Monolithic Total Disc Replacement Made of Polyurethane Lattice based on Anatomical Features

Lower back pain (LBP) is included in the top 10 contributors to the overall disease burden. One of the etiologies of LBP is the intervertebral disc (IVD) degeneration, which in some cases, needs to be replaced with an artificial disc, the so-called total disc replacement (TDR). Unfortunately, TDR might provide post-surgical complications, including the failure in the metal-polymer assembly of TDR. The failure was argued due to the rigidity of the metal part and the shape of TDR that was not fully compliant with the anatomical features. Due to these complications, we proposed PU and monolithic construct to be alternative materials and comply with anatomical relevance. This study designed and developed a monolithic TDR made of PU lattices based on anatomical features. We focused on the IVDs in the lumbar section of the spine. The design step consisted of 3 phases: segmentation of DICOM files of IVDs using a 3D Slicer software, alignment using an Autodesk Meshmixer software, and lattice design using an Autodesk Inventor software. The manufacturing step started with a configuration setup in Simplify3D, software for computer-aided manufacturing (CAM) in 3D printing. The lattice features were fabricated using a Creality CP01 3D printer with two types of PU filaments: TPU 87A and TPU 95A. The printing results were able to construct the external curvature of the IVDs. Unfortunately, the microscopic measurement results showed that struts and holes' dimensions deviated from the design, which must be resolved in the next studies.