Patent Description:
Surgical screw-based rod instrumentation in specialty surgery, i.e. pedicle screws, are surgically implanted medical devices that include, but are not limited to, a specialized screw commonly used in spine surgery for the stabilization of spinal sections. This intervention is commonly performed to produce spinal stability for neuronal function preservation, pain relief, deformity correction, etc. In conventional spinal instrumentation, the screw and rod construction is composed of multiple components which generally includes a screw head, a closure cap, a screw shaft, and a spinal rod which is used to connect two or more screws together in a segmental or non-segmental series.

The metal alloy composition of the spinal rod is usually stainless steel, titanium, cobalt chromium or other, though other compounds with less rigid composition have also been developed. Internal anatomy and pathophysiology differs widely and no two individuals requiring surgery have uniform spinal alignment. Additionally, intentional correction of undesired spinal alignment requires the development of a personalized rod structure. Additional surgery, during which connection of a construct with a previously implanted construct, requires real-time adjustments of implanted metal. Lastly, there are also changing variables to rod alignment based on the surgical technique and comfort level of the operating surgeon.

As such, during surgery the spinal rod must be adjusted and bent from predetermined shape of straight or nearly straight to form the appropriate curvature for engaging the already placed screw constructs, i.e. pedicle screw, that also corresponds with the larger alignment of concavity and convexity desired for the spinal column. This process requires a traditional manual manipulation of the rod or repositioning of implanted screws. This is labor intensive, and bending the spinal rod can be mentally difficult. Attempting to recapitulate the three dimensional contour required for implantation is done in a separated environment (over the patient or on the back table). This is labor intensive and it can also significantly increase surgery times. This process requires a great degree of trial-and-error until the curvature of the spinal rod is matched the internal or desired internal alignment. Of note, a similar process can be required in a number of additional surgical specialties, as this specifically speaks to spinal fixation.

The present invention relates generally to spinal fixation devices for the internal fixation of the spine, particularly within the fields of neurosurgery, orthopedics, and other fields associated with spinal alignment procedures and spinal implants that include pedicle screws, lateral mass screws, anterior, lateral, oblique spinal screws, occipital, sacral and pelvic fixation and spinal rods for fixing, correcting and retaining vertebral bones relative to one another.

Various embodiments are disclosed for forming spinal rod members for use in pedicle screws; lateral mass screws; trans-articular screws; cortical screws; laminar screws; facet screws; anterior, lateral and oblique screws; occipital, sacral and pelvic fixation screws (from now on generally referred to as a "pedicle screw") for spinal instrumentation and fixation surgery and systems. A particular pedicle screw system can include a pedicle screw having a pedicle screw head and a pedicle screw shaft, the pedicle screw head being configured to receive and retain a spinal rod member relative to the pedicle screw. The spinal rod member can include a predetermined rigid rod configuration, an elongated tubular membrane having a flexible body and a spinal rod body formed of a compound, where the spinal rod body is formed by insertion of a liquid compound into the elongated tubular membrane and a hardening of the liquid compound. The pedicle screw head can include a channel or an aperture configured to receive and retain the spinal rod member relative to the pedicle screw and relative to bone.

Further, but not claimed, a method can include attaching a first pedicle screw to a first vertebrae of a spine and attaching a second pedicle screw to a second vertebrae of the spine, where the first pedicle screw and the second pedicle screw each include a pedicle screw head and a pedicle screw shaft. The pedicle screw head can be configured to retain a spinal rod member relative to the first pedicle screw and the second pedicle screw. Further, the method can include forming the spinal rod member by positioning a flexible and elongated tubular membrane that will maintain a competent inner channel into the pedicle screw head of the first pedicle screw and the second pedicle screw, inserting a liquid compound into the elongated tubular membrane, hardening the liquid compound to form a hardened spinal rod member body. Additional embodiments can include forming the spinal rod member by positioning a multi-segmented flexible and elongated rod to the pedicle screw head of the first pedicle screw and the second screw that after capturing the rod within the pedicle screw head will then made rigid by a collapsing of the segments to a rigid construct. Additional embodiments would include yet to be developed easily influenced liquids, semi-solid or solid compounds that can be converted into a rigid state in a fashion that can be implanted for the purposes of spinal instrumentation and fixation.

