Coaxial screw gear sleeve mechanism

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DESCRIPTION

Apparatus for distraction and fusion of the vertebral body using a coaxial helical gear sleeve mechanism

RELATED APPLICATION

The present application claims the benefit of the United States Provisional Application No. 61 / 271,548, filed on July 22, 2009, and the United States Provisional Application No. 61 / 365,131, filed on July 16, 2010.

Field of the Invention

The present invention relates to the distraction and fusion of vertebral bodies. More specifically, the present invention relates to devices for the distraction and fusion of vertebral bodies using coaxial helical gear sleeve mechanisms.

Background of the invention

The concept of intervertebral fusion for the cervical and lumbar spine after a discectomy was generally introduced in the 1960s. It involved removing a bone graft from the hip and implanting the graft into the disc space. The disk space was prepared by expanding the space to match the implant. The advantages of this concept were that it provided a large bone-to-bone contact surface and placed the graft under loading forces that allowed osteoconduction and induction of bone fusion. However, the technique is rarely practiced today due to numerous disadvantages, including prolonged operating time, destruction of a large part of the disc space, high risk of nerve injury and hip pain after removal of the bone injert.

Currently, at least two devices are commonly used to perform the intervertebral portion of an intervertebral body fusion: the first is the distraction device and the second is the intervertebral body fusion device, often referred to as a cage. The cages can be implanted as independent devices or as part of a circumferential fusion approach with pedicle screws and rods. The concept is to introduce an implant that distracts a collapsed disc and decompresses the nerve root, allows the load to be shared to improve bone formation and implant a device small enough to allow implantation with minimal retraction and pulling the nerves .

In a typical intervertebral body fusion procedure, a portion of the intervertebral disc is removed first from between the vertebral bodies. This can be done through a direct open approach or a minimally invasive approach. Disc shavers, pituitary gouge tweezers, curettes and / or disc scrapers can be used to remove the nucleus and a portion of the anterior or posterior ring to allow implantation and access to internal disc space. The distraction device is inserted into the clear space to enlarge the disc space and the vertebral bodies are separated by actuating the distraction device. The enlargement of the disc space is important because it also opens the foramen where the nerve root exists. It is important that during the distraction process the facet joints are not too distracted. An intervertebral fusion device is then inserted into the distracted space and bone growth factor, such as autograft, a collagen sponge with bone morphogenetic protein or another bone enhancing substance, can be inserted before or after the device is inserted into the space disc, in the space within the intervertebral fusion device to promote the fusion of the vertebral bodies.

Intervertebral fusion and distraction can be performed through anterior, posterior, oblique and lateral approaches. Each approach has its own anatomical challenges, but the general concept is to fuse the adjacent vertebra in the thoracic or lumbar cervical spine. The devices have been manufactured with various materials. Such materials include cadaverous spongy bone, carbon fiber, titanium and polyether ether ketone (PEEK). The devices have also been manufactured in different shapes, such as a bean shape, soccer ball shape, banana shape, wedge shape and a threaded cylindrical cage.

As an example of a spacer device, US2007 / 0255415 by Edie et al describes an expandable intervertebral spacer that can be inserted between the vertebral limbs and expanded. US2007 / 0250171 of Bonin, JR describes another expandable intervertebral device, designed to replace one or more vertebral members. WO2009 / 064787 discloses an intervertebral implant of adjustable height for total, partial or nuclear replacement of an intervertebral disc space.

It is important that a device that is used both for fusion of the intervertebral body and for distraction be small enough to facilitate insertion into the intervertebral space and of sufficient height to maintain the normal height of the disc space. The use of a device of insufficient size that cannot be expanded to a sufficient height can cause inadequate fusion between adjacent vertebrae and cause

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additional complications for the patient, such as migration of the device inside or extrusion out of the disc space. Solving these problems may require the use of several devices of different sizes to be used in series to expand the disk space by the appropriate amount, which increases the time required to carry out the procedure, increasing the cost and risk associated with The procedure.

Accordingly, there is a need in the art for a device of sufficient strength that can distract from an initial size small enough to initially adjust in the disc space at a height sufficient to restore and maintain the normal height of the disc space.

Summary of the Invention

Improved apparatuses for distraction and fusion of the vertebral body according to various embodiments of the present invention employ one or more coaxial helical gear sleeve mechanisms.

According to the present invention, a fusion device of the distracting intervertebral body adapted for implantation in an intervertebral disc space of a patient having a first support surface configured to interconnect with an end plate of an upper vertebra of the intervertebral disc space and is provided is provided. a second support surface configured to interconnect with an end plate of a lower vertebra of the intervertebral disc space, further characterized in that the device includes at least one coaxial helical gear sleeve mechanism disposed between the first support surface and the second support surface, the coaxial helical gear sleeve mechanism that includes a post having an outer surface threaded into a part of the post protruding inward from one of the first support surface and the second support surface; and a corresponding sleeve configured to surround the post and having: an internal surface threaded in a part of the sleeve projecting inwardly from the other of the first support surface and the second support surface and configured to interconnect with the threaded outer surface of the pole; and an outer gear surface in a portion of the sleeve; the outer gear surface defined in a thread that extends in a helical pattern along a sleeve height; and a drive mechanism that has a surface configured to interact with the outer gear surface of the sleeve and drive it, so that the selective operation of the drive mechanism causes a distraction of the first support surface and the second support surface with respect to the upper vertebra and the lower vertebra of the intervertebral disc space due to a telescopic expansion resulting from the sleeve that is it moves relative to one of the first support surface and the second support surface simultaneously with the post-translation with respect to the sleeve.

In various embodiments, coaxial helical gear sleeve mechanisms include a pole with a threaded outer surface and a corresponding sleeve configured to surround the pole, the corresponding sleeve has a threaded inner surface configured to interface with the threaded outer surface of the pole and a outer gear surface. A drive mechanism can be configured to interact with the outer gear surface of the sleeve, causing the device to distract.

In one embodiment, a device for intervertebral distraction and fusion of an intervertebral disc space is used. The device may include a first support surface and a second support surface with at least one coaxial helical gear sleeve mechanism disposed between them. The coaxial helical gear sleeve mechanism includes a post with a threaded outer surface that projects inwardly from one of the bearing surfaces and a corresponding sleeve configured to surround the post. The sleeve can project inwards from the other of the support surfaces and have a threaded inner surface configured to interconnect with the threaded outer surface of the pole and an outer gear surface.

