Periprosthetic joint infection risk is comparable between unicompartmental knee arthroplasty to total knee arthroplasty conversion and primary total knee arthroplasty: A systematic review and meta‐analysis

Purpose Unicompartmental knee arthroplasty (UKA) offers benefits over total knee arthroplasty (TKA), but some studies indicated higher revision rates, often involving conversion to TKA. The infection risk associated with UKA to TKA conversion compared to primary TKA is not definitively established. This systematic review and meta‐analysis aimed to determine if patients undergoing UKA to TKA conversion had a higher rate of periprosthetic joint infection (PJI) compared to primary TKA. Methods Following preferred reporting items for systematic reviews and meta‐analysis guidelines, PubMed, EMBASE and SCOPUS were searched for clinical studies comparing PJI rates in adult patients undergoing UKA to TKA conversion versus primary TKA. Data on reoperations and component use were also extracted. A random‐effects model was used for the meta‐analysis. Results Six retrospective studies involving 456 UKA to TKA conversion and 719 primary TKAs were included. No significant difference in the rate of PJI was found between the UKA to TKA conversion cohort (0.66%) and the primary TKA cohort (0.70%) (odds ratio [OR] 1.21, 95% confidence interval [CI] [0.27, 4.46]; p = 0.91). However, UKA to TKA conversion was associated with a significantly higher likelihood of requiring augments (15.6% vs. 3.9%; OR 8.71, 95% CI [1.29, 58.80]; p = 0.03) and stems (36.6% vs. 1.7%; OR 45.83, 95% CI [9.53, 220.55]; p < 0.00001), indicating greater surgical complexity. Conclusion Based on current literature, UKA to TKA conversion is associated with a similar surgical site infection/PJI rate compared to primary TKA. UKA to TKA conversion procedures necessitated significantly more revision‐specific components. Level of Evidence Level III.