Airflow and Hip Prosthesis Infections: A Registry Study Comparing Laminar vs. Turbulent Flow in the Danish Hip Arthroplasty Register.

Rationale and background

Prosthetic joint infection (PJI) is one of the most feared complication after total hip arthroplasty (THA), with increased mortality and morbidity, as well as a significant cost for society. Since the 1960s, in addition to systemic prophylactic antibiotics and antibiotic-laden bone cement, efforts have been made to make the air in the operating rooms (OR) as clean as possible with filtering and replacement of the air .

This has led to the official current PJI incidence of 0.57-0.80 % in the first year after surgery according to the Danish Hip Arthroplasty Register (DHR) and the Swedish Hip Arthroplasty Register (SHAR), even though the true incidence of PJI probably is about 40 % higher, due to under-registration in the registers following revision surgery .

The risk of PJI is potentially affected by contamination in the OR, patient related risk factors and prosthesis factors. The prosthesis factors include type of implant and implant fixation method. Cemented implants have a lower overall revision rate, although the results are not unanimous when it comes to revision due to PJI.

The risk of contamination in the OR is affected by the cleanliness of the air. There are two different types of ventilation systems used to achieve a clean environment in an OR. The first is turbulent airflow (TAF), where the air is continuously replaced with filtered ultra-clean air that trickles down from the ventilation shaft. The second is laminar airflow (LAF) where the ultra-clean air flows in a single direction, with the goal to prevent particles carrying bacteria, that are floating in the air, to land on the patient or sterile equipment.