FIELD OF INVENTION

The present invention in some embodiments thereof, relates to composite material bone implant devices, for example to spinal devices such as pedicle screw constructs, and/or to manufacturing methods for such devices, and/or to surgical instrumentation and procedures used during implantation and removal of the said composite material bone implants.

BACKGROUND OF THE INVENTION

Spinal fusion is a common surgery for the treatment of various spinal pathologies. During a spinal fusion, two or more vertebrae are fused together in order to eliminate abnormal motion caused by various pathologies (e.g., degenerative disc). Supplementary bone tissue, either from the patient or a donor, is used in conjunction with the patient' natural bone growth processes, to fuse the vertebrae.

Improvements in spinal fusion operations were achieved with the introduction of internal fixation devices, which are used as an adjunct to spinal fusion. The fixation device contributes to the stabilization and immobilization of the treated spinal segment, thereby enhancing fusion and reducing pain. One such device is a construct of pedicle screws and rods: two screws are placed into the pedicles of each treated vertebrae, and rods are used to longitudinally connect the screws, using locking elements.

Pedicle screw systems, with or without fusion, are used, for example, for stabilizing broken vertebrae until healing (fracture union), oncologic cases, and treatment of vertebra abnormal curvatures, such as scoliosis and kyphosis. Also, dynamic stabilization method, using pedicle screw system without spinal fusion, is also performed nowadays.

U.S. Pat. No. 5,683,392 to Richelsoph et al. discloses “A locking mechanism for locking a rod to a bone member. The locking mechanism includes a bone fixation member for attachment to the bone member, the bone fixation member having a spherical portion; an inner housing member having a channel for receiving the rod and having a spherical portion for engaging the spherical portion of the bone fixation member; and an outer housing member for locking the inner housing member to the rod and the spherical portion of the bone fixation member.”

Normally, the pedicle screw-rod constructs are made of metal, such as titanium and stainless steel. Although metallic implants provide numerous advantages, they also have a few drawbacks. Metals obstruct visualization of the implant and surrounding tissue upon using fluoroscopy, CT and MR imaging. It is noted, that about 20%-30% of the patients continue to suffer following surgery with intra-pedicular implants. As the pedicle screws are located in adjacent to the spinal cord and nerves, such imaging means are highly important for follow-up evaluation, including for identifying screws exact location and determining whether the screws are the cause for pain. This problem also exist in cervical surgeries, where, for example, metal plates and screws are used for stabilizing cervical vertebrae with various pathologies (such as degenerative disc, fracture, tumor, stenosis), normally during fusion surgeries. Also, in oncology cases, evaluation of tumor progress may be limited due to artifacts produced by the metallic implants. Furthermore, metallic implants interfere with radiotherapy given to oncological patients. The relatively large electronic mass and the scattering phenomena reduce the radiation effectiveness and necessitate radiation in higher doses, that further provoke side effects on surrounding tissue.

In addition, metal construction normally provides adequate bending and torsion strength, thus reducing problems associated with implant fracture. However, the rigid metal implant, having different elasticity than that of the bone, may contribute to stress shielding phenomena. Furthermore, metals such as stainless steel may cause biocompatibility problems related to corrosion and sensitization reaction (mainly due to allergy to nickel). In addition, a resistance of metals to fatigue loads may be poorer than a resistance of some composite materials to a similar fatigue load.

Non-metal, composite material, spinal bone implants are currently available on the market, for example cage and vertebral body replacement devices made of carbon-polyetheretherketone (PEEK). Lumbar and/or cervical cages are also produced from PEEK, carbon fiber reinforced polymer or carbon.

Metal pedicle screw systems with rods made of polymer material (e.g., PEEK) are also market available. Yet, those devices provide for lower stiffness compared to metal devices and are used in limited indications. In addition, metal pedicle screw systems with rods or plates made of carbon fiber reinforced polymer (e.g., PEEK or PEKEKK) are also available.

Composite material bone implants, made of, for example, carbon fiber-reinforced PEEK, are also used for other bone applications, such as intramedullary nails and bone plates (CarboFix Orthopedics Ltd.).

