Résultats radiographiques du système iASSIST versus navigation conventionnelle pour les prothèses totales de genou – étude prospective randomisée

Abstract

A novel sensing technology system for TKA, based on accelerometers and gyroscopes, has been developed recently. This system should improve the acquisition time of reference points, avoid pins far from joint, guide precisely the tibial and distal femoral cuts, and validate these cuts intraoperatively. The system includes two small electronic pods clipped on a non-specific ancillary, which communicate via a local wireless network. Our study assessed if the iASSIST system (Zimmer Inc), was as precise as a validated optical navigation system like Navitrack (Orthosofty). Forty patients, operated from 8th October 2013 to 4th March 2014 with primary total knee arthroplasty were randomized. None of them was excluded. Twenty patients were navigated by iASSIST system and 20 others by the Navitrack system. Preoperative HKA angles were greater than 10 degrees from the neutral axis in 7 patients of iASSIST group and in 4 of the Navitrack group. After 6 weeks postoperatively, HKA angle of the iASSIST group was about 178.5 (175.1 to 181.3) whereas the mean of the Navitrack group was 180.5 (177 to 184.2). After the same timeline, in iASSIST group, 100% of tibial components and 95% of femoral components were measured less than 3 degrees from the neutral axis, against just 90% of femoral and tibial components navigated by the Navitrack system. Those results are confirmed by the 6 months postoperative review. HKA mean angles of the iASSIST group were 179.5 (176.2 to 182.6) and 181.1 (177.1 to 185.9) in the Navitrack group. Furthermore, 100% of tibial and femoral components showed less than 3 degrees from the neutral mechanical axis in the iAssist group compared to 85% in the Navitrack group. Our study shows that iASSIST system seems as accurate and precise as a validated optical navigation system to position implants, moreover, with an easier implementation.