title: Kinematic analysis of a posterior-stabilized knee prosthesis.
abstract: BACKGROUND
  The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data.
  
  
  METHODS
  Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion.
  
  
  RESULTS
  Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, "rollback" compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis.
  
  
  CONCLUSIONS
  There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.
authors.forename: Zhi-Xin
authors.initials: ZX
authors.lastname: Zhao
authors.forename: Liang
authors.initials: L
authors.lastname: Wen
authors.affiliation: Department of Orthopedics, Beijing Chao Yang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Tie-Bing
authors.initials: TB
authors.lastname: Qu
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Hou
authors.forename: Dong
authors.initials: D
authors.lastname: Xiang
authors.forename: Jia
authors.initials: J
authors.lastname: Bin
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007720:Knee Prosthesis