The present invention is defined in claim <NUM> and claim <NUM> while preferred embodiments are set forth in the dependent claims. The present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, with emphasis instead being placed upon clearly illustrating the principles of the disclosure.

The present disclosure relates to a pedicle screw spinal rod placement system that includes a temporarily flexible member and a method of fabricating the same. A pedicle screw as outlined in this disclosure represents a number of screw fixation techniques utilized in the fixation and stabilization of the spinal columns and includes open, percutaneous, minimally invasive and other surgical techniques. Other similar screw types used for stabilization that are also represented within the identification of "pedicle screw" include, but are not limited to, lateral mass screw; trans-articular screw; cortical screw; laminar screw; facet screw; anterior, lateral and oblique screw; and occipital, sacral and pelvic fixation, though the specifics of screw differentiation will not be discussed here.

As noted above, pedicle screws are medically implanted surgical devices that include a specialized screw commonly used in surgery for the stabilization of spinal sections to create spinal stability, correct pathologic spinal alignment, achieve preservation or improvement of neuronal or other medically dependent function, and/or to relieve or alleviate pain. In conventional screw fixation, the screw is composed of multiple basic components generally including, but not limited to, a screw head which can be in a fixed orientation to polyaxial in nature, a closure cap or entrapment construct to house the spinal rod construct, a shaft with a variety in pitch for thread development, and a spinal rod which is used to connect two or more screws together in a non-segmental or segmental series. The spinal rod characteristics typically represent an elongated rod implant that is cylinder in shape and can be of various lengths, though other embodiments include a less circular shape, plating type system or other type devices used to connect vertebral segments. The spinal rod is usually composed of a type of stainless steel, including but not limited to, titanium or cobalt chromium, though additional less or more rigid rod composition is sometimes employed.

Historically, certain systems used for spinal fixation have been referred to as a Harrington rod. As such, during surgery the spinal rod must be adjusted and bent from a predetermined shape of straight or nearly straight to form the appropriate curvature for engaging the already placed screw constructs, i.e. pedicle screw, that also corresponds with the larger alignment of concavity and convexity desired of the spinal column. This alignment can be determined to maintain a currently determined alignment based on a patient's pathophysiology or to correct the alignment with subsequent fixation for healing to achieve a desired radiographic and clinical outcome.

The process of spinal rod adjustment traditionally requires a manual manipulation of the rod or repositioning of implanted screws. Manually adjusting and bending of the spinal rod can be mentally difficult to recapitulate the three-dimensional contour required for internal implantation, as this process of manual bending traditionally is completed in a separate environment (over the patient or on the back table) and is labor intensive. In situ spinal rod bending is also difficult and potentially hazardous as large amounts of force are required with instruments that can be difficult to get into the surgical site. Spinal rod bending can significantly increase surgery times. This process requires a great degree of trial-and-error until the curvature of the spinal rod can match the implanted and desired internal anatomy. In addition, a similar process of trial-and-error can be required in a number of other surgical procedures for implantation of a rigid construct to allow for correction and stabilization of physiologic structures though this document specifically speaks to spinal fixation.

Accordingly, various embodiments are disclosed regarding the forming of spinal rod members for use in pedicle screw systems during spinal fixation surgery. In addition, various embodiments are disclosed regarding the systems that require improved techniques for adjusting and do not require manual bending of stainless steel metal spinal rods or other members. A system can include a pedicle screw having a pedicle screw head and a pedicle screw shaft, where the pedicle screw head is configured to receive and retain a spinal rod member relative to the pedicle screw. The spinal rod member can include an elongated tubular membrane having a flexible body and a spinal rod body formed of a single element or compound, including but not limited to a derivative of a plastic compound, primary element, metal alloy, other compound or other, where the spinal rod body is formed by insertion of a liquid compound into the elongated tubular membrane and a hardening of the liquid compound.

