Background: Although the rate of periprosthetic joint infection following shoulder arthroplasty is low, it is a morbid and costly complication. Airborne particulates have long been recognized as a potential source of wound contamination and operating room mounted, and smaller localized laminar air flow devices have been developed to minimize airborne particulates. This randomized controlled trial evaluated the effectiveness of a localized laminar flow device in reducing the intrusion of ambient airborne particles and bacteria into the surgery site during shoulder arthroplasty as measured by overall particle counts and colony forming units.
Methods: Patients undergoing primary anatomic or reverse shoulder arthroplasty were eligible for participation. After informed consent, patients were randomly assigned to the air barrier system (ABS) or control group. For all patients, the ABS was placed on the surgical field but was only turned on by the technician for subjects randomized to ABS. Study participants, surgeons and surgical staff were blinded to group assignment. Bacterial colony forming units (CFU) were collected from within 5 cm of the surgical wound every 10 minutes, while airborne particulates were collected every minute. Poisson regression models were used to determine if differences existed in CFUs and particulate counts between the ABS and control groups.
Results: Forty-three patients were randomized into the ABS (n=21) and control (n=22) groups. Surgical time (p=.53) and the average staff count (p=.16) in the operating room did not differ between groups. Poisson regression showed that ABS group had significantly lower CFUs (β=-0.583, p<0.001) along with surgical time and particulates with a diameter greater than 5μm. Staff count and particulates smaller than 5μm were not significant predictors of CFUs. Infection was not a primary outcome, but no postoperative infections have been reported in either study group with a minimum of 1-year follow-up for all patients.
Discussion: This double-blinded, randomized trial demonstrated that a localized laminar flow device dramatically reduces the count of CFUs in the air directly above the wound and beneath the air barrier system (adjusted for the number of OR personnel and surgical time). The use of the device was not associated with a longer case duration; however, there was some additional set up time prior to surgical incision to place the device. Further study is required to determine the clinical implications of this finding; specifically, if such devices result in lower rates of periprosthetic joint infection after shoulder arthroplasty.
Level of evidence: Level I; Randomized Controlled Trial; Treatment Study.
Keywords: airborne particulates; colony forming units; laminar flow device; operating room air flow; periprosthetic joint infection; randomized controlled trial; shoulder arthroplasty.