The device may also include a drive mechanism having a surface configured to interact with the outer gear surface of the sleeve and actuate it, which causes a distraction of the first support surface and the second support surface. A method of distraction and fusion of the intervertebral body is described, which involves the implantation of a distracting intervertebral body fusion device in an intervertebral disc space. The device is inserted so that a first support surface is connected with an end plate of an upper vertebra of the intervertebral disc space and a second support surface is connected with an end plate of a lower vertebra of the disc space. At least one coaxial helical gear sleeve mechanism is disposed between the bearing surfaces and includes a threaded post, a corresponding sleeve having an inner thread that engages with the threaded post and an outer gear that engages with a drive mechanism. . The method includes distracting the device from a folded configuration to an expanded configuration by operating the drive mechanism to rotate the sleeve relative to the post, thereby expanding the first support surface with respect to the second support surface.

The foregoing summary of the various embodiments of the invention is not intended to describe each illustrated embodiment or each implementation of the invention. This summary represents a simplified description of certain aspects of the invention to facilitate a basic understanding of the invention and is not intended to identify key or critical elements of the invention or delineate the scope of the invention.

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Brief description of the drawings

The invention can be more fully understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:

Figure 1A is a perspective view of an intervertebral body fusion device that can be separated according to an embodiment of the present invention in a folded configuration.

Figure 1B is a perspective view of the fusion device of the distractible intervertebral body of Figure 1A in an expanded configuration.

Figure 1C is an exploded view of the fusion device of the distractible intervertebral body of Figure 1A.

Figure 1D is a partial sectional view of the fusion device of the distractible intervertebral body of Figure 1A.

Figure 2A is a partial side view of an intervertebral body fusion device that can be separated in accordance with an embodiment of the present invention.

Figure 2B is a partial side view of the fusion device of the distractible intervertebral body of Figure 2A.

Figure 3A is a partial side view of an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 3B is a partial side view of the intervertebral body fusion device that can be separated from Figure 3A.

Figure 4A is a partial top view of an intervertebral body fusion device that can be separated in accordance with an embodiment of the present invention.

Figure 4B is a partial top view of the intervertebral body fusion device that can be separated from Figure 4A.

Figure 5A is a perspective view of an insertion tool and an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 5B is a perspective view of an insertion tool and an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 5C is a perspective view of an insertion tool and an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 5D is a partial perspective view of an insertion tool according to an embodiment of the present invention.

Figure 6A is an end view of an intervertebral body fusion device that can be separated in accordance with an embodiment of the present invention.

Figure 6B is an end cross-sectional view of the intervertebral body fusion device that can be separated from Figure 6A taken facing the page.

Figure 7A is a front view of an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 7B is a cross-sectional view of the intervertebral body fusion device that can be separated from Figure 7A taken along lines 7B-7B.

Figure 8A is a front view of an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 8B is a cross-sectional view of the intervertebral body fusion device that can be separated from Figure 8A, taken along lines 8A-8A.

Figure 9A is an exploded view of an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

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Figure 9B is a perspective view of the fusion device of the distractible intervertebral body of Figure 9A.

Figure 9C is a front view of the fusion device of the distractible intervertebral body of Figure 9A.

Figure 9D is a cross-sectional view of the fusion device of the distractible intervertebral body of Figure 9A, taken along lines 9D-9D in Figure 9C.

Figure 10A is an exploded view of an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 10B is a perspective view of the fusion device of the distractible intervertebral body of Figure 10A.

Figure 10C is a bottom view of the intervertebral body fusion device that can be separated from Figure 10A.

Figure 10D is a cross-sectional view of the intervertebral body fusion device that can be separated from Figure 10A, taken along lines 10D-10D in Figure 10C.

Figure 11A is a perspective view of an intervertebral body fusion device that can be separated according to an embodiment of the present invention.

Figure 11B is a front view of the intervertebral body fusion device that can be separated from Figure 11A.

Figure 11C is a cross-sectional view of the intervertebral body fusion device that can be separated from Figure 11A, taken along lines 11C-11C in Figure 11B.

Figure 11D is a cross-sectional view of the intervertebral body fusion device that can be separated from Figure 11A, taken along lines 11D-11D in Figure 11B.

Figure 12A is a perspective view of a distracting intervertebral body fusion device according to an embodiment of the present invention.

Figure 12B is a side view of the fusion device of the distractible intervertebral body of Figure 12A.

Figure 13A is a perspective view of an intervertebral body fusion device that can be separated in accordance with an embodiment of the present invention.

Figure 13B is a side view of the fusion device of the distractible intervertebral body of Figure 13A.

Figure 14A is a perspective view of an intervertebral body fusion device that can be separated in accordance with an embodiment of the present invention.

Figure 14B is a side view of the fusion device of the distractible intervertebral body of Figure 14A.

Fig. 15 is a perspective view of a pair of intervertebral body fusion devices that can be separated according to an embodiment of the present invention.

Figure 16A is a top view of a distractible device according to an embodiment of the present invention in a compressed configuration.

Figure 16B is a top view of the distractible device of Figure 16A in an expanded configuration.

Figure 17A is a perspective view of a distractible device according to an embodiment of the present invention.

Figure 17B is a partial sectional view of the distractible device of Figure 17A.

Fig. 18A is a perspective view of a distractible device according to an embodiment of the present.

invention.

Figure 18B is a partial view of the distractible device according to Figure 18A.

Figure 18C is a partial view of the distractible device according to Figure 18A.

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Figure 18D is a partial view of the distractible device according to Figure 18A.

Although the invention is susceptible to various modifications and alternative forms, details thereof have been shown by way of example in the drawings and will be described in detail. However, it should be understood that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents and alternatives that fall within the scope of the invention as defined in the appended claims.

Detailed description of the drawings

In the following detailed description of the present invention, numerous specific details are set forth to provide a thorough understanding of the present invention. However, one skilled in the art will recognize that the present invention can be practiced without these specific details. In other cases, the well-known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the present invention.

With reference to FIGS. 1A-1C, a fusion device 100 of the distractible intervertebral body adapted for implantation in an intervertebral disc space of a patient according to an embodiment of the present invention can be seen. Figure 1A shows the device 100 in a fully compressed configuration, Figure 1B shows the device 100 in a fully expanded configuration, and Figure 1C shows an exploded view of the device 100.

