title: Radiographic outcomes in the coronal plane with iASSIST™ versus optical navigation for total knee arthroplasty: A preliminary case-control study.
abstract: 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.
  
  
  
  The rate of mechanical axis restoration (±3°) is not lower with iASSIST™ than with the conventional navigation system Navitrack™.
  
  
  
  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).
  
  
  
  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).
  
  
  
  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™.
  
  
  
  III, prospective case-control study.
authors.affiliation: 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.
authors.forename: A
authors.initials: A
authors.lastname: Desseaux
authors.affiliation: Clinique Pasteur-Lanroze, 32, rue Kervern, 29200 Brest, France.
authors.forename: P
authors.initials: P
authors.lastname: Graf
authors.affiliation: 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.
authors.forename: F
authors.initials: F
authors.lastname: Dubrana
authors.affiliation: Zimmer CAS, 75, Queen Street, Montreal, QC H3C2N6, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Marino
authors.affiliation: 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.
authors.forename: A
authors.initials: A
authors.lastname: Clavé
mesh_terms: D061725:Accelerometry; D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000000981:diagnostic imaging; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D011184:Postoperative Period; D011446:Prospective Studies; D011859:Radiography; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013977:Tibia / Q000000981:diagnostic imaging
keywords: Computer-assisted surgery; IASSIST; Knee; Positioning; Total knee arthroplasty