WO2008083153A2

WO2008083153A2 - Vertebral disc annular fibrosis tensioning and lengthening device

Info

Publication number: WO2008083153A2
Application number: PCT/US2007/088815
Authority: WO
Inventors: Miguelangelo J. Perez-Cruet; John R. Pepper; John A. Miller
Original assignee: Mi4Spine, Llc
Priority date: 2006-12-28
Filing date: 2007-12-26
Publication date: 2008-07-10
Also published as: WO2008083153A9; WO2008083153A3

Abstract

A vertebral disc annular fibrosis tensioning and lengthening device that restores the loss of disc height as a result of disc degeneration and other factors. The vertebral disc annular fibrosis tensioning and lengthening device includes pedicle screws having heads with cup-shaped cavities. The pedicle screws are threaded into the vertebral bodies of adjacent vertebrae through the pedicles so that open parts of the heads of the pedicle screws face each other. A spring is inserted into the cup-shaped cavities in compression so that the spring bias forces the pedicle screws apart, thus increasing the height of the disc space.

Description

VERTEBRAL DISC ANNULAR FIBROSIS TENSIONING AND LENGTHENING DEVICE

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] This invention relates generally to a vertebral disc annular fibrosis tensioning and lengthening device and, more particularly, to a vertebral disc annular fibrosis tensioning and lengthening device that employs opposing pedicle screws and a spring member positioned therebetween.

2. Discussion of the Related Art

[0002] The human spine includes a series of vertebrae interconnected by connective tissue referred to as intervertebral discs that act as a cushion between the vertebrae. The discs allow for movement of the vertebrae so that the back can bend and rotate.

[0003] The intervertebral disc is an active organ in which the normal and pathologic anatomies are well known, but the normal and pathologic physiologies have not been greatly understood. The intervertebral disc permits rhythmic motions required of all vertebrate animals in their various forms of locomotion. The disc is a high-pressure system composed primarily of absorbed water, an outer multilayered circumferential annulus of strong, flexible, but essentially inelastic collagen fibers, and an inner core of a hydrogel called the nucleus pulposus. The swelling of the contained hydrogel creates the high pressure that tightens the annular fibers and its laminations. Degeneration of discs in humans is typically a slow, complex process involving essentially all of the mechanical and physiologic components with loss of water holding capacity of the disc. Discogenic pain arises from either component, but is primarily due to altered chemistry. When this pain is severely disabling and unyielding, the preferred contemporary treatments are primarily surgical, particularly fusion and/or disc replacement.

[0004] Annular collagen fibers are arranged in circumferential belts or laminations inserting strongly and tangentially in right- and left-handed angulated patches into each adjacent vertebral body. Inside the annular ring is contained an aggrecan, glycosaminoglycan, a protein-sugar complex gel having great hygroscopic ability to hold water. The swelling pressure of this gel of the nucleus maintains the pressure within the annulus, forcing the vertebrae apart and tightening the annular fibers. This tightening provides the primary mechanical stability and flexibility of each disc of the spinal column. Further, the angulated arrangement of the fibers also controls the segmental stability and flexibility of the motion segment. Therefore, the motion of each segment relates directly to the swelling capacity of the gel and secondarily to the tightness of intact annulus fibers. The same gel is also found in thin layers separating the annular laminar construction, providing some apparent elasticity and separating the laminations, reducing interlaminar torsional abrasion. With aging or degeneration, nucleus gel declines, while collagen content, including fibrosis, relatively increases.

[0005] Disc degeneration, which involves matrix, collagen and aggrecan, usually begins with annular tears or alterations in the endplate nutritional pathways by mechanical or pathophysiologic means. However, the disc ultimately fails for cellular reasons. It is believed that at an early age the central core of the disc, the nucleus pulposus, is made up of notochordal cells. These cells lead to the formation of the spinal column and the intervertebral disc. The notochordal cells help to create a proteoglycan matrix that holds water and supports the weight of the vertebral column. As one ages, typically after about 10 years in humans, there is a loss of the notochordal cells within the disc. As these cells are lost, they are replaced by chondrocytes that make up the mature nucleus pulposus.

[0006] There is also a relative decline in the proteoglycan matrix that holds water. Therefore, the disc begins to dry out or desiccate. As this process progresses, the disc loses its height and water holding capacity, and the disc degeneration process begins. The outer fibers of the disc starts to get annular tears, leading to further disc degeneration and desiccation. As the disc collapses, the nerves can get progressively compressed or pinched as they leave the spine, resulting in back pain conditions. Additionally, the back pain can result from disc degeneration itself without nerve compression. This condition is not entirely understood and results in tremendous health dollar expenditures and loss of worker productivity. Currently, there are no treatment options available to slow down, impede or stop disc degeneration, and it remains a part of the aging process of the intervertebral disc.

