Stem design in radial head arthroplasty: a systematic review and meta-analysis

Radial head arthroplasty (RHA) is increasingly used for complex elbow instability, yet controversy persists over optimal stem fixation and implant polarity. This study systematically reviews the evidence to determine revision rates, radiographic loosening, and reoperation rates after primary RHA, stratified by stem fixation (intentional loose-fit, press-fit, cemented) and polarity (monopolar vs. bipolar), with specific attention to surveillance time bias.

MEDLINE, Embase, Scopus, and Cochrane databases were searched from inception to October 20, 2025. Studies reporting outcomes of primary RHA with ≥12 months of follow-up and design-specific data were included. Risk of bias was assessed with the Methodological Index for Non-Randomized Studies tool and quality of evidence using Grading of Recommendations Assessment, Development and Evaluation. Both conventional pooled-proportion meta-analysis and incidence-rate (events per 100 patient-years) meta-analysis were performed to adjust for differences in follow-up duration.

Forty-six studies (4,467 distinct elbows) were included. In the unadjusted pooled analysis, intentional loose-fit stems demonstrated a lower revision rate (3.4% vs. 8.0%; P < .001) compared to press-fit stems. However, after adjusting for exposure time in the incidence-rate meta-analysis, this survival advantage was no longer significant, although the point estimate for press-fit stems remained higher (loose-fit 0.97 vs. press-fit 2.01 revisions/100 patient-years; P = .10). No difference was found between monopolar and bipolar designs in any analysis (revision 5.8% vs. 5.8%; P = .74).

This large RHA meta-analysis shows the widely reported survival advantage of intentional loose-fit stems may be partly attributable to shorter follow-up in those cohorts. After adjustment for surveillance time, the difference in revision rates between loose-fit and press-fit stems was no longer statistically significant, although the point estimate for press-fit stems remained numerically higher. Implant polarity was not associated with revision risk in any analysis. The additional complexity and cost of bipolar implants may not translate into improved revision-free survival in this dataset.