OBJECTIVES: Septic revision surgery after total knee replacement (TKR) may be performed in one or two stages. Reinfection and amputation risks and costs following septic revision are poorly described in the literature. This study evaluates the proportion and risks of patients treated with one- vs two-stage revision.

METHODS: Patients from Truven Commercial and Medicare databases with an identifiable infection-free TKR followed by an inpatient admission for lower leg infection and revision were included. Index was defined as the date of revision surgery. Patients were categorized based on revision type (one-, two-stage or “other”). One-stage procedures comprised definitive revision surgery in one inpatient admission, without evidence of preceding spacer implantation or implant removal. Two-stage procedures had evidence of spacer implantation preceding placement of a new TKR. “Other” revisions could not be classified based on inconsistent procedure coding. All patients had at least 6-months pre- and 12-months post-index continuous enrollment. Occurrence for, and costs of primary and re-infection/continued infection/amputation treatments were analyzed. Covariates included demographic and comorbidities (Elixhauser Index (EI)). Generalized linear models were built to evaluate adjusted risks and payments for care related to reinfection/amputation.

RESULTS: 1,960 patients included 63% two-stage, 20% one-stage and 17% other revisions. The cohort was 46.9% female, at average age 60.4 (SD: 10.1), EI 3.6 (SD 2.5) and 12-month risk for reinfection: 12.3% and amputation: 0.7%. Adjusted rates for reinfection for two-stage, one-stage and other revisions, respectively, were 5.6% (95%CI: 4.2%-7.6%), 17.9% (95%CI: 15.0%-21.4%) and 26.6% (95%CI: 23.2%-30.5%). Adjusted total 12-months payments (including index and re-infection/amputation costs) averaged US$ 56K for one-staged, US$ 58K for “Other” and US$ 93K for two-staged revisions. Differences in reinfection risks and costs across groups were significant.

CONCLUSIONS: After adjusting for demographic and comorbid factors, two-stage revision was associated with overall higher costs but lower 12-month re-infection rates compared to other revision approaches.