title: Morphological evaluation of the sagittal plane femoral load-bearing surface in computer-simulated virtual total knee arthroplasty implantation at different flexion angles.
abstract: OBJECTIVE
  To examine the effect of implantation of the femoral component of a total knee arthroplasty (TKA) system in 0°, 3°, and 6° of flexion on the sagittal plane morphology of the femoral load-bearing surfaces. It was hypothesized that increasing the flexion angle would result in undersizing of the anterior surface without changing the flexion gap.
  
  
  METHODS
  Computer simulation of a TKA using three-dimensional models of 10 healthy knees, matched to three different sized femoral components. Size discrepancy in the sagittal plane anterior, distal, and posterior joint surfaces between the native and prosthetic knees was calculated at 0°, 3°, and 6° of flexion.
  
  
  RESULTS
  The required component size varied with the angle of implantation: 0°, size 3/size 4 (N = 7/3), 3°, size 3 (N = 10); and 6°, size 2/size 3 (N = 4/6). Component undersizing ranged between 4.4-6.3 mm at the anterior lateral surface, with a significant difference between 0° and 6° (p < 0.05), and 1.2-3.5 mm at the anterior medial surface. Component oversizing of the distal surface of the lateral condyle (2.9 mm) and undersizing of the medial surface of the posterior condyle (1.6-2.3 mm) were comparable at all three flexion angles of component implantation.
  
  
  CONCLUSIONS
  Increasing the flexion angle of implantation increased the incidence of using a smaller size of femoral component without significant interference with the flexion gap. However, the effect of a smaller femoral component on undersizing of the anterior surface of the condyle and the impact on the extensor mechanism need to be considered.
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.
authors.forename: Shichang
authors.initials: S
authors.lastname: Chen
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.
authors.forename: Mengning
authors.initials: M
authors.lastname: Yan
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.
authors.forename: Bing
authors.initials: B
authors.lastname: Yue
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China. drwangyou@163.com.
authors.forename: You
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D003198:Computer Simulation; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D019736:Prostheses and Implants; D016059:Range of Motion, Articular / Q000502:physiology; D000066908:Simulation Training; D016474:Weight-Bearing / Q000502:physiology*
keywords: Computer-simulation; Femoral component; Implant flexion; Morphometry; Total knee arthroplasty
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