Non-metal spinal screw

Abstract

A medical implant (10) includes: a non-metallic core (26) comprising polyetheretherketone (PEEK); and a non-metallic reinforcing layer (34) coupled to the core. The core is at least partially encapsulated by the reinforcing layer, and the reinforcing layer comprises carbon fiber strands.

Description

Background Technology

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 593,383, filed on October 26, 2023, the entire contents of which are incorporated herein by reference.

[0002] Treatment for spinal conditions such as degenerative disc disease, herniated disc, scoliosis or other curvature abnormalities, and fractures often requires surgery. For example, implants can be used to maintain movement between spinal structures.

[0003] Surgical treatment often involves the use of longitudinal members, such as spinal rods. Spinal rods can be attached to the outside of two or more vertebral members to aid in the treatment of spinal conditions. Spinal rods provide a stable, rigid column that facilitates bone fusion and can redirect stress over a wider area away from the damaged or defective region. Furthermore, the rigidity of the spinal rod can aid in spinal alignment. The spinal rod is secured to the vertebral members using a connector body and spinal screws that fasten it to the vertebral members. Summary of the Invention

[0004] The technology disclosed herein generally relates to the treatment of spinal disorders and the use of medical implants having a non-metallic core and a non-metallic (e.g., woven) reinforcing layer.

[0005] In one aspect, this disclosure provides a medical implant having a nonmetallic core and a nonmetallic reinforcing layer, the nonmetallic core comprising polyetheretherketone (PEEK), the nonmetallic reinforcing layer being coupled to the core. The core is at least partially encapsulated by the reinforcing layer, and the reinforcing layer comprises carbon fiber strands.

[0006] In another aspect, this disclosure provides a method for forming a nonmetallic medical implant. The method includes forming a nonmetallic core comprising polyetheretherketone (PEEK), weaving carbon fiber strands together to form a nonmetallic reinforcing layer, and placing the reinforcing layer on the core. Attached Figure Description

[0007] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate various aspects of the invention and, together with the written description, serve to explain the principles, characteristics, and features of the invention. In the drawings:

[0008] Figure 1 A perspective view of a spinal screw according to some aspects of this disclosure is shown.

[0009] Figure 2 Examples Figure 1 A partial cross-sectional view of the screw.

[0010] Figure 3A This is a schematic diagram of an exemplary fabric according to some aspects of this disclosure.

[0011] Figure 3B This is a top view schematic diagram of an exemplary fabric according to some aspects of this disclosure.

[0012] Figure 3C This is a schematic diagram of a vertical cross-section of a fabric wound around a core according to some aspects of this disclosure.

[0013] Figure 4 This is a schematic diagram of another exemplary fabric according to some aspects of this disclosure.

[0014] Figure 5 This is a schematic diagram illustrating the manufacture of screws according to some aspects of this disclosure. Detailed Implementation

[0015] The following description of the various aspects is merely exemplary in nature and is in no way intended to limit the invention, its application, or its uses. Before explaining any aspect of this disclosure in detail, it should be understood that this disclosure is not limited in its application to the construction details and component arrangements set forth in the following description or illustrated in the drawings. This disclosure can have other aspects and can be practiced or implemented in various ways.

[0016] The various aspects of the system disclosed in this invention are described in detail with reference to the accompanying drawings, in which the same reference numerals denote the same or corresponding elements in each of the several views. In the following description, well-known functions or constructions are not described in detail to avoid obscuring this disclosure with unnecessary detail.

[0017] Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered restrictive. As used herein, the use of “comprise” and “include” and their variations is intended to cover the items listed thereafter and their equivalents, as well as any additional items.

[0018] In spinal surgery, spinal screws are used to attach rods to the vertebrae to align different segments of the spine. Typically, spinal screws are made of metal. In some patients who require spinal screws, such as those with cancer, metal screws may interfere with other treatment procedures. Some patients require spinal screws that are not metal or contain less metal than is typically used in surgery, allowing them to qualify for therapeutic treatments that are only available to patients with non-metallic implants or implants made with a limited amount of metal. The disclosed aspect of spinal screw 10 is formed of carbon fiber reinforced PEEK instead of metal.

