Computer Modeling

Using finite element analysis to study the biomechanics of orthopaedic implants and musculoskeletal tissues, to develop improved implant designs and treatment methods.

Scope
The investigators of the Computer Analysis Laboratory employ state-of-the-art finite element techniques to compute the stresses, strains and displacements that an orthopaedic implant and the associated skeletal tissues are subjected to during use by a patient. These analytical methods form a complement to the "bench" modeling conducted in the Implant Biomechanics Laboratory, and the animal modeling of the Bone and Tissue Biomechanics Laboratory, again with the goal of developing improved implants and the associated surgical techniques that will provide a lifetime of use to the patient.
Current Research
The current research includes the investigation of the effects of the mechanical factors on the stability of fixation of artificial hips, including modeling of the bonding of the cement-bone and/or cement-metal interfaces, the surface finish and geometry of prostheses, and material properties. Other studies have evaluated the thermal necrosis of the bone due to cement polymerization in surface replacements of hip joints, and the effects of the contact stresses, contact areas and creep on the wear of polyethylene.
Apparatus
The finite element modeling is conducted on Intel workstations, using the Patran modeling program, and the Abaqus analysis programs.
Staff
The Computer Analysis Laboratory is under the direction of Zhen Lu, Ph.D.

Publications

  1. Lu, Z. and McKellop, H.A.: Effects of Cement Creep on Stem Subsidence and Stresses in the Cement Mantle of a Hip Replacement. J Biomed Mater Res, 34:2, 221-226, 1997.
  2. Lu, Z. and McKellop, H.A.: Frictional Heating of Bearing Materials Tested in a Hip Joint Wear Simulator. Pro Instn Mech Engrs, 211: H, 101-108, 1997.
  3. Lu, Z., McKellop H.A., Liao, P., and Benya, P.: Potential Thermal Artifacts In Hip Joint Wear Simulators. J Biomed Mater Res (Appl Biomater), 48:4, 458-464, 1999.
  4. Campbell, P., Beaule, P.E., Ebramzadeh, E., LeDuff, M., Smet, K.D., Lu, Z., Amstutz, H.C.: The John Charnley Award: A study of implant failure in metal-on-metal surface arthroplasties. Clin Orthop Relat Res, 453:35-46, 2006.
  5. Beaule, B.E., Campbell, P., Lu. Z., Beck, M., Leunig M., Thomas, B., Ganz, R.: Vascularity of the arthritic femoral head and hip resurfacing. J Bone Joint Surg Am, 88 Suppl 4:85-96, 2006.
  6. Lu, Z., McKellop, H.: Use of a constant load to generate equivalent viscoelastic strain in finite element analysis of cemented prosthetic joints subjected to cyclic loading. Proc. Inst. Mechanical Engineers, Part H, Journal of Engineering in Medicine, in press.

Contact
The Computer Analysis Laboratory welcomes industry-sponsored projects, as well as collaborations with other academic institutions. For additional information, please contact Zhen Lu, Ph.D., email ZLu@mednet.ucla.edu, or telephone             (213) 742-1065