阅读说明：本技术 脊柱植入物及其使用方法 (Spinal implant and method of use ) 是由 W·A·雷扎切 J·M·梅 R·R·巴拉德 于 2019-10-17 设计创作，主要内容包括：一种外科联接构件,其包括轴,所述轴限定轴线并且包括具有外螺纹形式的至少一个螺纹。所述外螺纹形式具有前侧翼和后侧翼。所述外螺纹形式限定螺距和螺顶,所述螺顶具有在所述外螺纹形式的所述螺距的约35％至约50％的范围内的宽度,其中,所述前侧翼和所述后侧翼相对于所述螺纹轴线在近侧取向上成一定角度,并且其中所述外螺纹形式被配置成与植入物接收器的内螺纹形式互锁。公开了系统、脊柱构建物、植入物和使用方法。(A surgical coupling member includes a shaft defining an axis and including at least one thread in the form of an external thread. The external thread form has a front flank and a rear flank. The external thread form defines a pitch and a crest having a width in a range of about 35% to about 50% of the pitch of the external thread form, wherein the anterior flank and the posterior flank are angled in a proximal orientation relative to the thread axis, and wherein the external thread form is configured to interlock with an internal thread form of an implant receiver. Systems, spinal constructs, implants, and methods of use are disclosed.)

1. A coupling member, comprising:

a shaft defining an axis and including at least one thread having an external thread form with a front flank and a rear flank, the external thread form defining a pitch and a crest having a width in a range of about 35% to about 50% of the pitch of the external thread form,

wherein the front and rear flanks are angled in a proximal orientation relative to the thread axis, and

wherein the external thread form is configured to interlock with an internal thread form of an implant receiver.

2. The coupling member of claim 1, wherein the front flank is disposed at a first angle relative to a lateral axis of the at least one thread and the rear flank is disposed at a second angle relative to the lateral axis, the first angle being greater than the second angle.

3. The coupling member of claim 2, wherein the first angle is greater than the second angle in a range of about 5 degrees to about 20 degrees.

4. The coupling member of claim 2, wherein the first angle is about 20 degrees greater than the second angle.

5. The coupling member of claim 2, wherein the first angle is about 15 degrees relative to the transverse axis and the second angle is about-5 degrees relative to the transverse axis.

6. A coupling member according to claim 1, wherein said width is about 45% of said pitch of said external thread form.

7. The coupling member of claim 1, wherein the external thread form includes a crest surface disposed in a generally parallel orientation relative to the thread axis.

8. The coupling member of claim 1, wherein the external thread form includes a thread top surface having a substantially planar configuration.

9. The coupling member of claim 1, wherein the at least one thread comprises a plurality of threads disposed along the shaft.

10. The coupling member of claim 1, wherein the implant receiver includes at least one thread in the form of the internal thread, the at least one thread including at least one rounded corner.

11. The coupling member of claim 1, wherein the thread of the implant receiver includes a crest having a width in a range of about 35% to about 50% of a pitch of the internal thread form.

12. A coupling member according to claim 1, wherein the implant receiver includes spaced apart walls, each wall including a thread in the form of the internal thread, each thread including a pair of rounded corners.

13. A spinal implant, comprising:

an implant receiver including at least one thread defining an internal thread form having at least one rounded corner; and

a coupling member including at least one thread defining a thread axis, and an external thread form having a front flank and a rear flank, the front flank and the rear flank being angled in a proximal orientation relative to the thread axis, the external thread form defining a crest having a width in a range of about 35% to 50% of a pitch of the external thread form,

the front flank is disposed at a first angle relative to a lateral axis of the at least one thread and the rear flank is disposed at a second angle relative to the lateral axis, the first angle being greater than the second angle,

the external thread form is configured to interlock with the internal thread form.

14. A spinal implant as recited in claim 13, wherein the implant receiver includes spaced apart walls, each wall including a thread in the form of the internal thread, each thread including a pair of rounded corners.

15. A spinal implant as recited in claim 13, wherein the first angle is about 20 degrees greater than the second angle.

16. A spinal implant as recited in claim 13, wherein the first angle is about 15 degrees relative to the lateral axis and the second angle is about-5 degrees relative to the lateral axis.