[0019] Now for reference Figure 1The image illustrates a perspective view of an exemplary spinal screw 10. The spinal screw 10 is formed from carbon fiber reinforced polyetheretherketone (“CFR-PEEK”) material, a reinforced, robust, medical-grade plastic. The screw 10 is formed using compression molding. The spinal screw 10 includes an elongated body 14 and an end 18. The elongated body 14 has threads 22 extending along the length of the body 14. The end 18 is a head that is at least partially rounded. The screw 10 is depicted as having more than one pitch along the length of the body. In some aspects, the body of the screw 10 may have a constant pitch.

[0020] Now go to Figure 2 This illustration shows an exemplary schematic diagram of a partial cross-section of an elongated body 14 between two threads 22 of a spinal screw 10. The elongated body 14 includes a core 26 encapsulated or surrounded by a reinforcing layer 34. A portion of the reinforcing layer 34 forms the threads 22. The core 26 may be a solid core, or the core may be a hollow core, such as along at least a portion of the longitudinal axis of the core 26 (e.g., along...). Figure 2 The hollow core (centerline of the core). In some aspects, the elongated body 14 may include a reinforcing layer 34 and may not include the core 26.

[0021] Core 26 is formed of polyetheretherketone (PEEK). In some aspects, core 26 can be approximately one-quarter millimeters thick. Reinforcing layer 34 is formed of CFR PEEK. CFR PEEK comprises carbon fibers that have been impregnated or coated with PEEK, for example, in prepreg form, before the PEEK material solidifies. Compared to unreinforced PEEK, CFR PEEK has increased compressive strength and load-bearing capacity. Figure 2 In the illustrated aspect, the reinforcing layer 34 may be a fabric 36 of CFR PEEK that has been wound or laid on the core 26 (see also...). Figures 3A to 4 The fabrics 136, 236, and 336 in the core or the carbon fiber strands 42 already wound around the core (see...) Figure 5 ).exist Figure 2In the illustrated aspects, the reinforcing layer 34 is thicker than the core 26. In some aspects, the reinforcing layer 34 includes a woven layer. If the reinforcing layer 34 includes a woven layer, the fabrics 36, 136, 236, and 336 of the woven layer can be thick fabrics, such that a large portion of the thickness of the body 14 is provided by the fabrics 36, 136, 236, and 336. In some aspects, the reinforcing layer 34 includes more than one woven layer wound or laid on the core 26. The total thickness of the reinforcing layer may depend on the fiber or strand thickness and the number of woven or wound carbon fiber layers used to construct the reinforcing layer 34. In some aspects, after the final layer is wrapped, laid, or wound on the core or formed around the mandrel, compression molding technology is applied to the reinforcing layer 34, including PEEK on the fibers or strands, thereby compressing the PEEK, fibers, and / or strands in a mold to form a spinal screw 10 with threads 22 upon hardening of the PEEK.

[0022] Figures 3A to 3C An example of an enhancement layer 34 that can be used in the main body 14 is shown. Figure 2 Exemplary aspects of fabrics. Figures 3A to 3C The different fabrics 36, 136, and 236 are three-dimensional (3-D) fabrics. Each fabric 36, 136, and 236 includes multiple carbon fiber strands 42A, 42B, and 42C woven together. In some aspects, fabrics 36, 136, and 236 may include approximately 5 to approximately 20 carbon fiber strands woven together. In some aspects, fabrics 36, 136, 236, and 336 may include 14 to 16 carbon fiber strands woven together.

[0023] 3-D fabrics are complex fabrics. Carbon fiber strands 42A, 42B, and 42C can intersect each other in multiple directions and locations. In a 3-D fabric, all carbon fiber strands 42A, 42B, and 42C can intersect each other at a single point. In some aspects, 3-D fabrics can resemble woven fabrics. In other aspects, 3-D fabrics can resemble bamboo or rattan woven fabrics. Compared to nonwoven CFR layers, Figures 3A to 3C The 3-D fabric of any one of the fabrics 36, 136, and 236 increases the strength of the fabric in multiple directions. For example, the strength of fabrics 36, 136, 236, and body 14 can be increased in the longitudinal, transverse, and radial directions. Figures 3A to 3C The 3-D fabrics of the exemplary fabrics 36, 136, and 236 also allow PEEK to move more easily through the carbon fiber strands 42A, 42B, and 42C, and through the thickness of the fabrics 36, 136, and 236.

