Preoperative Corticosteroid Injections Are Not Associated with Deep Infection after Unicompartmental Knee Arthroplasty

Prior to unicompartmental knee arthroplasty (UKA), corticosteroid injections (CSI) are a common nonoperative treatment for arthritis. It is unclear whether CSI prior to UKA impacts the likelihood of postoperative infection. This study sought to determine if there is a time- and/or dose-dependent relationship between preoperative CSI and postoperative infection. An administrative claims database was queried for patients undergoing UKA with more than 1 year of pre-enrollment and follow-up. Of 31,676 patients with a UKA who met enrollment criteria, 8,628 patients had a CSI 0 to 3 months prior to surgery, 111 had a CSI 3 to 12 months prior to surgery, and 22,937 never received an injection. Overall, 246 postoperative deep infections were reported (0.8%). Time-dependent and dose-dependent relationships were modeled using multivariable logistic regressions. Postoperative deep infections occurred in 64 patients with CSI 0 to 3 months prior to surgery (0.7%), compared with 0 patients with CSI 3 to 12 months before surgery (0.0%) and 182 controls (0.8%, p = 0.58). CSI within 1 month prior to UKA was not statistically associated with postoperative infection ( p = 0.66). Two or more CSI within 3 months prior to UKA were associated with a twofold elevated odds of infection, compared with receiving a single injection (odds ratio [OR]: 2.08, p = 0.03). Univariable predictors of infection included younger age, increasing Charlson Comorbidity Index, smoking, asthma, chronic obstructive pulmonary disease, chronic kidney disease, diabetes, liver disease, and obesity. Multivariable analysis controlling for these characteristics elicited no relationship between recent CSI administration and postoperative infection. CSI within 3 months of surgery (1.5%) or 3 to 12 months (1.8%) were associated with increased conversion to total knee arthroplasty (TKA) compared with those who did not receive an injection (1.1%, p = 0.01), although TKA for indication of periprosthetic joint infection was not statistically different ( p = 0.72). Preoperative CSI within 3 months of UKA is not associated with postoperative infection, although significant medical comorbidity does show an association. Preoperative CSI is associated with increased conversion from UKA to TKA for noninfectious indications.