Patent Description:
Spinal pathologies and disorders such as kyphosis, scoliosis and other curvature abnormalities, degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, tumor, and fracture may result from factors including trauma, disease and degenerative conditions caused by injury and aging. Spinal disorders typically result in symptoms including deformity, pain, nerve damage, and partial or complete loss of mobility.

Non-surgical treatments, such as medication, rehabilitation and exercise can be effective, however, may fail to relieve the symptoms associated with these disorders. Surgical treatment of these spinal disorders includes correction, fusion, fixation, discectomy, laminectomy and implantable prosthetics. As part of these surgical treatments, spinal constructs including bone fasteners are often used to provide stability to a treated region. Such bone fasteners are traditionally manufactured using a medical machining technique. From <CIT> a spinal implant system is known comprising a head assembly including a part, such as, for example, a crown and a retainer that is pre-assembled with an implant receiver, wherein a portion of some inner surfaces of the spinal implant system are porous. From <CIT> a spinal implant system comprising a modular screw system is known including a body for attachment of an implant receiver with a screw shaft, wherein a portion of some inner surfaces of the spinal implant system are porous. From <CIT> bone anchor assemblies are known. From <CIT> implants are known including a biocompatible substrate, wherein the biocompatible substrate includes a plurality of pores, and wherein said implant is configured as a transcutaneous implant, wherein the implants are made entirely of porous material. From <CIT> a bone screw incorporating a porous surface for enhancing bony fixation is known, wherein a porous surface is only used for the threads of the shaft. This disclosure describes an improvement over these prior technologies.

The present invention relates to a spinal bone screw according to claim <NUM> and a method for fabricating the spinal bone screw according to claim <NUM>. Further embodiments are set forth in the dependent claims. Reference to "embodiments" throughout the description which are not under the scope of the appended claims merely represent possible exemplary executions and are therefore not part of the present invention. According to the invention, a bone screw is provided. The bone screw includes a shaft including at least one thread having an external thread form; and an implant receiver including a first portion and a second portion. The first portion has a solid configuration relative to the second portion. To further the understanding of the spinal bone screw, systems, spinal constructs, surgical instruments and methods using the spinal bone screw are discussed.

The implant receiver includes a body having spaced apart walls defining a U-shaped cavity which is preferably configured for disposal of a spinal rod.

According to the invention, a method for fabricating the inventive bone screw is provided. The method comprising the steps of: forming the first portion of the implant receiver of the spinal bone screw by a first manufacturing method, the implant receiver including the body having the spaced apart walls that define a U-shaped cavity configured for disposal of a spinal rod; and forming the second portion of the implant receiver, being part of the base of the implant receiver by a second manufacturing method including an additive manufacturing method wherein a processor instructs an additive manufacturing apparatus to form the second portion.

The exemplary embodiments a bone screw and a method for fabricating the inventive bone screw are described in conjunction with surgical system and not claimed related methods of using the inventive bone screw to further the understanding of the invention in terms of medical devices for the treatment of musculoskeletal disorders and more particularly, in terms of a variable structured spinal implant. The spinal implant system can include a spinal implant comprising a variable structured implant receiver.

The spinal implant system can comprise a bone screw having an implant receiver configured as a screw head that promotes bony in-growth. In some embodiments, the bone screw of the present disclosure comprises an implant receiver having a variable structure, such as, for example, any combination of solid, roughened surfaces, porous surfaces, honeycomb filled, structure having a trabecular configuration, or other porous or roughened configurations. In some embodiments, the implant receiver of the present disclosure aids in the promotion of bony fusion after posterior spinal instrumentation. In some embodiments, the implant receiver of the present disclosure includes a screw head having a porous layer to facilitate bone growth into a base of the screw head. The porous layer is disposed about a portion of the base, about an outer diameter of the base. In some embodiments, this configuration optimizes bony in-growth with the screw head of a pedicle screw to promote fusion. The spinal implant system can comprise a modular screw system including screw shaft assemblies and implant receiver/head assemblies that may be joined together during manufacturing or intra-operatively, such as, for example, during a surgical procedure in an operating room.

