Document Detail

Femoral prosthesis implantation induces changes in bone stress that depend on the extent of porous coating.
MedLine Citation:
PMID:  8064485     Owner:  NLM     Status:  MEDLINE    
The objective of this study was to evaluate the effect of implantation of porous-coated anatomic medullary fitting prostheses on stress in the proximal femur. Three-dimensional finite element models of a cadaveric femur before and after implantation were used to evaluate the resulting changes in stress in the bone. Models of the femur were generated automatically from computed tomographic scan data with use of an innovative mesh-generation technique. The models were analyzed for three levels of porous coating (proximal, 5/8, and full), with the assumption of ideal ingrowth (perfect bonding) over porous areas and a frictionless, tension-free surface on smooth areas. All models were loaded and restrained to represent conditions of normal gait. The stresses predicted in the implanted femur are consistent with clinical observations of proximal cortical atrophy (normal stress reduced to 6-9% of normal at the calcar and 50-55% at mid-prosthesis) and of hypertrophy at the porous coating junctions (normal stress at the 5/8-coating junction, 123% of stress proximal to the junction) and hypertrophy near the distal tip of the prosthesis (anterior and posterior normal stresses 200-800% of normal). The fully coated prosthesis induced stresses in the bone near the tip of the prosthesis that were most like stresses in the normal femur (medial and lateral normal stress 105 and 102% of the stress in the normal femur). Below the collar, the normal stress associated with the proximally coated prosthesis was 6% greater than that produced with the other two levels of coating but still was only 2% of normal. The 5/8-coated prosthesis appeared to combine the worst features of the fully coated and proximally coated prostheses--greater stress-shielding at the calcar and higher stress near the tip of the prosthesis.
H B Skinner; A S Kim; J H Keyak; C D Mote
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of orthopaedic research : official publication of the Orthopaedic Research Society     Volume:  12     ISSN:  0736-0266     ISO Abbreviation:  J. Orthop. Res.     Publication Date:  1994 Jul 
Date Detail:
Created Date:  1994-09-22     Completed Date:  1994-09-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8404726     Medline TA:  J Orthop Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  553-63     Citation Subset:  IM    
Department of Orthopaedic Surgery, University of California, San Francisco 94143-0728.
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MeSH Terms
Artificial Limbs / adverse effects*,  instrumentation
Femur / pathology,  physiology*,  radiography
Middle Aged
Prostheses and Implants / adverse effects*
Stress, Mechanical
Tomography, X-Ray Computed

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