The hardening process of the liquid compound can comprise a number of potential methods. Methods can include, but are not necessarily limited to, waiting a predetermined amount of time, an application of an additional agent that invokes a chemical reaction to harden the liquid compound, photo or electrical curation, a multistep process of hardening, metal alloy selection that has intrinsic properties for hardening, use of other element or compound that has innate or adjustable properties that can be manipulated or adjusted in a controlled fashion to convert from a first state that can easily be maneuvered to a more rigid state, temperature curing methods, a combination thereof, or other currently established or future developed procedures for conversion of a malleable/flexible rod to a rigid structure whether this process is completed within the surgical wound or outside the surgical wound for implantation. The tensile and fatigue strength of the spinal rod can be variable and can depend on the desired rigidity of the rod based on previous surgery, the surgical expectations by the surgical team and long-term goals of the construct. The pedicle screw head can include a channel configured to receive and retain the spinal rod member, as can be appreciated.

Further, but not claimed, a method can include attaching a first pedicle screw to a first vertebrae of a spine and attaching a second pedicle screw to a second vertebrae of the spine, where the first pedicle screw and the second pedicle screw each include a pedicle screw head and a pedicle screw shaft that can be cannulated, pores or not. The rigid or polyaxial pedicle screw head can be configured to retain a spinal rod member relative to the first pedicle screw and the second pedicle screw. Further, the method can include forming the spinal rod member by positioning a flexible and elongated tubular membrane into the pedicle screw head of the first pedicle screw and the second pedicle screw, inserting a liquid compound into the elongated tubular membrane, hardening the liquid compound to form a hardened spinal rod member body. Additional embodiments can include forming the spinal rod member by positioning a multi-segmented flexible and elongated rod to the pedicle screw head of the first pedicle screw and the second screw that after capturing the rod within the pedicle screw head will then be made rigid by a collapsing of the segments to a rigid construct. Additional embodiments can further include yet to be developed easily influenced liquids, semi-solid, or solid compounds that can be converted into a rigid state in a fashion that can be implanted for the purposes of spinal instrumentation and fixation.

Turning now to <FIG>, a non-limiting example of a pedicle screw <NUM> and a spinal rod member <NUM> is shown according to various embodiments. The pedicle screw <NUM> and the spinal rod member <NUM> can be used as a component in a spinal rod type spine fixation system or assembly, as will be appreciated.

More specifically, the pedicle screw <NUM>, similar screw implant, or other similar apparatus can be employed to attach or fix a section of the spinal rod member <NUM> or similar rod construct, plating system, or other similar system relative to a vertebrae or section of vertebra of the spine with or without fixation to the skull base, sacrum and/or pelvis (not shown). More specifically, the pedicle screw <NUM> is configured to be attached to a vertebra in a manner known in the art by skilled surgeons or other medical practitioners, while a pedicle screw head <NUM> of the pedicle screw <NUM> comprises a pedicle screw aperture <NUM> that receives, fixes, retains, and holds a section of the spinal rod member <NUM> therein. It is understood that the vertebra can include vertebra of a mammal, such as a human, dog, cat, horse, or other mammal. In some embodiments, the pedicle screw head <NUM> can be movable and repositioned relative to the pedicle screw <NUM>.

Further, in some embodiments, the pedicle screw head <NUM> includes a coupling element <NUM> that is detachable and can be attached to the pedicle screw head <NUM>, for instance, to capture and retain the spinal rod member <NUM> or similar rod construct, plating system or other to the pedicle screw <NUM>. The pedicle screw head <NUM> can be attached to a pedicle screw shaft <NUM>, which can include threaded elements (i.e., male threaded elements) for insertion into bone, such as vertebrae or other spinal segmental anatomical locations of a spinal column or other suitable bone structure.

