A Randomized Controlled Trial on the Use of Body Exhaust System in Primary Total Knee Arthroplasty

Abstract

INTRODUCTION: There are conflicting evidences in the literature regarding the effectiveness of the modern positive-pressure surgical helmet body exhaust systems (BES) against periprosthetic joint infection (PJI) in primary total knee arthroplasty (TKA). The function of the BES is the reduce intraoperative contamination of the surgical field. A recent report from New Zealand National Joint Registry showed increased incidence of acute infection when BES was used. We carried out this study to investigate the efficacy of BES in preventing intraoperative contamination and early infection in primary TKA. METHODS: Thirty-two patients (64 knees) who underwent bilateral one-stage sequential TKA were recruited from Jan 2016 to Aug 2016. Their limbs were randomized before the surgery. The same surgical team performed one side TKA wearing BES and the other side wearing conventional gowns (CON) without BES in a designated surgical theatre with laminar airflow. The sequence of wearing different gowns were also randomized. We documented the surgical time, the intraoperative change of gloves, and the number of times when the surgeons touched their helmet. Intraoperative wound swabs were collected for bacteria culture from the following sites of each knee at different time points (2 swabs from each site): 1) subcutaneous layer after skin incision, 2) proximal tibia bone cut surface before implantation, 3) distal femoral bone cut surface before implantation, 4) anterior prosthetic femoral condyle before arthrotomy closure, and 5) subcutaneous layer before skin closure. Qualitative and quantitative bacterial cultures were performed by a microbiologist. The swabs were first dipped into 2mL diluent (saline) and serial dilutions (1:10, 1:100) were made if needed. 100ul of the direct count and dilutions were spread onto blood agar plates and placed in aerobic chamber. The plates were examined after 48 hours. RESULTS: There were 22 female patients and 10 male patients. The mean age was 66.8±6.6 years. The mean body mass index was 27.43±4.97 kg/m2. The preoperative varus deformity was 15.03±8.44° in the BES group, and 14.82±6.76° varus in the CON group (p>0.05). The mean operative time was 85.39±19.48 min in the BES group and 86.10±31.45 min in the CON group (p>0.05). The number of times the surgeon changed gloves were 0.77±1.45 in BES group and 1.71±1.51 in CON group (p<0.05). The number of times the surgeons touched their helmets was 0.06±0.25 in BES group. None of the intraoperative wound swabs yielded positive bacterial culture results. All patients completed 6 months follow up. There was no infection or wound related complication in both BES and CON groups. DISCUSSION AND CONCLUSION: Our study demonstrated no benefit in the use of BES in decreasing the rate of wound contamination compared to the conventional gown, when other anti-infection measures are strictly observed. The BES is not a must to prevent PJI. However the BES can be considered as a protective device for the surgical team against patients' body fluid contact.