Risk of Periprosthetic Joint Infection in Patients With Ipsilateral Infected Arthroplasties.

Background: The risk of periprosthetic joint infection (PJI) subsequently developing at a second site after an initial PJI has been documented to be approximately 18%-20%. To the best of our knowledge, only a single study has evaluated the incidence in ipsilateral joints and if the risk of infection would be different. While this was the only other study to evaluate this specific subfield, we set to re-evaluate and confirm the incidence of developing a second PJI in the setting of an ipsilateral prosthesis and possible associated risk factors. Methods: We retrospectively reviewed all patients treated surgically for lower-extremity PJI at our institution by 5 surgeons from 2015 to 2021. Patients with multiple arthroplasties on the ipsilateral extremity were included. Time between initial and subsequent infection, risk factors for infection, bacterial source, and bacteremia were identified. Results: Of 392 patients treated for PJI, 179 (45.6%) had multiple prosthetic joints. Forty-seven of those 179 patients had ipsilateral extremity prosthesis, which made up our study population. Three patients (6.4%) developed a separate infection at an ipsilateral TJA. In total, 10 patients (21.3%) developed a separate PJI. Patients on immunosuppressants had a higher likelihood of developing second PJI on the ipsilateral extremity ( Conclusions: Our study identified the risk of developing an ipsilateral PJI to not be any greater than that in patients with contralateral TJAs. It appears that sharing an extremity with an infected TJA does not pose substantially increased risk of subsequent infection of the un-involved prosthesis. Furthermore, immunosuppressant use may increase the risk of a separate ipsilateral PJI.