[0024] like Figure 3CAs shown, in the 3-D weave of fabric 236, carbon fiber strands 42A, 42B, and 42C are woven together such that when fabric 236 is wound around core 26, the carbon fiber strands 42A, 42B, and 42C have varying radial positions throughout the fabric. For example, when fabric 236 is wound around core 26, at some radial positions, carbon fiber strand 42A is adjacent to core 26, and at other radial positions, carbon fiber strand 42A is adjacent to the outer periphery of fabric 236. This increases the strength of fabric 236 in multiple directions.

[0025] Figure 4 Another aspect of fabric 336 is illustrated. Fabric 336 can be referred to as a two-dimensional fabric (2-D). Fabric 336 comprises multiple carbon fiber strands 42A, 42B, 42C, and 42D woven together. Fabric 336 is a simple fabric. In a 2-D fabric, only some carbon fiber strands overlap each other. For example, carbon fiber strand 42A crosses strands 42B and 42C, but not strand 42D. The surface of fabric 36 may have a lattice-like appearance.

[0026] In fabrics 36, 136, 236, and 336, the thickness of the carbon fiber strands can be increased or decreased to control the strength, flexibility, and thickness of the fabrics 36, 136, 236, and 336. Increasing the thickness of the carbon fiber strands increases the amount of pure PEEK in thread 22 and reduces the amount of carbon fiber strands extending into thread 22. Decreasing the thickness of the carbon fiber strands reduces the amount of pure PEEK in thread 22 and increases the amount of carbon fiber strands extending into thread 22.

[0027] Return to reference Figure 2 In some respects, marker 46 can be positioned between core 26 and reinforcing layer 34. Marker 46 allows for easy identification of spinal screw 10 on X-rays (e.g., a visualization component of spinal screw 10). Figure 1 The marker 46 may be a fine thread (e.g., about 0.005 inches in diameter) or a sheet of material that extends the length of the body 14 so that it can be easily identified in X-rays if the spinal screw 10 is bent or broken. The marker 46 may be made of a high-density biocompatible material, such as stainless steel or tantalum. In some aspects, the marker 46 may extend only a portion of the length of the body 14. In some aspects, it is envisioned that the marker material may also, or alternatively, be included as strands in the weave of the reinforcing layer 34. In some aspects, the marker 46 may be arranged as one or more loops around the core of the spinal screw 10.

[0028] The method of forming the body 14 of the spinal screw 10 may begin by forming a core 26. The core 26 can be formed by spraying or adding a thin layer of pure PEEK to a cylindrical mandrel, thereby forming a hollow core cylinder of pure PEEK material. Alternatively, the core 26 can be formed by directly machining the PEEK without using a mandrel. In some embodiments, the hollow core can be formed by core drilling or drilling along the longitudinal axis (e.g., the centerline) of the core 26. A pure PEEK core 26 improves manufacturing efficiency because pure PEEK is a material that is easier to drill than CFR PEEK. Markers 46 can be added to the outer surface of the core 26.

[0029] like Figures 3A to 4 As shown, fabrics 36, 136, 236, and 336 can be formed by weaving carbon fiber strands 42A, 42B, and 42C together. Prepreg carbon fiber strands can be further used to form fabrics 36, 136, 236, and 336. After weaving fabrics 36, 136, 236, and 336, they can be impregnated with PEEK and laid on core 26. In some aspects, prepreg fabrics 36, 136, 236, and 336 are laid on core 26, and a PEEK layer can be coated or spread onto fabrics 36, 136, 236, and 336. In some aspects, a single layer of fabric 36, 136, 236, and 336 is positioned on core 26. In some respects, additional layers of fabric 36, 136, 236, 336 are positioned on the core 26 to increase the strength or thickness of the screw 10. In some respects, (multi) layers of fabric 36, 136, 236, 336 are positioned on the mandrel, and the PEEK core 26 is not used.