The spinal implant system can include a bone screw having an implant receiver and head assembly comprising a variable structure. In some embodiments, the variably structured implant receiver and/or head assembly combines a manufacturing method, such as, for example, one or more traditional manufacturing features and materials and a manufacturing method, such as, for example, one or more additive manufacturing features and materials. In some embodiments, the bone screw is configured for engagement with cortical and/or cancellous bone. In some embodiments, captured cortical and/or cancellous bone is embedded within the implant receiver and/or head assembly as bone graft to facilitate promotion of bone growth and bone screw fusion. In some embodiments, external grafting materials or biologics may be prepacked within the implant receiver and/or head assembly.

In some embodiments, the spinal implant system can be configured to enhance fixation of inventive bone screws with bone. In some embodiments, the spinal bone screw is configured to enhance the ability for a bone screw to be engaged with tissue.

The spinal implant system can comprise a spinal bone screw having an implant receiver head assembly having a hybrid configuration that combines a manufacturing method, such as, for example, one or more traditional manufacturing features and materials and a manufacturing method, such as, for example, one or more additive manufacturing features and materials. In some embodiments, additive manufacturing includes <NUM>-D printing. In some embodiments, additive manufacturing includes fused deposition modeling, selective laser sintering, direct metal laser sintering, selective laser melting, electron beam melting, layered object manufacturing and stereolithography. In some embodiments, additive manufacturing includes rapid prototyping, desktop manufacturing, direct manufacturing, direct digital manufacturing, digital fabrication, instant manufacturing and on-demand manufacturing. The spinal implant system can comprise one or more components, as described herein, of a spinal bone screw being manufactured by a fully additive process and grown or otherwise printed. In some embodiments, the implant receiver and/or head assembly of the present disclosure includes a non-solid portion, for example, a porous layer that is applied to a base of the implant receiver and/or head assembly via additive manufacturing, for example, <NUM>-D printing. In some embodiments, this configuration avoids compromising the integrity of a spinal construct and promotes bone fusion.

The spinal implant system can comprise an inventive spinal bone screw manufactured by combining traditional manufacturing methods and additive manufacturing methods. In some embodiments, the bone screw is manufactured by applying additive manufacturing material in areas where the bone screw can benefit from materials and properties of additive manufacturing. In some embodiments, traditional materials are utilized where the benefits of these materials, such as physical properties and cost, are superior to those resulting from additive manufacturing features and materials.

The spinal bone screw of the present disclosure may be employed to treat spinal disorders such as, for example, degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, scoliosis and other curvature abnormalities, kyphosis, tumor and fractures. The spinal bone screw of the present disclosure may be employed with other osteal and bone related applications, including those associated with diagnostics and therapeutics. The spinal bone screw of the present disclosure may be alternatively employed in a surgical treatment with a patient in a prone or supine position, and/or employ various surgical approaches to the spine, including anterior, posterior, posterior mid-line, lateral, postero-lateral, and/or antero-lateral approaches, and in other body regions such as maxillofacial and extremities. The spinal bone screw of the present disclosure may also be alternatively employed with procedures for treating the lumbar, cervical, thoracic, sacral and pelvic regions of a spinal column. The spinal bone screw of the present disclosure may also be used on animals, bone models and other non-living substrates, such as, for example, in training, testing and demonstration.

The present disclosure may be understood more readily by reference to the following detailed description of the embodiments taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this application is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments of the bone screw and the method of manufacturing the bone screw by way of example only and is not intended to be limiting. In some embodiments, as used in the specification and including the appended claims, the singular forms "a," "an," and "the" include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It is also understood that all spatial references, such as, for example, horizontal, vertical, top, upper, lower, bottom, left and right, are for illustrative purposes only and can be varied within the scope of the disclosure. For example, the references "upper" and "lower" are relative and used only in the context to the other, and are not necessarily "superior" and "inferior".

