TRI-CALCIUM PHOSPHATE REINFORCED PHB/PHV COPOLYMER FOR USE IN AN INTRAMEDULLARY FRACTURE FIXATION DEVICE

Corey J. Senowitz, Dr. Alex O. Aning, and Michael Stawovy
National Science Foundation and Technology Center:
High Performance Polymeric Adhesive and Composites, and
Department of Materials Science and Engineering
Virginia Polytechnic Institute and State University
Blacksburg, Virginia

ABSTRACT

Mechanical Alloying (MA), a high energy ball milling process, has been used to process a biocomposite made up of Polyhydroxybutyrate/Polyhydroxyvalerate (PHB/PHV) reinforced with tri-calcium phosphate (TCP). This composite is designed for use in an intramedullary fracture fixation device. The current material of choice for this application is 316L stainless steel. The use of stainless steel for this application has some drawbacks. These drawbacks include: in vivo it releases toxic metal ions, it has an unacceptably high modulus, and it must be surgically removed at some point. The material being developed would be an improvement because it is bioactive, biodegradable, and piezoelectric. This eliminates the need for surgical removal in the future while at the same time allowing for a gradual load transfer to the healing bone. In addition, the fact that the composite is non-metallic eliminates the problem of toxic metal ions being released into the body. The bioactivity and piezoelectricity of the composite stimulates and improves bone growth and hence fracture mending. This composite was subjected to mechanical, thermal, crystallographic, and optical analysis. A significant increase in mechanical properties was achieved in the composite by the addition of the TCP reinforcement without altering the thermal or crystallographic properties of the constituent materials to a great extent.