[0030] After the fabrics 36, 136, 236, and 336 are placed on the core 26, the core 26 is placed in a mold and compressed to cure the CFR PEEK. Pressure and heat are applied to the mold to cure the CFR PEEK and form the body 14. The mold also forms threads 22. The mold includes threaded sections such that when pressure is applied to the mold, some of the PEEK in the reinforcing layer 34 is pushed out of the carbon reinforcement and into the threaded sections of the mold to form the threads 22. In some respects, most of the threads 22 are formed of PEEK with little or no CFR or with a CFR distribution smaller than that in the reinforcing layer 34. As described above, the ratio of PEEK to CFR in the threads 22 can be adjusted by adjusting the thickness of the individual carbon fiber strands.

[0031] The end 18 of the screw 10 can be formed in a manner similar to that of the body 14. In some respects, the same mandrel used to form the core 26 is used to form the end 18 of the screw 10. In other respects, different mandrels can be used to form the end 18 of the screw 10. Fabrics 36, 136, 236, and 336 can be used to form the end 18. On the other hand, it can be formed by using a winding method (see below). Figure 5 (Detailed description) to form the end portion 18. When forming the end portion 18 of the spinal screw 10, the carbon fibers can be arranged in a manner that increases the circumferential strength of the end portion 18 in order to reduce the chance of the end portion 18 being stripped. For example, in some aspects, the end portion 18 can be formed by arranging the carbon fiber strands parallel to the elongated body 14 and extending upward through the end portion 18 in the same direction along the contour of the end portion 18. Alternatively or additionally, the carbon fiber strands can be arranged around the circumference of the end portion 18.

[0032] Figure 5 An example is shown forming the screw body 14 and the screw tip 18 ( Figure 1 Another method. In Figure 5 In the middle, reinforcement layer 34 ( Figure 2 ) is not made of fabrics 36, 136, 236, 336 ( Figures 3A to 4 Instead of being formed by twisting parallel carbon fiber strands 42 around a PEEK core 26, the carbon fiber strands 42 are wound around the core 26 and then impregnated with PEEK. The carbon fiber strands 42 can be wound around the core 26 in a first direction to form a first layer, and then wound around the core 26 in a second direction to form a second layer. The two layers of carbon fiber strands with two different directions increase the strength of the body 14. In some aspects, the reinforcing layer 34 can be formed by using a first layer of fabric 36, 136, 236, 336, followed by the carbon fiber strands 42 of the wound layer. In some aspects, the reinforcing layer can be formed by using the carbon fiber strands 42 of the wound layer, followed by the second layer of fabric 36, 136, 236, 336.

[0033] Although this disclosure focuses on the manufacture of screws, similar processes can be used to manufacture other medical implants, such as nails.

[0034] Since various modifications can be made to the exemplary aspects described above with reference to the corresponding figures without departing from the scope of the invention, all content contained in the foregoing description and shown in the drawings is intended to be illustrative rather than restrictive. Therefore, the breadth and scope of the invention should not be limited to any of the exemplary aspects described above, but should be defined only by the claims and their equivalents.

[0035] Example 1. A non-metallic medical implant, the non-metallic medical implant comprising:

[0036] A non-metallic core comprising polyetheretherketone; and a non-metallic reinforcing layer coupled to the core, wherein the core is at least partially encapsulated by the reinforcing layer, and wherein the reinforcing layer comprises carbon fiber strands.

[0037] Example 2. The medical implant according to Example 1, wherein the medical implant is a spinal screw, and wherein the reinforcing layer defines the external thread of the spinal screw.

[0038] Example 3. The medical implant according to any one of the foregoing examples, wherein the core is composed only of polyetheretherketone.

[0039] Example 4. The medical implant according to any one of the foregoing embodiments, wherein the reinforcing layer is thicker than the core.

[0040] Example 5. A medical implant according to any one of the foregoing embodiments, wherein the carbon fiber strands extend parallel to each other and are wound around the core.

[0041] Example 6. A medical implant according to any one of Examples 1 to 4, wherein the reinforcing layer comprises a woven layer of the carbon fiber strands.

[0042] Example 7. The medical implant according to Example 6, wherein the carbon fiber strands in the woven layer have been impregnated or covered with polyetheretherketone in the form of a prepreg.

[0043] Example 8. The medical implant according to any of Examples 6 or 7, wherein the woven layer comprises 5 to 20 carbon fiber strands woven together.

