title: All-polyethylene tibial components in distal femur limb-salvage surgery: a finite element analysis based on promising clinical outcomes.
abstract: BACKGROUND
  Whether all-polyethylene tibial (APT) components are beneficial to patients who received distal femur limb-salvage surgery lacks high-quality clinical follow-up and mechanical evidence. This study aimed to investigate the biomechanics of the distal femur reconstructed with APT tumor knee prostheses using finite element (FE) analysis based on our previous, promising clinical outcome.
  
  
  METHODS
  Three-dimensional FE models that use APT and metal-backed tibial (MBT) prostheses to reconstruct distal femoral bone defects were developed and input into the Abaqus FEA software version 6.10.1. Mesh refinement tests and gait simulation with a single foot both in the upright and 15°-flexion positions with mechanical loading were conducted. Stress distribution analysis was compared between APT and MBT at the two static positions.
  
  
  RESULTS
  For both prosthesis types, the stress was concentrated on the junction of the stem and shaft, and the maximum stress in the femoral axis base was more than 100 Mpa. The stress on the tibial surface was relatively distributed, which was 1-19 MPa. The stress on the tibial bone-cement layer of the APT prosthesis was approximately 20 times higher than that on the MBT prosthesis in the same region. The stress on the proximal tibial cancellous bone and cortical bone of the APT prosthesis was 3-5 times greater than that of the MBT prosthesis, and it was more distributed.
  
  
  CONCLUSIONS
  Although the stress of bone-cement around the APT component is relatively high, the stress was better distributed at the polyethylene-cement-bone interface in APT than in MBT prosthesis, which effectively protects the proximal tibia in distal femur tumor knee prosthesis replacement. These results should be considered when selecting the appropriate tibial component for a patient, especially under the foreseeable conditions of osteoporosis.
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China.
authors.forename: Fan
authors.initials: F
authors.lastname: Tang
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China.
authors.forename: Wenli
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Min
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Shi
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Duan
authors.affiliation: Department of Orthopedics, West China Hospital, Sichuan University, Guoxue Xiang #37, Chengdu, 610041, Sichuan, People's Republic of China. tcqbonetumor@163.com.
authors.forename: Chongqi
authors.initials: C
authors.lastname: Tu
mesh_terms: D000328:Adult; D005266:Femoral Neoplasms / Q000601:surgery*; D005269:Femur / Q000601:surgery*; D020342:Finite Element Analysis; D006801:Humans; D007720:Knee Prosthesis; D023821:Limb Salvage / Q000295:instrumentation*; D008297:Male; D020959:Polyethylene; D013314:Stress, Mechanical; D013977:Tibia / Q000601:surgery*
chemical_list: D020959:Polyethylene
keywords: All-polyethylene tibial implant; Distal femur; Finite element analysis; Metal-backed tibial prosthesis; Tumor knee prosthesis