17. A spinal implant as recited in claim 13, wherein the width is about 45% of the pitch of the external thread form.

18. A spinal implant system, comprising:

at least one bone screw comprising an implant receiver and a tissue penetrating shaft, the implant receiver comprising at least one thread defining an internal thread form having at least one rounded corner;

a set screw comprising at least one thread defining a thread axis, and an external thread form having a front flank and a rear flank, the front and rear flanks being angled in a proximal orientation relative to the thread axis, the external thread form defining a crest having a width in the range of about 35% to 50% of a pitch of the external thread form, the front flank being disposed at a first angle relative to a transverse axis of the at least one thread, the rear flank being disposed at a second angle relative to the transverse axis, the first angle being greater than the second angle,

the external thread form is configured to interlock with the internal thread form; and

a spinal rod configured to be disposed with the implant receiver and to engage the set screw.

19. The spinal implant system of claim 18, wherein the first angle is about 20 degrees greater than the second angle.

20. A spinal implant as recited in claim 18, wherein the width is about 45% of the pitch of the external thread form.

Technical Field

The present disclosure relates generally to medical devices for treating spinal disorders, and more particularly to spinal implant systems including bone fasteners and methods for treating the spine.

Background

Spinal pathologies and disorders such as scoliosis, kyphosis and other curvature abnormalities, degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, tumors, and fractures may result from factors such as trauma, disease, and degenerative conditions resulting from injury and aging. Spinal disorders often result in symptoms that include deformity, pain, nerve damage, and loss of partial or complete mobility.

Non-surgical treatments, such as drug therapy, rehabilitation, and exercise, may be effective, however, symptoms associated with these conditions may not be alleviated. Surgical treatment of these spinal disorders includes correction, fusion, fixation, discectomy, laminectomy, and implantable prosthesis. As part of these surgical treatments, implants such as bone fasteners, plates, connectors, and vertebral rods are commonly used to provide stability to the treated area. These implants can redirect stresses away from a damaged or defective area while healing occurs to restore concentricity and generally support vertebral members. For example, the plates, connectors, and/or rods may be attached to the exterior of one or more vertebral members via fasteners. The present disclosure describes improvements over these prior art techniques.

Disclosure of Invention

In one embodiment, a surgical coupling member is provided. The coupling member includes a shaft defining an axis and including at least one thread in the form of an external thread. The external thread form has a front flank and a rear flank. The external thread form defines a pitch and a crest having a width in a range of about 35% to about 50% of the pitch of the external thread form, wherein the anterior flank and the posterior flank are angled in a proximal orientation relative to the thread axis, and wherein the external thread form is configured to interlock with the internal thread form of the implant receiver. The external thread form defines a crest having a width in the range of about 35% to 50% of the pitch of the external thread form. The front and rear flanks are angled in a proximal orientation relative to the thread axis. The external thread form is configured to interlock with the internal thread form of the implant receiver. In some embodiments, systems, spinal constructs, implants, and methods are disclosed.

In one embodiment, a spinal implant is provided. The spinal implant includes an implant receiver having at least one thread defining an internal thread form having at least one rounded corner. The coupling member includes at least one thread defining a thread axis, and an external thread form having a front flank and a rear flank. The front and rear flanks are angled in a proximal orientation relative to the thread axis, the external thread form defining a crest having a width in a range of about 35% to 50% of a pitch of the external thread form. The front flank is disposed at a first angle relative to a lateral axis of the at least one thread and the rear flank is disposed at a second angle relative to the lateral axis. The first angle is greater than the second angle. The external thread form is configured to interlock with the internal thread form.

In one embodiment, a spinal implant system is provided. The spinal implant system includes at least one bone screw having an implant receiver and a tissue penetrating shaft. The implant receiver includes at least one thread defining an internal thread form having at least one rounded corner. The set screw includes at least one thread defining a thread axis and an external thread form having a front flank and a rear flank. The front and rear flanks are angled in a proximal orientation relative to the thread axis. The external thread form defines a crest having a width in the range of about 35% to 50% of the pitch of the external thread form. The front flank is disposed at a first angle relative to a lateral axis of the at least one thread and the rear flank is disposed at a second angle relative to the lateral axis. The first angle is greater than the second angle. The external thread form is configured to interlock with the internal thread form. A spinal rod configured to be disposed with the implant receiver and to engage the set screw.

