Retaining Well-Balanced Articulating Metal-on-Polyethylene Total Knee Spacers for Periprosthetic Joint Infection: A Potential Alternative to Two-Stage Exchange.

Abstract

Although the gold standard for treatment of periprosthetic joint infection (PJI) is a two-stage exchange, patients may elect to retain a well-functioning spacer. The aim of this retrospective review was to evaluate the survivorship, complications, and patient-reported outcome measures (PROMs) of retained articulating total knee arthroplasty (TKA) spacers with patellar component replacement. All PJI patients from a tertiary care academic center who received a balanced, articulating metal-on-polyethylene TKA spacer with patellar component replacement were reviewed. After the stage-one spacer, all patients were offered a second-stage exchange within six months, with some electing to retain their spacers beyond one year. Reoperations, recurrent infections, periprosthetic fractures, and PROMs were compared between scheduled second-stage revisions within 6 months and retained spacers beyond one year. Independent t-tests were used for comparisons. A total of 48 patients were included, with 23 undergoing scheduled stage-two revision and 25 electing to retain their spacer beyond one year. In the retained-spacer cohort, one died from an aseptic etiology 47 months postoperatively. Of the 24 living patients, the mean follow-up was 29 months (SD = 19 months). Of the 25 patients in the retained-spacer cohort, five underwent stage-two reimplantation for aseptic loosening of the spacer (none catastrophic), of which one patient (4%) had reinfection after reimplantation. There were no other reinfections, dislocations, periprosthetic fractures, or reoperations that occurred in the retained-spacer cohort. Although not significantly different, 17% (four patients) of the scheduled stage-two cohort had infection recurrence compared to 4% in the retained-spacer cohort. There were no differences in final PROMs between cohorts. Patients who retained well-balanced, articulating TKA spacers had low infection recurrence, no catastrophic failures, and comparable PROMs to those undergoing scheduled two-stage revision for PJI. Well-balanced articulating metal-on-polyethylene spacers may offer an alternative to two-stage revision in select patients.