To examine any association between the timing of ipsilateral postoperative corticosteroid injection following simple knee arthroscopy and infection.
Private payer (PP) and Medicare (MC) national insurance databases were queried for patients who underwent simple arthroscopic knee procedures. Patients undergoing concomitant open or more complex procedures with grafts were excluded. Patients who underwent ipsilateral corticosteroid injections within 2, 4, 6, and 8 weeks postoperatively were then identified. Postoperative infection within 90 days after the injection was assessed using International Classification of Diseases, 9th Revision, and Current Procedural Terminology coding and compared using a multivariate binomial logistic regression analysis.
A total of 5,533 patients were identified, including 725 that received an injection within 2 weeks; 1,236 patients within 4 weeks; 1,716 patients within 6 weeks; and 1,856 patients that received an injection within 8 weeks postoperatively. In both the PP and MC datasets, the rate of infection was significantly higher in the 2-week group compared with the 6- (PP: odds ratio [OR] 3.81, P = .012; MC: OR 9.36, P = .001) and 8-week (PP: OR 8.59, P = .003; MC: OR 7.80, P = .001) groups. The rate of infection was also higher in the 4-week group compared with the 6- (PP: OR 2.54, P = .024; MC: OR 8.91, P = .001) and 8-week (PP: OR 5.64, P = .009; MC: OR 7.80, P = .001) groups. There was no difference in infection rates between the 2- and 4-week groups in either dataset (PP: P = .278; MC: P = .861).
Level III, retrospective comparative study.
There is a significant association between intra-articular knee corticosteroid injections within 4 weeks of surgery and an increased incidence of postoperative infection in both MC and PP patients after knee arthroscopy compared with patients with steroid injections more than 4 weeks postoperatively and matched controls who did not receive injections.