The device 100 includes a first member 110 having a support surface 102 configured to interact with an end plate of one of an upper or lower vertebra of the intervertebral disc space and a second member 150 that has a support surface 104 configured to connect with an end plate from the other of the upper or lower vertebra. In one embodiment, the support surfaces 102, 104 may include a textured surface, such as that provided by grooves 114, to create friction with the end plates of the vertebra to prevent accidental extrusion of the device 100. The spokes of the striated valley 114 and the upper striated width 114 can be maximized to minimize the notch factor and reduce tension while still providing a striated design that reduces the propensity of the device 100 to extrude from the disk space. One or both members 110, 150 may also include an opening 173, 153 that extends through the member to facilitate bone growth through the device 100. In other embodiments, the opening can be filled with a gel, rubber or other complaint material that can replicate the core of an intervertebral disc and complement the resistance of the device under conditions of compression, shear and torsional load. Alternatively, a generally solid surface, a textured or etched surface, a grooved or grooved surface, or a surface with multiple openings in each member 110, 150 can be provided.

The device 100 may also include a pair of coaxial helical gear sleeve mechanisms including threaded post members 111, 112 extending from the first member 110 and a pair of threaded gear sleeves 120, 130 configured to surround the members 111 , 112 post. The threaded post members 111, 112 may have threads 113, 115 defined on an outer surface thereof. The gear sleeves 120, 130 may have both inner threads 122, 132 configured to interconnect with threads 113, 115 of threaded members 111, 112 and outer threads 121, 131. In one embodiment, both the outer and inner threads 121 of one of the sleeves 120 are of one hand opposite the threads 131, 132 of the other sleeve 130. The outer threads 121, 131 of the sleeves 120, 130 may have teeth 124, 134 gear cut into the thread. In one embodiment, the gear teeth 124, 134 are not cut to the root, or smaller diameter, of the threads 121, 131 to maximize the strength of the threads. In the compressed configuration, the threaded gear sleeves 120, 130 may be fitted within the sleeve openings 161, 162 in the second member 150. The openings 161, 162 may include threaded portions 151, 152 which are engaged with threads 121, 131 outer sleeves 120, 130 gear. In one embodiment, the sleeve openings 161, 162 extend completely through the support surface 104 of the second member 150. In some embodiments, as shown, the threaded gear sleeves 120, 130 may be substantially solid. In other embodiments, threaded gear sleeves may include one or more grooves through the sleeve for mass reduction and material savings or to promote bone growth.

The device 100 can be expanded with the aid of an endless screw 140 that extends through an endless screw opening 154 in the device 100. The worm 140 may have a first 142 and second 141 opposite threaded sections configured to interconnect with the outer threads having gear teeth 124, 134 of gear sleeves 120, 130 threaded through a pair of openings 157, 158 in portions 151, 152 threaded openings 161, 162 of sleeve. The worm 140 may include a hex 143, 144 at each end of the worm 140 that allows it to be operated by a delivery system (described below). Such a delivery system can also be attached to the device 100 when the worm 140 is driven into the threaded hole 156A or the threaded hole 156B to stabilize the delivery system. The device 100 can include a hexagon 143, 144 and a threaded hole 156A, 156B at each end of the device, so that the device 100 can be inserted and operated from any end, or it can include

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a hexagonal and threaded hole on one side of the device, which limits the device to insertion and distraction from a single direction. The lower member 150 may also include one or more festoons 155 above the endless screw 154 which provides increased strength and thickness while allowing the threaded gear sleeves 120, 130 to rotate.

A partial sectional view of a fusion device 100 of the distractible intervertebral body in Figure 1D helps illustrate how the device can employ multiple coaxial helical gear sleeve mechanisms as telescopic mechanisms using threaded post elements 111, 112, sleeves 120, 130 threaded and the endless screw 140 to expand the first member 110 and the second member 150 with respect to each other. By turning hexagon 144 counterclockwise, and therefore the worm 140, counterclockwise, the first threaded section 142 of the worm 140 pulls the teeth 134 of the gear sleeve 130 of threaded gear towards the hexagonal head 144. This causes the sleeve 130 to move upwardly from the second member 150 along the internal threads 152. When the sleeve 130 rotates while moving upward, the threaded post member 112 extending from the first member 110, which cannot rotate, also moves upwardly with respect to the sleeve 130 and the second member 150. This second transfer results from the external threads 115 of the opposite hand of the threaded post element 112 driven by the corresponding internal threads 132 of the sleeve 130. The same mechanics are occurring on the other side of the device with the sleeve 120 oppositely threaded that has external threads 121 and internal threads 122, a post element 111 having external threads 113 and a second threaded section 141 of the endless screw 140.

Because the threads for similar components for each device are opposite, the threads 142 on one side of the worm 140 will be pulling the teeth 134 of the threaded gear sleeve 130 while the threads 141 on the other side of the screw 140 will be pushing the teeth 124 of the gear into the other sleeve 120, or vice versa, depending on the direction of rotation of the worm 140. These opposite forces applied to the endless screw 140 by the threaded gear sleeves 120, 130 are carried in tension or compression by the endless screw 140. Therefore, the worm 140 is not substantially driven into or out of the opening of the worm 154 when the device 100 expands or contracts. This is advantageous because a pin or other retainer is not required to retain the worm and balance the forces in the device. Such a pin can be a point of excessive wear that can cause the life cycle of the device to be shorter. In some embodiments, a pin can be used to prevent the worm 140 from being pushed or pushed axially, which can cause the device to get stuck.

Alternative drive mechanisms to the worm drive include piezoelectric actuators and any impulse that imparts collision mechanism or configuration. In addition, a drive mechanism, such as a worm, could be an integrated part of a delivery system. In such an embodiment, the external threads of the threaded gear sleeves would be both of the same hand and the worm would be screwed into the compressed device in the opening of the worm. As the worm is turned, the axial position of the worm would be restricted by the supply system, rather than a pin, which would cause a distraction of the device. Once the device reaches the desired height, the worm can be screwed out of the opening of the worm and the device can be locked in place by screwing a threaded worm. The worm could have an additional screwing or adjustment feature that allows permanent or detachable attachment to the device. The locking worm could be made of a transparent radio material such as PEEK, which would allow imaging through the worm. The locking screw would only need to be strong enough to prevent threaded gear sleeves from entering or leaving the device, and would not need to be strong enough to cause distraction. A larger radius transparent window could be formed by removing a part of the sides of the lower member on each side of the opening in the lower member along the length of the device, provided that the device retains a necessary amount of stiffness.