[0007] Progressive injury and aging of the disc occurs normally in later life and abnormally after trauma or metabolic changes. In addition to the chemical effects on the free nerve endings as a source of discogenic pain, other degenerative factors may occur. Free nerve endings in the annular fibers may be stimulated by stretching as the disc degenerates, bulges, and circumferential delamination of annular fibers occurs. This condition may lead to a number of problems. It has been shown that a person's disc is typically taller in the morning when a person awakes. This phenomenon may be due in part to the reduction of body weight forces on the disc when lying in a recumbent position overnight that causes the disc height to restore. Therefore, the reduction of compressive forces on the disc may help to restore disc height.

[0008] As discussed above, as a person ages, the discs of the spine degenerate, and the disc space height collapses. Further, the ligaments and facets of the spine degenerate as well. These problems lead to a reduction in the foramenal height of the vertebrae, often causing central or lateral canal stenosis. The foramen is an opening through the vertebrae that allows the nerve from the spinal cord to pass through. Because the nerve passes through the foramen, the nerve will often get pinched as the disc height decreases, leading to various types of back pain. Further, these problems often lead to difficulty in walking. Additionally, lateral canal stenosis causes the nerve to get pinched in the spinal canal. These conditions often lead to neurogenic claudication, where the patient typically responds by walking shorter distances, then sitting down, and then flexing the spine by leaning over or by walking with the aid of a device, which helps to flex the spine.

SUMMARY OF THE INVENTION

[0009] In accordance with the teachings of the present invention, a vertebral disc annular fibrosis tensioning and lengthening device is disclosed that restores the loss of disc height as a result of disc degeneration and other factors. In one non-limiting embodiment, the vertebral disc annular fibrosis tensioning and lengthening device includes pedicle screws having screw heads with cup-shaped cavities. The pedicle screws are threaded into the vertebral bodies of adjacent vertebrae through the pedicles so that open parts of the heads of the pedicle screws face each other. A spring is inserted into the cup-shaped cavities in compression so that the spring bias forces the pedicle screws apart, thus increasing the height of the disc space.

[0010] Additional features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a perspective view of a pedicle screw employed in a vertebral disc annular fibrosis tensioning and lengthening device of the invention;

[0012] Figure 2 is a perspective view of a spring employed in the vertebral disc annular fibrosis tensioning and lengthening device of the invention;

[0013] Figure 3 is a side view of the vertebral disc annular fibrosis tensioning and lengthening device of the invention including two of the pedicle screws with the spring therebetween;

[0014] Figure 4 is a cross-sectional side view of the vertebral disc annular fibrosis tensioning and lengthening device shown in figure 3;

[0015] Figure 5 is a top view of the vertebral disc annular fibrosis tensioning and lengthening device shown in figure 3;

[0016] Figure 6 is a perspective view of a vertebral disc annular fibrosis tensioning and lengthening device, according to another embodiment of the present invention;

[0017] Figure 7 is a side view showing a vertebral disc annular fibrosis tensioning and lengthening device of the invention inserted within adjacent vertebrae;

[0018] Figure 8 is a top view of two vertebral disc annular fibrosis tensioning and lengthening devices of the invention inserted within the adjacent vertebrae; [0019] Figure 9 is a side view showing a vertebral disc annular fibrosis tensioning and lengthening device inserted within adjacent vertebrae, and a syringe injecting a biologic substance into the disc for disc regeneration purposes, according to another embodiment of the present invention;

[0020] Figure 10 is a confocal microscope image showing notochordal and chondrocyte differentiated stem cells in a post-injected nucleus pulposus of an animal;

[0021] Figure 11 is a side view of a vertebral disc annular fibrosis tensioning and lengthening device, according to another embodiment of the present invention;

[0022] Figure 12 is a top view of a spring member for the vertebral disc annular fibrosis tensioning and lengthening device shown in figure 11 ;

[0023] Figure 13 is a broken-away side view of a body portion of a surgical screw including a roughened surface for facilitating bone in-growth to the screw, according to an embodiment of the present invention;

[0024] Figure 14 is a broken-away side view of a body portion of a surgical screw including sintered beads for facilitating bone in-growth to the screw, according to another embodiment of the present invention;

[0025] Figure 15 is a broken-away cross-sectional view of a body portion of a surgical screw including an outer layer for facilitating bone in-growth to the screw, according to another embodiment of the present invention;

[0026] Figure 16 is a broken-away side view of a body portion of a surgical screw including channels for facilitating bone in-growth to the screw, according to another embodiment of the present invention;

[0027] Figure 17 is a perspective view of a surgical screw including axial holes within screw threads for facilitating bone in-growth to the screw, according to another embodiment of the present invention; and

[0028] Figure 18 is a perspective view of a surgical screw including radial slots within screw threads for facilitating bone in-growth to the screw, according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS [0029] The following discussion of the embodiments of the invention directed to a method for disc regeneration using a vertebral disc annular fibrosis tensioning and lengthening device and a biologic substance is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses.

