Delaying Total Knee Arthroplasty More than 4 Weeks after Intra-Articular Knee Injection Does Not Further Decrease Risk of Septic Revision.

Hyaluronic acid (HA) and corticosteroid (CS) injections are utilized in symptom management for patients with osteoarthritis. However, contamination of the joint may increase the risk of infection following total knee arthroplasty (TKA). Therefore, the purpose of this study was to examine 90-day surgical site infection (SSI) and manipulation under anesthesia (MUA) as well as up to 2-year prosthetic joint infection (PJI) in intra-articular knee injection recipients prior to TKA compared with patients who did not have knee injections. We specifically assessed (1) timing of HA and CS prior to TKA; (2) type of intra-articular knee injection; as well as (3) associated risk factors. We queried a national database to identify patients who underwent primary TKA from September 2015 to October 2020 ( n  = 1.5 million). Patients with prior knee injections were stratified to five cohorts: HA within 4 weeks ( n  = 140), HA 4 to 6 weeks prior ( n  = 337), CS within 4 weeks ( n  = 2,344), CS 4 to 6 weeks ( n  = 2,422), and a no injection, control, cohort prior to TKA ( n  = 5,000). Bivariate chi-square analyses of outcomes were conducted, and multivariate regressions were used to adjust for comorbidities and assess associated risk factors. The adjusted analysis showed a significant risk in infection for patients receiving an injection within 4 weeks of TKA ( p  < 0.023) and showed no difference in type of injection ( p  > 0.050). Additionally, SSIs were increased 1.58 times in the CS within 4 weeks of TKA cohort ( p  = 0.023). However, no difference in MUA risk was shown at 90-day postoperative ( p  > 0.212). Furthermore, tobacco use was identified as a risk factor that further increased likelihood of PJI. Intra-articular knee injection less than 4 weeks before TKA increased the risk for PJI; however, past 4 weeks did not confer infection risk. Tobacco use was identified as an associated risk factor that further increased likelihood for PJI. These results highlight the need for surgeons to wait 4 weeks between knee injection and TKA to decrease risk of septic revision.