IS IT TIME FOR DURABLE FUNCTIONAL ANTIBIOTIC-LADEN SPACERS TO SUPPLANT TWO-STAGE EXCHANGE ARTHROPLASTY AS THE GOLD STANDARD FOR TREATING TKA-PJI?

Background A durable functional antibiotic-laden spacer (DFAS) is a method for treating subacute or chronic periprosthetic joint infection (PJI) in a single surgery using a new durable primary metal-on-polyethylene total knee arthroplasty (TKA) articulation fixed with high-dose antibiotic-laden cement that is weaker than would be chosen for gold-standard two-stage exchange arthroplasty. The purpose of this study was to compare outcomes of using DFAS or the gold-standard two-stage exchange arthroplasty using a static non-durable high-dose antibiotic-laden cement-only spacer prior to revision to a durable metal-on-polyethylene TKA with low-dose antibiotic-laden cement for PJI. Methods A retrospective review was performed to create a list of patients treated with DFAS for TKA-PJI and a comparison cohort of two-stage exchange arthroplasty. Patients of all follow-up lengths were included for survival analysis. Clinical data was collected on demographic and surgical variables. Mann-Whitney tests, two-sample t-tests, Fisher's exact tests, and chi-square tests were used for statistical analysis, and Fine-Gray sub-distribution hazard models were used for survival analysis, treating death as a competing risk. Results There was no significant difference in infection free survival between DFAS and two-stage exchange arthroplasty (88% vs 88%, p>0.999). The postoperative Knee Society scores of a DFAS (median: 94, range 55-100) were like a two-stage exchange arthroplasty (median: 89, range 45-100; p=0.402). Patients undergoing two-stage exchange arthroplasty underwent significantly more operations (median: 2, range: 2-6) when compared to DFAS (median: 1, range 1-4, p<0.001). There was no difference in all-cause failure (Hazard Ratio [HR]: 1.19, 95% Confidence Interval [CI]: 0.65–2.16, p=0.570), aseptic failure (HR: 0.83, CI: 0.34–2.04, p=0.680), or septic failure when comparing DFAS to two-stage exchange arthroplasty (HR: 1.39, 95% CI: 0.60–3.22, p=0.440). However, the types of revision surgeries following septic failure differed between groups with DFAS have double the odds of ultimate re-implantation than two-stage exchange arthroplasty (p=0.44). Conclusion The non-inferiority of the DFAS to two-stage exchange arthroplasty with respect to overall and infection-free survival with fewer surgeries and reduced morbidity upon re-operation raises the question of whether DFAS should supplant two-stage exchange arthroplasty as the gold-standard for treating PJI after being applied in a broader non-selected patient population.