Femoral Strain Distribution and Subsidence After Physiological Loading of a Cementless Canine Femoral Prosthesis: The Effects of Implant Orientation, Canal Fill, and Implant Fit

Authors

  • ROBERT T. PERNELL DVM, MS,

    Corresponding author
    1. Departments of Small Animal Surgery and Medicine, Aerospace Engineering, Large Animal Surgery and Medicine, Auburn University, AL
    2. Hughston Orthopedic Clinic, Columbus, GA
    3. Research and Development, Howmedica, Inc., Rutherford, NJ.
      Coastal Carolina Veterinary Surgery. PA., 1861 Remount Rd. North Charleston, SC 29406.
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  • ROBERT S. GROSS PhD,

    1. Departments of Small Animal Surgery and Medicine, Aerospace Engineering, Large Animal Surgery and Medicine, Auburn University, AL
    2. Hughston Orthopedic Clinic, Columbus, GA
    3. Research and Development, Howmedica, Inc., Rutherford, NJ.
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  • JAMES L. MILTON DVM, MS, Diplomate ACVS,

    1. Departments of Small Animal Surgery and Medicine, Aerospace Engineering, Large Animal Surgery and Medicine, Auburn University, AL
    2. Hughston Orthopedic Clinic, Columbus, GA
    3. Research and Development, Howmedica, Inc., Rutherford, NJ.
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  • RONALD D. MONTGOMERY DVM, MS, Diplomate ACVS,

    1. Departments of Small Animal Surgery and Medicine, Aerospace Engineering, Large Animal Surgery and Medicine, Auburn University, AL
    2. Hughston Orthopedic Clinic, Columbus, GA
    3. Research and Development, Howmedica, Inc., Rutherford, NJ.
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  • JAMES G. W. WENZEL DVM, PhD, Diplomate ACT,

    1. Departments of Small Animal Surgery and Medicine, Aerospace Engineering, Large Animal Surgery and Medicine, Auburn University, AL
    2. Hughston Orthopedic Clinic, Columbus, GA
    3. Research and Development, Howmedica, Inc., Rutherford, NJ.
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  • CARL G. SAVORY MD, FACS,

    1. Departments of Small Animal Surgery and Medicine, Aerospace Engineering, Large Animal Surgery and Medicine, Auburn University, AL
    2. Hughston Orthopedic Clinic, Columbus, GA
    3. Research and Development, Howmedica, Inc., Rutherford, NJ.
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  • HAROLD M. ABERMAN DVM, MSE

    1. Departments of Small Animal Surgery and Medicine, Aerospace Engineering, Large Animal Surgery and Medicine, Auburn University, AL
    2. Hughston Orthopedic Clinic, Columbus, GA
    3. Research and Development, Howmedica, Inc., Rutherford, NJ.
    Search for more papers by this author

Coastal Carolina Veterinary Surgery. PA., 1861 Remount Rd. North Charleston, SC 29406.

Abstract

Twelve normal greyhound femora were divided into three groups. In group one, femoral stems were placed in neutral position with maximal fill. Group two had undersized femoral stems placed in neutral position. Group three had undersized femoral stems placed in varus position. Intact and implanted femora were loaded from 10 newtons (N) to 300 N in axial compression at a rate of 25 N/s for 10 replications. A strain gauge analysis showed that the strain distribution of all implanted femora were substantially different from intact femora, but femora with large implants placed in neutral position had the least amount of deviation from normal. An undersized stem in neutral position had significantly less compressive longitudinal strains along the proximomedial and proximocranial cortices. An undersized stem in varus position improved implant fit along the proximomedial and distolateral cortices, which resulted in increased tensile hoop strains. There were multiple significant correlations between the strain data and implantation variables (implant alignment, canal fill, and implant fit). Subsidence was significantly greater for the undersized implant in neutral position. There was not a difference in subsidence between the large neutral and varus groups. The most important variable that decreased subsidence was increased lateral implant fit (r= -0.86, P= .0003).

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