Aseptic glenoid baseplate loosening after reverse total shoulder arthroplasty with a lateralized convex baseplate: helical blade versus central peg fixation.

PURPOSE: To compare aseptic glenoid baseplate loosening (AGBL) and AGBL-free survival after primary reverse total shoulder arthroplasty (RTSA) using a lateralised convex baseplate with either helical blade or central peg fixation. METHODS: Multicentre retrospective analysis of 231 primary RTSAs with ≥ two years follow-up (helical blade, n = 127; central peg, n = 104), all with non-locking peripheral screws. AGBL was assessed radiographically; septic and post-traumatic loosenings were not classified as AGBL. AGBL rates and survival times were compared using Kaplan-Meier estimates and log-rank tests. Clinical outcomes were assessed in 219 unrevised shoulders. RESULTS: Mean follow-up was 4.4 ± 1.8 years (range, 2 to 9.5 years). AGBL occurred in 9/231 cases (3.9%): in 7/127 cases (5.5%) in the helical blade group and 2/104 cases (1.9%) in the central peg group (p = 0.16). AGBL-free survival was similar in both groups (log-rank p = 0.38). Revisions were performed in 8/127 cases in the helical blade group (6.3%) and in 4/104 cases in the central peg group (3.8%; p = 0.40). Both groups had similar clinical improvement: the overall Constant score at last follow-up was 67.6 ± 15.0 and the mean subjective shoulder value was 80.3 ± 15.6. Complication rates did not differ significantly between the two groups. CONCLUSION: In these patients who underwent RTSA using a lateralised convex baseplate, AGBL rates and functional improvement at two years' follow-up did not differ significantly between helical blade and central peg fixation.