title: Three-dimensional reconstruction method for measuring the knee valgus angle of the femur in northern Chinese adults.
abstract: The purpose of this study was to establish a method for measuring the knee valgus angle from the anatomical and mechanical axes on three-dimensional reconstruction imaging models, and to use this method for estimating an average knee valgus angle value for northern Chinese adults. Computed tomographic angiography data in DICOM format for 128 normal femurs from 64 adult subjects were chosen for analysis. After the femur images were subjected to three-dimensional reconstruction, the deepest point in the intercondylar notch (point A), the midpoint of the medullary cavity 20 cm above the knee-joint line (point B), and the landmark of the femoral head rotation center (point C) were identified on each three-dimensional model. The knee valgus angle was defined as the angle enclosed by the distal femoral anatomical axis (line AB) and the femoral mechanical axis (line AC). The average (mean±SD) of knee valgus angle for the 128 femurs was 6.20°±1.20° (range, 3.05° to 10.64°). Significant positive correlations were found between the knee valgus angles of the right and left sides and between the knee valgus angle and age. During total knee arthroplasty, choosing a valgus cut angle of approximately 6° may achieve a good result in reestablishing the natural mechanical alignment of the lower extremity for patients of northern Chinese ethnicity. Larger valgus cut angles should be chosen for older patients.
authors.affiliation: Department of Orthopedics, China-Japan Union Hospital of Jilin University, Changchun 130033, China; Norman Bethune Medical School, Jilin University, Changchun 130021, China; School of Nursing, Changchun University of Chinese Medicine, Changchun 130117, China; Department of Orthopedics, the Second Hospital of Jilin University, Changchun 130041, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Liu
authors.forename: Chen-yu
authors.initials: CY
authors.lastname: Wang
authors.forename: Jian-lin
authors.initials: JL
authors.lastname: Xiao
authors.forename: Lan-yu
authors.initials: LY
authors.lastname: Zhu
authors.forename: Xue-zhou
authors.initials: XZ
authors.lastname: Li
authors.forename: Yan-guo
authors.initials: YG
authors.lastname: Qin
authors.forename: Zhong-li
authors.initials: ZL
authors.lastname: Gao
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography; D019645:Arthroplasty, Replacement, Knee; D044466:Asian People; D001696:Biomechanical Phenomena; D002681:China; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D011857:Radiographic Image Interpretation, Computer-Assisted; D012016:Reference Values; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
keywords: Knee valgus angle; Northern Chinese adults; Preoperative design; Three-dimensional reconstruction femoral model; Total knee arthroplasty
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