Drawings

The disclosure will become more readily apparent from the specific description taken in conjunction with the following drawings, in which:

FIG. 1 is a perspective view of components of one embodiment of a surgical system according to the principles of the present disclosure;

FIG. 2 is a cross-sectional view of the components shown in FIG. 1;

FIG. 3 is a perspective view of components of one embodiment of a surgical system according to the principles of the present disclosure;

FIG. 4 is a side view of components of one embodiment of a surgical system according to the principles of the present disclosure;

FIG. 5 is a cross-sectional view taken along line A-A shown in FIG. 4; and

fig. 6 is an exploded view of detail B shown in fig. 5.

Detailed Description

Exemplary embodiments of the disclosed surgical systems and associated methods of use are discussed by way of example of a medical device for treating musculoskeletal disorders, and more particularly, by way of example of a spinal implant system including bone fasteners and methods for treating the spinal column.

In some embodiments, a spinal implant system of the present disclosure includes a spinal implant, such as a bone fastener having a receiver and a set screw. In some embodiments, the set screw is configured to facilitate engagement of the set screw with the receiver. In some embodiments, the set screw is configured to contact and interlock with the receiver to reduce splaying of the receiver.

In some embodiments, the set screw includes a thread form having a crest. In some embodiments, the crests include a selected thickness. In some embodiments, the thickness comprises a percentage of the pitch. In some embodiments, the thickness of the crests is about 45% of the pitch. In some embodiments, the thickness at the screw top is configured to provide an increase in the strength of the set screw or mating receiver. In some embodiments, the surgical system of the present disclosure includes a set screw configured to withstand increased load capacity. The set screw is configured to resist and/or prevent splaying of the arms of the receiver that may occur due to excessive loading. In some embodiments, flaring is due to the set screw being off axis within the receiver, resulting in overloading of the threads due to reduced thread contact and narrowing of the width of the crest. In some embodiments, the angle of the rear and front flanks is disposed in a proximal orientation relative to the thread axis. In some embodiments, the thread geometry provides a wider crest width over the minor diameter of the tulip head and the major diameter of the set screw. In some embodiments, the increase in the width of the crest helps to resist and/or prevent shear forces generated by the clamping force generated during engagement of the set screw with the receiver. In some embodiments, the set screw is configured to matingly engage the receiver.

In some embodiments, the receiver includes internal threads having smooth rounded corners configured to eliminate binding and/or cut into the set screw. In some embodiments, the rounded corner becomes the bearing surface during engagement of the set screw with the receiver. In some embodiments, the arcuate configuration of the corners resists and/or prevents the corners from cutting into the set screw. In some embodiments, this configuration may be beneficial when the receiver comprises a harder material than the set screw.

In some embodiments, the threads include a leading edge and a trailing edge. In some embodiments, the angle of the leading edge and the trailing edge forms a selected thickness of the crests. In some embodiments, the leading edge is disposed at an angle greater than the angle of the trailing edge. In some embodiments, the angle of the leading edge is about 20 degrees greater than the angle of the trailing edge.

In some embodiments, the leading edge is disposed at an angle relative to the lateral axis. In some embodiments, the leading edge angle is about 15 degrees relative to the lateral axis. In some embodiments, the trailing edge is disposed at an angle relative to the transverse axis. In some embodiments, the trailing edge angle is about-5 degrees relative to the transverse axis, i.e., a reverse angle of about 5 degrees. In some embodiments, the leading flap edge is angled approximately 20 degrees from the trailing flap edge.

