Complications of fixed infrared emitters in computer-assisted total knee arthroplasties.
BACKGROUND
The first stage in the implant of a total knee arthroplasty with computer-assisted surgery is to fasten the emitters to the femur and the tibia. These trackers must be hard-fixed to the bone. The objectives of our study are to evaluate the technical problems and complications of these tracker-pins, the necessary time to fix them to the bone and the possible advantages of a new femoral-fixed tracker-pin.


METHODS
Three hundred and sixty seven tracker-pins were used in one hundred and fifty one computer-assisted total knee replacements. A bicortical screw was used to fix the tracker to the tibia in all cases; in the femur, however, a bicortical tracker was used in 112 cases, while a new device (OrthoLock) with percutaneous fixation pins was employed in the remaining 39.


RESULTS
Technical problems related to the fixing of the trackers appeared in nine cases (2.5%). The mean surgery time to fix the tracker pin to the tibia was 3 minutes (range 2-7), and 5 minutes in the case of the femoral pin (range: 4-11), although with the new tool it was only three minutes (range 2-4) (p < 0.001). No complications were observed with this new device.


CONCLUSIONS
The incidence of problems and complications with the fixing systems used in knee navigation is very small. The use of a new device with percutaneous pins facilitates the fixing of femoral trackers and decreases the time needed to place them.
Department of Orthopaedic Surgery, Hospital San Agustin, Avilés School of Medicine, University of Oviedo, Spain. dhernandezv@meditex.es
Daniel
D
Hernández-Vaquero
Abelardo
A
Suárez-Vázquez
D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods; D001863:Bone Screws / Q000592:standards*; D006801:Humans; D007259:Infrared Rays; D007431:Intraoperative Complications / Q000453:epidemiology* / Q000517:prevention & control; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods