Design and experimental research of a personalized hybrid intervertebral disc implant prototype

The degeneration of the intervertebral disc, characterized by chronic pain, restricted range of motion, and progressive deterioration of functional spinal units, represent a serious surgical condition. For the treatment the total or partial arthroplasty is often suggested. Currently, 3D printing is frequently utilized in the development of disc prostheses, owing to its high precision and capacity to create patient-specific implants. Integrated with the replication of the intact biphasic structure, this approach facilitates the preservation of the natural biomechanical response to physiological loads. For the artificial annulus fibrosus, gyroid-based structures fabricated using biocompatible materials show significant promise due to their unique mechanical properties. Hydrogels can serve as candidates for the nucleus pulposus replacement, owing to their structural similarity and viscoelastic behavior. This work proposes design methodologies for a gyroid-based annulus fibrosus manufactured via extrusion-based 3D printing. Furthermore, a fabrication technique for hydrogels exhibiting controlled swelling and a tailored elastic modulus to mimic the nucleus pulposus was developed and implemented. Mechanical testing was conducted to evaluate the elastic-hysteretic properties of the hybrid implantprototypes under physiological loading conditions. The results demonstrate a close correspondence between these properties and those of the intact disc.