[0030] Figure 1 is a perspective view of a pedicle screw 10 for use in a vertebral disc annular fibrosis tensioning and lengthening device (figure 3) of the invention. The pedicle screw 10 includes a threaded and tapered body portion 12 having a tip 14. The body portion 12 includes a plurality of holes 24 that allow bone to grow therein when the screw 10 is threaded into the vertebral body so that the pedicle screw 10 is better anchored within the vertebra. The use of holes in the body portion of a pedicle screw to facilitate bone growth therein can be employed in other types of pedicle screws for other uses besides vertebral disc annular fibrosis tensioning and lengthening devices, such as spinal fusion pedicle screw and rod instrumentation, well known to those skilled in the art. The holes 24 can come in a variety of numbers, diameters and configurations. In one non-limiting embodiment, the diameter of the body portion 12 is about 6.5 mm and the diameter of the holes is about 0.5 mm. The pedicle screw 10 can include a bore 26 that extends through the body portion 12 to make it cannulated so that a K-wire (not shown) can extend therethrough to direct the pedicle screw 10 for percutaneous placement over a K-wire previously placed through the pedicle into the vertebral body, as is well understood to those skilled in the art. The pedicle screw 10 further includes a screw head 16 having an extended cup shape defining a cavity 18. The cavity 18 includes an open side 20 for reasons that will become apparent from the discussion below. An annular recess 22 is formed around an outside of the head 16 also for reasons that will become apparent from the discussion below. The pedicle screw 10 can be made of any suitable material, such as titanium, as would be well understood to those skilled in the art.

[0031] Figure 2 is a perspective view of a spring 30 having a cylindrical body 32 that is also part of the vertebral disc annular fibrosis tensioning and lengthening device of the invention. A series of slots 34 are cut into the body portion 32, as shown, in an alternating configuration that allows the body portion 32 to be compressed and provide an expansive spring force. The spring 30 includes generally rounded ends 36 and 38 that are shaped to conform to the shape of the inner surface of the cavity 18. The spring 30 can be made of any suitable material for the purposes described herein, such as nitinol, which is a flexible metal having a memory. Other materials may also be suitable, such as a shape memory alloy. An example of a suitable alloy includes about 50% nickel and about 50% titanium.

[0032] Figure 3 is a side view, figure 4 is a cross-sectional view, side view and figure 5 is a top view of a vertebral disc annular fibrosis tensioning and lengthening device 40, according to an embodiment of the present invention. The vertebral disc annular fibrosis tensioning and lengthening device 40 includes two of the pedicle screws 10 where the open sides 20 of the heads 16 face each other, as shown. The spring 30 is inserted into the cavities 18 of the heads 16 so that the ends 36 and 38 conform to the inner surface of the cavities 18. The inner surface of the cavities 18 and the ends 36 and 38 can be coated with a suitable low friction material, such as chrome, cobalt, ceramic, etc., to prevent or reduce wear particle formation as the spring 30 and the pedicle screws 10 rub against each other. Initially, the spring 32 is compressed so that it provides an expansive force to separate the pedicle screws 10. In one non-limiting embodiment, the expanded or relaxed length of the spring 30 is in the range of about 3 cm - 4 cm restoring disc height and foraminal height. The diameter of the spring 32 can be any diameter suitable for the purposes described herein.

[0033] An oval posterior ring 42 is positioned within the recesses

22, and operates to maintain the screws 10 in their proper orientation, and prevent the pedicle screws 10 from separating beyond a predetermined limit. The fixed diameter of the ring 42 allows for the tips 14 of the pedicle screws 10 to separate greater relative to the heads 16. This imparts lordosis. Further, as the spring 30 causes the pedicle screws 10 to separate, the ring 42 maintains the top end of the pedicle screws 10 stationary to create a pivot and restore the height of the disc and lordosis of the spine. Also, the configuration and orientation of the spring 30, the ring 42 and the screws 10 preserves the motion of the spine as the person performs normal physical movement in that it allows for continued flexion, extension, as well as axial rotation of the spine. The spring 30 operates as a compressible link and the posterior ring 42 operates as a rigid link. In one non- limiting embodiment, the ring 42 has an axial stiffness from one to 30 million pounds per inch.

[0034] Figure 6 is a perspective view of a vertebral disc annular fibrosis tensioning and lengthening device 50, according to another embodiment of the present invention, where like elements to the vertebral disc annular fibrosis tensioning and lengthening device 40 are identified by the same reference numeral. In this embodiment, the heads 16 of the pedicle screws 10 include a slot 52. The ring 42 is replaced with a dumbbell member 54 including a cylindrical body portion 56 and end portions 58 and 60. The body portion 56 extends through the slots 52 so that the end portions 58 and 60 are positioned outside of the heads 16, and also operates to limit the expansion of the pedicle screws 10 and control the posterior aspects of the screws 10, thus allowing restoration of the lordosis, i.e., normal curvature, of the spine.

