IntroductionIn acute periprosthetic knee infections, debridement and implant retention (DAIR) is the preferred treatment prior to one- and two-stage revisions. The aim of this study is to compare the outcomes of arthroscopic and open debridement of infected primary total knee arthroplasties (TKA).Material and methodsWe analyzed clinical, laboratory, and antibiotic treatment data, collected in patients with periprosthetic knee infection treated with DAIR at a Swiss Level 1 orthopedic and trauma center over a 10-year period between January 2005 and May 2015. Inclusion criteria were primary total knee arthroplasty and early postoperative or acute hematogenous periprosthetic joint infection (PJI). The primary endpoint was the need for further revision surgery due to persistent infection. The secondary endpoint was the prosthesis salvage in further infection surgeries.ResultsForty-two patients with 44 acute or hematogenous periprosthetic knee infections were included. We recorded 20 recurrent infections (45%) in our study population: 10 (77%) out of 13 in the arthroscopic DAIR group and 10 (32%) out of 31 in the open DAIR group. Two-stage revision, meaning complete removal of the TKA, insertion of a spacer and replantation at a second stage, had to be performed in three patients treated initially arthroscopically (23%) and in six patients treated initially with an open surgical procedure (21%).ConclusionsOpen debridement for acute periprosthetic knee infection shows clear benefits in terms of infection eradication and prosthesis salvage compared to arthroscopic DAIR.