Navigation of the tibial plateau alone appears to be sufficient in computer-assisted unicompartmental knee arthroplasty.
OBJECTIVE
The aim of this study was to present our technique to implant unicompartmental knee arthroplasty (UKA) using navigation and to give our first results regarding the accuracy of the device.


METHODS
A total of 33 patients with medial femorotibial osteoarthritis (31) or avascular necrosis (2) were included in this study. The mean preoperative hip-knee-ankle (HKA) angle was 172.7 ± 2.2° (range 167-177°) and the preoperative planning aimed to reach an HKA angle between 175 and 179° (177 ± 2°), a tibial varus at 3 ± 1°, which means a tibial mechanical angle (TMA) close to 87 ± 1°, and posterior tibial slope at 3 ± 2°. In all cases, we used the OrthoPilot® device with dedicated software allowing us to navigate only the tibial plateau.


RESULTS
The preoperative plan was reached in 93.9 % of cases for HKA angle, 84.8 % for TMA and 100 % for the posterior slope.


CONCLUSIONS
Unicompartmental knee navigation is reliable. The navigation of only the tibial bone cut is a reasonable option as has been shown in this study. Its role is invaluable in the positioning of mobile-bearing UKA, where the risk of overcorrection should not be underestimated.
Department of Orthopaedic Surgery and Sport Traumatology, Grenoble South Teaching Hospital, Avenue de Kimberley, BP 338, 38434, Échirolles Cedex, France. DSaragaglia@chu-grenoble.fr
Dominique
D
Saragaglia
Frédéric
F
Picard
Ramsay
R
Refaie
D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000502:physiology; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D005271:Femur Head Necrosis / Q000601:surgery*; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D016059:Range of Motion, Articular / Q000502:physiology; D012984:Software; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013977:Tibia / Q000601:surgery*; D016896:Treatment Outcome