Psoriasis Is a Risk Factor for Surgical Site Infection After Primary TKA

Background The relationship between psoriasis and complications after primary TKA is not well defined. Current studies are limited to small, single-center studies evaluating fewer than 150 patients with psoriasis, with some studies reporting an increased risk of surgical site infection (SSI) and another reporting no associated risk. There is a need to reevaluate the risk of psoriasis and postoperative complications, including SSI, to better risk-stratify and guide practice in this patient population. Questions/purposes (1) Compared with patients without psoriasis, after accounting for potential confounders such as age, insurance, and comorbidities, do patients with psoriasis have a higher odds of superficial SSI after primary TKA? (2) Do patients with psoriasis have a higher odds of deep SSI after primary TKA? Methods Patients 18 years or older who underwent unilateral, primary TKA between 2015 and 2019 were identified in the PearlDiver database (n = 490,722). Patients with rheumatoid, septic, or posttraumatic arthritis were excluded, as well as patients with bone neoplasias (n = 188,557). Additionally, patients with less than 2 years of follow-up (n = 53,673) were excluded. In all, 248,492 patients were included in this study; 0.4% (1078) were in the psoriasis group and 99% (247,414) were in the control group. Overall 2-year superficial and deep SSI rates were stratified and compared between patients with psoriasis and a control group of patients who did not have psoriasis as the primary outcome. Secondary outcomes included the odds of undergoing an aseptic revision or manipulation under anesthesia. Results In the multivariable analysis, which controlled for potential confounders such as age, sex, Elixhauser comorbidity index, hypertension, diabetes mellitus, and liver disease, the odds of SSI—either superficial or deep—remained higher for patients with psoriasis (OR 1.74 [95% confidence interval 1.03 to 2.96]; p = 0.04). When focusing on superficial infections in the multivariable analysis, patients with psoriasis had a higher odds of superficial SSI than those in the control group (OR 2.83 [95% CI 1.26 to 6.34]; p = 0.01). The odds of deep SSI were not different between the two cohorts in our multivariable analysis (OR 1.32 [95% CI 0.66 to 2.66]; p = 0.43). Patients with psoriasis did not have an increased odds of undergoing an aseptic revision (OR 0.79 [95% CI 0.48 to 1.32]; p = 0.38) or manipulation under anesthesia (OR 0.74 [95% CI 0.52 to 1.06]; p = 0.10). Conclusion Patients with psoriasis had higher overall rates of SSI at 2 years of follow-up than patients without psoriasis. Our findings suggest that psoriasis is a risk factor for superficial SSI after primary TKA and is an important comorbidity for surgeons to consider before surgery. Further research is needed to assess the role of adjunctive interventions in patients with psoriasis to mitigate the elevated odds of superficial SSI. Level of Evidence Level II, prognostic study.