Beyond Traditional Approaches: The Rush Rod Construct for Managing Chronic Periprosthetic Joint Infection in Total Knee Arthroplasty.

BACKGROUND: Traditional management strategies for total knee arthroplasty (TKA) periprosthetic joint infection (PJI), such as two-stage arthroplasty with static or dynamic spacers, have limitations. We developed a Rush Rod-reinforced articulating construct intended for use as both a first-stage spacer in two-stage revision and as a definitive 1.5-stage solution. The purpose of this study was to evaluate the construct's infection-free survival and functional outcomes in the management of chronic TKA PJI.

METHODS: We performed a retrospective cohort study of patients who have a chronic TKA PJI treated with a Rush Rod construct between 2010 and 2023 at a single tertiary referral center. Patients were categorized as planned for two-stage revision or definitive 1.5-stage revision. The primary outcome was re-infection-free survival, analyzed using Kaplan-Meier methods. The secondary outcomes included tier-based outcomes as per the Musculoskeletal Infection Society (MSIS) outcome reporting tool (ORT) and postoperative knee range of motion (ROM). There were 40 patients who were included who had a mean age of 66 years and a median follow-up of 39 months (range, 12 to 133).

RESULTS: There were nine patients (22.5%) who retained the Rush Rod construct as a definitive 1.5-stage solution. Overall, 32 patients (80%) remained free of reinfection during follow-up. Using the MSIS ORT, 7.5% of cases failed management due to PJI. Following Rush Rod construct implantation, mean knee flexion exceeded 100°, with preservation of near-full extension, with further improvement observed following second-stage reimplantation. There was one episode of construct dislocation observed.

CONCLUSIONS: The Rush Rod construct provides durable infection control and preserves knee ROM when used as the first stage of a two-stage revision or as a definitive 1.5-stage solution for chronic TKA PJI. A substantial proportion of patients retained the Rush Rod construct as definitive treatment while maintaining satisfactory function. This technique represents a reliable and flexible alternative to traditional spacer strategies.