The Effects of Implant Orientation, Canal Fill, and Implant Fit on Femoral Strain Patterns and Implant Stability During Catastrophic Testing of a Canine Cementless Femoral Prosthesis

Authors

  • ROBERT T. PERNELL DVM, MS, Diplomate ACVS,

    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; and Research and Development, Howmedica, Inc, Rutherford, NJ.
      Coastal Carolina Veterinary Surgery, PA, 1861 Remount Road, N Charleston, SC 29406.
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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; and Research and Development, Howmedica, Inc, Rutherford, NJ.
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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; and 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; and 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; and 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; and 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; and Research and Development, Howmedica, Inc, Rutherford, NJ.
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Coastal Carolina Veterinary Surgery, PA, 1861 Remount Road, N Charleston, SC 29406.

Abstract

Cementless femoral stems were placed into 12 normal greyhound femora. The implanted femora were divided into three groups by stem orientation and implant size and loaded in axial compression at a rate of 25 newtons (N) per second until failure. Rosette strain gauges were used to measure femoral principal strains at 500 N, 1,000 N, 1,500 N, and at maximum load. During maximum load, varus orientation of the femoral stem had significantly higher tensile hoop strains in the proximomedial cortex, whereas neutral orientation had higher tensile hoop strains along the cranial cortex. Femoral fractures occurred in these areas of peak tensile strain. There was no difference in maximum load between groups, therefore varus orientation did not predispose to fracture. Maximizing canal fill and implant fit increased implant stability.

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