Referring now to Figures 2A and 2B, a preferred adjustment of the gear teeth 124, 134 of the threaded gear sleeves 120, 130 in the internal threaded portions 151, 152 of the second member 150 is shown. As the teeth of the gear 124, 134 are pushed into the internal threads 151, 152 of the second member 150 by the worm, the load between the teeth 124, 134 of the gear and the threads 151, 152 are balanced by the surfaces 163, 164 of support between the components, which results in the ability of the device 100 to distract a substantial load. This adjustment between the teeth 124, 134 of the gear and the internal threads 151, 152 may contrast with the adjustment shown in Figures 3A and 3B. In those figures, when the gear teeth 124 ', 134' of the threaded sleeves 120 ', 130' are pushed towards the internal threads 151 ', 152' of the second member 150 ', the force is not balanced with surfaces of support as in Figure 2B, but by force the internal threads 151 ', 152' are applied to the gear teeth 124 ', 134'. This can result in the teeth 124 ', 134' of the gear acting as a wedge and jamming against the internal threads 151 ', 152', which dramatically reduces the ability of the device to distract substantial loads and makes the device more friction sensitive between components. Optionally, a liquid or gaseous lubricant, such as silicon lubricant, can be used to reduce friction in the mechanism. The saline solution can also be used as a lubricant.

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It should be noted that although the threads depicted in the figures are all thyme threads in the form of protruding helical ribs, the "thread" for the purposes of the present invention may also refer to any other mechanism that translates rotational force into translational or longitudinal movement. . For example, in some embodiments, the threads may be composed of a recirculating or spiral bearing arrangement or any other low friction arrangement, such as cooperating magnets.

In one embodiment, the height of the device 100 between the support surfaces 102, 104 in the fully compressed configuration is 6.5 millimeters and the maximum fully distracted height is 12 millimeters, thus providing a large amount of distraction in relation to the initial height of the device. The maximum height is defined by the highest height at which the device can meet the dynamic compression, shear and torsion requirements for implantable intervertebral body fusion devices. Variables that determine this height include the width of the threaded gear sleeves, which is limited by the desired width of the device and the material from which the device is made. With respect to the material for the device, materials with greater fatigue performance allow the maximum height of the device to be higher even with a narrower width. In one embodiment, the device is made of titanium. The device can also be made of cobalt chrome, MP35N or PEEK, to increase the resistance characteristics or increase the radiolucent characteristics, depending on the material. X-ray transparency is a desirable property, since it allows imaging of the fusion bone through the device. In one embodiment, the device can be designed so that in the compressed configuration the threaded gear sleeves project through the support surface of the second member in order to provide an even greater amount of distraction. To accommodate the device in the implant, the openings configured to contain the protruding portions of the sleeves can be cut in the adjacent vertebral endplate.

Once distracted, the device 100 does not require a locking mechanism to maintain the desired height within the body. This is because, when pushed back, the device exhibits a very high transmission ratio that causes even the least friction in the system to overwhelm any amount of compression, torsion or shear load that can be applied to the device. In the dynamic shear, torsion and compression tests, the maximum amount in which the height of the device was modified was approximately 0.01 millimeters. The device 100, because the height can be maintained at any point along the threaded gear sleeves, therefore also exhibits a very high resolution height control, of the order of 1 micrometer.

In one embodiment, the external threads 121, 131 and the gear teeth 124, 134 in the threaded gear sleeves 120, 130 may be substantially trapezoidal. In one embodiment, the thread is a trapezoidal metric thread of 8 millimeters by 1.5 millimeters. A trapezoidal design allows a relatively large gear tooth size and, consequently, a larger area over which the distraction load is distributed. Additionally, with precise manufacturing, multiple gear teeth 124, 134 can be coupled to the threaded gear sleeves 120, 130 by means of the worm 140 at the same time along the angle of pressure ANG, as shown in Figures 4A and 4B. The distribution of the distraction load on multiple teeth of the sleeves 120, 130 and the endless screw 140 is critical to achieve the minimum size of the device while providing a maximum amount of distraction and load capacity.

In FIGS. 5A (compressed configuration) a delivery system 200 for implanting an intervertebral body fusion device is shown which can be separated according to an embodiment of the present invention, 5B (partially distracted configuration, and 5C (fully distracted configuration) ) The delivery system 200 also includes an actuation tool 300 to activate the distraction.

To distract the device 100, a hex 143 or 144 of the device is first connected to the supply system 200 through a socket controller at one end 201 of the supply axis 203. In order to more securely link the device 100 and the supply system 200, a threaded end 202 of the supply shaft 204 can be screwed into one of the threaded holes 156A or 156B in the second member 150 of the device 100. The device 100 can then be inserted into the body by a standard transforaminal lumbar intercorporal fusion (TLIF) or posterior lumbar interbody fusion (PLIF) procedure using the delivery system 200. A lateral intersomatic fusion through the lateral retroperitoneal corridor is another approach. The delivery system 200 can guide the location of the device 100 as it is inserted with the use of the handle 213.

The supply system 200 includes a hexagon 215 and a circumferential groove 214 at the near end of the supply shaft 204, and also has a hexagonal and circumferential groove (not shown) at the end of the supply shaft 203. Once the device 100 is in the disc space, the drive tool 300 can be connected to the supply system by coupling an internal hexagonal socket controller of the drive tool with the hexagon at the end of the supply shaft 203, 204. In some embodiments, an inner elastic ring or circumferential spring in the drive tool 300 may be coupled to the circumferential groove in the supply shaft 203 to ensure that the drive tool 300 does not accidentally disengage during use.

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By rotating the drive tool 300, the user transmits the torque through the supply shaft 203 to the endless thyme 140, which distracts the device 100. As the supply shaft 203 is rotated, a slider 206 advances as length of threads 209 on shaft 203. The height of the device 100 as it expands can be represented in the delivery system 200 by the position of the slider 206 along the supply axis 204 with fiducial marks 208, as best shown in Figure 5D. Marks 208 may be placed at any desirable range along supply axis 204, and slider 206 may include a viewing slot 207 for more complete viewing of marks 208 when reached by slider 206. In a embodiment, each mark 208 may represent a distracted height of 1 millimeter.

The delivery system 200 can be configured so that when the device 100 reaches its maximum desired height, the slider 206 stops with the stop 205 so that it cannot advance further, thereby limiting the height of the device 100. Allowing the system 200 supply limits the expansion, any damage due to excessive torque is immediately evident in the supply system 200, so that the device 100 is not damaged. In another embodiment, the device 100 may limit its own expansion. welding two of the gear teeth 124, 134 into one of the gear sleeves 120, 130 threaded together so that they are attached to the worm 140 when the device 100 has reached its maximum desired height. Similarly, in other embodiments, one or more of the gear teeth 124, 134 may be omitted or a small post may be inserted into the interstitial space between two gear teeth to limit the expansion of the device.

