The Delta reverse shoulder arthroplasty (RSA) is commonly used worldwide and is the most frequently used RSA in Norway. The aim of this registry-based study was to report 10- and 20-year implant survival, risk of revision, and reasons for revision in two consecutive time periods for Delta III (1994-2010) and Delta Xtend (2007-2020) prostheses.
We included 3,650 primary RSAs reported to the Norwegian Arthroplasty Register; 315 Delta III (42% cemented stems) and 3,335 Delta Xtend (88% cemented stems). We used Kaplan-Meier analyses to investigate implant survival. Reasons for revision were compared for the two designs and fixation technique. Factors that could influence the risk of revision, such as implant design, fixation technique and patient factors, were investigated using Cox regression analyses with adjustments for age, sex and diagnosis.
Patients operated with Delta III were more likely diagnosed with inflammatory disease or fracture sequela whereas acute fracture, osteoarthritis, and cuff arthropathy were the most frequent indications for Delta Xtend. 10-year survival was 93.0% (95% CI 87.0-99.0) (cemented stem) and 81.6% (75.3-87.9) (uncemented stem) for Delta III and 94.7% (93.3-96.1) (cemented stem) and 95.7% (88.3-100) (uncemented stem) for Delta Xtend. 20-year survival for Delta III (uncemented stem) was 68.2% (58.8-77.6). Compared to DeltaXtend (cemented stem) at 10-year follow-up we found a higher risk of revision for the Delta III (uncemented stem) (Hazard Ratio (HR) 2.9 (95%CI 1.7-5.0)), while no significant difference were found for the Delta III (cemented stem) and Delta Xtend (uncemented stem). The most common reason for revision of Delta III (uncemented stem) was glenoid loosening followed by deep infection and instability. Instability was the most frequent revision cause for Delta Xtend (both cemented and uncemented stem). Men had an overall higher revision risk than women (HR 2.8 (2.0-3.9)) and patients with fracture sequela had increased risk for revision (HR 2.8 (1.7-4.7)) compared to osteoarthritis patients.
We found that Delta III (uncemented stem) had higher risk of revision compared to Delta Xtend (cemented stem). The risk of revision for glenoid component loosening was lower for Delta Xtend, but revisions due to instability/dislocation is still a concern. This register study cannot determine whether the differences found were caused by differences in implant design or other factors that changed during the study period. Risk of revision may have been affected by the indication for primary operation.

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