[0035] Figure 7 is a side view and figure 8 is a top view of two of the vertebral disc annular fibrosis tensioning and lengthening devices 40 coupled to two adjacent lumbar vertebra 70 and 72 having a disc 68 therebetween. The pedicle screws 10 are threaded through pedicles 74 of the vertebra 70 and 72 and into the vertebral body 76. Once the pedicle screws 10 are in place, then the spring 30 is positioned within the cavities 18 under compression, as discussed above. As the spring bias forces the vertebra 70 and 72 apart, the height of a disc space 78 between the vertebra 70 and 72 increases and is restored. Further, as the height of the disc space 78 increases, the disc 68 is able to regenerate due to reduced sheer or compressive forces applied to the disc 68. The device 40 creates a controlled distraction force and distraction distance on the annulus fibrosis and a controlled dynamic motion of the vertebra. Further, the device 40 allows motion of the spine while maintaining the stress tension effect on the disc 68. Particularly, the device 40 provides a tension force across a compromised vertebral disc providing a distractive force to elicit the stress tension effect on the annulus fibrosis. The pedicle screws and links therebetween are arranged in a parallelogram shape to provide the desired distraction. Because most systems work like a hinge, the front or anterior portion of the disc moves much more than the back or posterior portion of the disc to restore lordosis or the natural curvature of the spine. This is not a natural motion, so with the vertebral linkage of the invention, a parallel or near parallel motion of the disc can be achieved. In one non-limiting embodiment, the motion pathway is an arc of a radius much longer than the pedicle screw length. Although the device 40 is shown coupled to adjacent vertebra, the device 40 can extend across any suitable number of vertebrae to increase the disc space of more than one disc.

[0036] Any suitable surgical procedure for placing the pedicle screws 10 can be used, including minimally invasive percutaneous surgical procedures by making the pedicle screws 10 cannulated. In one known process of percutaneous pedicle screw instrumentation, a Jamshidi needle is used to dock on to the junction of the vertebrae between the facet complex and the transverse process of the vertebra. Gentle taps with a mallet cause the Jamshidi needle to be advanced through the pedicle 74, making sure not to cross the medial border of the pedicle 74, which can result in nerve root injury, until the junction between the pedicle base and the vertebral body is reached. Fluoroscopic visualization into the anterior posterior and lateral planes of the vertebra is used to see the orientation of the Jamshidi needle. The correct trajectory of the Jamshidi needle should place the tip of the needle in the center of the pedicle in the anterior posterior view when the tip of the Jamshidi needle lies at the pedicle vertebral body junction in the lateral view.

[0037] Once the junction between the base of the pedicle wall and the vertebral body is reached, the Jamshidi needle can be directed in a more medial fashion. The Jamshidi needle is typically passed to about one-half the depth of the vertebral body, and then a K-wire is passed down the Jamshidi needle and into the vertebral body a little farther to seat it into the bone. The Jamshidi needle is then removed. A series of cannulated muscle dilators are then passed over the K-wire to prevent the soft tissue from going into the threads of the tap. The pedicle is tapped and a cannulated pedicle screw is then passed down the dilators.

[0038] After the vertebral disc annular fibrosis tensioning and lengthening device 40 has restored some or all of the disc height and has possibly facilitated disc regeneration, the present invention also includes further facilitating disc regeneration using a biologic substance, such as stem cells, injected into the disc. Other suitable biologic substances may include, but are not limited to, bone morphogenic proteins, condroitin sulfates, synthetic proteoglycan matrixes and collagens.

[0039] Figure 9 is a side view of the device 40 coupled to the lumbar vertebrae 70 and 72 in the same manner as shown in figure 7. Also shown is a syringe 66 for injecting the biological substance into the disc 68 in a percutaneous manner. Other processes may be applicable for inserting the biological substance into the disc 68 to biologically restore the degenerated disc. The device 40 increases the height of the disc 68 as discussed above, and provides an area in which the biological substance can grow within the nucleus of the disc 68. It has been shown that stem cells injected into a disc tend to differentiate along the chondrocyte lineage and differentiate into disc material in an in-vivo animal model. This differentiation acts to regenerate the nucleus pulposus in the inner core of the disc 68. It is believed that stem cells will synthesize the nucleus pulposus of the disc 68 and differentiate into the chondrocytes and/or notochordal cells in a mature human nucleus. The device 40 may be able to be removed after the disc 68 has been regenerated by the biological substance.

[0040] Figure 10 is a confocal microscope image showing notochordal and chondrocyte differentiated stem cells in a nucleus pulposus of an animal. The image was taken some time after the stem cells were injected into the disc. The image shows that stem cells have survived and differentiated into disc material, including notochordal cells and chondrocytes.

[0041] Although the device 40 is used above to restore the disc height and create an area for differentiation of the biological substance with the nucleus of the disc 68, the present invention contemplates any suitable expansive device that separates the vertebrae 70 and 72 to provide the area for the biological substance to restore the disc 68.