As used in the specification and including the appended claims, "treating" or "treatment" of a disease or condition refers to performing a procedure that may include administering one or more drugs to a patient (human, normal or otherwise or other mammal), employing implantable devices, and/or employing instruments that treat the disease, such as, for example, microdiscectomy instruments used to remove portions bulging or herniated discs and/or bone spurs, in an effort to alleviate signs or symptoms of the disease or condition, wherein the procedure is describer to further the understanding of the inventive bone screw and the inventive method for manufacturing it. Alleviation can occur prior to signs or symptoms of the disease or condition appearing, as well as after their appearance. Thus, treating or treatment includes preventing or prevention of disease or undesirable condition (e.g., preventing the disease from occurring in a patient, who may be predisposed to the disease but has not yet been diagnosed as having it). In addition, treating or treatment does not require complete alleviation of signs or symptoms, does not require a cure, and specifically includes procedures that have only a marginal effect on the patient. Treatment can include inhibiting the disease, e.g., arresting its development, or relieving the disease, e.g., causing regression of the disease. For example, treatment can include reducing acute or chronic inflammation; alleviating pain and mitigating and inducing re-growth of new ligament, bone and other tissues; as an adjunct in surgery; and/or any repair procedure. Also, as used in the specification and including the appended claims, the term "tissue" includes soft tissue, ligaments, tendons, cartilage and/or bone unless specifically referred to otherwise.

The following discussion includes a description of a spinal bone screw and a method of manufacturing the spinal bone screw, and related components and methods of employing a surgical system using a bone screw in accordance with the principles of the present disclosure are described to further understanding of the invention. Alternate embodiments are disclosed. Reference is made in detail to the exemplary embodiments of the present disclosure, which are illustrated in the accompanying figures. Turning to <FIG>, there are illustrated components of a spinal implant system <NUM> including an inventive bone screw, surgical instruments and medical devices.

Spinal implant system <NUM> includes a bone screw <NUM>. Bone screw <NUM> includes an implant receiver and/or head assembly having variably structured configuration that facilitates bone growth through bone screw <NUM> and/or fixation of bone screw <NUM> with tissue. Bone screw <NUM> comprises a screw shaft <NUM> and an implant receiver <NUM>. Receiver <NUM> includes a portion that defines an implant cavity <NUM> and a portion that defines a base <NUM> having a porous layer <NUM> to enhance fixation and/or facilitate bone growth, as described herein.

Receiver <NUM> defines an even, uninterrupted edge surface and includes an even, solid surface relative to the surface of layer <NUM>, as described herein, which provides a variable configuration bone screw <NUM>. In some embodiments, receiver <NUM> is fabricated by a first manufacturing method. In some embodiments, the manufacturing method can include a traditional machining method, such as, for example, subtractive, deformative or transformative manufacturing methods. In some embodiments, the traditional manufacturing method may include cutting, grinding, rolling, forming, molding, casting, forging, extruding, whirling, grinding and/or cold working. In some embodiments, the traditional manufacturing method includes components being formed by a medical machining process. In some embodiments, medical machining processes can include use of computer numerical control (CNC) high speed milling machines, Swiss machining devices, CNC turning with living tooling and/or wire EDM 4th axis. In some embodiments, the manufacturing method includes a finishing process, such as, for example, laser marking, tumble blasting, bead blasting, micro blasting and/or powder blasting.

Receiver <NUM> includes a body <NUM> having a pair of spaced apart arms <NUM>, <NUM>. Arms <NUM>, <NUM> define implant cavity <NUM> therebetween. Implant cavity <NUM> is configured for disposal of a component of a spinal construct, such as, for example, a spinal rod. Arms <NUM>, <NUM> each extend parallel to an axis X1. In some embodiments, arm <NUM> and/or arm <NUM> may be disposed at alternate orientations, relative to axis X1, such as, for example, transverse, perpendicular and/or other angular orientations such as acute or obtuse, coaxial and/or may be offset or staggered. Arms <NUM>, <NUM> each include an arcuate outer surface extending between a pair of side surfaces. At least one of the outer surfaces and the side surfaces of arms <NUM>, <NUM> have at least one recess or cavity therein configured to receive an insertion tool, compression instrument and/or instruments for inserting and tensioning bone fastener <NUM>. In some embodiments, arms <NUM>, <NUM> are connected at proximal and distal ends thereof such that receiver <NUM> defines a closed spinal rod slot.

