J Korean Orthop Res Soc.  2002 Apr;5(1):26-33.

The Effect of the Cross-pins on the Fixation Stiffness using Finite Element Method in Fracture of Femoral Shaft

• Lee MK
• Kim JK
• Choi KW
• Choi IH
• Khang G

Abstract

PURPOSE: A compression plate fixation was generally used in the fracture of a femoral diaphysis but it produced the stress shielding problem which resulted in a decrease of bone mass and impaired mechanical properties. This study was designed to compare with the stiffnesses of three different internal fixation types ; fixation with only plate, with only cross-pins, and with both a plate and cross-pins.
MATERIALS AND METHODS
To compare the stress distribution and stiffness of three types of fixation devices, the device-bone system are analyzed under axial compression(70Kg) and 3-point bending(500Nmm) in planes using the 2-D finite element method(ABAQUS 5.8). Also the stiffness of each device was evaluated at seven different time points during fracture healing by increasing Young's modulus of callus.
RESULTS
The plate fixation model had the highest stress distribution and occurred the stress concentration in the cortex beneath the plate. During the healing of bone fracture, the fixation with cross-pins relatively had a higher compression and bending stiffness. The fixation with only cross-pins was as stiff as that with an only plate in bending but less stiff than in compression.
CONCLUSION
The internal fixation added to cross-pins may decrease the stress shielding problems due to dispersing the stress concentration and also improve the stiffness of a device-bone system.

Keyword

Fracture; Internal fixation; Strength analysis; Finite element analysis

MeSH Terms

Bony Callus
Diaphyses
Elastic Modulus
Finite Element Analysis
Fracture Healing
Fractures, Bone