One- versus two-stage septic hip and knee revision surgery: a comparative cohort outcome study with short- to mid-term follow-up.

Introduction: One-stage revisions seem to have similar reinfection rates compared to two-stage revisions for the treatment of periprosthetic joint infections based on retrospective cohort studies with a large variety of indications and treatment protocols. This study aimed to compare outcomes between comparable groups of one-stage and two-stage revision patients. Materials and methods: We performed a retrospective cohort study, where equal numbers of one-stage and two-stage patients (knee: $n=24$ ; hip: $n=40$ ) were randomly included with the same inclusion and exclusion criteria. Patient characteristics and infection-related outcomes at latest follow-up were obtained via chart review. Functional outcomes (knee: Knee Society Score (KSS), range of motion (ROM), and visual analogue scale (VAS) pain and satisfaction; hip: Oxford Hip Score (OHS), Hip Disability and Osteoarthritis Outcome Score-Physical Function Shortform (HOOS-PS), VAS pain and satisfaction, and European Quality of Life 5 Dimensions 3 Level version (EQ5D-3L)) preoperatively (hip only) and at 1-year follow-up were extracted from a revision database. Outcomes were compared between one- and two-stage groups and for knee and hip cases separately. Results: One- and two-stage groups were comparable for baseline characteristics. Reinfection occurred for both the knee and hip cohorts in one one-stage patient and one two-stage patient ( $P=1.00$ for both cohorts). More adverse events, of which two were spacer-related, were observed in two-stage hip patients ( $n=7$ ) compared to in one-stage patients ( $n=2$ ) ( $P=0.13$ ). Functional outcomes did not differ between one- and two-stage patients for both knee and hip cohorts. Conclusions: This study showed no differences in terms of reinfection rates and functional outcomes between comparable groups of one- and two-stage septic knee and hip revision patients. A trend towards more adverse events in two-stage hip patients was seen, which was partly due to spacer complications.