant failures or UHMWPE component wear. DISCUSSION We compared our results with those published by other authors. When considering the functional outcomes, our results are comparable with those published previously. Compared to other studies, an interesting result is the low incidence of scapular notching. In our cohort of patients, it was only present in 10 (2.7%) cases. We attribute this to the design of the SMR® implant which meets the main criterium of a modern shoulder arthroplasty system: modularity of both glenoid components. The glenospheres are available in 36, 40 and 44mm sizes with standard and distalised options. Furthermore, the system also contains the Axioma® revision glenoid component. Humeral stems are available in a range of sizes and lengths including revision stems. The humeral body is also available in two sizes. The short variant is optimal for revision with hemiarthroplasty to reverse conversion. CONCLUSIONS During a period of 14 years, we performed 496 implantations of RSAs using the SMR® system. We evaluated 368 cases with an average follow-up of 5.5 years. During long-term follow-up we experienced no implant failures or complications indicative of any constructional insufficiencies. We saw no signs of UHMWPE liner wear. The SMR® system allows for treatment of even the most complex shoulder affections due to its high modularity. Key words: shoulder joint replacement, reverse shoulder arthroplasty, SMR®, Axioma®, outcomes, ROM, scapular notching, complication, polyethylene wear, UHMWPE.