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ACPA Seropositivity: A Paradoxical Benefit in Silicone Metacarpophalangeal Arthroplasty for Rheumatoid Arthritis
Adam Schluttenhofer, BS
1, Zoe Postal, BS
1, Audrey Bankes, BS
1; Marco Rizzo, MD
2(1)Mayo Clinic, Rochester, MN, (2)Division of Hand Surgery, Mayo Clinic, Rochester, MN
Introduction: Silicone metacarpophalangeal (MCP) arthroplasty for rheumatoid arthritis (RA) relies on fibrous encapsulation for stability. Anti-citrullinated peptide antibodies (ACPAs) are present in a subset of RA patients and associated with increased disease severity and joint inflammation. This differential inflammatory setting may influence long-term MCP arthroplasty results. We report differences in rates of revision, all-cause reoperation, and coronal plane deviation between ACPA seropositive and seronegative RA patients who underwent primary silicone MCP arthroplasty.
Materials & Methods: We utilized our institution's prospective joint registry to identify primary MCP arthroplasties in patients with RA from 2000 to 2022. Patients were stratified by ACPA status (seropositive ?20 U, seronegative <20 U). Kaplan-Meier estimates were used to assess survival free from revision, all-cause reoperation, and radiographic progression of coronal deviation ?10º after four weeks (timeline of implant fibrous encapsulation). We used cluster-robust Cox proportional hazard models to determine the effect of ACPA seropositivity on these endpoints while accounting for potential confounders.
Results: There were 133 joints in 39 ACPA seropositive patients (8.7 years mean follow-up) and 64 joints in 22 ACPA seronegative patients (5.2 years mean follow-up). There were more females in the seropositive group (91% vs 69%, p < 0.001), but otherwise no differences in patient demographics, operative characteristics, or disease-modifying RA medication use. At 10 years, ACPA seropositive patients had significantly higher survival free from revision (93.3% vs 64.8%), all-cause reoperation (91.7% vs 60.8%), and >10º coronal deviation (34.6% vs 19.8%). After adjusting for patient sex, ACPA seropositivity was associated with reduced hazard for revision (HR 0.17, p = 0.04), all-cause reoperation (HR 0.20, p = 0.03), and >10º coronal deviation (HR 0.43, p = 0.02).
Conclusions: ACPA seropositivity is associated with significantly reduced risk of revision, all-cause reoperation, and coronal plane instability after silicone MCP arthroplasty. These findings suggest that ACPA seropositivity may paradoxically benefit silicone implant longevity. We hypothesize this may be related to an altered inflammatory milieu in ACPA-positive patients, potentially leading to a more robust fibrous encapsulation of the implant.
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