The methods disclosed herein of generating three-dimensional lattice structures and reducing stress shielding have applications including use in medical implants. One method of generating a three-dimensional lattice structure can be used to generate a structure lattice and/or a lattice scaffold to support bone or tissue growth. One method of reducing stress shielding includes generating a structural lattice to provide sole mechanical spacing across an area for desired bone or tissue growth. Some examples can use a repeating modified rhombic dodecahedron or radial dodeca-rhombus unit cell. Some methods are also capable of providing a lattice structure with anisotropic properties to better suit the lattice for its intended purpose.

The invention disclosed herein includes implant features that can be used, in some embodiments, on devices with a volumetric density of less than about 100 percent and devices with a surface roughness of some value. The implant features include one or more protrusions mounted on the forward edge of an implant that can ease the distraction of tissue during implantation and reduce the occurrence of damage during a manufacturing process. In some embodiments, the protrusions have gaps in a non-axial direction with respect to the implant to allow axial compression with respect to the protrusions. In some embodiments, the protrusions have a circumferential gap between them and a body of a device to reduce any impact on the device's elastic modulus.

The present invention provides implants and a method of designing and manufacturing implants using an additive process that avoids damage when removing the implant from a build surface of an additive process machine. The inventive method involves designing an implant and build orientation with a portion of increased volumetric density in contact with the build surface. In some embodiments, the contact area between a device and a build surface is reduced to provide easier detachment after the additive process is complete.

The present invention includes markers for use in implants that have a variable lucency or radiolucency. The use of a variably lucent marker can provide a surgeon a quick indication of the implant's alignment during implantation. A variably lucent marker can also provide a doctor or technician a quick indicator of an implant's position during post-operation imaging.

The variably lucent markers can be used in any implant that has some level of lucency when viewed through an imaging device. The variably lucent markers can be used in the lattice with increased or optimized lucency disclosed herein or in other structure known in the art.

The biocompatible lattice structures disclosed herein have an increased or optimized lucency, even when constructed from a metallic material. The lattice structures can also provide an increased or optimized lucency in a material that is not generally considered to be radiolucent.

The biocompatible lattice structures disclosed herein with an increased or optimized lucency are prepared according to multiple methods of design disclosed herein. The methods allow for the design of a metallic material with sufficient strength for use in an implant and that remains radiolucent for x-ray imaging.

In some aspects, the present invention is a medical implant with an independent endplate structure that can stimulate bone or tissue growth in or around the implant. When used as a scaffold for bone growth, the inventive structure can increase the strength of new bone growth. The independent endplate structures generally include implants with endplates positioned on opposite sides of the implant and capable of at least some movement relative to one another. In most examples, the endplates have a higher elastic modulus than that of the bulk of the implant to allow the use of an implant with a low elastic modulus, without risk of damage from the patient's bone.

A method of designing independent endplate implants is also disclosed, including ranges of elastic moduli for the endplates and bulk of the implant for given implant parameters. Implants with elastic moduli within the ranges disclosed herein can optimize the loading of new bone growth to provide increased bone strength.

The biocompatible lattice structures disclosed herein with an increased or optimized lucency are prepared according to multiple methods of design disclosed herein. The methods allow for the design of a metallic material with sufficient strength for use in an implant and that remains radiolucent for x-ray imaging.

Orthopedic implants, particularly interbody spacers, have a combination of correct pore size and stiffness/flexibility. When the implants have the proper pore size and stiffness, osteocytes are able to properly bridge the pores of the implant and then experience a proper compressive load to stimulate the bone cells to form bone within the pores. An implant includes a body formed of an osteoconductive material and having a stiffness of between 400 megapascals (MPa) and 1,200 MPa. Additionally, the body includes a plurality of pores having an average size of between 150 microns and 600 microns. The pores permit the growth of bone therein. The body is formed of packs of coils which may be formed using an additive manufacturing process and using traditional orthopedic implant materials such as titanium and titanium alloys while still achieving desired stiffness and pore sizes of the implants.

The biocompatible lattice structures and implants disclosed herein have an increased or optimized lucency, even when constructed from a metallic material. The lattice structures can also provide an increased or optimized lucency in a material that is not generally considered to be radiolucent. Lucency can include disparity, maximum variation in lucency properties across a structure, or dispersion, minimum variation in lucency properties across a structure. The implants and lattice structures disclosed herein may be optimized for disparity or dispersion in any desired direction. A desired direction with respect to lucency can include the anticipated x-ray viewing direction of an implant in the expected implantation orientation.