¹Center for Musculoskeletal Surgery, Charité – Universitätsmedizin Berlin, Berlin, Deutschland
²Center for Musculoskeletal Surgery, Charité, Berlin, Deutschland
³German Arthroplasty Registry (EPRD Deutsche Endoprothesenregister gGmbH), Berlin, Deutschland
⁴i+M Fachklinik Herzogenaurach, Herzogenaurach, Deutschland

Text

Objectives and questions: Total knee arthroplasty has often been preferred for rheumatoid arthritis (RA) patients, as it addresses all compartments of the knee and provides a more comprehensive solution. However, with advancements in RA treatment, particularly the increased use of disease-modifying antirheumatic drugs, unicompartmental knee arthroplasty (UKA) is being reconsidered as a viable alternative in certain cases. This study aimed to compare the risk of revision surgery between patients with rheumatic diseases undergoing primary UKA and those without rheumatic diseases.

Material and methods: Data from the German Endoprosthesis Register (EPRD) were used to compare 723 cases of primary UKA in patients with rheumatic diseases (RAs) to 6,1729 cases in patients without (Non-RAs) over an 8-year period.

Revisions were classified into major (revision of at least the femoral or tibial component) and minor (no bony component revision, including only insert exchange), based on the surgical and procedural codes recorded in the register.

The cumulative risk of these procedures was analyzed overall and separately for septic and aseptic revisions using the Kaplan-Meier estimator. Statistical significance of differences in revision rates between RAs and Non-RAs was assessed using the Log-Rank test.

Results: The cumulative risk for major revisions in RAs with primary UKA after 8 years was 9.8% (confidence interval [CI] 6.2–15.1) and in Non-RAs 7.4% (CI 7.0–7.8, p = 0.4). The cumulative risk for minor revisions in RAs after 8 years was 2.8% (CI 1.7–4.6) and in Non-RAs 1.9% (CI 1.7–2.0; p = 0.06). A trend towards higher revision rates was seen after 2 years in RAs.

The analysis, stratified by septic and aseptic revisions, showed no significant differences in the risk of revision surgeries for RA compared to those without RA in aseptic major (8.8% vs. 6.9%; p = 0.5) and septic major (1.1% vs. 0.5%; p = 0.7), as well as for aseptic minor (2.4% vs. 1.5%; p = 0.07) and septic minor (0.4% vs. 0.4%; p = 0.6).

Discussion and conclusions: While rheumatic diseases do not appear to impact the risk of revision surgery, a notable trend towards increased minor revisions after two years suggests ongoing monitoring is needed for long-term outcomes.