Abstract
INTRODUCTION
Total Knee Arthroplasty (TKA) survival is directly dependent on precise component placement. As showed by Mason meta-analysis in 2007, only 68.2% of TKAs achieved axis less than 3° with conventional methods versus 91% with Computer Assisted Surgery (CAS). However, if CAS seems to have more accuracy its use is in less than 10% procedures in United States because of its cost, operative time and need of extra pin sites. Smart technology, providing no requirement or arrays for registration, no need of pre operative images and lest cost effective seems to be an encouraging way.
OJBECTIVES
We report our experience of a new system that is an accelerometer-based portable navigation with a disposable display console and reference sensor; gyrometer is like smartphone ones. This system permits to realize femoral distal cut, and tibial proximal cut, adjusting varus-valgus, flexion-extension and tibial slope regardless implants used. Goal of the study was to determine accuracy and reliability of the system.
METHODS
We've utilized it on 40 patients (28 female, 12 male; 70.4 years old) operated for arthritis and have reviewed all of them at 6 months with goniometry and angle measurements. Predominant pre operative deformity was varus (29 cases) rather than valgus (11 cases).
RESULTS
Use of this handled system doesn't lengthen surgery more than 10 minutes. Accuracy for tibial cut was confirmed with a mechanic angle of 90.1° +/− 1.8; all except 2 were less than 2°. Tibial slope had a mean of 3.2° +/− 1.8 but only 60% were less or equal to 3°. All femurs were orthogonal or in valgus with an average angle of 93° +/− 2; mean flexion was 5° +/− 4, independently of pre operative deformity.
CONCLUSION
The smart technology studied seems to be convenient and a good device to ensure tibial cut (better in coronal plane) but is less effective for femur with a valgus and flexion tendency. Discussion about software, calibration, landmarks or positioning must be lead.
