Host Factors Affect the Outcome of Arthroscopic Lavage Treatment of Septic Arthritis of the Knee

: The purpose of this study was to determine the prognostic factors related to the outcome of lavage surgery in patients with septic arthritis of the knee. A total of 55 patients with acute septic arthritis who underwent arthroscopic lavage were enrolled in the study. Host factors, including age, medical comorbidities, and medication use, were evaluated according to the Musculoskeletal Infection Society staging system, and patients were then stratified into 3 types: type A, no compromising factors; type B, 1 to 2 compromising factors; and type C, more than 2 compromising factors. Routes of infection were classified. Causative organisms were classified as gram positive, gram negative, mixed, or culture negative. Multivariable analysis confirmed that type C hosts showed more than 16 times the risk for failure of a single arthroscopic lavage than type A hosts. Type B hosts showed no significant differences from either type A or type C hosts. Patients with gram-positive cultures had more than 13 times the risk for failure than patients who were culture negative. Patients with gram-negative and mixed cultures showed no significant differences from the other groups. The sex of the patient and the route of infection were not related to the success of a single arthroscopic lavage surgery. Patients in poor health (ie, very medically ill) and with gram-positive cultures should be counselled regarding potential failure after a single arthroscopic debridement procedure. [Orthopedics. 2018; 41(2):e184-e188.].