Mechanical strength and biocompatibility properties of materials for bone internal fixation: A brief overview

An ideal bone internal fixation material does more than just fracture union. It ensures the preservation of Bone Mineral Density (BMD) and body-bone's integrity. This has been a major fight in osteosynthesis from the ancient time till date. Animal skeletons that were first used as internal fixations though had some desirable mechanical properties comparable to bones, their usage resulted in mild pus formation, difficulty with resorption of sterile bones and non-union. A shift to metallic bone implants resulted in corrosion and bio-incompatibility, stress shielding, imaging and radiotherapy interference, temperature sensitivity, revision surgery with extreme difficulty, growth restriction, metal-in tissue accumulation, bone-metal elastic modulus mismatch to mention but a few. Advances in osteosynthesis have, however, led to great improvement on metallic bone fixations, yet leaving some fundamental issues unresolved. Exploration of biodegradable polymers and their composites is fast solving most of the problems encountered through the use of skeletal and metallic fixations. Their low Young's moduli and excellent biocompatibility, non-carcinogenicity and bioresorbability have made them viable materials for bone fracture healing. This brief overview covers the biomechanical properties of popular biological materials, metallic fixations and polymeric scaffold.