In some embodiments, the present disclosure may be used to treat spinal disorders such as degenerative disc disease, disc herniation, osteoporosis, lumbar spondylolisthesis, stenosis, scoliosis and other curvature abnormalities, kyphosis, tumors, and fractures. In some embodiments, the present disclosure may be used with other bone and bone related applications, including those associated with diagnostics and therapy. In some embodiments, the disclosed surgical system may alternatively be used in surgical treatment of patients in prone or supine positions, and/or for various surgical approaches to the spine, including anterior, posterior midline, direct lateral, posterolateral and/or anterolateral approaches, as well as for other body regions. The present disclosure may also alternatively be used with procedures for treating the lumbar, cervical, thoracic, sacral and pelvic regions of the spine. The surgical systems of the present disclosure may also be used on animals, bone models, and other inanimate substrates, 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 conjunction with the accompanying drawings, which form a part hereof. It is to be understood that this application is not limited to the particular devices, methods, conditions or parameters described and/or illustrated herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting. In some embodiments, as used in the specification, 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. When such a range is expressed, another embodiment includes from the one particular value and/or to the other 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 should also be understood that all spatial references (e.g., horizontal, vertical, top, upper, lower, bottom, left, and right) are for illustrative purposes only and may be varied within the scope of the present disclosure. For example, references to "upper" and "lower" are relative and are used only in context, and not necessarily "upper" and "lower".

The following discussion includes a description of a surgical system including one or more spinal implants, related components, and methods of using a surgical system according to the principles of the present invention. Alternative embodiments are disclosed. Reference will now be made in detail to the exemplary embodiments of the present disclosure that are illustrated in the accompanying drawings. Turning to fig. 1-5, components of a spinal implant system 10, such as a coupling member and a bone fastener, including a spinal implant are illustrated.

The components of the spinal implant system 10 may be made of biologically acceptable materials suitable for medical applications, including metals, synthetic polymers, ceramics, and bone materials and/or composites thereof. For example, the components of the spinal implant system 10 may be made of the following materials, either individually or collectively: stainless steel alloys, commercially pure titanium, titanium alloys, grade 5 titanium, superelastic titanium alloys, cobalt-chromium alloys, superelastic metal alloys (e.g., nitinol, superelastic plastic metals, such as GUM)) Ceramics and composites thereof, e.g. calcium phosphates (e.g. SKELITE)^TM) Thermoplastics, such as Polyaryletherketones (PAEK), including Polyetheretherketones (PEEK), Polyetherketoneketones (PEKK) and Polyetherketones (PEK), carbon-PEEK composites, PEEK-BaSO₄Polymer rubber, polyethylene terephthalate (PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers, polymeric rubber, polyolefin rubber, hydrogels, semi-rigid and rigid materials, elastomers, rubbers, thermoplastic elastomers, thermoset elastomers, elastomer composites, rigid polymers, including polyphenylenes, polyamides, polyimides, polyetherimides, polyethylenes, epoxies, bone materials, including autografts, allografts, xenografts, or transgenic cortical and/or cancellous bone, as well as tissue growth or differentiation factors, partially absorbable materials, such as composites of metal and calcium-based ceramics, PEEK and absorbable polymers, fully absorbable materials, such as calcium-based ceramics, such as calcium phosphate, tricalcium phosphate (TCP), Hydroxyapatite (HA) -TCP, calcium sulphate or other resorbable polymers, such as polyitacide (polyaet)ide), polyglycolide, polytyrosine carbonate, polycaprolactone (polycarothereof), and combinations thereof.

The various components of the spinal implant system 10 can be provided with material composites including the above-described materials to achieve various desired characteristics, such as strength, rigidity, flexibility, compliance, biomechanical properties, durability and radiolucency or imaging preference. The components of the spinal implant system 10 may also be made, individually or collectively, of heterogeneous materials, such as a combination of two or more of the above materials. The components of the spinal implant system 10 may be integrally formed, integrally connected, or incorporate fastening elements and/or instruments as described herein.

The spinal implant system 10 includes a coupling member, such as a set screw 12 configured to engage the bone screw 100, as described herein. The set screw 12 includes a portion, such as a head 14, and a portion, such as a shaft 16. Head 14 includes a tool engaging portion 18, tool engaging portion 18 being configured to engage a surgical tool or instrument (not shown), as described herein. In some embodiments, portion 18 includes a hexagonal cross-section to facilitate engagement with a surgical tool or instrument. In some embodiments, the head 14 may have an optional cross-section, such as, for example, rectangular, polygonal, hexagonal, elliptical, or irregular. In some embodiments, portion 18 may have a cross, phillips, square, polygonal, or star-shaped cross-sectional configuration configured to seat a correspondingly shaped portion of a surgical tool or instrument. In some embodiments, head 14 includes a hollow break-away set screw and an internal drive mechanism for removing the set screw.