Cavity <NUM> is substantially U-shaped. In some embodiments, all or only a portion of cavity <NUM> may have alternate cross section configurations, such as, for example, closed, V-shaped, W-shaped, oval, oblong triangular, square, polygonal, irregular, uniform, non-uniform, offset, staggered, and/or tapered. Receiver <NUM> includes an inner surface <NUM>. A portion of surface <NUM> includes a thread form located adjacent arm <NUM> and adjacent arm <NUM>. The thread form is configured for engagement with a coupling member, such as, for example, a setscrew (not shown), to retain the spinal rod within cavity <NUM>. In some embodiments, surface <NUM> may be disposed with the coupling member in alternate fixation configurations, such as, for example, friction fit, pressure fit, locking protrusion/recess, locking keyway and/or adhesive. In some embodiments, all or only a portion of surface <NUM> may have alternate surface configurations to enhance engagement with the spinal rod and/or the setscrew, such as, for example, rough, arcuate, undulating, mesh, porous, semi-porous, dimpled and/or textured. In some embodiments, receiver <NUM> may include alternate configurations, such as, for example, closed, open and/or side access.

In some embodiments, receiver <NUM> includes a surface configured for disposal of a part, such as, for example, a crown (not shown). The crown is configured for disposal within implant cavity <NUM>. In some embodiments, the crown includes a curved portion configured for engagement with the spinal rod.

<FIG> shows a cross section view of base <NUM> of <FIG>. Base <NUM> of receiver <NUM> includes a wall <NUM>. Wall <NUM> includes an inner surface <NUM> that defines a cavity <NUM>, and an outer surface <NUM>. Cavity <NUM> is configured for disposal of a head <NUM> of screw shaft <NUM>. Wall <NUM> includes an even, uninterrupted configuration and includes an even, solid surface <NUM> relative to the surface of layer <NUM>. Surface <NUM> is configured for providing a fabrication platform for forming layer <NUM> thereon with a second manufacturing method such as, for example, an additive manufacturing method, as described herein. In some embodiments, the overall width of wall <NUM> and layer <NUM> is the same as a width of a traditional receiver.

Layer <NUM> is applied with a second manufacturing method by disposing a material onto surface <NUM> of wall <NUM>, as described herein. Layer <NUM> is applied to at least a portion of an outer circumference of surface <NUM>. Layer <NUM> includes a non-solid configuration, such as, for example, a porous structure and/or a trabecular configuration. In some embodiments, additive manufacturing includes <NUM>-D printing, as described herein. In some embodiments, additive manufacturing includes fused deposition modeling, selective laser sintering, direct metal laser sintering, selective laser melting, electron beam melting, layered object manufacturing and stereolithography. In some embodiments, additive manufacturing includes rapid prototyping, desktop manufacturing, direct manufacturing, direct digital manufacturing, digital fabrication, instant manufacturing or on-demand manufacturing. In some embodiments, layer <NUM> is applied by additive manufacturing, as described herein, and mechanically attached to surface <NUM> by, for example, welding, threading, adhesives and/or staking.

In various embodiments, the non-solid configuration provides one or a plurality of pathways to facilitate bone through growth within, and in some embodiments all of the way through, from one surface to an opposite surface of bone screw <NUM>. In some embodiments, one or more portions, layers and/or substrates of layer <NUM> may be disposed side by side, offset, staggered, stepped, tapered, end to end, spaced apart, in series and/or in parallel. In some embodiments, layer <NUM> defines a thickness, which may be uniform, undulating, tapered, increasing, decreasing, variable, offset, stepped, arcuate, angled and/or staggered. In some embodiments, layer <NUM> includes one or more layers of a matrix of material. In some embodiments, layer <NUM> includes one or a plurality of cavities, spaces and/or openings. In some embodiments, layer <NUM> may form a rasp-like configuration. In some embodiments, layer <NUM> is configured to engage tissue, such as, for example, cortical bone and/or cancellous bone, such as, to cut, shave, shear, incise and/or disrupt such tissue. In some embodiments, all or a portion of layer <NUM> may have various configurations, such as, for example, cylindrical, round, oval, oblong, triangular, polygonal having planar or arcuate side portions, irregular, uniform, non-uniform, consistent, variable, horseshoe shape, U-shape or kidney bean shape. In some embodiments, layer <NUM> may be rough, textured, porous, semi-porous, dimpled, knurled, toothed, grooved and/or polished to facilitate engagement and cutting of tissue.

