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Background: Racial and ethnic disparities have been suggested to be associated with poor outcomes after total knee arthroplasty (TKA). While socioeconomic disadvantage has been studied, analyses of race as the primary variable are lacking. Therefore, we examined the potential differences between Black and White TKA recipients. Specifically, we assessed 30-day and 90-day, as well as 1 year: (1) emergency department visits and readmissions; (2) total complications; (3) as well as risk factors for total complications., Methods: A consecutive series of 1,641 primary TKAs from January 2015 to December 2021 at a tertiary health care system were reviewed. Patients were stratified according to race, Black (n = 1,003) and White (n = 638). Outcomes of interest were analyzed using bivariate Chi-square and multivariate regressions. Demographic variables such as sex, American Society of Anesthesiologists classification, diabetes, congestive heart failure, chronic pulmonary disease, and socioeconomic status based on Area Deprivation Index were controlled for across all patients., Results: The unadjusted analyses found that Black patients had an increased likelihood of 30-day emergency department visits and readmissions (P < .001). However, in the adjusted analyses, Black race was demonstrated to be a risk factor for increased total complications at all-time points (P ≤ .0279). Area Deprivation Index was not a risk for cumulative complications at these time points (P ≥ .2455)., Conclusion: Black patients undergoing TKA may be at increased risk for complications with more risk factors including higher body mass index, tobacco use, substance abuse, chronic obstructive pulmonary disease, congestive heart failure, hypertension, chronic kidney disease, and diabetes and were thus, "sicker" initially than the White cohort. Surgeons are often treating these patients at the later stages of their diseases when risk factors are less modifiable, which necessitates a shift to early, preventable public health measures. While higher socioeconomic disadvantage has been associated with higher rates of complications, the results of this study suggest that race may play a greater role than previously thought., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Arthrofibrosis following total knee arthroplasty (TKA) is a debilitating condition typically diagnosed based on clinical findings. To gain insight into the histopathologic immune cell microenvironment of arthrofibrosis, we assessed the extent of tissue fibrosis and quantified immune cell populations in specific tissue regions of the posterior capsule. We investigated specimens from three prospectively-collected, matched cohorts, grouped as patients receiving a primary TKA for osteoarthritis, revision TKA for arthrofibrosis, and revision TKA for non-arthrofibrotic, non-infectious reasons. Specimens were evaluated using hematoxylin and eosin staining, picrosirius red staining, immunofluorescence, and immunohistochemistry with Aperio®-based digital image analysis. Increased collagen deposition and increased number of α-SMA/ACTA2 expressing myofibroblasts were present in the arthrofibrosis group compared to the two non-arthrofibrotic groups. CD163 + macrophages were the most abundant immune cell type in any capsular sample with specific enrichment in the synovial tissue. CD163 + macrophages were significantly decreased in the fibrotic tissue region of arthrofibrosis patients compared to the patients with primary TKA, and significantly increased in adipose tissue region of arthrofibrotic specimens compared to non-arthrofibrotic specimens. Synovial CD117 + mast cells were significantly decreased in arthrofibrotic adipose tissue. Together, these findings inform diagnostic and targeted therapeutic strategies by providing insight into the underlying pathogenetic mechanisms of arthrofibrosis., (© 2022. The Author(s).)

The dense formation of abnormal scar tissue after total knee arthroplasty results in arthrofibrosis, an unfortunate sequela of inflammation. The purpose of this study was to use a validated rabbit model to assess the effects on surgically-induced knee joint contractures of two combined pharmacological interventions: celecoxib (CXB) loaded on an implanted collagen membrane, and subcutaneously (SQ) injected ketotifen. Thirty rabbits were randomly divided into five groups. The first group received no intervention after the index surgery. The remaining four groups underwent intra-articular implantation of collagen membranes loaded with or without CXB at the time of the index surgery; two of which were also treated with SQ ketotifen. Biomechanical joint contracture data were collected at 8, 10, 16, and 24 weeks. At the time of necropsy (24 weeks), posterior capsule tissue was collected for messenger RNA and histopathologic analyses. At 24 weeks, there was a statistically significant increase in passive extension among rabbits in all groups treated with CXB and/or ketotifen compared to those in the contracture control group. There was a statistically significant decrease in COL3A1, COL6A1, and ACTA2 gene expression in the treatment groups compared to the contracture control group (P < .001). Histopathologic data also demonstrated a trend towards decreased fibrous tissue density in the CXB membrane group compared to the vehicle membrane group. The present data suggest that intra-articular placement of a treated collagen membrane blunts the severity of contracture development in a rabbit model of arthrofibrosis, and that ketotifen and CXB may independently contribute to the prevention of arthrofibrosis. Statement of clinical significance: Current literature has demonstrated that arthrofibrosis may affect up to 5% of primary total knee arthroplasty patients. For that reason, novel pharmacologic prophylaxis and treatment modalities are critical to mitigating reoperations and revisions while improving the quality of life for patients with this debilitating condition., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)