Shaft 16 extends between ends 20 and 22 and defines an axis X1, as shown in fig. 1. As shown in FIG. 2, axis X2 extends transversely, e.g., orthogonal, to axis X1. In some embodiments, the axis X2 may alternatively be oriented relative to the axis X1, such as, for example, an acute or obtuse angular orientation. The shaft 16 includes an outer surface 26. Surface 26 includes threads 28. In some embodiments, the surface 26 includes one or more threads 28 configured to enhance fixation with the receiver 102, as described herein. In some embodiments, the thread 28 is continuous along the surface 26. In some embodiments, the threads 28 may comprise a single thread turn or a plurality of discrete threads. In some embodiments, a penetrating element may be positioned on the shaft 16, such as a nail arrangement, barbs, spreading elements, raised elements, ribs, and/or spikes, to facilitate engagement of the shaft 16 with the bone screw 100.

As shown in FIG. 1, the threads 28 include a minor diameter D1 and a major diameter D2. The threads 28 include an external thread form 32. The external thread form 32 defines the profile shape of one complete thread 28. Thread form 32 includes a front flank 34 and a rear flank 36, as shown in FIG. 2. As shown in fig. 1, 2 and 6, the external thread form 32 is angled in a proximal and/or reverse angular orientation relative to the axis X1. For example, thread form 32, such as front and/or rear flanks 34, 36, is angled toward end 20.

The front flank 34 includes a surface 38 disposed at an angle α 1 relative to the axis X2, as shown in fig. 2 and 6. In some embodiments, angle α 1 is about 15 degrees relative to axis X2. In some embodiments, the surface 38 may be oriented in another manner relative to the axis X2, such as by being perpendicular to the axis X2 and/or having another angular orientation relative to the axis X2, such as an acute or obtuse angle.

The rear flap 36 includes a surface 50 disposed at an angle α 2 relative to the axis X2, as shown in fig. 2 and 6. In some embodiments, angle α 2 is about-5 degrees relative to axis X2. In some embodiments, the surface 50 may alternatively be oriented relative to the axis X2, e.g., perpendicular and/or at other angles, such as acute or obtuse angles.

In some embodiments, angle α 1 differs from angle α 2 by more than a difference Δ 1, as shown in FIG. 6. In some of these embodiments, angle α 1 is greater than angle α 2, and in other embodiments contemplated, angle α 1 is less than angle α 2. In some embodiments, for example, the difference Δ 1 is in the range of about 5 degrees to about 20 degrees. In some embodiments, the difference Δ 1 is about 20 degrees.

The threads 28 define a pitch P1, the pitch P1 having a length L1 extending between adjacent rear flaps 36, as shown in FIG. 2. The front flap 34 and the rear flap 36 meet at a screw top surface C1. In various embodiments, the thread top surface C1 extends along the major diameter D2. The thread top surface C1 includes a width W1 along the major diameter D2. In various embodiments, the width W1 is a percentage of the length L1 of the pitch P1. In some embodiments, width W1 is a percentage of length L1 that is in the range of about 35% to about 50% of length L1. In some embodiments, the width W1 is about 45% of the length L1. The value of the width W1 is selected to disperse the load applied by shear forces during engagement of the set screw 12 with the receiver 102. As such, the width W1 is configured to resist and/or prevent the effects of shear forces on the set screw 12 and receiver 102 during tightening.

In some embodiments, the width W1 has a predetermined relationship with the pitch P1. In various embodiments, the relationship includes the bone screw 100 being configured such that the width W1 is a preset percentage of the pitch P1, such as the width W1 is between about 40% and about 50% of the pitch P1. In various embodiments, the width W1 is any one of between about 47% and about 43% of the pitch P1, between about 46% and 44% of the pitch P1, and about 45% of the pitch P1.

