Articulating Spacers as a Modified One-Stage Revision Total Knee Arthroplasty: A Preliminary Analysis

Periprosthetic joint infection (PJI) following primary total knee arthroplasty (TKA) is a challenging complication for surgeons and patients alike. Although two-stage revision arthroplasty remains the gold standard PJI management in the United States, one-stage revision has had success in many parts of Europe. The aim of this study was to retrospectively review: 1) ultimate treatment success; 2) necessary antibiotic duration; 3) change in knee range of motion (ROM); and 4) final Knee Society Scores (KSS) in a case series of patients managed with retention of articulating antibiotic spacers following PJI.

A retrospective review was performed on all patients treated for chronic PJI after primary TKA with retention of articulating antibiotic spacers at a minimum of one-year follow-up. Descriptive analysis was utilized to evaluate demographic characteristics, discharge destination, follow-up and antibiotic durations, Knee Society Score (KSS), and rates of treatment failure. Paired-Samples t-Tests were utilized to evaluate mean changes in flexion and extension between the preoperative and postoperative time periods.

Our final cohort included 29 patients who were managed with articulating spacer retention at a mean follow-up of 16.8 (range, 12.0 to 23.1) months, with 21 patients (72.4%) medically unfit for multiple surgeons and eight patients (27.6%) satisfied with their function. Mean age was 61.3 (range, 41 to 85) years and mean Charlson Comorbidity Index (CCI) was 6.1 (mean, 0 to 12). The predominant infecting organism was Methicillin-Resistant Staphylococcus aureus (MRSA), which was involved in eight patients (27.6%). There was a significant increase in postoperative knee flexion (+14.7°; p<0.001) and no decrease in postoperative knee extension (+2.3°; p=0.361). Treatment success in our cohort was 79.3% (23 patients), with four patients (13.8%) having chronic wound drainage and two patients (6.9%) requiring multiple spacer exchanges. Sixteen patients (55.2%) were able to complete their antibiotic regimen, with the remaining patients unable to discontinue their antibiotics by latest clinic follow-up.

One-stage exchange arthroplasty offers the advantage of a single procedure with analogous failure rates compared to two-stage exchange, decreases hospitalization, and improves cost-effectiveness, which is paramount in today's healthcare environment. To our knowledge, this is the first study in the United States to evaluate outcome scores, function, and success rate of a modified one-stage revision TKA technique. Although we are unable to make definitive conclusions based on the small sample size, the outcomes in this study are encouraging.