Image-Guided Intra-articular Hip Injections and Risk of Infection After Hip Arthroscopy

Background: Although intra-articular injections are important in the management of patients who may later undergo hip arthroscopy, conflicting data are available regarding the safety of such injections when administered within 3 months of surgery. Furthermore, despite the increasing use of image-guided intra-articular hip injections, it is unknown whether the type of imaging modality used is associated with infection after hip arthroscopy. Purpose: To assess the risk of infection associated with image-guided intra-articular injections before hip arthroscopy and, secondarily, compare that risk between ultrasound (US) and fluoroscopic (FL) guidance. Study Design: Cohort study; Level of evidence, 3. Methods: This was a retrospective cohort study of patients in a large national insurance database who underwent hip arthroscopy between 2007 and 2017. Patients were required to have continuous enrollment from at least 1 year before to 6 months after hip arthroscopy. Patient age, sex, geographic region, medical history, surgical details, and hip injections were collected. Patients who underwent injection ≤3 months preoperatively and >3 to ≤12 months preoperatively were compared with patients who did not undergo preoperative injection. Bivariate analyses and multivariable logistic regressions were used to assess the association between ipsilateral preoperative hip injection and surgical site infection within 6 months of surgery. Results: We identified 17,987 patients (36.3% female; mean ± SD age, 37.6 ± 14.0 years) undergoing hip arthroscopy, 2276 (12.7%) of whom had an image-guided hip injection in the year preceding surgery (53.0% FL). Patients who underwent intra-articular injection ≤3 months preoperatively had similar infection rates to patients who did not undergo preoperative injection in the year before surgery for both the FL (0.46% vs 0.46%; P≥ .995) and the US cohorts (0.50% vs 0.46%; P = .76). Results persisted in adjusted analysis (FL ≤3 months: OR, 1.04; 95% CI, 0.32-3.37; P = .94; US ≤3 months: OR, 1.19; 95% CI, 0.36-3.90; P = .78). Similar results were seen for patients undergoing injections >3 to ≤12 months preoperatively. Conclusion: Postoperative infection was rare in patients undergoing intra-articular hip injection ≤3 months before hip arthroscopy and was no more common than in patients not undergoing preoperative injection. Moreover, no differences were seen in infection risk between US and FL guidance. Although intra-articular hip injections should always be administered with careful consideration, these results do not suggest that these injections are uniformly contraindicated in the 3 months preceding hip arthroscopy.