Deployment system and method for an expandable vertebral implant

Embodiments of the invention include expandable implants incorporated into a system for deploying the expandable implants to replace skeletal structures such as one or more vertebrae or portions of the spine or vertebrae. Some embodiments include related methods of implanting devices using deployment systems.

FIELD OF THE INVENTION

The present invention relates generally to the field of replacing portions of the human structural anatomy with medical implants, and more particularly relates to an expandable implant incorporated into a system for deploying the expandable implant to replace skeletal structures such as one or more vertebrae or portions of the spine or vertebrae.

BACKGROUND

Expandable medical implants are often useful at least because the implants may be introduced into a surgical site with a reduced profile that facilitates reduced disruption of surrounding tissues. Expandable medical implants may be useful in at least some spinal fusion procedures and in at least some vertebral body replacement procedures. Spinal fusion procedures are often effective to restore proper vertebral spacing and relieve pressure on nerves and consequent pain. Also, it is sometimes necessary to remove one or more vertebrae, or a portion of the vertebrae, from the human spine in response to various pathologies. For example, one or more of the vertebrae may become damaged as a result of tumor growth, or may become damaged by a traumatic or other event. Removal, or excision, of a vertebra may be referred to as a vertebrectomy. Excision of a generally anterior portion, or vertebral body, of the vertebra may be referred to as a corpectomy. An implant is usually placed between the remaining vertebrae to provide structural support for the spine as a part of a corpectomy or vertebrectomy. This may generally be referred to as vertebral body replacement.

Many prior art devices have deployed expandable medical implants with the aid of relatively large or complex insertion, expansion, distraction, and retraction instruments. Some devices require a significant incision and retraction of tissue to enable controlled expansion of the implant. A smaller incision may be particularly useful with a posterior approach to the spine. To effectively make a posterior approach, an implant may be placed through a window created between a nerve root, the spinal cord, and an extent of an excised vertebra. The nerve root may be mobilized to increase the size of the window slightly, but excess movement may risk damage to the nerve root. Therefore, for a posterior approach, an initially small expandable implant may have particular utility. A posterior approach may be preferred for patients with circumferential tumors or for patients more susceptible to the risks associated with a more extensive anterior approach. Similarly, initially small implants enabling minimal tissue disruption may be useful from any surgical approach to reduce trauma to surrounding tissues and to enhance patient recovery. Likewise, a deployment mechanism that does not require tissue disruption beyond the disruption required to introduce an implant is advantageous.

Connections between bones and implants may also be useful in replacing bones or portions of joints or appendages such as the legs and arms, or other bones. Examples include, but are not limited to, a femur, tibia, fibula, humerus, radius, ulna, phalanges, clavicle, and any of the ribs. Use of the mechanisms described and claimed herein are equally applicable to treatment or repair of such bones or appendages.

SUMMARY

One embodiment of the invention is a system for deploying an expandable medical implant. The expandable medical implant may include a base and an expandable end and an enclosed volume between the base and the expandable end. The expandable medical implant may also include an elongated member with a distal end and a proximal end. The distal end is coupled to the expandable end of the expandable medical implant, and the elongated member is in contact with the base of the expandable medical implant to provide a connection between the expandable end and the base. The proximal end extends from the expandable implant and the proximal end is configured to receive a force applied along its length.

An embodiment of the invention is a method of implanting an expandable medical implant. The method may include providing an expandable medical implant with a base and an expandable end and an enclosed volume between the base and the expandable end, and an elongated member with a distal end and a proximal end wherein the distal end is coupled to the expandable end of the expandable medical implant and the elongated member is in contact with the base of the expandable medical implant. The method may also include introducing the expandable medical implant through an incision in a patient, and applying a compressive force to the elongated member to push apart the base and the expandable end of the expandable medical implant.

Another embodiment of the invention is a method of implanting an expandable medical implant. The method may include providing an expandable medical implant with a base and an expandable end and an enclosed volume between the base and the expandable end, and an elongated member with a distal end and a proximal end. The distal end is coupled to the expandable end the expandable medical implant and the elongated member are in contact with the base of the expandable medical implant. The method may also include applying a tensile force to the elongated member to pull together the base and the expandable end of the expandable medical implant, introducing the expandable medical implant through an incision in a patient, and releasing the tensile force applied to the elongated member to allow the base and the expandable end of the expandable medical implant to separate.

