Chronic periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is most commonly addressed with a 2-stage exchange procedure. The purpose of this study is to examine the natural history of patients who have undergone prosthesis removal and spacer placement and evaluate risk factors for outcomes other than reimplantation.
Patients who underwent removal of an infected TKA and placement of an antibiotic spacer for PJI were identified in a Medicare database. Patients with a study outcome within 1 year were then identified: (1) in hospital mortality, (2) knee arthrodesis, (3) amputation, (4) repeat debridement procedure without reimplantation, and (5) reimplantation. Independent risk factors for these outcomes were evaluated with a multivariate logistic regression analysis.
A total of 18,533 patients were included. Within 1 year postoperatively, 691 patients (3.7%) died in a hospital setting, 852 patients (4.5%) underwent a knee arthrodesis, 574 patients (3.1%) underwent an amputation, 2683 patients (14.5%) underwent a repeat debridement procedure without being reimplanted, 2323 patients (12.5%) retained their spacer, and 11,420 patients (61.6%) underwent spacer removal and reimplantation within 1 year. Numerous independent patient-related risk factors for these outcomes were identified.
A large number of patients (38.4%) do not undergo reimplantation within 1 year of prosthesis removal and spacer placement. Outcomes after prosthesis removal and antibiotic spacer placement are variable, and there are several independent risk factors for such outcomes that may be used to develop and improve existing treatment strategies for patients presenting with chronic PJI after TKA.