In one embodiment, a lever for applying a torque to the shaft 204 may be fixed to the hexagon 215 at the end of the shaft 204. The lever may be shaped and oriented so that when the device 100 is properly coupled with the supply system 200 , the position of the lever allows access to the drive shaft 203, while when the device is not properly coupled, the lever does not allow access to the drive shaft 203. In another embodiment, the slider 206 may be contained with the handle 213 to reduce the length of the delivery system 200. In another embodiment, a tube capable of supporting the torsional load around one of the axes 203, 204 can be implemented for increase the structural rigidity of the supply system. A small foot can be placed in the tube to further support the delivery system's ability to transport and transmit, torsionally loading to and from the device. In another embodiment, the axis of the supply system 200 may be curved or bayonet-shaped to allow viewing through a minimally invasive system and a working channel.

The drive tool 300 may include a recess or loop 304 that allows the user to rotate the drive tool 300 with a single finger and / or large grip surfaces 301 that the user can grasp to rotate the drive tool 300. In one embodiment, the loop may be coated with a slippery or support surface to allow the loop to easily rotate around the user's gloved fingers. The drive tool 300 may also include a large surface 303 designed to receive the impact of a hammer for implantation. The recesses 302 can also be included in the drive tool 300 to provide the user with an improved view of the device 100 while it is being implanted. The drive tool 300 may encompass both supply shafts 203, 204 and may extend over and / or receive the handle 213 of the supply system 200. In another embodiment, instead of being driven by the hand-operated tool 300, the device 100 may be driven by an electrically driven implement such as a pneumatic or electric drill or a motorized screwdriver mechanism, which, in some embodiments, may allow The tool is controlled remotely.

In other embodiments, the actuation tool, manual or automatic, employs sensors in the device to transmit data with respect to the implantation parameters and the environment, such as the device load and muscle tension, to an operator or operating system for improve the performance of the surgical procedure and the result. The delivery system 200 could use small voltage meters located in the device 100 and / or load cells attached to the delivery axes 203, 204 and actuation tool to measure the loads present during the implantation and distraction process. These meters and / or load cells could be monitored by a microcontroller board located in the delivery system 200 and the feedback information to a monitoring computer through a standard interface such as a USB or wireless connection. This information could be used to closely monitor the progress of a procedure, warn of impending problems and improve future procedures. If you do not have a complete bridge, the meters could be configured as a half bridge inside the device and completed outside the device. Standard signal conditioning amplifiers could be used to excite and condition the signal to produce a measurable voltage and current output.

In one embodiment, the device 100 may have a second reinforced member 150 as shown in Figures 6A and 6B. This can be done by lowering the opening of the endless screw 154, and therefore the endless screw 140, so that when the device 100 expands to its full height, the endless screw 140 engages with a full gear tooth 134A in the threaded gear sleeve 130 closest to the bottom 136 of the threaded gear sleeve 130. This allows an upper surface 166 of the second member 150 to be lowered, which allows the first member 110 to be thicker and, therefore, more resistant, while maintaining the same initial height, this allows the material 168 between the upper surface 166 of the second member 150 and the opening 154 of the worm becomes thicker. An additional advantage of this configuration is that at least

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A complete internal thread 152A of the second member 150 is coupled with the threaded gear sleeve 134 when the device is completely distracted. In such a configuration, an additional thickness 167 may be added to the side of the second member 150 opposite the opening of the endless screw 154 to what was previously described as the upper surface 166A of that side of the second member 150. This allows a complete internal thread 152B to engage the threaded gear sleeve 130 on the side opposite the internal thread 152A. By capturing the threaded gear sleeve with a full thread on both sides, when the device is loaded with shear and torsion, a maximum amount of material resists the load, which minimizes the resulting tension and increases the fatigue life of the device 100.

Figures 7A and 7B represent another embodiment of the present invention in which the threaded posts 111, 112 employ a reinforcing thread 113A, 115A (compare threads 113A in Figure 7B with threads 113, 115 in Figure 1D). A buttress thread configuration causes the thread face that supports the load to be perpendicular to the screw axis of the post 111, 112, which increases the axial resistance of the device. Figures 8A and 8B represent a further embodiment using a standard 113 degree thread, 115B, 115B on threaded posts 111, 112. 60 degree threads are considered industry standard and therefore can be created with common machining practices. This can result in a device that can be produced more quickly and economically.

Referring now to FIGS. 9A-9D, another embodiment of a fusion device 400 of the distractible intervertebral body includes a single pair of threaded gear posts 423 extending between the first member 410 and the second member 450 instead of the sleeves. 120, 130 separate threaded gear and threaded posts 111, 112 described above. The threaded gear posts 423 each include a threaded gear portion 421 and a pole portion 411. The threaded gear portions 421 fit inside the openings 461 in the second member 450 and interconnect with the endless screw 440 and the internal threads 451 to cause the device 400 to distract. The portions 411 of posts fit into the openings 416 in the first member 410 and can be attached to the washers 418. The washers 418 hold the first member 410 in position relative to the threaded gear posts 423 when the threaded gear posts 423 rotate freely independently of the first member 410 when the device 400 is operated. Therefore, as seen in Figures 9C and 9D, the distraction between the first member 410 and the second member 450 is caused by the thicker threaded gear portions 421 while the pole portions 411 remain inside the openings 416 in the first member 410. This leads to a device 400 that has an increased axial resistance.

Figures 10A-10D represent a further embodiment of a fusion device 500 of the distractible intervertebral body allowing differential adjustment of the threaded gear sleeves 520. The threaded posts 511 may each include an arcuate portion 515 corresponding to an arcuate recess 517 in the first member 510. The arched interface between the threaded posts 511 and the first member 510 created by the corresponding arcuate portions 515 and the arcuate recesses 517 allow the first member 510 to rotate and engage in relation to the second member 550. A pin joint can be used that it uses a pivot pin 572 to hold an interface fixed between the first member 510 and a threaded post 511, while the other interface may slide due to arcuate surfaces. A positioning pin 570 is used to prevent the screw 540 from leaving the second member 550 when the device is distracted. The worm 540 can be a two-part worm that includes a first portion 546 that has a first threaded section 543 and a second portion 548 that has a second threaded section 544 that fits a post 547 of the first portion 546. Therefore, the two parts 546, 548 can be rotated independently of each other, with each driving a separate gear sleeve 520. Because each threaded gear sleeve 520 can be coupled separately, different amounts can be distracted, resulting in a first angled member 510, as more clearly shown in Figure 10D. Such a configuration accommodates lordotic or kyphotic geometry. Optionally, the arcuate recesses 517 in the first member 550 and the arcuate surfaces 515 of the posts 511 could be replaced by bending joints or by ball joint or cylinder and bushing.