SUMMARY OF THE INVENTION

Some embodiments of the present invention are exemplified by the following examples. It is noted that features form examples may be combine and some embodiments of the invention. Also some embodiments of the invention include the features of a plurality of examples selected from any combination of the examples herein.

Example 1. A pedicle screw implant construct kit, comprising:

at least one pedicle screw including a head, said screw comprising composite material including reinforcing filaments embedded in a polymer matrix;

at least one unitary collar, said collar comprising composite material including reinforcing filaments embedded in a polymer matrix, said collar including at least one recess defining a cavity shaped and sized for receiving a rod, said collar sized, shaped and configured to be coupled to said head of said pedicle screw;

an elongated rod sized and shaped for connecting said collar to one or more additional collars, thereby coupling between said at least one pedicle screw and one or more additional screws, said rod comprising composite material including reinforcing filaments embedded in a polymer matrix; and

at least one locking ring, said ring comprising composite material including reinforcing filaments embedded in a polymer matrix, said ring sized and shaped to be positioned over at least portion of said collar and restrict relative movement of one or both of the screw head and the rod relative to said collar, by exerting radial compression force onto said collar.

Example 2. A kit according to example 1, wherein said collar and said ring do not have threading at an interface therebetween.

Example 3. A kit according to any of the preceding examples, wherein said kit is less than 1% by weight atoms with an atomic number over 25.

Example 4. A kit according to any of the preceding examples, wherein said kit is less than 0.01% by weight atoms with an atomic number over 25.

Example 5. A kit according to any of the preceding examples, wherein said kit contains no radio-opaque markers.

Example 6. A kit according to any of the preceding examples, wherein said cavity shaped and sized for a receiving a rod has a different cross-section than said rod and/or has no rotationally symmetric offset relative to the rod shape.

Example 7. A kit according to example 6, wherein said cavity shaped and sized for a receiving a rod is elongated in a direction radial to a longitudinal axis thereof.

Example 8. A kit according to example 7, wherein said elongation is over an entire length of said cavity.

Example 9. A kit according to example 7 or example 8, wherein said elongation is different at ends of said cavity from any elongation at a center of said cavity.

Example 10. A kit according to any of examples 7-9, wherein said elongation support the engagement by said cavity of both straight rods and rods bent with a radius of curvature of at least 30 mm.

Example 11. A kit according to any of examples 7-10, wherein said elongation is vertical with respect to said collar.

Example 12. A kit according to any of the preceding examples, wherein said ring is mounted on said collar prior to said ring causing said motion restriction.

Example 13. A kit according to example 12, wherein said ring is mounted in a narrowing in an outer profile of said collar, vertically adjacent to a gradual widening in said outer profile and is configured to lock to said widening by friction.

Example 14. A kit according to example 13, wherein said ring is mounted vertically adjacent an abrupt widening in said outer profile.

Example 15. A kit according to any of examples 12-14, comprising at least two rings, both mounted on said collar without causing said restricting.

Example 16. A kit according to any of examples 12-15, wherein said collar is slotted at both a proximal end and a distal end thereof.

Example 17. A kit according to any of the preceding examples, comprising two locking rings for said collar and wherein said collar includes two regions for locking of said rings to said collar.

Example 18. A kit according to example 17, wherein both said rings are pre-loaded on said collar prior to them causing said restricting.

Example 19. A kit according to example 17 or example 18, wherein said collar includes at least one radial extension which prevents sliding off of at least one ring from said collar.

Example 20. A kit according to any of examples 17-19, wherein at least one ring is narrower away from said collar than adjacent said collar.

Example 21. A kit according to any of examples 17-20, wherein said collar is slotted at both a proximal and at a distal end thereof and each ring is mounted at a vertical position corresponding to a different one of said slots.

Example 22. A kit according to any of examples 17-21, wherein said collar is shaped so that locking one ring only restricts the movement of one of said rod and said head of said screw.

Example 23. A kit according to any of examples 17-22, wherein said collar is shaped so that locking of the two rings requires movement of the two rings in a same direction.

Example 24. A kit according to any of examples 17-22, wherein said collar is shaped so that locking of the two rings requires movement of the two rings in opposite directions.

Example 25. A kit according to any of examples 17-24, wherein said two rings are mounted below said rod.

