A 10-year comparative analysis of the 2 most common reverse total shoulder arthroplasty implants (Delta Xtend and SMR) in the New Zealand Joint Registry.

HYPOTHESIS AND BACKGROUND

As the incidence of reverse total shoulder arthroplasty (rTSA) continues to rise, better understanding of the long-term risks and complications is necessary to determine the best choice of implant. The majority (75%) of rTSAs performed in New Zealand use either SMR (Systema Multiplana Randelli; Lima-LTO) or Delta Xtend (DePuy Synthes). The aim of this registry-based study was to compare implant survival, risk of revision, and reasons for revision between the 2 most frequently used rTSA prostheses: SMR and Delta Xtend.

METHODS

Using data from the New Zealand Joint Registry between 1999 and 2022, we identified 5891 patients who underwent rTSA using either SMR cementless (62.8%) or Delta Xtend prostheses (37.2%). Delta Xtend was subdivided into cementless (31.4% of total) and cemented humeral stem (5.8% of total) subgroups for analysis. Revision-free implant survival and functional outcomes (Oxford Shoulder Score [OSS] at 6 months, 5 years, and 10 years were adjusted by age, American Society of Anesthesiologists [ASA] grade, indication, sex, and surgeon volume for between-group comparisons.

RESULTS

Ten-year revision-free implant survival was 93.0%, 92.5%, and 95.8% for Delta Xtend cemented, Delta Xtend cementless, and SMR, respectively. The Delta Xtend cemented implant had a 2-fold higher adjusted revision risk compared with both the Delta Xtend cementless and the SMR cementless implants (hazard ratio [HR] = 2.04, P = .011; and HR = 2.59, P < .001, respectively). There was no significant difference between the Delta Xtend cementless and SMR cementless groups (HR = 1.28, P = .129). The Delta Xtend cemented group was significantly (P ≤ .01) older, had more comorbidities (ASA 3 or 4), female, and indicated for fracture compared with other groups. The most common reason(s) for revision was aseptic loosening and infection for Delta Xtend cementless; aseptic loosening, instability or dislocation, and infection for Delta Xtend cemented; and aseptic loosening alone for SMR cementless. Average OSS was significantly lower in Delta Xtend cemented compared with Delta Xtend cementless and SMR cementless at 6 months (30.8, 35.9 vs. 35.6, respectively, P < .01) and 5 years (37.4, 40.7 vs. 39.5, respectively, P < .01).

CONCLUSIONS

Overall, we found that the Delta Xtend cemented group had more than a 2-fold risk of revision compared with Delta Xtend cementless and SMR cementless groups, whereas there was no difference in revision risk between the Delta Xtend and SMR cementless prostheses. As the incidence of rTSA continues to rise, better understanding of the long-term risks and complications is necessary to determine the best choice of implant.