An intervertebral body fusion device 600 is shown in Figures 11A-11D which can be separated according to another embodiment of the present invention. The device 600 uses three coaxial helical gear sleeve mechanisms, each having a threaded gear sleeve 620 and a threaded post 621, between the first member 610 and the second member 650. As seen in Figures 11C and 11d, to distract the device, the worm drive 640 rotates and engages with one of the threaded gear sleeves 620, causing it to rotate. When the first threaded gear sleeve 620 rotates, it engages with the other two threaded sleeves 620, causing them to rotate and the device 600 distract. The rotation of the threaded gear sleeves 620 also causes the threaded posts 621 to distract, as described above. The use of three coaxial helical gear sleeve mechanisms provides a device that has increased resistance in the axial direction, a wider surface area to support the end plate of the vertebral body, and a more precise geometry. Optionally, each of the three distraction mechanisms could be activated independently to adjust the surface of the device to additional degrees of freedom. To achieve some geometries, the drive mechanisms may need to be flexible, in which case a spiral or spiral laser cutting drive mechanism capable of bending and transmitting the torque could be implemented. More specifically, one of those drive mechanisms could involve many

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distraction mechanisms and distract each one with a single entry. In another embodiment, a flexible drive mechanism could be useful for operating multiple drive mechanisms separately to control the members of the device in many spatial degrees.

Figures 12A and 12B depict a melting device 700 of the distractible intervertebral body that employs only a single coaxial screw gear mechanism having a threaded gear sleeve 720 and a threaded post 721 to distract the first member 710 from the second member 750 with screw 740 endless. The device 700 may also include first 774 and second 776 telescopic support elements. Telescopic support elements 774, 776 serve to maintain the relative rotating position of the first member 710 with respect to the second member 750, allowing the threaded gear sleeve 720 to rotate with respect to both the first member 710 and the second member 750 to distract the 700 device. Figures 13A and 13B represent a further variation of the device 700 using a plurality of pins 778 extending from the first member 710 and the second member 750 to rotationally restrict the first member 710 and the second member 750. In operation, the pins 778 contact the adjacent vertebral end plates and are fixed to the end plates to prevent the first member 710 and the second member 750 from rotating together. A further embodiment is shown in Figures 14A and 14B. This embodiment includes only a threaded gear sleeve 720 between the first member 710 and the second member 750 and allows the first member 710 to rotate with the sleeve 720 when the device 700 is distracted by rotating the endless screw 740. Optionally, the first member 710 could be free from rotation with respect to the threaded gear sleeve 720 so that the first member 710 engages and does not rotate against the end plate of the vertebral body.

In one embodiment, intervertebral body fusion devices that can be separated as described herein may be made of titanium and the delivery system may be made primarily of stainless steel. The components of each mechanism that slide against each other can be made of different types of general material. For example, the first member can be made of Ti 6A1 4V standard titanium, which has a high performance of mild fatigue, while threaded gear sleeves can be manufactured from Ti 6A1 4V ELI, which has a high fatigue performance in notches Such a combination results in each component being made of a preferred material for its fatigue notch factor, while the general mechanism implements different materials where the components are slidably arranged.

In various embodiments, the device is shaped to be ergonomic. The device can have various shapes, such as rectangular, kidney or soccer ball. A kidney or soccer device maximizes contact between the device and the vertebral bodies because the end plates of the vertebrae tend to be slightly concave. One or both ends of the device can also be narrowed to facilitate insertion. This minimizes the amount of force necessary to initially insert the device and separate the vertebral bodies. In addition, the device can be convex along its length and width, or bi-convex. The device can be constructed in various sizes depending on the type of vertebra and the size of the patient with which it is being used.

The device can be manufactured in various ways with, in some embodiments, different components of the device that can be manufactured in different ways. In one embodiment, the thread milling can be implemented to manufacture the various threads in the device. The electro eroded by thread can be used to make some or all of the holes and openings in the device. Assembly templates and post-processing steps can also be used to allow the device to be manufactured to the most demanding standards.

In some embodiments, after the distraction of the device, a bone growth stimulant, such as autograft, bone morphogenic protein, or bone enhancer material, can be administered in the device. In one embodiment, the bone growth stimulant is delivered through a hollow chamber in the insertion tool before the insertion tool is disengaged from the device. The device accepts loads in vivo during the time in which fusion occurs between the vertebral bodies.

In one embodiment, the surface of the device can be treated to minimize surface roughness or to reduce pitting of the material within the body. A rough surface or pitting may increase the tension in the device, which may cause shortening of the fatigue life and / or reduce fatigue resistance. In one embodiment, the surface can be treated with electro polishing, removing burrs from the edges of the device and finishing the surface. In another embodiment, the surface can be left untreated because a rough surface on the end plates helps prevent accidental extrusion of the device. In one embodiment, the device can also be coated with a highly elastic waterproof material to prolong its fatigue life. Specifically, the impermeable material would prevent the corrosive properties of the blood from degrading the device. In another embodiment, the device may be composed of a biocompatible material, so that no coating is necessary. In a further embodiment, the device may be made of a biodegradable material designed to degrade in the body at a selected stage of the healing process, such as after bone fusion.