In some embodiments, the non-solid configuration is configured as a lattice extending along surface <NUM>. In some embodiments, the lattice may include one or more portions, layers and/or substrates. Disclosures herein involving a porous, or other particular type of non-solid structure, are meant to disclose at the same time analogous embodiments in which other non-solid structure in addition or instead of the particular type of structure.

In some embodiments, layer <NUM> is fabricated according to instructions received from the computer and processor based on the digital rendering and/or data of the selected configuration, via the additive manufacturing process.

In one embodiment, one or more manufacturing methods for fabricating layer <NUM> and other components of bone screw <NUM>, such as, for example, screw shaft <NUM> and receiver <NUM> include imaging patient anatomy with imaging techniques, such as, for example, x-ray, fluoroscopy, computed tomography (CT), magnetic resonance imaging (MRI), surgical navigation, bone density (DEXA) and/or acquirable <NUM>-D or <NUM>-D images of patient anatomy. Selected configuration parameters of screw shaft <NUM>, receiver <NUM> and layer <NUM> and/or other components of bone screw <NUM> are collected, calculated and/or determined. Such configuration parameters can include one or more of patient anatomy imaging, surgical treatment, historical patient data, statistical data, treatment algorithms, implant material, implant dimensions, porosity and/or manufacturing method. In some embodiments, the configuration parameters can include implant material and porosity of layer <NUM> determined based on patient anatomy and the surgical treatment. In some embodiments, the implant material includes a selected porosity of layer <NUM>, as described herein. In some embodiments, the selected configuration parameters of screw shaft <NUM>, receiver <NUM> and layer <NUM> and/or other components of bone screw <NUM> are patient specific. In some embodiments, the selected configuration parameters of screw shaft <NUM>, receiver <NUM> and layer <NUM> and/or other components of bone screw <NUM> are based on generic or standard configurations and/or sizes and not patient specific. In some embodiments, the selected configuration parameters of screw shaft <NUM>, receiver <NUM> and layer <NUM> and/or other components of bone screw <NUM> are based on one or more configurations and/or sizes of components of a kit of spinal implant system <NUM> and not patient specific.

Screw shaft <NUM> defines an even, uninterrupted edge surface and includes an even, solid surface relative to the surface of layer <NUM>. Shaft <NUM> is configured to penetrate tissue, such as, for example, bone. In some embodiments, shaft <NUM> includes an outer surface having an external thread form. In some embodiments, the external thread form may include a single thread turn or a plurality of discrete threads. Head <NUM> includes a tool engaging portion configured to engage a surgical tool or instrument, as described herein. In some embodiments, the tool engaging portion includes a hexagonal cross-section to facilitate engagement with a surgical tool or instrument, as described herein. In some embodiments, the tool engaging portion may have alternative cross-sections, such as, for example, rectangular, polygonal, hexalobe, oval, or irregular. In some embodiments, head <NUM> includes a plurality of ridges to improve purchase of head <NUM> with the crown. Head <NUM> is configured for attachment with receiver <NUM>, as described herein.

In some embodiments, the external thread form is fabricated to include a fine, closely-spaced and/or shallow configuration to facilitate and/or enhance engagement with tissue. In some embodiments, the external thread form is fabricated to be continuous along shaft <NUM>. In some embodiments, the external thread form is fabricated to be intermittent, staggered, discontinuous and/or may include a single thread turn or a plurality of discrete threads. In some embodiments, shaft <NUM> is fabricated to include penetrating elements, such as, for example, a nail configuration, barbs, expanding elements, raised elements, ribs, and/or spikes. In some embodiments, the external thread form is fabricated to be self-tapping or intermittent at a distal tip. In some embodiments, the distal tip may be rounded. In some embodiments, the distal tip may be self-drilling. In some embodiments, the distal tip includes a solid outer surface.

