The purpose of this study is to evaluate the influence of intra-articular corticosteroid injections prior to knee arthroscopy on the rate of postoperative infection and define a safe timing interval between intra-articular corticosteroid injections and subsequent knee arthroscopy. The PearlDiver Database was used to identify patients who underwent a knee arthroscopy from 2007 to 2017. Patients were sorted into an injection cohort if they received any intra-articular corticosteroid injections within 6 months before surgery and a control cohort if they received no such injections. The injection cohort was then stratified into subgroups based on the timing of the most recent injection. We identified two types of postoperative infection in the 6 months following surgery: a broad definition of infection using knee infection diagnoses, and a narrow definition of infection requiring surgical treatment. The effects of the timing of preoperative corticosteroid injections on the rates of postoperative infection were investigated. The rate of broadly defined postoperative infection was significantly higher in the 0 to 2 weeks injection group (6.90%, 20/290) than the control group (2.01%, 1,449/72,089, p < 0.001; odds ratio [OR]:3.61 [95% confidence interval [CI]: 2.29, 5.70]). We observed a significant difference regarding the rate of narrowly defined postoperative infection requiring surgical treatment between the 0 and 2 weeks injection group (1.38%, 4/290) and the control group (0.27%, 192/72,089, p < 0.001, OR:5.24 [95% CI: 1.94, 14.21]). No significant differences were observed between other subgroups and the control group in both types of postoperative infection. Intra-articular corticosteroid injections within 2 weeks of knee arthroscopy were statistically significantly associated with higher rates of postoperative infection. This is a Level III, retrospective comparative study.
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