DETAILED DESCRIPTION

FIG. 1illustrates a system100for deploying an expandable medical implant1. The expandable medical implant1includes a base2and an expandable end3. The illustrated expandable medical implant1includes a membrane5and an expansion mechanism6. The expansion mechanism6shown inFIG. 1is a bellows. The expansion mechanism of other embodiments may be, without limitation, a combination of nested, telescoping cylinders, as illustrated inFIGS. 6-9, a ratchet mechanism, a threaded or partially threaded mechanism, or any other mechanism that may drive or hold expansion of an expandable medical implant.

The membrane5is illustrated in a partially expanded configuration inFIG. 1. The membrane5of some embodiments is configured to be placed between vertebrae and expanded such that an upper surface52contacts a first vertebra and an opposite lower surface53contacts a second vertebra to provide support between the vertebrae. The longitudinal axis, or linear expansion direction L, of the expandable medical implant1is illustrated inFIG. 1. Lateral expansion of the membrane5is also accomplished in some embodiments. As used herein, the term lateral means directions approximately normal to the linear expansion direction L.

The membrane5may be constructed, in whole or in part, of a non-permeable material. The membrane5may include compliant or non-compliant balloon materials such as those commonly used to manufacture coronary and Kyphoplasty medical devices. Such materials may include, but are not limited to, mylar, rubber, polyurethane, vinyl, latex, polyethylenes, ionomer, and polytetrapthalate (PET), as well as less flexible materials such as Kevlar®, PEBAX®, stainless steel, titanium, nickel-titanium alloys, and other metals and alloys and/or ceramics. A compliant membrane may include reinforcing to limit one or both of the size and shape of the membrane to a clinically advantageous extent. A non-compliant membrane may expand more elastically to more completely fill an irregular opening, depending on the amount of material introduced into the membrane.

Likewise the membrane5may be constructed, in whole or in part, of a permeable material, which allows a certain amount of a fill material to pass through the membrane5. All or a portion may be made permeable by fabricating a material, including but not limited to, the membrane materials listed above, into a fabric, weave, mesh, composite, bonded fiber assembly, or any other manufacture known to those skilled in the art. For example, all or part of the upper surface52and the opposite lower surface53may be constructed of a permeable material to allow fill material to move through the membrane5and to come into contact with vertebrae.

In the embodiment shown inFIG. 1, the expansion mechanism6defines an enclosed volume, and the membrane5defines an enclosed volume that incorporates the enclosed volume of the expansion mechanism6. The enclosed volumes of both the expansion mechanism6and the membrane5are therefore volumes between the base2and the expandable end3.

The system100for deploying an expandable medical implant1shown inFIG. 1includes an elongated member101with a distal end103and a proximal end102. The illustrated distal end103is coupled to the expandable end3of the expandable medical implant1. The elongated member101is in contact with the base2of the expandable medical implant1at a point8to provide a connection between the expandable end3and the base2. The proximal end102extends from the expandable implant1inFIG. 1through an opening or port7. The illustrated connection between the expandable end3and the base2with the elongated member101is a sliding connection because the elongated member101slides relative to the base2when the elongated member is removed from or pushed into the port7.

The proximal end102is configured to receive a force applied along its length. Arrow105shows the direction of a pushing or compressive force applied along the length of the elongated member101at its proximal end102. Arrow107shows the direction of a pulling or tensile force applied along the length of the elongated member101at its proximal end102. In other embodiments where the elongated member101is actuated by an alternative mechanism, the force applied to the elongated member101may be a twisting, winding, turning, or other effective force to push apart or pull together the base2and the expandable end3. For example, and without limitation, the elongated member101may include threaded portions, turnbuckle portions, fasteners, or multiple members that move relative to one another to lengthen or shorten the elongated member101. In some embodiments, the elongated member101is a wire, rod, or other relatively rigid device that is capable of transmitting both tensile and compressive forces to either or both pull together or push apart the base2and the expandable end3. In other embodiments where it is only necessary to pull together the base2and the expandable end3, the elongated member101may be a strand, string, rope, cable, or other member configured primarily to transmit tensile forces.