Example 26. A kit according to any of the preceding examples, wherein said collar is shaped so that a locking ring can be mounted thereon without said restricting and then locked without extending during a mounting state nor during a locking state more than 1 mm below said collar.
Example 27. A kit according to example 26, wherein said collar is shaped so that said ring locks by a distal movement away from said two cavities.
Example 28. A method of tightening a collar on a pedicle screw, comprising:providing a collar having a composite locking ring mounted thereon;adjusting the position and/or orientation relative to the collar of at least one of a rod and a screwhead within the collar;moving said locking ring from one configuration on the collar to another configuration on the collar, thereby causing the collar to radially reduce in size and engage said rod and/or said screwhead.
Example 29. A method of tightening a collar on a pedicle screw, comprising:providing a collar;adjusting the position and/or orientation relative to the collar of at least one of a rod and a screwhead within the collar;moving at least two locking ring relative to said collar to radially reduce a cavity in said collar, thereby engaging said rod and/or said screwhead.
Example 30. A method according to example 29, comprising moving said locking rings in opposite directions along an axis of said collar.
Example 31. A method according to example 29 or example 30, comprising moving said locking rings in same directions along an axis of said collar.
Example 32. A method according to any of examples 29-31, comprising moving said locking rings at a same time.
Example 33. A method according to any of examples 29-32, comprising separately clocking said rod and said screwhead by separately moving said two locking rings.
Example 34. A method of selecting kit components for a spinal fixation procedure, comprising:

determining a desired layout of two rods, including different bending for the two rods, said different bendings including a first bend with a bending radius of between 30 and 60 mm and a second bend with at least a double bending radius; and

selecting a same collar for both rods, independent of said different bendings.

Example 35. A method of providing radiation treatment to a patient, comprising:

determining that said patient needs radiation treatment near or via a spine thereof;selecting an all composite spinal fixation kit which does not interfere with radiation more than aluminum based on said determination;implanting said system; andproviding radiation treatment to the patient.
Example 36. A method according to example 35, comprising removing an existing metal-containing spinal fixation component prior to said selecting and after said determining.
Example 37. A method according to example 35 or example 36, comprising providing said radiation treatment to said patient with no metal adjacent said spine and associated with said kit.
Example 38. A locking collar for use with a rod and a pedicle screw for spinal fixation, comprising:

at least one collar body, said collar comprising composite material including reinforcing filaments embedded in a polymer matrix, said collar including at least one recess defining a cavity shaped and sized for receiving a rod, said collar sized, shaped and configured to be coupled to said head of said pedicle screw; and

at least one locking ring, said ring comprising composite material including reinforcing filaments embedded in a polymer matrix, said ring sized and shaped to be positioned over at least portion of said collar and restrict relative movement of one or both of the screw head and rod relative to said collar by exerting radial compression force onto said collar.

Example 39. A collar according to example 38, having two locking rings for locking at two different vertical locations on said collar, relative to a spine and/or wherein said collar is flexible enough and said cavity shaped to allow said collar to be advanced along a rod bent in a direction and/or amount which does not match said cavity and/or wherein said collar is slotted and is flexible enough to be transversely mounted on a rod suitable for locking in said cavity using said locking ring.
Example 40. A locking collar for use with a rod and a pedicle screw for spinal fixation, comprising:

at least one unitary collar body, said collar comprising composite material including reinforcing filaments embedded in a polymer matrix, said collar including at least one recess defining a cavity shaped and sized for receiving a rod, said collar sized, shaped and configured to be coupled to said head of said pedicle screw; and

at least one locking ring, said ring comprising composite material including reinforcing filaments embedded in a polymer matrix, said ring sized and shaped to be positioned over at least portion of said collar and restrict relative movement of one or both of the screw head and rod relative to said collar by exerting radial compression force onto said collar.

Example 41. A locking collar according to example 40, comprising at least two locking rings.

Example 42. A locking collar according to example 41, wherein said rings are positioned on said collar below said cavity for a rod.

Example 43. A locking collar according to any of examples 40-42, wherein said collar and said ring do not have threading at an interface therebetween.

