Abstract
BackgroundWhether 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.MethodsThree-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.ResultsFor 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.ConclusionsAlthough 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.
Highlights
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
Multiple studies have suggested that APT component prostheses seem to be acceptable devices with significantly better implant survival and reduced rates of early revision, postoperative infection, fracture, and tibial-component loosening than metal-backed tibial (MBT) component prostheses in total knee arthroplasty (TKA) [8, 9]
The stress distribution at the entrance of the femoral medial axis inter surface was 4–137 Mpa, and the MBT was slightly higher than the APT prosthesis
Summary
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. As one of the original tibial component designs, allpolyethylene tibial (APT) components have been shown to produce excellent outcomes with long-term survival of over 90% in total knee arthroplasty (TKA) [1, 2]. In 2003, Faris et al [5] published results of anatomic graduated component-APT components and showed the disastrous results of a flat-on-flat-designed APT implant. The combination of the biomechanical and anatomic graduated component studies led surgeons to choose the metal-backed tibial (MBT) component [4, 5]. Multiple studies have suggested that APT component prostheses seem to be acceptable devices with significantly better implant survival and reduced rates of early revision, postoperative infection, fracture, and tibial-component loosening than MBT component prostheses in TKA [8, 9]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call