No need to change the skin knife in modern arthroplasty surgery.

Earlier studies have found varying contamination rates using separate skin and deep knives in total hip (THA) and total knee (TKA) arthroplasty surgery. Previous studies were primarily conducted in the setting of concomitant use of laminar airflow and/or plastic adhesive draping. This has lead to conflicting conclusions regarding discarding the skin knife or not. This study evaluates the prevalence of contamination of a separate skin knife using modern antiseptic technique in primary THA and TKA without laminar airflow. Three knives from each primary THA and TKA surgery in non-laminar airflow operating rooms were collected: one used for the skin, one used for deeper tissues and one control knife. A total of 831 knife blades from 277 patients were cultured 12 days. Contamination of the skin knife was found in eight patients (2.8 %), contamination of the "deep" knife in five patients (1.8 %) and contamination of the control knife in five patients (1.8 %). No patient developed an infection with 1-year follow-up. Our findings suggest a very low rate of contamination of the skin knife using modern antiseptic technique without laminar airflow and/or plastic adhesive draping and do not support the use of a separate skin knife in arthroplasty surgery.