[0042] Although a specific type of spring has been described above for the vertebral disc annular fibrosis tensioning and lengthening device, the present invention contemplates any linearly expandable link suitable for the purposes described herein. The link exerts a force creating a stress tension effect within the disc allowing it to regenerate according to Wolffs law. The link also allows parallel distraction of the disc, distraction along the coronal plane of the disc tissue, puts the annulus fibrous in tension and provides torsional rotation of the vertebral construct. Further, the pedicle screws can be replaced with any suitable mounting member. By a more general description, the vertebral disc annular fibrosis tensioning and lengthening device includes a caudle vertebral body attachment member and a cephelad vertebral body attachment member having a non-rigid interconnection member therebetween that creates the tension stress effect on the annulus fibrosis. The posterior ring 42 acts as a rigid member coupled between the attachment members that also operates to provide the distractive force and lordosis.

[0043] Figure 11 is a side view of a vertebral disc annular fibrosis tensioning and lengthening device 80, according to another embodiment of the present invention. The device 80 includes pedicle screws 82 each having a screw body 84 and a screw head 86. An annular mounting portion 88 is provided between the screw head 86 and the screw body 84. The device 80 also includes a spring member 90 having a spring 92 and end plates 94 and 96. Figure 12 is a top view of the spring member 90. The spring 92 can be any suitable spring, such as a helical spring. Holes 98 and 100 are provided through the end plates 94 and 96, respectively. A U-shaped coupling member 102 is attached to the end plate 94 and a U-shaped coupling member 104 is attached to the end plate 96. The U-shaped coupling members 102 and 104 have a size that conforms to the diameter of the annular mounting portion 88. The surgeon will use a suitable tool (not shown) that is inserted in the holes 98 and 100 to compress the spring 92 and position the U-shaped coupling members 102 and 104 around the annular mounting portions 88 so as to provide a separation force to the pedicle screws 82 for the reasons discussed above.

[0044] As discussed above, the pedicle screws 10 include the holes 24 for facilitating bone growth therein. Such a concept eliminates or reduces the halo around the known pedicle screws that reduces the joining of the screw to the bone. With the holes 24, the screw will act more like natural bone and increase the integrity of the bonding between the screw and the vertebra, and provide the desired motion preserving affect.

[0045] The holes 24 are one example for accepting bone growth in a surgical screw. Other configurations can also be employed for pedicle screws, and for other screws permanently placed in a bony structure to provide bone interdigitation. Suitable examples include an non-smooth or porous surface on the screw body, interdigitation cavities formed by the addition of sintered beads on the outside of the screw body, interdigitation cavities formed by laser processing, interdigitation cavities formed by machining grooves, a roughened surface provided by sand blasting, a hydroxyl appetite coating, etc. Further, the screws are not limited to pedicle screws, but can be screws for other surgical applications, such as maxio-facial applications, hip fractures, podiatric fusions and fraction repair, periarticular fracture fixation, arthroplasty device anchoring, long bone fracture repair, cervical fusion construct anchoring, tendon anchoring, etc.

[0046] Figure 13 is a broken-away side view of a body portion 110 of a surgical screw, according to an embodiment of the present invention. The body portion 110 includes a non-smooth or roughened surface 112 that operates to facilitate bone in-growth to the screw once the screw is surgically implanted in the bone. The roughened surface 112 can be provided by any suitable method that would be selected depending on the desired degree of roughness of the surface 112, the type of material of the body portion 110, the extent of the bone in-growth desired, etc. For example, the roughened surface 112 can be provided by acid etching, laser deformation, abrasive media blasting, such as sand blasting, etc. Also, the roughened surface 112 can be provided by depositing a mixture of substances on the body portion 110, where one of the substances is a leachable material so that when the body portion 130 is dipped in a suitable etchant, the leachable material will be removed from the surface creating the roughened surface 112.

[0047] Figure 14 is a broken-away side view of a body portion 120 of a surgical screw, according to another embodiment of the present invention. A plurality of sintered beads 124 are formed to the body portion 120, where the sintered beads 124 facilitate bone growth to the screw once the surgical screw is surgically implanted in the bone. The number of the beads 124, the size of the beads 124, the material of the beads 124, etc. would depend on the particular application, surgical procedure, desired bone in-growth facilitation, etc. The sintered beads 124 can be formed to the surface 122 by any suitable sintering process.

[0048] Figure 15 is a broken-away, cross-sectional view of a body portion 130 of a surgical screw, according to another embodiment of the present invention. The body portion 130 includes an outer layer 132 that is made of a suitable material for facilitating bone in-growth. In one non-limiting embodiment, the outer layer 132 is hydroxyapetite, which is a mineral that is the principal storage form of calcium and phosphorous in bone. Therefore, the hydroxyapetite is conducive with the natural bone for providing a strong bond therebetween.

[0049] Figure 16 is a broken-away side view of a body portion 140 of a surgical screw, according to another embodiment of the present invention. In this embodiment, channels 142 are formed, such as by sawing, in the outer surface of the body portion 140 to provide indentations that facilitate bone ingrowth to the screw. The channels 142 are by way of a non-limiting example in that any machined indentations that facilitate bone in-growth can be provided.