As noted above, conventional spinal rod implants or Harrington rods including screws, rods, hooks and connectors are composed of stainless steel or other type of metal or high tensile strength materials. Implant construct testing includes the fatigue strength of the construct over time. As such, during surgery, the spinal rod must be adjusted and bent from a predetermined shape of straight or nearly straight to form the appropriate curvature for engaging the already placed screw constructs (e.g., a pedicle screw) that also corresponds with the larger alignment of concavity and convexity desired of the spinal column.

The alignment can be determined to maintain a desired alignment based on a patient's pathophysiology or to correct the alignment with subsequent fixation for healing to achieve a desired radiographic and clinical outcome. This commonly requires bending of a particular rod in multiple three-dimensional directions for proper implantation. The process of spinal rod adjustment traditionally requires a manual manipulation of the rod or repositioning of implanted screws. Manually adjusting and bending of the spinal rod can be mentally difficult to recapitulate the three-dimensional contour required for internal implantation as this process of manual bending traditionally is completed in a separate environment (over the patient or on a back table in an operating room) and is labor intensive. Spinal rod bending can significantly increase surgery times. This process requires a great degree of trial-and-error until the three-dimensional curvature of the spinal rod can match the implanted and desired internal anatomy. As such, according to various embodiments of the present disclosure, a spinal rod member <NUM> can be formed, for instance, during a surgery on a spinal column or other portion of the body without having to bend stainless steel or other material.

In various embodiments, the spinal rod member <NUM> can include an elongated tubular membrane <NUM> having a flexible body. In some embodiments, the elongated tubular member <NUM> can be formed of plastic, other semi-solid, malleable solid or other suitable material. The flexible body can be used, for instance, to position the elongated tubular membrane <NUM> in the screw head aperture <NUM> (or other receptacles of channels) of one or more screw heads <NUM>. In some embodiments, after the elongated tubular member <NUM> is positioned in the channels <NUM>, the coupling element <NUM> or other functionally similar coupling element can be used to secure the elongated tubular membrane <NUM> to the pedicle screws <NUM>. The elongated tubular membrane <NUM> can include a hollow interior <NUM> in some embodiments. As such, the elongated tubular member <NUM> can be formed of a material that provides some structural resistance when the coupling element <NUM> is attached, such that a body of the spinal rod member <NUM> to be formed includes a substantially uniform or a uniformity that is not statistically and/or functionally significantly different in cross-section across all portions of the spinal rod member <NUM>. The spinal rod member <NUM> can include a substantially straight shape or a curvilinear shape, as shown in <FIG>.

In one embodiment the hollow interior <NUM> of the elongated tubular membrane <NUM> can be filled by insertion of a compound <NUM>, as shown in <FIG>, such as a liquid or semisolid compound, thereby forming a spinal rod body <NUM> when the compound has settled and hardened. The method for hardening can be one of a number of different controlled properties of the initial compound or an activation of the liquid or semi-solid compound by any of a number of external factors. The extent of potential external factors are not limited within this description. Further, as shown in <FIG>, the elongated tubular member <NUM> is shown as being positioned in channels <NUM> of multiple pedicle screws 100a. 100c, where the pedicle screws 100a. 100c include pedicle screw heads 120a. 120c and pedicle screw shafts 140a. 140c, as shown in <FIG>. Referring again to <FIG>, in some embodiments, the compound includes polymethylmethacrylate (PMMA) or other suitable compound. Additional embodiments would include yet to be developed easily influenced liquids, semi-solid, solid compounds, or a combination thereof, that be converted into a rigid state in a fashion that can be implanted for the purposes of spinal instrumentation and fixation.