Surface <NUM> facilitates engagement of head <NUM> with base <NUM> via a pressure and/or force fit connection. In some embodiments, surface <NUM> facilitates a non-instrumented assembly with receiver <NUM> and head <NUM> via an expandable ring. In some embodiments, receiver <NUM> may be disposed with head <NUM> in alternate fixation configurations, such as, for example, friction fit, pressure fit, locking protrusion/recess, locking keyway and/or adhesive. In some embodiments, receiver <NUM> is configured for rotation relative to head <NUM>. In some embodiments, receiver <NUM> is configured for rotation in range of <NUM> degrees relative to head <NUM> to facilitate positioning of shaft <NUM> with tissue. In some embodiments, receiver <NUM> is configured for selective rotation in range of <NUM> degrees relative to and about head <NUM> such that shaft <NUM> is selectively aligned for rotation in a plane relative to receiver <NUM>.

In some embodiments, receiver <NUM> is manually engageable with screw shaft <NUM> in a non-instrumented assembly, as described herein. Manual engagement and/or non-instrumented assembly of receiver <NUM> and screw shaft <NUM> can include coupling without use of separate and/or independent instrumentation engaged with screw shaft <NUM> components to effect assembly. Manual engagement and/or non-instrumented assembly can include a practitioner, surgeon and/or medical staff grasping receiver <NUM> and screw shaft <NUM> and forcibly assembling the components. Manual engagement and/or non-instrumented assembly can include a practitioner, surgeon and/or medical staff grasping receiver <NUM> and screw shaft <NUM> and forcibly snap fitting the components together, as described herein. Manual engagement and/or non-instrumented assembly can include a practitioner, surgeon and/or medical staff grasping receiver <NUM> and screw shaft <NUM> and forcibly pop fitting the components together and/or pop fitting receiver <NUM> onto screw shaft <NUM>, as described herein. In some embodiments, a force in a range of <NUM>-<NUM> N is required to manually engage receiver <NUM> and screw shaft <NUM> and forcibly assemble the components. For example, a force in a range of <NUM>-<NUM> N is required to snap fit and/or pop fit assemble receiver <NUM> and screw shaft <NUM>. In some embodiments, a force in a range of <NUM>-<NUM> N is required to manually engage receiver <NUM> and screw shaft <NUM> and forcibly assemble the components. For example, a force in a range of <NUM>-<NUM> N is required to snap fit and/or pop fit assemble receiver <NUM> and screw shaft <NUM>. In some embodiments, screw shaft <NUM> is manually engaged with base <NUM> and/or receiver <NUM> in a non-instrumented assembly, as described herein, such that removal of receiver <NUM> and screw shaft <NUM> requires a force and/or a pull-out strength of at least <NUM> N. In some embodiments, this configuration provides manually engageable components that are assembled without instrumentation, and subsequent to assembly, the assembled components have a selected pull-out strength and/or can be pulled apart, removed and/or separated with a minimum required force. In some embodiments, spinal implant system <NUM> comprises a spinal implant kit, as described herein, which includes a plurality of screw shafts <NUM> and/or receivers <NUM>.

In some embodiments, bone screw <NUM> can include various configurations, such as, for example, a posted screw, a pedicle screw, a bolt, a bone screw for a lateral plate, an interbody screw, a uni-axial screw, a fixed angle screw, a multi-axial screw, a side loading screw, a sagittal adjusting screw, a transverse sagittal adjusting screw, an awl tip, a dual rod multi-axial screw, midline lumbar fusion screw and/or a sacral bone screw.

In assembly, operation and use, spinal implant system <NUM> can be employed to treat an affected section of vertebrae. A medical practitioner obtains access to a surgical site including the vertebrae in any appropriate manner, such as through incision and retraction of tissues. The components of spinal implant system <NUM> including bone screw <NUM> are employed to augment a surgical treatment. Bone screw <NUM> can be delivered to a surgical site as a pre-assembled device or can be assembled in situ. Spinal implant system <NUM> may be may be completely or partially revised, removed or replaced.