[0050] Figure 17 is a perspective view of a surgical screw 150 including axial holes 152 extending through screw threads 154 for facilitating bone in-growth to the screw 150, according to another embodiment of the present invention.

[0051] Figure 18 is a perspective view of a surgical screw 160 including radial slots 162 circumferentially disposed around screw threads 164 for facilitating bone in-growth to the screw 160, according to another embodiment of the present invention. In this embodiment, the slots 162 extend partially into the major diameter of the screw 160.

[0052] The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.

Claims

CLAIMS What is Claimed is:

1. A vertebral disc annular fibrosis tensioning and lengthening device comprising: a pair of screws including screw heads, each screw head having a cup-shaped cavity and an open area where the open area of the screw heads face each other; and a spring positioned between the screws, said spring including opposing ends that are positioned within the cup-shaped cavity of the screw heads, said spring applying a bias to the screws that causes the screws to separate.

2. The device according to claim 1 wherein the spring includes a cylindrical body between the opposing ends.

3. The device according to claim 2 wherein the cylindrical body includes a plurality of spaced apart slots that allow the spring to be compressed.

4. The device according to claim 1 further comprising a rigid posterior ring positioned around an outside of the heads.

5. The device according to claim 4 wherein the ring is positioned within an annular recess in the heads.

6. The device according to claim 1 further comprising a dumbbell member, said screw heads including a slot where an end of the dumbbell member is positioned within the slots to control the maximum distance between posterior aspects of the screws.

7. The device according to claim 1 wherein an inner surface of the cavity in the screw heads includes a low friction material to reduce wear particle formation.

8. The device according to claim 1 wherein the screws are pedicle screws effective to be threaded through a pedicle of a vertebra and into a vertebral body.

9. The device according to claim 1 wherein the screws include a screw body, said screw body including recesses for accepting bone growth.

10. The device according to claim 1 wherein the spring has a length in the range of 3 cm - 4 cm.

11. The device according to claim 1 wherein the screws are cannulated.

12. The device according to claim 1 wherein the spring is made of a memory alloy.

13. The device according to claim 12 wherein the spring is made of nitinol.

14. A vertebral disc annular fibrosis tensioning and lengthening device for increasing the disc space between adjacent vertebra, said device comprising: a pair of pedicle screws including screw heads, each screw head having a cup-shaped cavity and an open area where the open area of the screw heads face each other, each screw head further comprising an outer recess; a spring member positioned between the screws, said spring member including a cylindrical body having generally rounded ends that are positioned within the cup-shaped cavity of the screw heads, said cylindrical body including a plurality of spaced apart slots that allow the spring member to be compressed, said spring member applying a bias to the screws that causes the screws to separate; and an oval shaped rigid posterior link positioned within the recesses in the heads.

15. The device according to claim 14 wherein an inner surface of the cavity in the screw heads includes a low friction material to reduce wear particle formation.

16. The device according to claim 14 wherein the screws include a screw body, said screw body including recesses for accepting bone growth.

17. A vertebral disc annular fibrosis tensioning and lengthening device for increasing the height of an intervertebral disc, said device comprising a pair of support members mounted to vertebra and a linearly expandable link member positioned between and in contact with the support members, said link member applying a bias to the support members that causes the support members to separate so as to provide a distractive force to the disc.

18. The device according to claim 17 further comprising a rigid member positioned between and in contact with the support members.

19. The device according to claim 17 wherein the link member is a cylindrical member coupled to heads of the support members, said link member including a cylindrical body having slots that allow the link member to be compressed.

20. The device according to claim 17 wherein the link member includes an elongated portion having a spring and end plates, said end plates including openings, said spring member further including U-shaped members at the end of each end plate, said U-shaped members being positioned in contact with the support members.

21. A vertebral device comprising a caudal vertebral body attachment member, a cephelad vertebral body attachment member and a non-rigid interconnection member coupled to the caudal vertebral body attachment member and the cephelad vertebral body attachment member, wherein the interconnection member creates a tension stress on an annulus fibrosis between vertebra.

22. The device according to claim 21 wherein the device provides a controlled distraction force and a controlled distraction distance on the annulus fibrosis and a controlled dynamic motion of the vertebra.

23. The device according to claim 21 wherein the interconnection member allows vertebral motion while maintaining stress tension on the annulus fibrosis.

24. The device according to claim 21 further comprising a rigid member coupled to the caudal vertebral body attachment member and the cephelad vertebral body attachment member.

25. A vertebral device comprising a caudal pedicle screw, a cephelad pedicle screw, a rigid link coupled to the caudal pedicle screw and the cephelad pedicle screw and a compressible link coupled to the caudal pedicle screw and the cephelad pedicle screw, wherein the rigid link and the compressible link provide a distractive force to an annulus fibrosis between vertebra.

