Effect of Bone Quality on the Failure of Locked Plate Fixation of Proximal Humerus

Principle Investigator: Jihui Li
Co-investigators: Robert Hymes, Jeff Schulman, Mark Theiss
Funded by: Inova Faculty Research Grant and Smith & Nephew Inc.

The goal of this study is to understand how bone quality affects the failure of locked plate fixation of humeral fractures. We will develop a sophisticated research tool that combines biomechanical testing, AE technique, computer simulation (finite element analysis) and microscopic observation to test the following hypotheses:

1. Patients’ average BMD will correlate to the pullout strength of the locked plate fixation. It will also correlate to the stiffness of compression, bending, and torsion, and the screw removal torques.
2. Cumulative AE microcracks will correlate to the local BMD of each bone-screw interface.
3. The finite element models of the humeral locked plate fixations developed by standardized procedures will have a 15% or less error in mechanical stiffness compared to that in biomechanical testing.

This research will provide insight into the failure mechanism of locked plate fixation of humeral fractures by quantifying the damages at each bone-screw interface and indicating the weakest point. The improved understanding of the failure mechanism will help physicians to better define the use of the locked plate system, and will help implant manufacturers to optimize their designs. This study will also create computer simulation procedures that could provide better services to Inova patients.