Surgical system <NUM> may be used with surgical methods or techniques including open surgery, mini-open surgery, minimally invasive surgery and percutaneous surgical implantation, whereby the vertebrae is accessed through a mini-incision, or sleeve that provides a protected passageway to the area. Once access to the surgical site is obtained, a surgical treatment, for example, corpectomy and/or discectomy, can be performed for treating a spine disorder.

Bone screw <NUM> can be connected with a surgical instrument, such as, for example, a driver (not shown) and can be delivered to the surgical site. Bone screw <NUM> can be manipulated including rotation and/or translation for engagement with cortical bone and/or cancellous bone. Receiver <NUM> can be manually engaged with screw shaft <NUM> in a non-instrumented assembly, as described herein. Bone screw <NUM> including base <NUM> having layer <NUM> enhances fixation and/or facilitates bone growth, as described herein. Tissue can become imbedded with layer <NUM> to promote bone growth, enhance fusion of bone screw <NUM> with vertebral tissue, and/or prevent toggle of bone screw <NUM> components.

In one embodiment, as shown in <FIG>, spinal implant system <NUM>, similar to the systems and methods described herein, includes a bone screw <NUM>, similar to bone screw <NUM> described herein. Bone screw <NUM> comprises a screw shaft <NUM>, as described herein, and a receiver <NUM>. Receiver <NUM> includes a portion that defines an implant cavity <NUM> and a portion that defines a base <NUM>.

Receiver <NUM> includes a body <NUM> having a pair of spaced apart arms <NUM>, <NUM>. Arms <NUM>, <NUM> each extend parallel to an axis X2. Arms <NUM>, <NUM> define implant cavity <NUM> therebetween, similar to cavity <NUM> described herein. Arms <NUM>, <NUM> include an even, uninterrupted surface and an even, solid surface relative to the surface of base <NUM>, as described herein, which provides a variable configuration bone screw <NUM>.

<FIG> shows a cross section view of base <NUM> of <FIG>. Base <NUM> includes a wall <NUM> having a surface <NUM> that defines a cavity <NUM>. Cavity <NUM> is configured for disposal of head <NUM> of screw shaft <NUM>, as described herein. In some embodiments, base <NUM> is manufactured by additive manufacturing, as described herein, and mechanically attached to body <NUM> by, for example, welding, threading, adhesives and/or staking.

Base <NUM> includes a non-solid configuration, such as, for example, a lattice <NUM>. In various embodiments, the non-solid configuration provides one or a plurality of pathways to facilitate bone through growth within, and in some embodiments all of the way through, from one surface to an opposite surface of bone screw <NUM>. In some embodiments, lattice <NUM> may include one or more portions, layers and/or substrates. In some embodiments, one or more portions, layers and/or substrates of lattice <NUM> may be disposed side by side, offset, staggered, stepped, tapered, end to end, spaced apart, in series and/or in parallel. In some embodiments, lattice <NUM> defines a thickness, which may be uniform, undulating, tapered, increasing, decreasing, variable, offset, stepped, arcuate, angled and/or staggered. In some embodiments, one or more layers of lattice <NUM> are disposed in a side by side, parallel orientation. Lattice <NUM> includes one or more layers of a matrix of material, such as, for example, a latticework <NUM>.

Latticework <NUM> includes a plurality of nodes <NUM> and openings <NUM>, which can be disposed in rows and columns, and/or in a random configuration. In some embodiments, nodes <NUM> and openings <NUM> are disposed in a series orientation. In some embodiments, nodes <NUM> and openings <NUM> are disposed in a parallel orientation. In some embodiments, lattice <NUM> may form a rasp-like configuration. In some embodiments, lattice <NUM> is configured to engage tissue, such as, for example, cortical bone and/or cancellous bone, such as, to cut, shave, shear, incise and/or disrupt such tissue. In some embodiments, all or a portion of lattice <NUM> may have various configurations, such as, for example, cylindrical, round, oval, oblong, triangular, polygonal having planar or arcuate side portions, irregular, uniform, non-uniform, consistent, variable, horseshoe shape, U-shape or kidney bean shape.