In some embodiments, elasticity in the material of the expansion mechanism6may serve as a biasing force to bias the expansion mechanism6toward an expanded or unexpanded state, as may be advantageous in various circumstances. For example, it may be advantageous to bias the expansion mechanism6toward an unexpanded state to provide a low profile device for insertion. Other devices, such as but not limit to the elongated member101, or a fluid injected through the port7, may be used to expand the expansion mechanism6. A fluid that drives linear expansion of the expandable medical implant1or maintains linear expansion of the expandable medical implant1may be introduced through the port7. The fluid may be merely for expansion and retention, or may be a component of a fill material intended to remain in the expansion mechanism6. As used in association with this function, a fluid may be a paste, gel, liquid, suspension, granular mixture, or similar substance. A substance as described herein will be considered a fluid even if it later cures or hardens to a non-fluidic state. Both the expansion mechanism6and the membrane5may be initially unexpanded linearly. The port7may also be used to handle the expandable medical implant1or to guide the implant into a position where it can be effectively deployed.

In other circumstances, it may be preferred to bias the expansion mechanism6toward an expanded state. With such an embodiment, another component, such as but not limit to the elongated member101, may be used to keep the expansion mechanism6in an unexpanded state while the expandable medical implant1is inserted. Following insertion, the expansion mechanism6may be released and allowed to increase toward its expanded state by releasing the elongated member101relative to the base2.

FIGS. 2-5show components of a system for deploying an expandable medical implant11. The expandable medical implant11includes a base12and an expandable end13. The illustrated expandable medical implant1includes an expansion mechanism16(FIGS. 2 and 4) and a stabilizing structure9(FIGS. 3 and 5). The expansion mechanism16is removed fromFIGS. 3 and 5to clearly show the stabilizing structure9. The expansion mechanism16shown is a bellows, but the expansion mechanism of other embodiments may be, without limitation, a telescoping mechanism, a ratchet mechanism, a threaded or partially threaded mechanism, or any other mechanism that may drive or hold expansion of an expandable medical implant. The embodiment ofFIGS. 2-5does not show a membrane such as the membrane5illustrated inFIG. 1, but other embodiments may include a membrane of a similar type in cooperation with the expandable medical implant11.

The stabilizing structure9is illustrated inFIG. 3with the expandable medical implant11in an unexpanded state, and inFIG. 5with the expandable medical implant11in an expanded state. Superior fingers91are spaced apart to create superior channels92among the superior fingers91. Inferior fingers93are spaced apart to create inferior channels94among the inferior fingers93. In operation, the inferior fingers93slide in the superior channels92, and the superior fingers91slide in the inferior channels94to maintain a substantially linear expansion of the expandable medical implant1while the base12and the expandable end13are moved toward or away from each other. In the embodiment shown, the stabilizing structure9is within the enclosed volume between the base and the expandable end. However, in other embodiments, the stabilizing structure may be outside of the enclosed volume.

The system for deploying an expandable medical implant11shown inFIGS. 2-5includes an elongated member101with a distal end103and a proximal end102(FIG. 5). The illustrated distal end103is coupled to the expandable end13of the expandable medical implant11. The elongated member101is in contact with the base12of the expandable medical implant11at least within the port17to provide a connection between the expandable end13and the base12. The proximal end102extends from the expandable medical implant11through a port17. The illustrated connection between the expandable end13and the base12with the elongated member101is a sliding connection because the elongated member101slides relative to the base12when the elongated member101is removed from or pushed into the port17.

The proximal end102is configured to receive a force applied along its length. Arrow105shows the direction of a pushing or compressive force applied along the length of the elongated member101at its proximal end102. Arrow107shows the direction of a pulling or tensile force applied along the length of the elongated member101at its proximal end102. In other embodiments where the elongated member101is actuated by an alternative mechanism, the force applied to the elongated member101may be a twisting, winding, turning, or other effective force to push apart or pull together the base12and the expandable end13. The character and function of the elongated member101is essentially similar to the character and function described in association withFIG. 1.

In some embodiments, elasticity in the material of the expansion mechanism16may serve as a biasing force to bias the expansion mechanism16toward an expanded or unexpanded state, as may be advantageous in various circumstances. The character and function of the expansion mechanism16and biasing of the expansion mechanism16are essentially similar to the character and function described in association withFIG. 1.