As shown in fig. 2, the thread top surface C1 is provided at a length L2 from the minor diameter D1. In various embodiments, the thread top surface C1 comprises a substantially planar configuration. In various embodiments, the thread top surface C1 is disposed parallel relative to the axis X1. In some embodiments, the thread top surface C1 may alternatively be oriented relative to the axis X1, such as transverse, and/or at other angles, such as acute or obtuse angles.

The end 20 and the head 14 form a cross-section, for example, with a neck 24 of the head 14, as shown in fig. 1 and in fig. 2, 4 and 5. In some embodiments, the end 20 includes a reduced diameter portion 60 at the neck 24. In some embodiments, portion 60 is frangibly connected to head 14. In some embodiments, portion 60 is made of a breaking and/or frangible material such that manipulation of head 14 relative to shaft 16 may cause a break at portion 60 to separate head 14 from shaft 16 at a predetermined force and/or torque limit, as described herein. In some embodiments, when a force and/or torque is applied to head 14 and the resistance increases, for example due to the fixation of shaft 16 within receiver 102, as described herein, predetermined torque and force limits are approached.

In some embodiments, head 14 may break and separate from neck 24 at a predetermined force or torque limit, which may be in a range of about 7 newton meters (Nm) to about 12.5 Nm. In some embodiments, the head 14 and/or the shaft 16 may be made of a homogeneous material or made non-homogeneously of different materials, and/or alternatively formed of a material having a greater degree of plastic deformability, frangible characteristics, and/or characteristics or properties of break-away quality to facilitate fracture and separation of the head 14 from the shaft 16. In some embodiments, head 14 includes an inner diameter that contributes to the desired breaking torque.

End 22 includes a surface 62, and surface 62 includes a penetrating element 64 extending distally from surface 62. Member 64 is configured to engage a spinal implant, such as spinal rod 66, as shown in fig. 4 and 5. Member 64 is configured to apply a force to spinal rod 66 to fix the spinal rod with bone screw 100, as described herein.

Bone screw 100 includes a receiver 102, as shown in FIG. 3. The receiver 102 includes a pair of spaced apart arms 104, 106, the arms 104, 106 defining an implant cavity 108 therebetween configured for placement of the spinal rod 66. The arms 104, 106 each extend parallel to the axis X3. In some embodiments, the arms 104, 106 may be disposed in alternative orientations relative to the axis X3, such as transverse, perpendicular, and/or other angular orientations, such as acute or obtuse angles, coaxial, and/or may be offset or staggered.

In various embodiments, the cavity 108 is substantially U-shaped. In some embodiments, all or only a portion of the cavity 108 may have alternative cross-sectional configurations, such as closed, V-shaped, W-shaped, oval, rectangular, triangular, square, polygonal, irregular, uniform, non-uniform, offset, staggered, and/or tapered shapes.

The receptacle 102 includes an inner surface 110, as shown in FIG. 3. The surface 110 includes threads 112. The threads 112 include a minor diameter D3 and a major diameter D4, as shown in FIG. 5. The threads 112 include an internal thread form 114. The internal thread form 114 defines the profile shape of one complete thread 112. The internal thread form 114 is angled in a distal orientation relative to the axis X3, as shown in fig. 4. For example, the internal thread form 114 is angled toward the distal end of the receiver 102.

The internally threaded form 114 includes a shoulder 116 and a shoulder 118, as shown in FIG. 6. The threads 112 define a pitch P2 having a length L4 extending between adjacent flanks 118, as shown in FIG. 6. In some embodiments, the pitch P1 (FIG. 2) is approximately equal to the pitch P2. In some embodiments, the pitch P1 is greater than the pitch P2. In some embodiments, the pitch P1 is less than the pitch P2.

The shoulder 116 includes a surface 120 extending transversely to the axis X3. Surface 120 is disposed in an orientation that facilitates engagement with front shoulder 34 to interlock set screw 12 with receiver 102. In some embodiments, the surface 120 may alternatively be oriented relative to the axis X3, e.g., perpendicular and/or at other angles, such as acute or obtuse angles.

