Articulating vs Static Spacers for Native Knee Infection in the Setting of Degenerative Joint Disease

Abstract

Background Patients with advanced knee arthritis who develop a septic joint are not adequately treated with irrigation and debridement and intravenous antibiotics because of antecedent cartilage damage. The gold standard treatment has been a 2-stage approach. The periprosthetic joint infection literature has demonstrated the superiority of articulating spacers, and metal-on-poly (MOP) spacers are being used with increasing frequency. The purpose of this study was to compare the postoperative outcomes of patients with infected, arthritic knees treated by a 2-stage approach to those of patients who received single-stage treatment with a MOP spacer. Methods Sixteen patients with native knee septic arthritis treated with an antibiotic spacer between 1998 and 2019 were reviewed. Demographic data, clinical data, knee motion, Knee Society score, Timed-Up-and-Go, and pain scores were collected. Survivorship of final implants was compared. Results Six of 16 knees (38%) received single-stage treatment, and 10 received 2-stage treatment (62%). Five of 6 MOP spacers (83%) were retained at a mean follow-up of 3 ± 1.2 years. Nine of 10 (90%) receiving static spacers had subsequent reconstruction, with 9 (100%) surviving at mean follow-up of 7 ± 3.2 years. The patients who received MOP spacers trended toward greater terminal flexion, higher Knee Society score, and faster Timed-Up-and-Go at final follow-up. Conclusion Infection in a native, arthritic knee may be effectively treated using single-stage MOP spacer. Postoperative outcomes of single-stage MOP spacers compare favorably to staged static spacers and with those undergoing revision surgery for other indications. Longer follow-up is needed to evaluate durability of MOP spacers.