Less than 1-year quiescent period after septic arthritis of the hip is associated with high risk of periprosthetic joint infection following total hip arthroplasty.

INTRODUCTION: Approximately 20,000 patients are diagnosed with septic arthritis annually, with 15% specifically affecting the hip joint. These cases exacerbate arthritic changes, often warranting a total hip arthroplasty (THA). Given their prior history of infection, these patients are predisposed to subsequent periprosthetic joint infections (PJIs). Multiple studies suggest delaying THA after a native septic hip, but no study utilizing a large cohort examined the specific timing to mitigate post-THA PJI risk within a short (<1-year) quiescent period after septic arthritis. We sought to compare patients who were diagnosed with septic hip arthritis at time intervals (0 to 6, or 6 to 12 months) prior to an ipsilateral primary THA to a cohort of THA patients who never had a septic hip history. Specifically, we assessed: 90-day to 2-year (1) revisions due to PJI and (2) associated risk factors for PJI at 2-years. METHODS: A national, all-payer database was queried to identify all patients who underwent a primary THA between 2010 to 2021 and patients who had prior ipsilateral septic hip arthritis were characterized using International Classification of Disease and Current Practice Terminology codes (n = 1,052). A randomized sample of patients who never had a history of septic arthritis prior to undergoing THA was used as a non-septic group comparison (n = 5,000). The incidences of PJI at 90 days through two years were then identified and compared using bivariate chi-square analyses. Risk factors for post-THA PJIs were then analyzed using multivariate regression models. RESULTS: The septic arthritis cohorts were more likely to require revisions due to PJIs, as compared to the non-septic group at 90-days, 1-year and 2-years (all p<0.0001). Patients who were diagnosed with septic arthritis between 0 to 6 months prior to THA were at greater PJI risk at both one-year (odds ratio (OR) of 43.1 versus 29.6, p<0.0001) and two-years (OR of 38.3 versus 22.1, p<0.0001) compared to patients who had diagnoses between 6 to 12 months. Diabetes mellitus, obesity, and tobacco use were associated risk factors for PJIs at 2-years in the septic hip cohort in comparison to the cohort without a septic hip history. CONCLUSION: Less than 1-year quiescent period after septic arthritis is associated with at 38 times increased risk and 22 times risk for post-THA PJI, at 0 and 6 months and 6 and 12 months, respectively. Though patients who undergo THA greater than 6 months after their septic arthritis treatment have a decreased risk compared to those between 0 and 6 months the risks are still high. Orthopaedic surgeons should be aware of the increased risks of PJIs when consider performing a THA in patients with a history of septic arthritis.