The flank 118 comprises a surface 150 extending transversely to the axis X3. The surface 150 is disposed in an orientation that facilitates engagement with the rear shoulder 36 to interlock the set screw 12 with the receiver 102. In some embodiments, the surface 150 may alternatively be oriented relative to the axis X3, e.g., perpendicular and/or at other angles, such as acute or obtuse angles.

The crest C2 extends between the flank 116 and the flank 118 and along the minor diameter D3. The thread top surface C2 includes a width W2 along the minor diameter D3. The width W2 is a percentage of the length L4 of the pitch P2. In some embodiments, width W2 is a percentage of length L1 that is in the range of about 35% to about 50% of length L4. In some embodiments, the width W2 is about 45% of the length L4. The width W2 is configured to disperse the load applied by shear forces during engagement of the set screw 12 with the receiver 102. As such, the engagement of the set screw 12 with the receiver 102 is configured to resist and/or prevent the effects of shear forces on the set screw 12 and the receiver 102 during tightening.

In some embodiments, the width W2 has a predetermined relationship with the pitch P2. In various embodiments, the relationship includes the bone screw 100 being configured such that the width W2 is a preset percentage of the pitch P2, such as the width W2 is between about 40% and about 50% of the pitch P2. In various embodiments, the width W2 is any one of between about 47% and about 43% of the pitch P2, between about 46% and 44% of the pitch P1, and about 45% of the pitch P2.

The thread top surface C2 is disposed at a length L3 from the major diameter D4, as shown in fig. 6. In some embodiments, distance L3 is greater than distance L2 by a difference Δ 2. These components are configured such that the difference Δ 2 is sufficient to provide a gap between the thread top surface C1 and the surface defining the major diameter D4, as shown in fig. 6. The clearance between the crest surface C1 and the major diameter D4 facilitates expansion of the threads 28 during engagement of the set screw 12 with the receiver 102. The space between the top thread surface C1 and the surface defining the major diameter D4 is configured to resist and/or prevent the set screw 12 from expanding the arms 104, 106 during engagement of the set screw 12 with the receiver 102.

In various embodiments, the shoulder 116 meets the dome surface C2 at surface 160. Surface 160 may include an arcuate configuration relative to minor diameter D3 such that surface 160 is circular.

The shoulder 118 meets the dome surface C2 at surface 162. Surface 162 includes an arcuate configuration relative to minor diameter D3 such that surface 162 is circular. In some embodiments, one or both of the surfaces 160, 162 comprise an arcuate configuration.

The arcuate configuration of the surfaces 160, 162 prevents the surfaces 160, 162 from cutting into the set screw 12. For example, the surfaces 160, 162 are load bearing surfaces when the set screw 12 is engaged with the receiver 102. The arcuate configuration of the surfaces 160, 162 resists and/or prevents the surfaces 160, 162 from cutting into the set screw 12 when a load is applied. This configuration may be particularly beneficial in some embodiments when the receiver 102 comprises a harder material than the set screw 12.

Bone screw 100 includes a shaft 180, as shown in fig. 4 and 5. The shaft 180 is configured for securing with tissue of a patient (not shown). In some embodiments, the shaft 180 has a cylindrical cross-sectional configuration and includes an outer surface having threads defining an external thread form. In some embodiments, the threads may comprise a single thread turn or a plurality of discrete threads. In some embodiments, engagement structures may be located on the shaft 180, such as nail arrangements, barbs, spreading elements, raised elements, and/or spikes, to facilitate engagement of the shaft 180 with tissue, such as vertebrae.

In some embodiments, all or only a portion of the shaft 180 may have alternative cross-sectional configurations, such as elliptical, rectangular, triangular, square, polygonal, irregular, uniform, non-uniform, offset, staggered, undulating, arcuate, variable, and/or tapered shapes. In some embodiments, the outer surface of the shaft 180 may have alternative surface configurations to enhance fixation to tissue, such as a rough, arcuate, undulating, mesh, porous, semi-porous, concave, and/or textured configuration. In some embodiments, all or only a portion of the shaft 180 may be disposed in alternating orientations with respect to the axis X4, such as transverse, perpendicular, and/or other angular orientations, such as acute or obtuse angles, coaxial, and/or may be offset or staggered. In some embodiments, all or only a portion of the shaft 180 may be hollow.