FIGS. 2-5illustrate nozzles14extending from the expandable medical implant11. The illustrated nozzles14are open to the interior of the expandable medical implant11. In some embodiments, a balloon (not shown) may extend from an open, distal end of the nozzles14. The balloon may be in fluid communication with the interior of the expandable medical implant11. The nozzles14and balloons of some embodiments are configured to extend from expandable medical implant11and into an endplate of an adjacent vertebra. The balloons may be filled with a material, such as a flowable material, to assist in attachment of the expandable medical implant11to the adjacent vertebrae. One or both of the flowable material and the balloons may additionally have a therapeutic effect on the vertebrae. For example, and without limitation, the nozzles14, the flowable material, and the balloons, alone or in combination, may help to stabilize the vertebrae. The flowable material passed through the nozzles14or used to inflate the balloons may be a curable material or may be a material that is used to expand the balloons, but does not cure in place. Once expanded, the balloons may also receive additional materials that permanently fill the balloons, or that have an additional therapeutic effect on the vertebrae. Any of the materials for use through the nozzles14or in the balloons may also be a fill material as described in detail below. In addition to the nozzles14or balloons, one or both ends of an embodiment of the expandable medical implant11my include teeth, spikes, ridges, indentations, roughening, knurling, or any other device for enhancing fixation between a vertebra and the expandable medical implant11.

FIGS. 6 and 7illustrate a system200for deploying an expandable medical implant21. The expandable medical implant21includes a base22and an expandable end23. The illustrated expandable medical implant21includes a membrane25and telescoping cylinders26. Rather than the telescoping cylinders26of the illustrated embodiment, other embodiments may be, without limitation, a bellows, a ratchet mechanism, a threaded or partially threaded mechanism, or any other mechanism that may drive or hold expansion of an expandable medical implant.

The telescoping cylinders26and membrane25are illustrated in an unexpanded state inFIG. 6, and in an expanded state inFIG. 7. The membrane25of some embodiments is configured to be placed between vertebrae and expanded such that an upper surface252contacts a first vertebra and an opposite lower surface253contacts a second vertebra to provide support between the vertebrae. The longitudinal axis, or linear expansion direction L, of the expandable medical implant21is illustrated inFIG. 7. Lateral expansion of the membrane25is also accomplished in some embodiments. As used herein, the term lateral means directions approximately normal to the linear expansion direction L.

The membrane25may be constructed, in whole or in part, of a non-permeable material or of a permeable material, which allows a certain amount of a fill material to pass through the membrane25. The membrane25may include compliant or non-compliant balloon materials such as those commonly used to manufacture coronary and Kyphoplasty medical devices. These and other operable materials are essentially similar to the materials described in association withFIG. 1above.

In the embodiment shown inFIGS. 6 and 7, telescoping cylinders26along with the base22and expandable end23define an enclosed volume. The membrane25defines an enclosed volume that incorporates the enclosed volume of the telescoping cylinders26along with the base22and expandable end23. The enclosed volumes of both the telescoping cylinders26along with the base22and expandable end23, and the membrane25are therefore volumes between the base22and the expandable end23.

The system200for deploying an expandable medical implant21shown inFIGS. 6 and 7includes an elongated member101with a distal end103and a proximal end102. The illustrated distal end103is coupled to the expandable end23of the expandable medical implant21. The elongated member101is in contact with the base22of the expandable medical implant21at a point28to provide a connection between the expandable end23and the base22. The proximal end102extends from the expandable implant21inFIG. 7through an opening or port27. The illustrated connection between the expandable end23and the base22with the elongated member101is a sliding connection because the elongated member101slides relative to the base22when the elongated member is removed from or pushed into the port27.

The proximal end102is configured to receive a force applied along its length. Arrow105shows the direction of a pushing or compressive force applied along the length of the elongated member101at its proximal end102. Arrow107shows the direction of a pulling or tensile force applied along the length of the elongated member101at its proximal end102. In other embodiments where the elongated member101is actuated by an alternative mechanism, the force applied to the elongated member101may be a twisting, winding, turning, or other effective force to push apart or pull together the base22and the expandable end23. For example, and without limitation, the elongated member101may include threaded portions, turnbuckle portions, fasteners, or multiple members that move relative to one another to lengthen or shorten the elongated member101. In some embodiments, the elongated member101is a wire, rod, or other relatively rigid device that is capable of transmitting both tensile and compressive forces to either or both pull together or push apart the base22and the expandable end23. In other embodiments where it is only necessary to pull together the base22and the expandable end23, the elongated member101may be a strand, string, rope, cable, or other member configured primarily to transmit tensile forces.