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In various embodiments, the devices as described herein can be used with various bone growth stimulants. In one embodiment, a 3D premineralized silk fibroin protein scaffolding support can be transported on or onto the surface of the device to administer a bone morphogenetic protein (BMP), which can optionally be combined with modified bone marrow stromal cells ( bMSC) to improve fusion. In other embodiments, a composite chitosan 3D fiber mesh scaffold or a jelly frame can be used. The device can also use vascular endothelial growth factor (VEGF) by depositing immobilized VEGF on titanium alloy substrates coated with thin adherent polidopamine film to increase the binding, viability and proliferation of human dermal cells to promote the development of blood supply to the bone fused through revascularization around the implant. In some embodiments, certain polymers such as biodegradable PLGA could be used to make a framework for VEGF to enhance neovascularization and bone regeneration. In some embodiments, VEGF can be used together with BMP to inhibit the function of BMPs in promoting osteogenesis to allow the device to adjust continuously over time. In various embodiments, scaffolds in or around the device could be seeded with bone marrow derived stem cells, dental pulp derived stem cells and adipose tissue derived stem cells. Scaffolds can also be composed of various materials including polyester (for example, polylactic acid-co-glycolic acid or poly-3-hydroxybutuerate-co-3-hydorxivalerate), silk (for example, biomimetic, porous biomaterial coated with apatite based on silk fibroin scaffolds), hydrogels such as polycaprolactone, polyepsiloncaprolactone / collagen (mPCL / Col) cospun with PEO or gelatin, mPCL / Col meshes with micron-sized fibers, and mPCL / Col microfibers reified with Heprasil, and porous titanium and titanium alloys (such as a titanium-niobium-zirconium alloy) functionalized by a variety of surface treatments, such as a coating of VEGF or calcium phosphate.

In some embodiments, the device may include a structure adapted to retain bone within or adjacent to the implant. Said structure may include a micron level matrix or scaffolds or slots, divots or other similar features in the body of the device. The bone can also be retained by using a porous material such that the bone is retained in the interstitial spaces of the material. You can also implement more extensive and extensible functions. Such features, such as a circumferential cover, could also have the additional function of tightening the device in torsion.

In some embodiments, more than one fusion device of the distractible intervertebral body according to the present invention can be implanted in the disc space. As shown in Figure 15, in one embodiment, a pair of devices 100 can be implanted in such a way that the outer surface 104 of the second member 150 of one of the devices 100 interacts directly with the outer surface 102 of the first member 110 of the another device 100. Such a configuration may allow the use of a smaller access channel to implant the devices. In one embodiment, the cooperating surfaces 102, 104 of the two devices are flat. The devices 100 can be activated simultaneously or separately. The devices could also be turned relative to each other to have both centrally located drive mechanisms. In addition, the devices could be configured to rotate or flex with respect to each other to allow the support surfaces of the devices to adjust their position to fit comfortably with the end plates of the vertebral bodies, or to preserve the movement of the spine .

In one embodiment, a rod and screws can be used with the device as part of an assembly attached to the vertebral body. Specifically, the posterior fixation, in which the rods and screws are used to complement the spine, can be used in combination with the device. In one embodiment, the rod (s) and screws may be fixed to, or designed to be coupled, to the implant. In another embodiment, the device members may extend and, in fact, bent over the sides of the adjacent vertebral bodies so that the device can be fixed to the vertebral bodies with screws placed through the extensions of the substantially parallel device members to the plane formed by the end plates of the vertebral bodies. In other embodiments, an adhesive, which can support osteogenesis, can be used to adhere the device to or within the column.

In another embodiment, the intervertebral body fusion device that can be distracted may comprise a terminal plate reinforced with flexures to be able to lean from front to back and / or from side to side. Additionally, coaxial helical gear sleeve mechanisms that use at least part of a flexible material can be oriented around the periphery of the device to allow tilt in a variety of axes. Generally, a device capable of tilting can be beneficial since providing additional degrees of flexibility incorporated in the device can promote bone growth, distribute stress on the surface of the endplates and allow the device to adjust to the curvature of the spine. vertebral of an individual.

In one embodiment, the device could be placed inside a small sock similar to a sock made, for example, of silk, which could be filled with bone. As the device expands and the volume of the device increases, the sock would prevent the bone from falling out of the implant and / or allow more bone to be introduced into the implant from the space around the implant inside the sock. Such a sock could be closable at one end.

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and could join the delivery system during device implantation. The sock could be released from the delivery system during any of the subsequent steps of implantation.

A device according to the various embodiments can be used for a variety of intervertebral fusion applications, including, for example, cervical, lumbar anterior thoracic, lumbar transforaminal, lumbar lateral end and lumbar posterior. Several embodiments of the implementation procedures for these applications may be the following:

Cervical: the device is implanted by an anterior approach at levels C3 to C7 using autograft. The device is used with supplementary anterior plate fixation

Lumbar transforaminal: the device is implanted by a posterior approach from levels L2 to S1 using autograft. The device is used with a supplementary rear rod fixation.

Posterior lumbar: the device is implanted by a posterior approach from levels L2 to S1 using autograft. Two devices are implanted; one on the left side of the disk space and the other on the right side of the disk space. The device is used with a supplementary rear rod fixation.

Anterior lumbar: the device is implanted by an anterior approach from levels L3 to S1 using autograft. The device is used with complementary anterior plate fixation of posterior rod fixation.

Lateral lumbar end: the device is implanted by a lateral approach from levels T12 to L4 using autograft. The device is used with a supplementary rear rod fixation.

In another embodiment, the device can be used in replacement of the vertebral body. After resection of a vertebral body or multiple vertebrae due to a fracture or tumor, the device can be distracted to join two separate vertebrae. The distracted device joins and supports the vacuum that remains after resection. The device can be constructed in different sizes to accommodate the difference in size of the cervical, thoracic and lumbar vertebrae.

In another embodiment, the device can be used as an interspinous distraction device as shown in Figures 16A and 16B. The device 800 can be placed between two adjacent spiny processes 801a, 801b through a minimum access system. The device can be inserted in a contracted configuration to facilitate placement. Once in position, the device can be operated in an expanded configuration with coaxial helical gear sleeve mechanisms 804 to block the vertebrae in a distracted position. Coaxial helical gear sleeve mechanisms 804 can be configured as previously described herein. The device may have gripping teeth 800 at the point of contact with spinous processes 801a, 801b to help fix it in place.

In another embodiment, the device can be used for interspinous fusion. The device can be placed between two adjacent spiny processes through a minimum access system in a collapsed configuration. Once in position, the device can be activated to block the vertebra in a distracted position. The device may have a bolt locking mechanism or a similar locking arrangement to lock the device in the distracted position and to block the locking plates through the spinous processes. The device may also have grip corrugations or features on the outside to help keep it in place. The autograft or bone fusion material can be placed in the open space in the device.

In another embodiment, the device can be used as a distractible fracture reducing device for osteoporotic bone. The device can be inserted under a fracture of the end plate through a minimally invasive pedicle approach. The device is then operated with an actuator of the delivery system. Once the fracture is reduced, the device is explanted and the vacuum is filled with acrylic cement or other bone filler that will strengthen the bone.