Example 44. A pedicle screw implant construct kit, comprising:

at least one pedicle screw including a head, said screw comprising composite material including reinforcing filaments embedded in a polymer matrix;

at least one collar, said collar comprising composite material including reinforcing filaments embedded in a polymer matrix, said collar including at least one recess defining a cavity shaped and sized for receiving a rod, said collar sized, shaped and configured to be coupled to said head of said pedicle screw;

an elongated rod sized and shaped for connecting said collar to one or more additional collars, thereby coupling between said at least one pedicle screw and one or more additional screws, said rod comprising composite material including reinforcing filaments embedded in a polymer matrix; and

at least one locking ring, said ring comprising composite material including reinforcing filaments embedded in a polymer matrix, said ring sized and shaped to be positioned over at least portion of said collar and restrict relative movement of one or both of the screw head and the rod relative to said collar, by exerting radial compression force onto said collar.

Example 45. A kit according to example 44, wherein said collar and said ring do not have threading at an interface therebetween and/or wherein said kit is less than 1% by weight atoms with an atomic number over 25 and/or wherein said cavity shaped and sized for a receiving a rod has a different cross-section than said rod and/or has no rotationally symmetric offset relative to the rod shape and/or wherein said ring is mounted on said collar prior to said ring causing said motion restriction and/or wherein the kit comprises two locking rings for said collar and wherein said collar includes two regions for locking of said rings to said collar and/or wherein the kit comprises two locking rings for said collar and wherein said collar includes two regions below said rod for locking of said rings to said collar.
Example 46. A device for tightening two locking rings on a collar, which collar is shaped and sized for holding a spine rod and a pedicle screw, comprising:

(a) at least one arm including at least one ring-engaging portion;

(b) at least one element adapted to engage said collar or a second ring; and

(c) a lever including a handle and coupled to said arm and separately coupled to said element and causing relative movement therebetween.

There is provided in accordance with some embodiments of the invention a pedicle screw implant construct kit, comprising:

at least one pedicle screw including a head, said screw comprising composite material including reinforcing filaments embedded in a polymer matrix;

at least one collar, said collar comprising composite material including reinforcing filaments embedded in a polymer matrix, said collar including at least one recess defining a cavity shaped and sized for receiving a rod, said collar sized, shaped and configured to be coupled to said head of said pedicle screw;

an elongated rod sized and shaped for connecting said collar to one or more additional collars, thereby coupling between said at least one pedicle screw and one or more additional screws, said rod comprising composite material including reinforcing filaments embedded in a polymer matrix; and

at least one locking ring, said ring comprising composite material including reinforcing filaments embedded in a polymer matrix, said ring sized and shaped to be positioned over at least portion of said collar and restrict relative movement of the screw head and rod by exerting radial compression force onto said collar.

In some exemplary embodiments of the invention, said collar comprises at least two portions that are movable towards each other in a direction perpendicular to a long axis of said collar. Optionally or alternatively, said collar comprises an integral cap section designed to encircle a part of said rod which faces away from said screw. Optionally or alternatively, said portions of said collar are separated by a slot extending transversely along at least an axial segment of the collar, and wherein said ring is configured to approximate said collar portions, thereby reducing a width of said slot.

In some exemplary embodiments of the invention, said ring comprises a non-threaded internal wall.

In some exemplary embodiments of the invention, said ring has an internal wall which defines a channel, and wherein said channel decreases in diameter in a distal direction. Optionally, a tapering angle of said internal wall is between 1-5 degrees relative to an axis passing through a center of the ring.

In some exemplary embodiments of the invention, said reinforcing filaments are carbon fibers and wherein said polymer matrix is PEEK.

In some exemplary embodiments of the invention, said collar includes at least one recess that defines a generally spherical cavity for coupling to said screw head and wherein said screw head comprises a spherical or nearly-spherical profile, defining a surface area which contacts between 50% and 95% of the inner surface of said spherical recess, thereby leaving spaces between the walls of the recess and the screw head, even when said collar is closed on said screw head.

In some exemplary embodiments of the invention, said collar includes at least one recess that defines a generally spherical cavity for coupling to said screw head and wherein said screw head comprises a generally-spherical profile, wherein a contact surface between said collar recess and said screw head is defined to lie at least 90% in a band around an equator of said screw head when said screw is vertically aligned in said collar and having an angular range of between 20 and 80 degrees and wherein, within said band said collar recess contacts said screw head over between 75% and 95% of said contact surface.