Bone screw <NUM> including base <NUM> having lattice <NUM> enhances fixation and/or facilitates bone growth, as described herein. In some embodiments, lattice <NUM> forms a tunnel configured to guide, drive and/or direct the tissue into openings <NUM> to facilitate fusion of bone screw <NUM> with tissue, such as, for example, vertebrae. Tissue can become imbedded into openings <NUM> to promote bone growth to enhance fusion of bone screw <NUM> with vertebral tissue.

As shown in <FIG>, spinal implant system <NUM>, similar to the systems and methods described herein, includes a bone screw <NUM>, similar to bone screw <NUM> described herein. Bone screw <NUM> comprises a screw shaft <NUM>, similar to screw shaft <NUM> described herein. Screw shaft <NUM> includes a base ring <NUM>. Base ring <NUM> can be configured and arranged to be engageable with a receiver, such as implant receiver <NUM>, in use of a resulting bone screw assembly.

Base ring <NUM> includes a non-solid configuration, similar to that described herein, for example, a lattice <NUM>, similar to lattice <NUM> described herein. Base ring <NUM> can be configured for attachment with head <NUM>. Base ring <NUM> can be fabricated on head <NUM> by an additive manufacturing process, a traditional manufacturing process - e.g., a subtractive manufacturing process - or a combination of additive and traditional manufacturing, as described herein.

Any of a wide variety of traditional processes, such as but not limited to any of various types of acid etching processes, and any of various types of shot-peening processes, can be implemented for achieving the functions and implant qualities of the present technology described herein.

Base ring <NUM> includes a wall <NUM> having a surface <NUM> that defines a cavity <NUM>. Cavity <NUM> is configured for disposal of head <NUM>. Base ring <NUM> is connectable with a receiver, for example, receiver <NUM> described herein. Bone screw <NUM> including base ring <NUM> having lattice <NUM> enhances fixation and/or facilitates bone growth, as described herein.

The base ring <NUM> has any of a wide variety is shapes. Surface <NUM> may be rough, arcuate, undulating, mesh, porous, semi-porous, dimpled and/or textured, for instance. Wall <NUM> in some embodiments forms one or more channels, grooves, or other change of surface elevation, as shown in <FIG>. Wall configuration can be selected to promote performance of the bone screw <NUM>, such as by promoting bone growth at, into, or through base ring <NUM>.

Base ring <NUM> may be configured to extend entirely around the screw shaft - e.g., around the head <NUM> - or by any amount only part way around the shaft.

Claim 1:
A spinal bone screw (<NUM>) comprising:
a shaft (<NUM>) including a head (<NUM>) and at least one thread having an external thread form; and
an implant receiver (<NUM>) including a first portion and a second portion, the first portion having a solid configuration relative to the second portion, wherein the implant receiver (<NUM>) includes a body (<NUM>) having a pair of spaced apart arms (<NUM>, <NUM>) that define an implant cavity (<NUM>) therebetween, and a base (<NUM>) connected to the body, wherein the base (<NUM>) has a wall (<NUM>), wherein the first portion includes the body (<NUM>) and the wall (<NUM>) of the base (<NUM>);
wherein the wall (<NUM>) of the base (<NUM>) includes an inner surface (<NUM>) that defines a cavity (<NUM>) configured for disposal of the head (<NUM>) of the shaft (<NUM>), and an outer surface (<NUM>),
wherein the second portion includes a layer (<NUM>) applied onto the outer surface (<NUM>) of the wall (<NUM>),
wherein the wall (<NUM>) includes an even, uninterrupted configuration and includes an even, solid surface relative to the surface of the layer (<NUM>), wherein the shaft (<NUM>) includes an even, solid surface relative to the surface of the layer (<NUM>); and
wherein the layer (<NUM>) includes a non-solid configuration such as a porous structure and/or a trabecular configuration.