It may be advantageous to bias the telescoping cylinders26toward an unexpanded state to provide a low profile device for insertion. Other devices, such as but not limit to the elongated member101, or a fluid injected through the port27, may be used to expand the telescoping cylinders26. A fluid that drives linear expansion of the expandable medical implant21or maintains linear expansion of the expandable medical implant21may be introduced through the port27. The fluid may be merely for expansion and retention, or may be a component of a fill material intended to remain in the telescoping cylinders26. As used in association with this function, a fluid may be a paste, gel, liquid, suspension, granular mixture, or similar substance. A substance as described herein will be considered a fluid even if it later cures or hardens to a non-fluidic state. Both the telescoping cylinders26and the membrane25may be unexpanded linearly. The port27may also be used to handle the expandable medical implant21or to guide the implant into a position where it can be effectively deployed.

In other circumstances, it may be preferred to bias the telescoping cylinders26toward an expanded state. With such an embodiment, another component, such as but not limit to the elongated member101, may be used to keep the telescoping cylinders26in an unexpanded state while the expandable medical implant21is inserted. Following insertion, the telescoping cylinders26may be released and allowed to increase toward its expanded state by releasing the elongated member101relative to the base22.

FIGS. 8 and 9show a specific embodiment that also includes a spring39that may server as a biasing member to bias a telescoping cylinder36toward either an unexpanded or expanded state. The spring39is shown in elevation view, although the expandable medical implant31is shown in cross-sectional view. The embodiment ofFIGS. 8 and 9is similar to the embodiment ofFIGS. 6 and 7, but includes the spring39to bias the telescoping cylinder36, particular adaptations to accommodate the spring39, and one telescoping cylinder36along with a base32and an expandable end33, rather than two telescoping cylinders26as are shown in the embodiment ofFIGS. 6 and 7.

The adaptations to accommodate the spring39include a shoulder34against which the spring39may push or pull, depending on whether the spring is biased toward an expanded or unexpanded state. It may be advantageous to bias the telescoping cylinder36toward an unexpanded state to automatically provide a low profile device for insertion. Other devices, such as but not limit to the elongated member101, or a fluid injected through the port37, may be used to expand the telescoping cylinder36. A fluid that drives linear expansion of the expandable medical implant31or maintains linear expansion of the expandable medical implant31may be introduced through the port37. The fluid may be merely for expansion and retention, or may be a component of a fill material intended to remain in the telescoping cylinder36. As used in association with this function, a fluid may be a paste, gel, liquid, suspension, granular mixture, or similar substance. A substance as described herein will be considered a fluid even if it later cures or hardens to a non-fluidic state. Both the telescoping cylinder36and the membrane35may be initially unexpanded linearly. The port37may also be used to handle the expandable medical implant31or to guide the implant into a position where it can be effectively deployed.

In other circumstances, it may be preferred to bias the telescoping cylinder36toward an expanded state. With such an embodiment, another component, such as but not limit to the elongated member101, may be used to keep the telescoping cylinder36in an unexpanded state while the expandable medical implant31is inserted. Following insertion, the telescoping cylinder36may be released and allowed to increase toward its expanded state by releasing the elongated member101relative to the base32.

FIG. 10illustrates a system400for deploying an expandable medical implant41. The expandable medical implant41includes a base42, an expandable end43, and an opposite expandable end44that extends from the base42in a direction opposite from the expandable end43. The illustrated expandable medical implant41includes a membrane45and an expansion mechanism46. The expansion mechanism46shown inFIG. 10is a pair of bellows that extend in two directions away from the base42. The expansion mechanism of other embodiments may be, without limitation, a combination of nested, telescoping cylinders, a ratchet mechanism, a threaded or partially threaded mechanism, or any other mechanism that may drive or hold expansion of an expandable medical implant.