In some exemplary embodiments of the invention, said kit further comprises an embracing structure configured to be positioned over said screw head, said embracing structure comprising at least one adapter, said at least one adapter defining a recess for said screw head, and wherein said locking ring acts as an external housing holding said collar on top of said at least one adapter upon implanting of said collar. Optionally, said at least one adapter comprises a plurality of adaptors that are positionable and cooperate to define a cylindrical or conical external profile.

In some exemplary embodiments of the invention, a distal portion of said collar comprises a second cavity configured to receive at least a portion of said screw head.

In some exemplary embodiments of the invention, a radiolucency level of the reinforced composite material used in all of said kit is high enough to support imaging the treated spine segment in the presence of said construct.

In some exemplary embodiments of the invention, the components have a low enough metal composition to allow imaging with CT or MRI within between 1.5 and 2.5 mm distant from said construct.

In some exemplary embodiments of the invention, the components have a low enough metal composition to not substantially interfere with visualization under CT or MRI imaging.

In some exemplary embodiments of the invention, at least one of said pedicle screw, collar, rod and ring comprise one or more radiopaque markers to enable visualization under imaging.

In some exemplary embodiments of the invention, said radiopaque markers are located along at least one of a long axis of said pedicle screw and a long axis of said rod.

In some exemplary embodiments of the invention, said radiopaque marker is in the form of powder incorporated within said composite material of one or more of said pedicle screw, collar, rod and ring, said powder occupying a content volume of 0.2%-2%. Optionally, said powder comprises gold.

In some exemplary embodiments of the invention, said rod comprises a marker in the form of a tantalum wire extending lengthwise along said rod, wherein said collar comprises a marker in the form of a tantalum pin positioned in a proximal portion of said collar, wherein the ring comprises a tantalum wire marker in the form of a non-closed ring; and wherein said pedicle screw comprises a marker in the form of metal powder embedded within at least a portion of said composite material of said pedicle screw.

In some exemplary embodiments of the invention, an external profile of said ring comprises a portion of larger diameter and a portion of smaller diameter.

In some exemplary embodiments of the invention, an external profile of said ring does not axially vary. Alternatively, said external profile comprises one or more of a generally cylindrical profile, a tapering profile, a conical profile and a stepped profile with at least one abrupt change in diameter.

In some exemplary embodiments of the invention, an external profile of said ring comprises at least one radially directed projection or recess sized for engaging of a tool thereby.

In some exemplary embodiments of the invention, an external profile of said ring comprises a portion of axial extent of at least 50% of a length of said ring which is cylindrical in profile.

In some exemplary embodiments of the invention, an external profile of said collar at a distal portion of said collar includes section which tapers in a distal direction following and due to positioning of said ring at said locking position over said collar.

In some exemplary embodiments of the invention, at least a portion of said pedicle screw is coated by a metal layer having a thickness between 1 μm-100 μm, wherein said metal layer does not substantially interfere with visualization of said screw under CT or MRI imaging.

In some exemplary embodiments of the invention, at least 50% of said reinforcing fibers of said pedicle screw are elongated fibers extending substantially in parallel to a longitudinal axis of said screw.

In some exemplary embodiments of the invention, said reinforced composite material of at least one of the collar, screw head and rod is elastic enough to slightly deform to at least partially fill spaces between said components when said radial compression force is applied by said ring.

In some exemplary embodiments of the invention, said cavity sized and shaped for receiving a rod comprises one of (a) an inner cylindrical profile and (b) an inner curved profile.

In some exemplary embodiments of the invention, said cavity sized and shaped for receiving a rod comprises an insert which modifies a geometry of inner walls of said recess defining said cavity.

