Total disc replacement devices: Structure, material, fabrication, and properties

The intervertebral disc (IVD) is an important component of the human spine that maintains physiological motion and distributes loads. Single- or multi-segment degeneration occurs alongside normal aging or damage to the human spine. These phenomena may in turn cause persistent pain and disability. This is among the major musculoskeletal system diseases worldwide. Total disc replacement (TDR) is one effective approach to treating symptomatic degenerative disc disease (DDD). Numerous ideas for TDR devices have been proposed. These devices seek to reproduce the biomechanical function of the functional spinal unit (FSU). However, the complex human physiological environment and long-term operational conditions pose substantial challenges that affect the structural design, material properties, and process strategies associated with TDR devices. This review introduces the main advantages and scientific challenges associated with existing TDR devices. Furthermore, a novel strategy to fabricate TDR devices by integrating cutting-edge technologies (e.g., bionic technology, functionally graded materials, and additive manufacturing) is described. How this approach can help to restore biofunction and improve performance is discussed. Finally, the future research directions of TDR devices are proposed. The research may provide new inspiration for the innovative design and manufacture of next-generation engineered TDR devices.