A Review of the Impacts of Implant Stiffness on Fracture Healing

Abstract

Featured Application: Interfragmentary movement is crucial in promoting callus formation during secondary fracture healing. Fixation stiffness is a critical factor, with excessive flexibility and rigidity hindering optimal healing. The concepts of flexible fixation, techniques for regulating implant stiffness, and material selection, favoring a lower Young’s modulus like titanium alloys, are emphasized. A novel TiNbSn alloy with a low Young’s modulus has been introduced as a potential solution that has shown efficacy in promoting osteosynthesis and superior mechanical properties. The bone healing process is influenced by various physiological factors. Fracture fixation traditionally relied on rigid metallic implants. However, excessively rigid constructs can lead to complications, necessitating revision surgery. This review focuses on approaches to improve bone healing by introducing adequate interfragmentary movement (IFM) at the fracture site. IFM promotes secondary fracture healing and callus formation. Studies suggest that rigid fixation may impair fracture healing by inhibiting callus formation and causing stress shielding. Titanium alloy locking plates have been shown to be biomechanically superior to stainless steel. Flexible fixation and techniques to regulate implant stiffness are crucial for managing fractures with bridge plating. Materials with a lower Young’s modulus balance biomechanical properties. A novel TiNbSn alloy with a low Young’s modulus has been developed to address stress shielding issues. It is effective in promoting osteosynthesis, bone healing, and superior mechanical properties compared with materials with higher Young’s moduli. The enhanced formation of bone and callus associated with TiNbSn alloy suggests its promise for use in fracture treatment plates. Understanding the biomechanics of fracture healing, optimizing fixation stiffness, and exploring innovative materials like TiNbSn alloys, are crucial for advancing approaches to accelerate and enhance bone healing.