Modelling XLPE vs non-XLPE glenoid revision rates for anatomic shoulder arthroplasty in osteoarthritis including differing polyethylene glenoid fixation designs.

Abstract

IntroductionWe compared anatomic total shoulder arthroplasty (aTSA) for osteoarthritis (OA) to both highly crosslinked polyethylene (XLPE) and non-highly crosslinked polyethylene (non-XLPE) to determine the rate of revision for multiple patient and implant characteristics, modelling the effect of variation in glenoid fixation design (glenoid component type). Materials and MethodsData from a large national arthroplasty registry were analysed for the period 16 April 2004 to 31st December 2022. The study population included all primary aTSA (stemmed and stemless shoulder arthroplasty) procedures with a primary diagnosis of OA and performed using prostheses in current use. These procedures were grouped into two cohorts: all polyethylene bearing glenoid components with either XLPE or non-XLPE. The cumulative percent revision (CPR) was determined using Kaplan-Meier estimates of survivorship and hazard ratios (HR) from Cox proportional hazard models adjusted for age, sex, humeral head size, humeral fixation, type of primary (total stemmed or stemless anatomic), glenoid component type (modular and non-modular metal backed glenoid, cemented polyethylene glenoid, and polyethylene glenoid with modified central peg), and surgeon volume (after 2008). Possible interactions were examined. A sub-analysis from 1 January 2017 captured the additional patient demographics of ASA score, BMI and glenoid morphology. ResultsOf 11,003 aTSA procedures the CPR at 14 years for all XLPE glenoids (n=3,865) was 5.8% (95% confidence interval (CI) 3.9, 8.7), and 18.7% (95% CI 16.6, 21.0) for non-XLPE (n=7,138). XLPE had a lower rate of revision from 2 years (non-XLPE vs XLPE 2 years+ HR=1.66, (95% CI 1.09, 2.53), p=0.018) adjusting for age, sex, humeral head size, type of primary, humeral stem fixation, and glenoid component type. Overall, glenoid component type and polyethylene type were strongly associated (p<0.001 and p=0.021, respectively) with all cause aTSA revision rates. The difference between non XLPE and XLPE is observed across all polyethylene glenoid types. When considering procedures performed between 2017 and 2022, XLPE vs non-XLPE rates of revision were not significantly different with extended adjustment at sub-analysis, but loosening did not predominate for non-XLPE until year 6 of follow-up. ConclusionBoth the glenoid design and the type of polyethylene predict the revision rate for aTSA. However, the relative rates of revision between glenoid designs did not differ with polyethylene type. While the polyethylene type was not associated with aTSA revision rates in a more contemporary analysis, the incidence of loosening in non-XLPE prostheses combinations was higher from 6 years may explain this.