Intervertebral spinal implant

#The present disclosure generally relates to fixation devices and systems for positioning and immobilizing at least two adjacent vertebrae and methods related to the same. In particular, the present disclosure relates to interbody fusion devices with an integrated solid support structure and porous ingrowth structure.

#The spine is the axis of the skeleton on which all of the body parts “hang”. In humans, the normal spine has seven cervical, twelve thoracic and five lumbar segments. The lumbar spine situs upon the sacrum, which then attaches to the pelvis, and in turn is supported by the hip and leg bones. The bony vertebral bodies of the spine are separated by intervertebral discs, which act as joints but allow known degrees of flexion, extension, lateral bending, and axial rotation.

#The typical vertebra has a thick anterior bone mass called the vertebral body, with a neural (vertebral) arch that arises from the posterior surface of the vertebral body. The central of adjacent vertebrae are supported by intervertebral discs. The spinal disc and/or vertebral bodies may be displaced or damaged due to trauma, disease, degenerative defects, or wear over an extended period of time. One result of this displacement or damage to a spinal disc or vertebral body may be chronic back pain. In many cases, to alleviate back pain from degenerated of herniated discs, the disc is removed along with all or part of at least one neighboring vertebrae and is replaced by an implant that promotes fusion of the remaining bony anatomy.

#A more complete understanding of the present disclosure, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

#FIGS. 1-4 are perspective, side, top and rear views, respectively, of an intervertebral implant according to one embodiment of the disclosure with the porous portions shown textured;

#FIGS. 5-7 are perspective, top and side views, respectively, of the intervertebral implant of FIGS. 1-4 with the porous portions removed to show the support structure;

#Embodiments of the disclosure are generally directed to intervertebral implants, systems, and method of use thereof. The implant may be suitable for use with the anterior, antero-lateral, lateral, and/or posterior portions of at least one motion segment unit of the spine. Traditionally, interbody spacers or implants intended to help facilitate intervertebral fusion may serve as a means to restore intervertebral height and/or lordosis. The implants may feature a central lumen to house bone graft material, for example. It is through this central lumen where most of the fusion may occur. The implants of the disclosure may incorporate a volumetric, interconnected porosity throughout the entire spacer or a portion thereof. This enables bone to growth into and/or through the spacer or a portion thereof, making it part of the fusion mass. The incorporation of a volumetric, interconnected porosity may encourage faster, stronger intervertebral fusion, thereby providing for better patient outcomes.

#Various forms of additive manufacturing, or 3D printing, have been developed which allow structures to be formed layer by layer. One illustrative 3D printing technology is Direct Metal Laser Sintering (DMLS) wherein parts are built using a laser to selectively sinter (heat and fuse) a powdered metal material into layers. The process begins once a 3D CAD file is mathematically sliced into multiple 2D cross sections and uploaded into the system. After the first layer is produced, the build platform is lowered, another powder layer is spread across the plate, and the laser sinters the second layer. This process is repeated until the part is complete. Layer-by-layer manufacturing allows for the direct fabrication of complex parts that would be cost-prohibitive, and often impossible, to produce through traditional manufacturing processes. The powder layer thickness used during the fabrication of the spacers may be as thin at 30 μm. The resolution of the laser may be as fine as 70 μm. Although it is envisioned that any suitable thickness or laser resolution may be used or selected.

#The disclosure is not limited to DMLS, but various 3D printing methods may be utilized. For example, VAT Photopolymerization utilizes a vat of liquid photopolymer resin which is cured through selective exposure to light (via a laser or projector) which then initiates polymerization and converts the exposed areas to a solid part. As another example, Powder Bed Fusion, of which DMLS is a subcategory, utilizes powdered materials which are selectively consolidated by melting it together using a heat source such as a laser or electron beam. The powder surrounding the consolidated part acts as support material for overhanging features. As yet another example, in Binder Jetting Liquid bonding agents are selectively applied onto thin layers of powdered material to build up parts layer by layer. The binders include organic and inorganic materials. Metal or ceramic powdered parts are typically fired in a furnace after they are printed. Material Jetting is another example of a 3D printing process which may be utilized wherein droplets of material are deposited layer by layer to make parts. Common varieties include jetting a photocurable resin and curing it with UV light, as well as jetting thermally molten materials that then solidify in ambient temperatures. As another example, in Sheet Lamination sheets of material are stacked and laminated together to form an object. The lamination method can be adhesives or chemical (paper/plastics), ultrasonic welding, or brazing (metals). Unneeded regions are cut out layer by layer and removed after the object is built. Another example of a 3D printing process that may be utilized is Material Extrusion wherein material is extruded through a nozzle or orifice in tracks or beads, which are then combined into multi-layer models. Common varieties include heated thermoplastic extrusion and syringe dispensing. Yet another example is Directed Energy Deposition wherein powder or wire is fed into a melt pool which has been generated on the surface of the part where it adheres to the underlying part or layers by using an energy source such as a laser or electron beam.