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An analytical approach to study the intraoperative fractures of femoral shaft during total hip arthroplasty

Malekmotiei, L ; Sharif University of Technology | 2013

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  1. Type of Document: Article
  2. DOI: 10.1115/1.4023699
  3. Publisher: 2013
  4. Abstract:
  5. An analytical approach which is popular in micromechanical studies has been extended to the solution for the interference fit problem of the femoral stem in cementless total hip arthroplasty (THA). The multiple inhomogeneity problem of THA in transverse plane, including an elliptical stem, a cortical wall, and a cancellous layer interface, was formulated using the equivalent inclusion method (EIM) to obtain the induced interference elastic fields. Results indicated a maximum interference fit of about 210 μm before bone fracture, predicted based on the Drucker-Prager criterion for a partially reamed section. The cancellous layer had a significant effect on reducing the hoop stresses in the cortical wall; the maximum press fit increased to as high as 480 μm for a 2 mm thick cancellous. The increase of the thickness and the mechanical quality, i.e., stiffness and strength, of the cortical wall also increased the maximum interference fit before fracture significantly. No considerable effect was found for the implant material on the maximum allowable interference fit. It was concluded that while larger interference fits could be adapted for younger patients, care must be taken when dealing with the elderly and those suffering from osteoporosis. A conservative reaming procedure is beneficial for such patients; however, in order to ensure sufficient primary stability without risking bone fracture, a preoperative analysis might be necessary
  6. Keywords:
  7. Intraoperative fracture ; Elasticity ; Misfit strain ; Press-fit ; Equivalent-inclusion method ; Hip stem ; Intra-operative ; Misfit strains ; Fracture ; Hip prostheses ; Presses (machine tools) ; Rivets ; Wave interference ; Arthroplasty ; Age distribution ; Analytic method ; Biomechanics ; Bone stress ; conservative treatment ; Cortical thickness (bone) ; Interference ; Femur shaft fracture ; Geriatric patient ; Mathematical model ; Musculoskeletal stiffness ; Osteoporosis ; Patient care ; Peroperative complication ; Preoperative period ; Risk assessment ; Total hip prosthesis ; Trabecular bone ; Femur fracture ; Hip arthroplasty ; Mechanical stress ; Arthroplasty, Replacement, Hip ; Computer Simulation ; Femoral Fractures ; Intraoperative Period ; Risk ; Stress, Mechanical
  8. Source: Journal of Biomechanical Engineering ; Volume 135, Issue 4 , 2013 ; 01480731 (ISSN)
  9. URL: http://biomechanical.asmedigitalcollection.asme.org/article.aspx?articleid=1675571