26. The device according to claim 25 wherein the device provides a controlled distraction force and a controlled distraction distance on the annulus fibrosis and a controlled dynamic motion of the vertebra.

27. The device according to claim 25 wherein the links and the pedicle screws are arranged in a parallelogram shape.

28. The device according to claim 25 wherein the links allow vertebral motion while maintaining stress tension on the annulus fibrosis.

29. The device according to claim 28 wherein the motion pathway is an arc having a radius much longer than a length of the pedicle screws.

30. A method for providing vertebral disc annular fibrosis tensioning and lengthening, said method comprising: providing a pair of screws within adjacent vertebra, said screws including screw heads, each screw head having a cup-shaped cavity and an open area where the open area of the screw heads face each other; and positioning a spring between the screws so that opposing ends of the screw are positioned within the cup-shaped cavity of the screw heads, wherein the spring applies a bias to the screws that causes a distractive force to the annular fibrosis of the vertebral disc.

31. The method according to claim 30 wherein the spring includes a cylindrical body between the opposing ends.

32. The method according to claim 31 wherein the cylindrical body includes a plurality of spaced apart slots that allow the spring to be compressed.

33. The method according to claim 30 further comprising providing a rigid posterior ring positioned around an outside of the heads.

34. The method according to claim 33 wherein the ring is positioned within an annular recess in the heads.

35. The method according to claim 30 further comprising providing a dumbbell member, said screw heads including a slot where an end of the dumbbell member is positioned within the slots to control the maximum distance between posterior aspects of the screws.

36. The method according to claim 30 wherein an inner surface of the cavity in the screw heads includes a low friction material to reduce wear particle formation.

37. The method according to claim 30 wherein the screws are pedicle screws threaded through a pedicle of a vertebra and into a vertebral body.

38. The method according to claim 30 wherein providing a spring includes providing a spring made of a memory alloy.

39. The method according to claim 38 wherein providing a spring includes providing a spring made of nitinol.

40. A method for providing vertebral disc annular fibrosis lengthening for increasing the height of an intervertebral disc, said method comprising mounting a pair of support members to opposing vertebra and applying a separation force to the support members using a linearly expandable link member positioned between and in contact with the support members so as to provide a continuous distractive force to the disc.

41. The method according to claim 40 further comprising providing a rigid member positioned between and in contact with the support members.

42. The method according to claim 40 wherein the link member is a cylindrical member coupled to heads of the support members, said link member including a cylindrical body having slots that allow the link member to be compressed.

43. The method according to claim 40 wherein the link member includes an elongated portion having a spring and end plates, said end plates including openings, said spring memberfurther including U-shaped members at the end of each end plate, said U-shaped members being positioned in contact with the support members.

44. A method for providing a continuous tension stress on an annulus fibrosis between two vertebra, said method comprising coupling a caudal vertebral body attachment member to one vertebra, coupling a cephelad vertebral body attachment member to another vertebra and coupling a non-rigid interconnection member to the caudal vertebral body attachment member and the cephelad vertebral body attachment member, wherein the interconnection member creates the tension stress.

45. The method according to claim 44 wherein the method provides a controlled distraction force and a controlled distraction distance on the annulus fibrosis and a controlled dynamic motion of the vertebra.

46. The method according to claim 44 wherein the interconnection member allows vertebral motion while maintaining stress tension on the annulus fibrosis.

47. The method according to claim 44 further comprising providing a rigid member coupled to the caudal vertebral body attachment member and the cephelad vertebral body attachment member.

48. The method according to claim 47 wherein the attachment members and the interconnection member are arranged in a parallelogram shape.

49. A method for regenerating a vertebral disc by hyperextension of an annulus fibrosis of the disc using screws coupled to separate vertebra and an expansive member coupled to the screws and providing an expansive force to the screws, said method creating a strain on the annular fibrosis to provide the disc regeneration.

50. The method according to claim 49 further comprising coupling a rigid member to the screws.

51. The method according to claim 50 wherein the expansive member and the rigid member are part of a parallelogram linked hardware.

52. The method according to claim 49 wherein the method provides uniform distraction distances within the sagittal plane of the disc.

53. A method for providing disc regeneration, said method comprising: coupling screws to separate vertebrae; coupling an expansive member to the screws to create a strain on an annular fibrosis of the disc; and inserting a biological substance into the disc.

54. The method according to claim 53 wherein inserting a biological substance into the disc includes percutaneously injecting a biological substance into the disc.

55. The method according to claim 53 wherein inserting a biological substance into the disc includes inserting stem cells into the disc.

56. The method according to claim 53 wherein inserting a biological substance into the disc includes inserting a biological substance into the disc selected from the group consisting of bone morphogenic proteins, condroitin sulfates, synthetic proteoglycan matrixes and collagens.

57. The method according to claim 53 further comprising removing the pedicle screws and the expansive member after the disc has been regenerated by the biological substance.

