Date of Award

Spring 2001

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical Engineering

First Advisor

David Hall

Abstract

Sliding hip screws are routinely used to repair Garden III femoral neck factures. This research seeks to better understand the influence of the hip screw angle on the performance of the fixation. The mechanics of fractured femurs repaired with 135- and 150-degree sliding fixation devices are explored using experimental, finite element, and analytical modeling. The experimental study involves testing of both intact and fixated femurs; the finite element work centers on two-dimensional models of intact and fixated femurs; and the analytical modeling explores the forces, moments and stresses in the fixation. The analytical model predicts that the screw will serve as a hinge point leading to compressive contact forces across the fracture faces below the screw. The peak stresses I the screw are seen to be a function of the installation position of the screw on the fracture plane. Screw are seen to have lower stresses when they are installed low on the fracture plane, especially in the case of the 150-degree screw. The experimental and finite element results both predict that the 150-degree fixation will be stiffer than the 135-degree fixation. The finite element calculations are verified by comparison with the experimental results.

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