There is provided in accordance with some embodiments of the invention a collar sized and shaped for coupling between a rod and a pedicle screw or one or more adapters of the screw, comprising:

a distal end comprising a geometry shaped to engage at least one of (a) a head of said pedicle screw and (b) one or more adapters, if any, mounted on said head of said pedicle screw;

a proximal end;

a portion adjacent said proximal end, said portion defines a cavity shaped and sized to receive at least a portion of a rod, wherein a collar wall defining said cavity extends over at least 60% of a top semicircular arc of a cross section of a rod positioned within said cavity. Optionally, walls of said cavity encircle at least 70% of a circumference of a rod received within said cavity. Optionally or alternatively, said geometry of said distal end of said collar defines a second cavity, shaped and sized to receive at least a portion of said pedicle screw. Optionally or alternatively, said collar comprises a slot separating a distal portion of said collar into at least two sub portions. Optionally, said collar wall defining said cavity extending over said top semicircular arc of the rod is arc shaped, and acts as a bridging load transferring element between first and second sub portions of said collar separated from each other by said slot. Optionally, said collar comprises reinforcing fibers arranged in an upside down U-shape complying with a contour of said collar wall.

In some exemplary embodiments of the invention, a distal portion of said collar comprises one or more slots extending from said distal end of said collar in the proximal direction to allow the collar to compressively fit over a head of a screw.

There is provided in accordance with some embodiments of the invention a method of coupling a composite material pedicle screw to a rod using a collar and a locking ring, comprising:

passing said rod through a first cavity of said collar;

positioning a second cavity of said collar over a head of said screw;

radially compressing at least a portion of said collar to fasten said collar to at least one of said rod and screw, such that at least 5% of the composite material of at least one of said screw head and collar enters recesses between said screw head and walls of said second cavity.

There is provided in accordance with some embodiments of the invention a method of assembling a pedicle screw construct, comprising:

implanting at least one pedicle screw onto which a locking ring is slideably mounted in a pedicle of a vertebra, said ring extending beyond said screw head to receive a collar;

positioning at least one collar over a rod, outside the body;

implanting the rod and collar assembly by positioning said collar above a head of said screw, while said ring acts as an external housing to couple between the screw head and the collar; and

fastening said collar over said rod and screw head by elevating said ring to an axial location in which the ring exerts radial compression onto the collar to restrain movement of said screw head and rod relative to each other. Optionally, the method comprises positioning said locking ring at a selected orientation relative to a longitudinal axis of said pedicle screw prior to implanting said rod and collar assembly. Optionally or alternatively, said screw head is embraced by one or more adapters which define a recess for said screw head, and wherein said collar is positioned over a proximal surface of said adapters while said ring acts as external housing holding said collar to said adapters. Optionally or alternatively, elevating said locking ring approximates at least two collar portions that are separated from each other towards each other, said portions defining a cavity for said rod such that said approximating presses said portions against said rod to restrain at least one of axial and rotational movement of said rod in said cavity. Optionally or alternatively, elevating of said locking ring exerts a first force on said collar which approximates lower collar portions and induces a second force which presses said collar against said rod.

There is provided in accordance with some embodiments of the invention a method for reshaping a composite material rod of a pedicle screw construct, comprising:

heating at least a portion of said composite material rod;

applying a force onto the heated portion of said rod to bend said portion relative to a longitudinal axis of the pre-deformed rod, while a cross sectional diameter of said rod portion at a direction substantially perpendicular to a post-deformation longitudinal axis of said rod changes less than 5% relative to a diameter of said rod before deformation.

There is provided in accordance with some embodiments of the invention a device for driving a pedicle screw into a vertebra and for engaging a locking ring positioned over the screw, comprising:

a shaft comprising:

a distal end comprising a recess shaped to receive a head of the pedicle screw while the locking ring is elevated over at least a portion of the screw;

a proximal end engageable or integrally attached to a handle for handling by a physician, said handle configured for firmly connecting said pedicle screw to said device and for rotating said shaft to rotate said distal end for screwing the screw into the pedicle;

an extension extending in a distal direction from said distal end of said shaft, said extension comprising a radially inward protrusion at its distal end, said protrusion shaped and sized to engage a portion of said ring and retract the ring by proximal pulling of said extension. Optionally, said shaft comprises an internal rod axially movable within said shaft, said rod comprising a distal end configured to be pushed in between a set of adapters which embrace the screw head to couple said device to said embraced screw.

There is provided in accordance with some embodiments of the invention a method of restraining relative movement of components of a pedicle screw construct, comprising:

coupling a rod and a pedicle screw using a collar;

radially compressing the collar to restrain movement of said rod relative to said pedicle screw. Optionally, said radially compressing comprises elevating a locking ring over said collar.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

