Circular frame in the presence of pre-existing arthroplasty: is there an unacceptable risk of infection?

IntroductionCircular external frames (CEF) are commonly used for a wide variety of indications, often when other devices are not appropriate. Circular frames are particularly associated with pin-site infection (PSI). Currently there is a gap in the available literature surrounding the risk of frame use with in-situ prosthetic joints. This retrospective study investigated the incidence of prosthetic joint infection (PJI) in a series of patients with in-situ arthroplasties treated with CEF.Materials & MethodsFrom a departmental database of 1052 frames performed from March 2007-March 2023, the outcomes of 34 patients (40 frames) with in-situ arthroplasties at the time of CEF were reviewed (mean follow-up 70 months). Patient identification was by review of all local and regional imaging. The primary outcome was development of PJI during or following CEF and subsequent need for surgical intervention. Secondary outcomes were development of superficial pin site or deep bone infection (without PJI).ResultsOf 40 frames used to treat 34 patients, no PJIs were detected. Average patient age was 67 (range 55–82). 22 had cardio-respiratory disease, 11 diabetes, 15 smoked and 8 were immunosuppressed. 53 arthroplasties were in situ at the time of treatment, 12 involving the same bone as the frame. Average time in frame was 253 days. 23 patients developed PSI, 2 required a further procedure for persistent deep bone infection not involving the arthroplasties.ConclusionsAlthough this study involves a relatively low numbers of patients, our results are reassuring that circular frame management in patients with in-situ arthroplasty does not represent an unacceptable risk of PJI. We hope to promote these findings and encourage multi-centre collaboration to expand on the available evidence to better answer this important yet under-reported clinical question.