Cemented metal-on-polyethylene spacers have similar cost profiles with lower complications rates compared to molded all-cement articulating spacers for treatment of knee periprosthetic joint infection.

BACKGROUND All-cement spacers or metal-on-polyethylene (MoP) spacers are types of articulating spacers used in two-stage treatment of total knee arthroplasty (TKA) periprosthetic joint infection (PJI). While MoP spacers have improved durability and versatility, there is concern that use of primary arthroplasty components as a temporary spacer is not cost-effective. We investigated the cost of MoP versus molded all-cement articulating spacers for the treatment of TKA PJI. METHODS A retrospective review of primary TKA PJIs treated with articulating spacers between 2013 and 2020 was performed. Primary TKA implants were used for MoP spacers and molds were used to create all-cement spacers. Supply, implant, and surgical encounter costs were reviewed. Total cost and complications were reviewed. RESULTS Thirty-two molded all-cement and 17 MoP spacers were included. There was no difference between all-cement and MoP spacer Stage 1 cost ($4184 vs $4365), Stage 2 cost ($20,026 vs $20,441) or total cost ($24,210 vs $24,614). Moreover, spacer cost accounted for 17% of total cost. 3 patients in the all-cement group had mechanical complications requiring additional surgery.The MoP group had a shorter length of stay (LOS) after stage 2 (2.06 vs 4.16 days). Spacer choice did not affect stage 1 LOS, discharge disposition, operating room time, or reinfection rate. CONCLUSION MoP spacers have similar cost profiles, but lower incidence of complications compared to molded all-cement articulating spacers for two-stage exchange in treatment of TKA PJI. More than 80% of the surgical implant and supply cost is incurred during Stage 2 regardless of the spacer construct utilized.