Medialization vs. lateralization of the glenoid baseplate in reverse shoulder arthroplasty: implications for clinical outcomes and functional performance: a systematic review and meta-analysis

Abstract

Background

Lateralization of the center of rotation (COR) in reverse shoulder arthroplasty (RSA) has been proposed to combat scapular notching and improve functional outcomes. Lateralizing the COR can be achieved by increasing the glenoid baseplate lateral offset. The aim of this review was to compare the effect of lateralization vs. medialization of the glenoid baseplate on outcomes, scapular notching, and complication rate in primary RSA.

Methods

A systematic review and meta-analysis were conducted as per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A search of PubMed, EMBASE, and Cochrane Library using keywords was undertaken in December 2023. The search provided 908 studies. After review by two independent authors, 12 met the inclusion criteria and qualified for meta-analysis.

Results

Meta-analysis showed a significant decrease in scapular notching in the lateralized glenoid baseplate group. There was a trend towards improved external rotation in the lateralized group (mean difference = 4.86); however, this difference did not reach significance (P = .067). No other significant difference in functional outcomes, range of motion, or complications was observed between the two groups. A subgroup analysis of four studies that contained a medialized baseplate and lateralized stem as the medialized group vs. lateralized baseplate with lateralized stem as the lateralized group showed significantly inferior American Shoulder and Elbow Surgeons in the lateralized group (P = .018). The mean follow-up period was 31.1 months.

Conclusion

Lateralization of the glenoid component results in a significant decrease in scapular notching, with no significant difference in functional outcomes, range of motion, or complications compared to a medialized glenoid baseplate. The study showed significantly inferior American Shoulder and Elbow Surgeons scores amongst those lateralized at both baseplate and stem vs. those with a medialized baseplate and lateralized stem. Lateralization of the COR in RSA is still a relatively novel concept, and further studies are required, isolating the glenoid and the humeral variables, with longer follow-up periods, to assess long-term functional outcomes and complication rates.