In some embodiments, one or more of the bone screws 100 and/or bone fasteners as described herein may include, for example, polyaxial screws, sagittal angulation screws, pedicle screws, monoaxial screws, uniplanar screws, facet screws, fixation screws, tissue penetrating screws, conventional screws, expansion screws, wedges, anchors, buttons, clips, snaps, friction fasteners, compression fasteners, expansion rivets, staples, nails, adhesives, posts, fixation plates, and/or fixation posts.

In assembly, operation, and use, similar to the systems and methods described herein, the spinal implant system 10 includes a set screw 12 and bone screw 100 as described herein and is used in conjunction with a surgical procedure for treating a spinal disorder affecting a segment of a patient's spine as described herein. In some embodiments, the components of the spinal implant system 10 are used with one or more vertebral levels of the spine. In some embodiments, the components of the spinal implant system 10 may include one or more bone fasteners, spinal rods, plates, connectors, and/or interbody devices.

In use, to treat the affected portion of the spine, a practitioner gains access to the surgical site in any suitable manner, such as by dissection and retraction of tissue. In some embodiments, the components of the spinal implant system 10 may be used in any existing surgical method or technique, including open surgery, mini-open surgery, and minimally invasive surgery, including percutaneous surgical implantation. Once the surgical site is reached, a specific surgical procedure is performed to treat the spinal disorder. The components of the spinal implant system 10, including the set screw 12 and bone screw 100, are used to enhance the surgical procedure. As described herein, the components of the spinal implant system 10 are delivered or implanted as a pre-assembled device or may be assembled in situ. The components of the spinal implant system 10 may be modified, removed, or replaced, in whole or in part. For example, shaft 180 is secured to tissue, such as vertebrae, such that spinal rod 66 is disposed with receiver 102 for connection to the vertebrae.

The set screw 12 is coupled to the bone screw 100 near a top surface of the receiver 102. The set screw 12 is rotated in a clockwise direction, as indicated by arrow C in fig. 4, and translated in a direction, as indicated by arrow D in fig. 4, via a surgical instrument or tool such that the threads 28 mate with the threads 112 to couple the set screw 12 with the bone screw 100. As such, male thread form 32 simultaneously mates with female thread form 114.

Translation of set screw 12 causes member 64 to engage spinal rod 66 such that set screw 12 provides a closure mechanism to position spinal rod 66 within cavity 108 and to secure spinal rod 66 within receiver 102 and to attach spinal rod 66 to the vertebrae. The width W1 at the top thread surface C1 and the width W2 at the top thread surface C2 spread the load applied by shear forces during engagement of the set screw 12 with the receiver 102. As such, the widths W1, W2 are configured to resist and/or prevent the effects of shear forces on the set screw 12 and receiver 102 during tightening. The arcuate surfaces 160, 162 inhibit and/or prevent the threads 112 from cutting into and/or biting into the surface of the set screw 12 during engagement with the receiver 102.

At the completion of the procedure, the surgical instruments, components, and non-implanted components of the spinal implant system 10 are removed and one or more incisions are closed, as described herein. One or more of the components of the spinal implant system 10 may be made of a radiolucent material such as a polymer. Radioactive markers may be included for identification under X-ray, fluoroscopy, CT or other imaging techniques. In some embodiments, the use of surgical navigation, microsurgery, and image guidance techniques may be used to access, view, and repair spinal deterioration or injury with the spinal implant system 10.

In one embodiment, the spinal implant system 10 includes an agent that can be disposed, packaged, coated, or layered within, on, or about a component and/or surface of the spinal implant system 10. In some embodiments, the agent may comprise a bone growth promoting material, such as a bone graft, to enhance fixation of the components and/or surfaces of the spinal implant system 10 to the vertebrae. In some embodiments, the agent may comprise one or more therapeutic and/or pharmacological agents for release, including sustained release, to treat, for example, pain, inflammation, and degeneration.

It should be understood that various modifications may be made to the embodiments disclosed herein. Accordingly, the above description should not be construed as limiting, but merely as exemplifications of the various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.