[0044] Example 9. A medical implant according to any one of Examples 6 to 8, wherein the carbon fiber strands intersect each other in multiple directions and locations in the woven layer.

[0045] Example 10. A medical implant according to any one of Examples 6 to 9, wherein the carbon fiber strands in the woven layer have varying radial positions throughout the woven layer.

[0046] Example 11. The medical implant according to any one of Examples 6 to 10, wherein the carbon fiber strands are woven together in a three-dimensional weave in the woven layer.

[0047] Example 12. The medical implant according to any one of Examples 6 to 10, wherein the carbon fiber strands are woven together in a two-dimensional weave in the woven layer.

[0048] Example 13. The medical implant according to any one of Examples 6 to 12, wherein the woven layer is a first woven layer, and wherein the reinforcing layer includes a second woven layer.

[0049] Example 14. A medical implant according to any of the preceding embodiments, wherein the thickness of one of the carbon fiber strands is greater in a portion of the reinforcing layer than in another portion of the reinforcing layer.

[0050] Example 15. The medical implant according to any one of the foregoing embodiments, the medical implant further comprising a marker positioned between the core and the reinforcing layer.

[0051] Example 16. A method for forming a non-metallic medical implant, the method comprising: forming a non-metallic core comprising polyetheretherketone; weaving carbon fiber strands together to form a non-metallic reinforcing layer; and placing the reinforcing layer on the core.

[0052] Example 17. The method according to Example 16, wherein the step of forming the non-metallic core includes applying a polyetheretherketone layer onto a cylindrical mandrel to form a hollow core.

[0053] Example 18. The method according to Example 16, wherein the step of forming the non-metallic core includes directly machining the core from polyetheretherketone.

[0054] Example 19. The method according to any one of Examples 16 to 18, wherein the weaving step includes weaving the carbon fiber strands into a first weaving layer and a second weaving layer.

[0055] Example 20. The method according to any one of Examples 16 to 19, wherein the weaving step includes weaving the carbon fiber strands such that the carbon fiber strands cross each other in a plurality of directions and positions.

Claims

1. A non-metallic medical implant, said non-metallic medical implant comprising: A non-metallic core comprising polyetheretherketone; and A non-metallic reinforcing layer is attached to the core, wherein the core is at least partially encapsulated by the reinforcing layer, and wherein the reinforcing layer comprises carbon fiber strands.

2. The medical implant of claim 1, wherein the medical implant is a spinal screw, and wherein the reinforcing layer defines the external threads of the spinal screw.

3. The medical implant according to any one of the preceding claims, wherein the core is composed solely of polyetheretherketone.

4. The medical implant according to any one of the preceding claims, wherein the reinforcing layer is thicker than the core.

5. The medical implant according to any one of the preceding claims, wherein the carbon fiber strands extend parallel to each other and are wound around the core.

6. The medical implant according to any one of claims 1 to 4, wherein the reinforcing layer comprises a woven layer of the carbon fiber strands.

7. The medical implant of claim 6, wherein the carbon fiber strands in the woven layer have been impregnated or coated with polyetheretherketone in the form of a prepreg.

8. The medical implant according to any claim 6 or 7, wherein the woven layer comprises 5 to 20 carbon fiber strands woven together.

9. The medical implant according to any one of claims 6 to 8, wherein the carbon fiber strands intersect each other in a plurality of directions and locations in the woven layer.

10. The medical implant according to any one of claims 6 to 9, wherein the carbon fiber strands in the woven layer have varying radial positions throughout the woven layer.

11. The medical implant according to any one of claims 6 to 10, wherein the carbon fiber strands are woven together in a three-dimensional manner in the woven layer.

12. The medical implant according to any one of claims 6 to 10, wherein the carbon fiber strands are woven together in a two-dimensional weave in the woven layer.

13. The medical implant according to claims 6 to 12, wherein the woven layer is a first woven layer, and wherein the reinforcing layer includes a second woven layer.

14. The medical implant according to any one of the preceding claims, wherein the thickness of one of the carbon fiber strands is greater in a portion of the reinforcing layer than in another portion of the reinforcing layer.

15. The medical implant according to any one of the preceding claims, the medical implant further comprising a marker positioned between the core and the reinforcing layer.

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