A Desseaux1, P Graf2, F Dubrana3, R Marino4, A Clavé5. 1. Université de Bretagne occidentale, faculté de médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU de Brest, service de chirurgie orthopédique et traumatologique, boulevard Tanguy-Prigent, 29200 Brest, France. Electronic address: antoine.desseaux@chu-brest.fr. 2. Clinique Pasteur-Lanroze, 32, rue Kervern, 29200 Brest, France. 3. Université de Bretagne occidentale, faculté de médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU de Brest, service de chirurgie orthopédique et traumatologique, boulevard Tanguy-Prigent, 29200 Brest, France. 4. Zimmer CAS, 75, Queen Street, Montreal, QC H3C2N6, Canada. 5. Université de Bretagne occidentale, faculté de médecine, 22, avenue Camille-Desmoulins, 29200 Brest, France; CHRU de Brest, service de chirurgie orthopédique et traumatologique, boulevard Tanguy-Prigent, 29200 Brest, France; LaTIM, Inserm UMR 1101, 2, avenue Foch, 29609 Brest cedex, France.
Abstract
BACKGROUND: The new navigation system iASSIST™ for total knee arthroplasty (TKA) relies on accelerometers and gyroscopes. The objective of this prospective study was to compare the accuracy of iASSIST™ to that of the conventional optical navigation system Navitrack™ by determining the rate of mechanical axis restoration (±3°), postoperative mean mechanical alignment, rate of adequate femoral and tibial component positioning, mean operative time, and occurrence of navigation-related adverse events. HYPOTHESIS: The rate of mechanical axis restoration (±3°) is not lower with iASSIST™ than with the conventional navigation system Navitrack™. MATERIAL AND METHODS: Of 40 patients who underwent primary TKA between October 2013 and March 2014, 20 had navigation using iASSIST™ and 20 using Navitrack™. Six months after TKA, an independent observer measured three parameters on coronal radiographs: the hip-knee-ankle angle (HKA), the mechanical lateral distal femoral angle (mLDFA), and the mechanical medial proximal tibial angle (mMPTA). RESULTS: The two groups showed no significant differences for the rates of HKA restoration (P=0.3), adequate coronal positioning of the femoral component (P=0.12) and tibial component (P=0.12), or optimal success (P=0.09). Significant differences in favour of iASSIST™ were demonstrated for the values and angular deviations of the HKA (P=0.02) and mMPTA (P=0.01), whereas no significant difference was found for mLDFA. There were no significant differences regarding the mean operative time (P=0.06) or the occurrence of navigation-related adverse events (P=0.18). DISCUSSION: The iASSIST™ system provides a neutral mechanical axis and optimal component position in the coronal plane in 95% of cases, indicating that it is as accurate as the optical navigation system Navitrack™. LEVEL OF EVIDENCE: III, prospective case-control study.
BACKGROUND: The new navigation system iASSIST™ for total knee arthroplasty (TKA) relies on accelerometers and gyroscopes. The objective of this prospective study was to compare the accuracy of iASSIST™ to that of the conventional optical navigation system Navitrack™ by determining the rate of mechanical axis restoration (±3°), postoperative mean mechanical alignment, rate of adequate femoral and tibial component positioning, mean operative time, and occurrence of navigation-related adverse events. HYPOTHESIS: The rate of mechanical axis restoration (±3°) is not lower with iASSIST™ than with the conventional navigation system Navitrack™. MATERIAL AND METHODS: Of 40 patients who underwent primary TKA between October 2013 and March 2014, 20 had navigation using iASSIST™ and 20 using Navitrack™. Six months after TKA, an independent observer measured three parameters on coronal radiographs: the hip-knee-ankle angle (HKA), the mechanical lateral distal femoral angle (mLDFA), and the mechanical medial proximal tibial angle (mMPTA). RESULTS: The two groups showed no significant differences for the rates of HKA restoration (P=0.3), adequate coronal positioning of the femoral component (P=0.12) and tibial component (P=0.12), or optimal success (P=0.09). Significant differences in favour of iASSIST™ were demonstrated for the values and angular deviations of the HKA (P=0.02) and mMPTA (P=0.01), whereas no significant difference was found for mLDFA. There were no significant differences regarding the mean operative time (P=0.06) or the occurrence of navigation-related adverse events (P=0.18). DISCUSSION: The iASSIST™ system provides a neutral mechanical axis and optimal component position in the coronal plane in 95% of cases, indicating that it is as accurate as the optical navigation system Navitrack™. LEVEL OF EVIDENCE: III, prospective case-control study.
Authors: Silvio Pflugi; Rakesh Vasireddy; Till Lerch; Timo M Ecker; Moritz Tannast; Nane Boemke; Klaus Siebenrock; Guoyan Zheng Journal: Int J Comput Assist Radiol Surg Date: 2017-11-29 Impact factor: 2.924