Background/Purpose: Reoperations following arthroplasty are a significant burden to patients and surgeons. In patients with RA who receive total hip (THA) or knee (TKA) arthroplasty, radiographic loosening, a common cause of reoperation, has been linked to increased disease activity.1,2 We sought to determine if synovitis in the operated joint at time of THA/TKA was associated with increased risk of reoperation.

Methods: RA patients who underwent primary THA/TKA and a reoperation on the same joint at our institution were identified via the EMR and clinical characteristics were extracted. Synovium specimens from THA/TKA were graded by a board-certified musculoskeletal pathologist for Synovial Lymphocytic Inflammation (SLI), Synovial Lining Hyperplasia (SLH), and Krenn synovitis score. SLI was graded from 0 (none) to 4 (band-like), with SLI 0–1 classified as non-inflammatory and 2–4 as inflammatory. Radiographs preceding reoperation were graded as loose or not loose by a board-certified radiologist based on a combination of periprosthetic lucency and implant position. Kaplan-Meier (KM) survival curves estimated risk of reoperation over time among subjects with a diagnosis of aseptic loosening, implant dislocation, or failure. Log rank tests were performed to assess differences in KM survival curves. Continuous and categorical variables were compared using two-tailed t-tests and Fisher’s exact tests, respectively. Logistic regression models assessed odds of reoperation within 5 years. Analyses were performed using STATA 18.0 with an alpha of 0.05.

Results: Thirty-nine patients meeting eligibility criteria were included; 109 cases were excluded due to secondary surgery on a different joint and 5 because index surgery occurred at another institution. Inflammatory synovium was present in 19 cases. 34 (85%) were female with mean ± SD age of 59± 10 years, BMI 30 ± 8.4 kg/m²; 15 (38.5%) had a loose implant, and 33 (82%) reoperations were revisions (Table 1). Time to reoperation did not differ between inflammatory and non-inflammatory groups (log-rank p-value > 0.05) (Figure 1). Neither diagnosis at reoperation (p-value = 0.24) nor radiographic loosening (53% vs. 25%, p-value = 0.10) differed between groups (Table 2). Inflammatory synovium was not associated with increased odds of reoperation within 5 years (OR 0.98, 95% CI 0.17, 5.83). Neither SLI, SLH, or Krenn score were associated with odds of reoperation within 5 years.

Conclusion: In this small cohort with a low incidence of secondary surgery, synovial inflammation at the time of primary surgery was not associated with increased risk of reoperation. Other factors, including systemic inflammation, may play a role in aseptic loosening and reoperation risk for RA patients undergoing THA or TKA and merit further investigation in a larger cohort. References1. Böhler C, Weimann P, Alasti F, Smolen JS, Windhager R, Aletaha D. Rheumatoid arthritis disease activity and the risk of aseptic arthroplasty loosening. Semin Arthritis Rheum. 2020;50(2):245-251. doi:10.1016/j.semarthrit.2019.07.011 2. Anil U, Singh V, Schwarzkopf R. Diagnosis and Detection of Subtle Aseptic Loosening in Total Hip Arthroplasty. J Arthroplasty. 2022;37(8):1494-1500. doi:10.1016/j.arth.2022.02.060

Table 1. Demographic, clinical, and histologic features of study patients

Table 2. Comparison of clinical characteristics at time of reoperation stratified by inflammatory status at primary surgery based on Synovial Lymphocytic Inflammation (SLI) grade

Figure 1. Kaplan-Meier survival curves for time to reoperation among patients with diagnosis at secondary surgery of implant loosening, dislocation, or failure, grouped by status as inflammatory or non-inflammatory. The proportion of patients undergoing reoperation surgery over time was not statistically different between groups (log-rank p > 0.05).

« Back to ACR Convergence 2025

ACR Meeting Abstracts - https://acrabstracts.org/abstract/synovial-inflammation-is-not-associated-with-reoperation-in-patients-with-rheumatoid-arthritis-undergoing-total-hip-or-knee-arthroplasty/