In another embodiment, the device can be used as a replacement for facet joint. After resection of a hypertrophic facet joint, the device can be activated. Each member can be attached to adjacent vertebrae with a pedicle screw. This will allow a movement similar to that of a facet joint and avoid instability. The device can be part of a soft fusion device system and can be used in combination with an intervertebral disc replacement device. The coaxial helical gear sleeve or threaded post mechanism can also be used to expand intervertebral disc replacement devices.

In another embodiment, the device can be used as a programmable distraction cage with a dynamizer and bone stimulator. A programmable micro machine actuator device can be implanted within the device. The device is distracted during implantation and can provide force readings through a radio frequency communicator after surgery. The shape of the device can be altered while implanted by distracting the limbs with the actuator device, which can cause lordosis, kyphosis, increased

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distraction or less distraction. In one embodiment, a battery device feeds the system and can also form a magnetic field that functions as a bone stimulator. The battery life may be limited to a short period of time, such as a week. Small movements of the device can be used to generate electric power with piezoelectric or conductive polymers that can be used to recharge batteries, capacitors or other energy storage devices. Alternatively, the device can be powered through an inductive RF arrangement or capacitively coupled.

In another embodiment, the device may be a self-active distraction cage. The device can be inserted into disk space in a collapsed state. Once the device is released, it can slowly distract at a preset height

In another embodiment, the device can be used in maxillary facial surgery as a fracture lengthening device for mandibular fractures. The device can be designed with narrow members that have perpendicular plates with holes that allow each member to be attached to a proximal or distal fracture. The device can be operated at a preset height. This will allow the lengthening of the defect in cases of bone loss due to fracture, dysplasia or hypoplasia.

In another embodiment, the device can be used in orthopedic applications such as an extension nail for the distraction of fractures of long bones. After an orthopedic fracture with bone loss occurs, an elongated nail can be placed that can be distended to lengthen the bone. Elongation occurs for a few days with micrometric movements. This application will involve a distraction device inserted between the mobile part of the nails that exerts counterdiscipline forces, which will provide a lengthening of the bone.

In another embodiment, the device can be used to replace the phalangeal joints in the hand, the metatarsal joints in the foot or the calcaneus-astragaline joints. These joints may have implants that will allow the movement of adjacent bones and limit hyperextension or hyperflexion.

Figures 17A and 17B depict a distractible device 900 that includes a coaxial coiled helical gear sleeve with recirculating bearings in accordance with another embodiment of the present invention. The device 900 includes a post 910, a sleeve 920 of coaxial helical wraparound gear, a worm 930 and a casing 940. The post 910 includes a smooth outer surface 912 and a channel 911 of mechanized helical rolling for the bearings 913. 8 A helical raceway (not shown) is also machined on the inner surface of the coaxial helical sleeve 920 which is complementary to the helical raceway 911 to accommodate the bearings 913. The inner surface of the coaxial helical sleeve 920 also It includes a mechanized tunnel for the recirculation of bearings 913 as the post 910 moves with respect to the sleeve 920. Recirculation bearings are shown as bearings 914 in Figure 17B. The outer surface of the coaxial worm gear sleeve also includes a helical raceway 921 for recirculating the bearings 914 and a worm gear 922. The worm 930 has a helical thread configured to be applied to the screw gear 922 of the sleeve 920. The inner surface of the housing 940 has a helical raceway (not shown) that cooperates with the helical raceway 921 to retain the bearings 914 and a tunnel to recirculate the bearings 914 when the coaxial helical gear sleeve 920 moves with with respect to the housing 940. Optionally, the coaxial helical gear sleeve 920 could have recirculation bearings both inside and outside the sleeve and the recirculation tunnel could be between the inside and outside of the sleeve, facilitating assembly and manufacturing.

To expand the device 900, the endless screw 930 rotates clockwise to engage the wraparound gear 922 to rotate and move the coaxial helical sleeve 920 casing out of the housing 940. This simultaneously causes that the post 910 is translated (but does not rotate) out of the coaxial helical gear sleeve 920 and away from the housing 940. The bearings 913, 914 allow the rotation of the sleeve 920 of coaxial helical gear wrap with very little friction, which allows the device 900 to have a very high mechanical advantage and a displacement control with a very high resolution. The use of the enveloped threaded gear 922 allows the interface between the worm 930 and the coaxial helical sleeve 920 to carry a substantially larger load.

Referring now to Figures 18A-18D, another distractible device 1000 can be seen that uses a coaxial helical gear sleeve according to an embodiment of the present invention. The device 1000 includes a coaxial coaxial helical gear 1010, a housing 1020 and an endless screw 1030. The outer surface of the coaxial coaxial helical gear sleeve 1010 includes a helical groove having a series of coaxial helical gear teeth 1014. The helical groove can cooperate with an internal thread 1021 on the inner surface 1022 of the housing 1020 to allow the device 1000 to carry an axial load. In another embodiment, the gear teeth 1014 can be machined directly on the outer surface of the coaxial helical gear sleeve 1010. In one embodiment, the outer surface of the coaxial helical gear sleeve 1010 may be a smooth machined surface that acts as a support surface when configured with a similar smooth support surface on the inner surface 1022 of the housing 1020 to allow The device 1000 carries a lateral load.

To expand the device 1000, the endless thyme 1030 is rotated to engage the teeth 1014 of the coaxial worm gear to rotate and translate the coaxial helical gear sleeve 1010 with respect to the housing 1020. In one embodiment, the surface Internal 1010 and central hole 1012 may be configured to contain a post similar to post 910 described in Figures 17A and 17B to compose the distraction 5 of the device. In one embodiment, there is no thread 1021 present on the inner surface 1022 of the housing 1020, so that the helical groove and / or the gear teeth 1014 of the coaxial coaxial screw gear sleeve 1010 cause the sleeve 1010 to be translated with with respect to the housing 1030 as the sleeve 1010 rotates. In such a configuration, the endless screw 1030 would carry any axial load, without the help of an inclined interface between the coaxial helical sleeve 1010 and the casing 1020.

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Various embodiments of systems, devices and methods have been described herein. These embodiments are given by way of example only and are not intended to limit the scope of the present invention. It should also be appreciated that the various features of the described embodiments can be combined in various ways to produce numerous additional embodiments. In addition, although various materials, dimensions, shapes, implantation locations, etc. have been described. for use with the described embodiments, others can be used in addition to those described, without exceeding the scope of the invention.