Intra-articular Hip Injections Prior to Total Hip Arthroplasty: Infection and Cost-Related Associations.

Intra-articular injections prior to total hip arthroplasty (THA) have been associated with postoperative infections. The purpose of this study was to determine whether a temporal relationship exists between hip injections prior to THA and infection. Specifically, we asked (1) Do patients who receive hip injections within 3 months of THA have a higher incidence of prosthetic joint infections (PJIs) or surgical site infections (SSIs)? and (2) Do these patients incur higher 90-day costs? Patients with hip injections prior to THA were identified using a national database from 2010 to 2019. Three laterality-specific groups (injection 0 to 3 months, 3 to 6 months, and 6 to 12 months prior to THA)were compared with a matched cohort without prior injection (n=277,841). Primary outcomes included PJIs, SSIs, and costs. Patients who had injections within 3 months of THA had a higher incidence of PJIs at 90 days (5.1% vs 1.6%, P<.01) and 1 year (6.8% vs 2.1%, P<.01), when compared with the matched cohort. They also had a higher incidence of SSIs at 90 days (2.8% vs 1.2%, P<.01) and 1 year (3.7% vs 1.7%, P<.01). Mean costs were 13.7% higher in this injection cohort. Patients who had injections between 3 and 6 months prior to THA had higher incidence and odds of postoperative PJIs at 90 days (2.6% vs 1.6%, P<.04), whereas those with injections beyond 6 months had no differences in PJIs (P≥.46). Patients who receive hip injections within 3 months of undergoing primary THA are at increased risk for postoperative PJIs, SSIs, and higher costs. This study reaffirms guidelines for when to perform THAs in these populations. [Orthopedics. 2023;46(1):19-26.].