One-stage knee replacement shows similar healing rates in patients with negative or positive preoperative cultures: a retrospective cohort study.

Introduction: Treatment of chronic periprosthetic joint infections (PJIs) involves prosthesis removal, reimplantation, and antibiotic treatment. This process can be performed as a two-stage replacement or a one-stage replacement. One-stage replacement is classically performed only in patients who meet very strict criteria. The objective of this study was to analyse the healing and failure rates of one-stage knee replacement in patients with positive preoperative cultures and in those with negative preoperative cultures. Secondarily, we analysed the healing rate in patients with a sinus tract. Material and methods: We included 56 patients diagnosed with likely or confirmed PJI who underwent one-stage knee replacement in our centre between January 2016 and December 2021, with a minimum follow-up of 1 year. We evaluated the differences between cases with positive and negative preoperative cultures. Survival differences were assessed according to preoperative culture positivity and the presence of a sinus tract. Results: Preoperative cultures had positive results in 43 patients (76.8 %) and negative results in 13 patients (23.2 %). The overall failure rate was 12.5 % (seven patients), with one of these patients having had negative preoperative cultures. Of the 49 patients (87.5 %) with good results, 12 had negative preoperative cultures, and 37 had positive cultures ( $p=1.00$ ). Only 6 (10.7 %) of the 56 patients studied presented with a sinus tract. The differences in terms of healing and failure rates between patients with and without a sinus tract were not statistically significant ( $p=0.57$ ). Discussion: Using less strict criteria for patients, such as allowing preoperative negative cultures or the presence of a sinus tract, produced similar results to those for patients with only positive cultures or intact soft tissue.