title: An additional reference axis improves femoral rotation alignment in image-free computer navigation assisted total knee arthroplasty.
abstract: Few studies have demonstrated improvement in accuracy of rotational alignment using image-free navigation systems mainly due to the inconsistent registration of anatomical landmarks. We have used an image-free navigation for total knee arthroplasty, which adopts the average algorithm between two reference axes (transepicondylar axis and axis perpendicular to the Whiteside axis) for femoral component rotation control. We hypothesized that addition of another axis (condylar twisting axis measured on a preoperative radiograph) would improve the accuracy. One group using the average algorithm (double-axis group) was compared with the other group using another axis to confirm the accuracy of the average algorithm (triple-axis group). Femoral components were more accurately implanted for rotational alignment in the triple-axis group (ideal: triple-axis group 100%, double-axis group 82%, P<0.05).
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inui
authors.forename: Shuji
authors.initials: S
authors.lastname: Taketomi
authors.forename: Kensuke
authors.initials: K
authors.lastname: Nakamura
authors.forename: Takaki
authors.initials: T
authors.lastname: Sanada
authors.forename: Sakae
authors.initials: S
authors.lastname: Tanaka
authors.forename: Takumi
authors.initials: T
authors.lastname: Nakagawa
mesh_terms: D000368:Aged; D000465:Algorithms; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D008297:Male; D012399:Rotation; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome