Do Ultraviolet Air Disinfection Units Reduce Contamination by Particulates in Total Knee Replacement Procedures?

BACKGROUND: Prosthetic joint infections have become the leading cause of joint replacement failure. The primary sources of contamination are skin flora and bacteria from airborne particles. Portable ultraviolet air disinfection units are used in the Operating Room (OR) to prevent contamination from airborne particles; however, their effectiveness is not proven. The purpose of this study was to compare the rate of contamination of sites with and without Ultraviolet (UV) air disinfection units during active surgeries. METHODS: Sedimentation rates of viable particles were measured during 40 primary TKA procedures. Half of the procedures were performed with ultraviolet air disinfection units. Air-borne particles were collected on nitrocellulose membranes at 5 locations within the OR. After incubation, all microbial colonies were counted and the sedimentation rates were reported in CFUs/m2/hr. 10 additional trials were performed in an empty OR with no staff present. RESULTS: The average contamination rate of all sites was 22 ± 1.1 CFUs/m2/hr in the empty OR vs. 21.3 ± 4.6 CFUs/m2/hr with UV units and 20.3 ± 4.9 CFUs/m2/hr without (P = .03, P = .03, P = .964). Viable contaminates were found in the sterile field in 25% of UV cases vs 45% non-UV. These differences were not statistically significant. There were differences found however, according to the number of staff in the room (6 vs 7 staff: P = .036, 6 vs 8 staff: P = .004). CONCLUSION: There was no statistical difference in contamination rate with the usage or non-usage of UV units. These 40 cases shows that the largest variables affecting the contamination rate were the number of staff present and size of the OR.

Total Knee Arthroplasty in the Osteoporotic Tibia: A Biomechanical Evaluation of the Role of Stem Extensions and Cementing Techniques.

INTRODUCTION: Poor functional outcomes and aseptic loosening increase when total knee arthroplasty is performed on osteoporotic patients. This biomechanical study evaluated the effect of stem extension on the stability of tibial fixation using different cementing techniques. METHODS: A standard design tibial tray was implanted in a replica of a male osteoporotic tibia. Twenty-four implantations were performed using three variations of implant and cementing, and then mounted on a material testing machine load frame at 500 cycles of multiaxial loading simulating walking. The three-dimensional components of tray-tibia micromotion were measured. RESULTS: The primary implant total interface motion with surface cementing was 25.9 µm ± 14.7 µm and 10.6 µm ± 7.6 µm with full cementing (P = 0.001). The three-dimensional motion of fully cemented primary implants with stem extension was 4.4 µm ± 3.9 µm, which represents a decrease in micromotion of 83% in surface cemented primary implants (P < 0.0001) and 58% in the fully cemented components without stem extension (P < 0.009). CONCLUSION: Fully cemented primary implants with stem extensions demonstrated decreased micromotion and should be considered for use in osteoporotic total knee arthroplasty patients.