title: Is the posterior cruciate ligament necessary for medial pivot knee prostheses with regard to postoperative kinematics?
abstract: OBJECTIVE
  Excellent clinical and kinematical performance is commonly reported after medial pivot knee arthroplasty. However, there is conflicting evidence as to whether the posterior cruciate ligament should be retained. This study simulated how the posterior cruciate ligament, post-cam mechanism and medial tibial insert morphology may affect postoperative kinematics.
  
  
  METHODS
  After the computational intact knee model was validated according to the motion of a normal knee, four TKA models were built based on a medial pivot prosthesis; PS type, modified PS type, CR type with PCL retained and CR type with PCL sacrificed. Anteroposterior translation and axial rotation of femoral condyles on the tibia during 0°-135° knee flexion were analyzed.
  
  
  RESULTS
  There was no significant difference in kinematics between the intact knee model and reported data for a normal knee. In all TKA models, normal motion was almost fully restored, except for the CR type with PCL sacrificed. Sacrificing the PCL produced paradoxical anterior femoral translation and tibial external rotation during full flexion.
  
  
  CONCLUSIONS
  Either the posterior cruciate ligament or post-cam mechanism is necessary for medial pivot prostheses to regain normal kinematics after total knee arthroplasty. The morphology of medial tibial insert was also shown to produce a small but noticeable effect on knee kinematics.
  
  
  METHODS
  V.
authors.affiliation: Department of Joint Surgery, The 6th Hospital of Ningbo, Ningbo, Zhejiang, China.
authors.forename: Chao-Hua
authors.initials: CH
authors.lastname: Fang
authors.affiliation: Department of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan.
authors.forename: Chia-Ming
authors.initials: CM
authors.lastname: Chang
authors.affiliation: Orthopaedic Device Research Center, National Yang Ming University, Taipei, Taiwan.
authors.forename: Yu-Shu
authors.initials: YS
authors.lastname: Lai
authors.affiliation: Orthopaedic Device Research Center, National Yang Ming University, Taipei, Taiwan.
authors.forename: Wen-Chuan
authors.initials: WC
authors.lastname: Chen
authors.affiliation: Naton Institute of Medical Technology, Beijing, China.
authors.forename: Da-Yong
authors.initials: DY
authors.lastname: Song
authors.affiliation: Department of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: McClean
authors.affiliation: School of Biological Science and Medical Engineering, Beijing University of Aeronautics and Astronautics, Beijing, China.
authors.forename: Hao-Yuan
authors.initials: HY
authors.lastname: Kao
authors.affiliation: Department of Orthopaedics, Beijing Chao-Yang Hospital, Affiliated Hospital of Capital Medical University, 8 Gongren Tiyuchang Nanlu, Chaoyang District, Beijing, 100020, China. qtb@medmail.com.cn.
authors.forename: Tie-Bing
authors.initials: TB
authors.lastname: Qu
authors.affiliation: Department of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan. ckcheng2009@gmail.com.|Orthopaedic Device Research Center, National Yang Ming University, Taipei, Taiwan. ckcheng2009@gmail.com.|Naton Institute of Medical Technology, Beijing, China. ckcheng2009@gmail.com.|School of Biological Science and Medical Engineering, Beijing University of Aeronautics and Astronautics, Beijing, China. ckcheng2009@gmail.com.|Institute of Biomedical Engineering, National Yang Ming University, No. 155, Sec. 2, Li-Nong St., Beitou Dist., Taipei, 112, Taiwan. ckcheng2009@gmail.com.
authors.forename: Cheng-Kung
authors.initials: CK
authors.lastname: Cheng
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena / Q000502:physiology*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D008954:Models, Biological; D016119:Posterior Cruciate Ligament / Q000502:physiology* / Q000601:surgery; D016059:Range of Motion, Articular / Q000502:physiology
keywords: Kinematics; Medial pivot; Posterior cruciate ligament; Total knee arthroplasty