Design and Development of Load Bearing Composite Scaffolds for Bone Implants

Abstract

Biocomposites mimicking hard tissue in the process of bone repair and regeneration have been in development for several decades. Contributions of several researchers in selection of materials, development of preparation routes, conduct of post surgery response studies and clinical trials for continual developments are commendable. Among several disciplines involved in this process, engineers role has been identified vital in materials and their processing. Natural bone made up of Collagen and reinforcement ceramic phase, has dense structure at the middle of the bone and porous structure at the ends. Damaged or diseased bone needs regeneration with implant reinforcements for load sharing during healing process. Essential requirement of an implant is to share the load and to stimulate the bone growth by proper mechanics. Structural point of view, mechanical properties of an ideal implant shall match native bone properties. Known the properties of Hydroxyapatite (HA), Ca10 (PO4)6 (OH)2 in bone applications for its bio active, bio conductive and bio inductive nature, it was chosen as bone material. Hydroxyapatite (HA) being ceramic, it suffers from low strength, low toughness and low tensile properties. In order to overcome the structural weaknesses of HA, Polyetheretherketone (PEEK-polymer) matrix was chosen to match the properties of Collagen. The polymer part of composite, PEEK, by brand name VESTKEEP 2000FP, a non-medical grade polymer is a justified selection due to its inherent superior properties such as- semi-crystalline, high strength, temperature resistant, chemically inert, bio inert, bio conductive, radiolucent, clinically proven and approved by Food and Drug Administration (FDA)-U S A. Hydroxyapatite, the reinforcing ceramic powder was extracted from chicken egg shells. Thoroughly washed egg shells were heated through predefined thermal cycles for the formation of CaO. Obtained CaO after thermal treatment has been chemically treated with tri-calcium phosphate (TCP) in wet condition at temperatures 10000