From clinic to lab: Advances in porous titanium-based orthopedic implant research

Solid titanium alloys are extensively employed in orthopedic applications due to their reliable mechanical strength, but the stress shielding phenomenon caused by its high elastic modulus and the disadvantage of lack of bone integration may lead to clinical complications. The design of porous structure is a feasible approach to reduce the elastic modulus and promote bone and vascular ingrowth. This paper reviewed the application and current challenges of solid titanium implants in orthopedics. To address the drawbacks and explore porous titanium implants that can effectively integrate with bone tissue while possessing sufficient mechanical strength, this review discussed the latest preclinical research from the perspectives of structural design, surface modification, and material composition. The porous structure parameters that affect bone ingrowth and mechanical strength in implants, including porosity, pore size, cellular structure, and gradient structure, were presented. Based on the current research progress, various surface modification techniques aimed at enhancing the performance of porous titanium implants were overviewed. Moreover, a range of titanium alloys including nickel-titanium alloy, β-titanium alloy, high-entropy alloy, and composite alloys are investigated for their prospective applications in orthopedics. Overall, this review provided valuable insights into the current state of research and highlighted the potential of porous titanium alloys in improving clinical outcomes in orthopedics.