In another embodiment, the elongated spinal rod body <NUM> can represent a multi-segmented flexible and elongated rod that will be positioned in channels <NUM> of multiple pedicle screws 100a. 100c, where the pedicle screws 100a. 100c include pedicle screw heads 120a. 120c and pedicle screw shafts 140a. After capturing the rod within the pedicle screw head <NUM> with screw cap <NUM>, the multi-segmented flexible rod will be made rigid by a collapsing process of the segments to a rigid construct.

In any spinal construct, the number of pedicle screw <NUM> segments fixed at an individual procedure is only limited by the surgical plan of the specialty surgeon and the anatomy of the patient. All embodiments detailed here can be used for fixation of any number of vertebral segments including fixation to the skull, sacrum and pelvis.

Referring next to <FIG>, a flowchart <NUM> is shown as an example of forming a spinal rod member <NUM> for use with one or more pedicle screws <NUM>. Beginning with step <NUM>, the method (not claimed) can include attaching a first pedicle screw 100a to a first vertebrae of a spine (not shown). Next, in step <NUM>, the method can include attaching a second pedicle screw 100b to a second vertebrae of the spine (not shown). The first pedicle screw 100a and the second pedicle screw 100b can each include a pedicle screw head <NUM> and a pedicle screw shaft <NUM>, as can be appreciated. Further, the pedicle screw head <NUM> of the first pedicle screw 100a and the second pedicle screw 100b can be configured to retain a spinal rod member <NUM> relative to the first pedicle screw 100a and the second pedicle screw 100b. In a similar fashion pedicle screw 100b can be configured to retain a spinal rod member <NUM> relative to a third pedicle screw 100c which will continue to retain a spinal rod member <NUM> relative to pedicle screw 100d.

Next, with respect to steps <NUM> to steps <NUM>, the spinal rod member <NUM> can be formed. For instance, with respect to step <NUM>, a flexible and elongated tubular membrane <NUM> can be positioned into the pedicle screw heads <NUM> of the first pedicle screw 100a and the second pedicle screw 100b (or other pedicle screws <NUM> as needed). Next, in step <NUM>, a compound <NUM>, such as a liquid, semi-solid or flexible solid compound configured to harden over time, can be inserted into the elongated tubular membrane <NUM>. In step <NUM>, the compound <NUM> can be hardened, for instance, to form a hardened spinal rod member body. In step <NUM>, in some embodiments, changes in temperature, light or electricity that aid or achieves the hardening of the compound <NUM> can be applied. In step <NUM>, the tubular membrane <NUM> can be optionally removed, although, in some embodiments, it is understood that the tubular membrane <NUM> can be left intact. Thereafter, the process can proceed to completion.

Disjunctive language such as the phrase "at least one of X, Y, or Z," unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., can be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present.

Claim 1:
A system, comprising:
a spinal rod member (<NUM>); and
a pedicle screw (<NUM>), comprising:
a pedicle screw head (<NUM>);
a pedicle screw shaft (<NUM>) for implanting the pedicle screw (<NUM>) in vertebra of a mammalian body; and
a pedicle screw aperture (<NUM>), the pedicle screw aperture (<NUM>) being configured to receive and retain the spinal rod member (<NUM>) relative to the pedicle screw (<NUM>); and
a coupling element (<NUM>) attachable to the pedicle screw head (<NUM>), the coupling element (<NUM>) being configured to secure the spinal rod member (<NUM>) within the pedicle screw aperture (<NUM>);
wherein the spinal rod member (<NUM>) comprises:
an elongated tubular membrane (<NUM>) having a flexible body, the elongated tubular membrane (<NUM>) being removable from the spinal rod member (<NUM>); and
a spinal rod body (<NUM>) detachable from the elongated tubular membrane (<NUM>) and formed of a hardened compound (<NUM>) having a liquid, semi-solid, or flexible compound hardened into the flexible body and converted into a solid body through a hardening, wherein the elongated tubular membrane (<NUM>) is removable and is configured to be removed from the spinal rod member (<NUM>) after the spinal rod body (<NUM>) is formed and converted into the solid body.