58. The method according to claim 53 wherein the screws are coupled to the vertebra using minimally invasive surgical techniques.

59. The method according to claim 53 wherein inserting a biological substance into the disc includes inserting the biological substance into the disc after the disc height has been at least been partially restored by the expansive member.

60. The method according to claim 53 further comprising coupling a rigid member to the screws.

61. The method according to claim 60 wherein the rigid member is coupled to the screws so that it creates a pivot force that causes tips of the screws to separate more than heads of the screws to provide a lordotic shape to the disc.

62. The method according to claim 53 wherein the screws include screw heads having a cup-shaped cavity and an open area where the open area of the screw heads face each other, and wherein the expansive member is a spring including opposing ends that are positioned within the cup-shaped cavity of the screw heads.

63. The method according to claim 62 wherein the spring includes a cylindrical body between the opposing ends.

64. The method according to claim 63 wherein the cylindrical body includes a plurality of spaced apart slots that allow the spring to be compressed.

65. A method for providing disc regeneration, said method comprising: coupling an expansive member to vertebrae to provide a distractive force between the vertebrae; and inserting a biological substance into the disc.

66. The method according to claim 65 wherein inserting a biological substance into the disc includes percutaneously injecting a biological substance into the disc.

67. The method according to claim 65 wherein inserting a biological substance into the disc includes inserting stem cells into the disc.

68. The method according to claim 65 wherein inserting a biological substance into the disc includes inserting a biological substance into the disc selected from the group consisting of bone morphogenic proteins, condroitin sulfates, synthetic proteoglycan matrixes and collagens.

69. The method according to claim 65 further comprising removing the expansive member after the disc has been regenerated by the biological substance.

70. The method according to claim 65 wherein inserting a biological substance into the disc includes inserting the biological substance into the disc after the disc height has been at least been partially restored by the expansive member.

71. A method for facilitating disc regeneration, said method comprising: providing an injecting device for holding stem cells; and percutaneously injecting the stem cells into the disc with the injecting device.

72. The method according to claim 71 wherein injecting the stem cells is done after the height of the disc has been restored.

73. A surgical screw comprising a head portion and a body portion, said body portion including a textured surface other than screw threads that facilitates bone in-growth to the screw so that the screw is more rigidly mounted to bone.

74. The screw according to claim 73 wherein the body portion includes a roughened surface for facilitating bone in-growth.

75. The screw according to claim 74 wherein the roughened surface is formed by abrasive media blasting.

76. The screw according to claim 74 wherein the roughened surface is formed by acid etching.

77. The screw according to claim 74 wherein the roughened surface is formed by depositing two or more materials onto the body portion and leaching out one of the materials.

78. The screw according to claim 74 wherein the roughened surface is formed by laser deformation.

79. The screw according to claim 73 wherein the body portion includes a plurality of sintered beads adhered to the body portion.

80. The screw according to claim 73 wherein the body portion includes an outer layer of hydroxya petite.

81. The screw according to claim 73 wherein the body portion includes a plurality of spaced apart grooves.

82. The screw according to claim 73 wherein the body portion includes holes for facilitating bone in-growth.

83. The screw according to claim 82 wherein the body portion includes screw threads, said holes being formed axially through the screw threads.

84. The screw according to claim 73 wherein the body portion includes screw threads, said screw threads including a plurality of circumferential Iy disposed slots for facilitating bone in-growth.

85. The screw according to claim 73 wherein the screw is a pedicle screw.

86. The screw according to claim 73 wherein the screw is selected from the group consisting of maxio-facial application screws, hip fracture screws, podiatric fusion screws, fraction repair screws, periarticular fracture fixation screws, arthroplasty device anchoring screws, long bone fracture repair screws, cervical fusion construct anchoring screws and tendon anchoring screws.

87. A pedicle screw for spinal fusion surgery, said screw comprising a head portion and a body portion, said body portion including a plurality of openings that facilitate bone growth to the screw so that the screw is more rigidly mounted to the vertebra.

88. The screw according to claim 87 wherein the openings are formed by abrasive media blasting.

89. The screw according to claim 87 wherein the openings are formed by acid etching.

90. The screw according to claim 87 wherein the openings are formed by depositing two or more materials onto the body portion and leaching out one of the materials.

91. The screw according to claim 87 wherein the openings are formed by laser deformation.

92. The screw according to claim 87 wherein the openings are a plurality of spaced apart grooves.

93. The screw according to claim 87 wherein the openings are holes.

94. The screw according to claim 93 wherein the body portion includes screw threads, said holes being formed axially through the screw threads.

95. The screw according to claim 87 wherein the body portion includes screw threads, said screw threads including a plurality of circumferentially disposed slots for facilitating bone in-growth.

96. A surgical screw comprising a head portion and a body portion, said body portion including an outer layer of hydroxys petite that facilitates bone in-growth to the screw so that the screw is more rigidly mounted to bone.

97. The screw according to claim 96 wherein the screw is a pedicle screw.