Spinal implant wear particles: Generation, characterization, biological impacts, and future considerations

The generation of wear debris from orthopedic implants is a known cause of implant failure, particularly in joint replacements. While much research has focused on wear particles from knee and hip implants, spinal implants, such as total disc replacements (TDRs), have received less attention despite their increasing clinical use. Spinal implants face unique biomechanical challenges, including a wider range of motion and higher loads, leading to complex tissue interactions. Studies reveal that TDR wear particles, though similar in size to those from knee implants, cause a stronger immune response, with more macrophages and giant cells found in the surrounding tissue. This may explain the high revision rates seen in spinal surgeries, with some interventions failing in over 30% of cases within 10 years. The younger population undergoing spinal surgery, combined with the productivity losses associated with implant failure, underscores the need for greater understanding. This review discusses recent research on the generation, characterization, and biological impacts of spinal implant wear debris. It draws on retrieval analysis, wear simulation, in vivo models, and a survey conducted with the AO Spine Knowledge Forum Degenerative to assess current clinical practices and highlight gaps in knowledge. Additionally, this critical review explores future strategies to reduce the biological impact of wear particles and improve the safety and longevity of spinal implants through better therapeutics and design innovations. By combining literature and clinical insights, this paper aims to guide future research in addressing the complexities of spinal implant wear and its biological consequences.