Presence of Metallosis Can Interfere With Culture Positivity in Prosthetic Joint Infection of the Hip.

Background: Metallosis is a well-described complication of total hip arthroplasty (THA); however, its impact on periprosthetic joint infection (PJI) diagnosis and treatment remains unknown. We assessed whether coexisting metallosis at the time of revision THA is associated with delayed diagnosis and poorer PJI treatment outcomes. Methods: We retrospectively reviewed patients undergoing revision THA due to chronic and acute hematogenous PJI with coexisting metallosis (metallosis and PJI group). A matched cohort of patients with chronic and acute hematogenous PJI without metallosis was established (control group). The 2018 International Consensus Meeting criteria were used to define PJI. Metallosis was diagnosed based on the intraoperative findings or serum chromium/cobalt levels. The primary outcomes were culture positivity and survival free of reoperation or revision. Thirteen and 42 patients were included in the metallosis and PJI and the control groups, respectively. Results: The initial set of cultures was negative in 38% of patients in the metallosis and PJI group, compared to only 12% in the control group (P = .03). Time elapsed between presentation of symptoms and first positive culture was significantly longer in the metallosis and PJI group compared to the control (14.5 vs 0 days, P < .001). The revision rate was 46% in the metallosis and PJI group and 24% in the control group (P = .12). Revision-free survival in patients treated with debridement, antibiotics, and implant retention was 28% in the metallosis and PJI group and 79.7% in the control group, (P = .21). Conclusions: Metallosis may increase the likelihood of initial false negative culture results and delay PJI diagnosis in patients undergoing revision THA.