The membrane45is illustrated in a partially expanded configuration inFIG. 10. The membrane45of some embodiments is configured to be placed between vertebrae and expanded such that an upper surface454contacts a first vertebra and an opposite lower surface453contacts a second vertebra to provide support between the vertebrae. The longitudinal axis, or linear expansion direction L, of the expandable medical implant41is illustrated inFIG. 10. Lateral expansion of the membrane45is also accomplished in some embodiments. As used herein, the term lateral means directions approximately normal to the linear expansion direction L.

The membrane45may be constructed, in whole or in part, of a non-permeable material or of a permeable material, which allows a certain amount of a fill material to pass through the membrane45. The membrane45may include compliant or non-compliant balloon materials such as those commonly used to manufacture coronary and Kyphoplasty medical devices. These and other operable materials are essentially similar to the materials described in association withFIG. 1above.

In the embodiment shown inFIG. 10, the expansion mechanism46defines an enclosed volume, and the membrane45defines an enclosed volume that incorporates the enclosed volume of the expansion mechanism46. The enclosed volumes of both the expansion mechanism46and the membrane45are therefore volumes between the base42and the expandable end43.

The system400for deploying an expandable medical implant41shown inFIG. 10includes an elongated member101with a distal end103and a proximal end102. The illustrated distal end103is coupled to the expandable end43of the expandable medical implant41. The elongated member101is in contact with the base42of the expandable medical implant41at a point48to provide a connection between the expandable end43and the base42. The proximal end102extends from the expandable implant41inFIG. 10through an opening or port47. The illustrated connection between the expandable end43and the base42with the elongated member101is a sliding connection because the elongated member101slides relative to the base42when the elongated member is removed from or pushed into the port47. The expandable medical implant41shown inFIG. 10additionally includes an opposite elongated member111with a distal end113and a proximal end112. The illustrated distal end113is coupled to the opposite expandable end44of the expandable medical implant41. The opposite elongated member111is in contact with the base42of the expandable medical implant41at a point49to provide a connection between the opposite expandable end44and the base42. The proximal end112extends from the expandable implant41inFIG. 10through the port47. The illustrated connection between the opposite expandable end44and the base42with the opposite elongated member111is a sliding connection because the opposite elongated member111slides relative to the base42when the elongated member is removed from or pushed into the port47.

The proximal end112of the illustrated embodiment is configured to receive a force applied along its length. Arrow105shows the direction of a pushing or compressive force applied along the length of the elongated member111at its proximal end112. Arrow107shows the direction of a pulling or tensile force applied along the length of the elongated member111at its proximal end112. In other embodiments where the opposite elongated member111is actuated by an alternative mechanism, the force applied to the opposite elongated member111may be a twisting, winding, turning, or other effective force to push apart or pull together the base42and the opposite expandable end44. For example, and without limitation, the opposite elongated member111may include threaded portions, turnbuckle portions, fasteners, or multiple members that move relative to one another to lengthen or shorten the opposite elongated member111. In some embodiments, the opposite elongated member111is a wire, rod, or other relatively rigid device that is capable of transmitting both tensile and compressive forces to either or both pull together or push apart the base42and the opposite expandable end44. In other embodiments where it is only necessary to pull together the base42and the opposite expandable end44, the elongated member111may be a strand, string, rope, cable, or other member configured primarily to transmit tensile forces.

In some embodiments, the elongated member101and the opposite elongate member111may be, in whole or in part, joined along their lengths. In some embodiments, the joining is near their respective proximal ends102,112. In this configuration, operation of the elongated member101and opposite elongated member111may be accomplished by a common application of a pushing or pulling force to the joined elongated members101,111.

In some embodiments, elasticity in the material of the expansion mechanism46may sever as a biasing force to bias the expansion mechanism46toward an expanded or unexpanded state, as may be advantageous in various circumstances. For example, it may be advantageous to bias the expansion mechanism46toward an unexpanded state to provide a low profile device for insertion. Other devices, such as but not limit to the elongated member101, the opposite elongated member111, or a fluid injected through the port47, may be used to expand the expansion mechanism46. A fluid that drives linear expansion of the expandable medical implant41or maintains linear expansion of the expandable medical implant41may be introduced through the port47. The fluid may be merely for expansion and retention, or may be a component of a fill material intended to remain in the expansion mechanism46. As used in association with this function, a fluid may be a paste, gel, liquid, suspension, granular mixture, or similar substance. A substance as described herein will be considered a fluid even if it later cures or hardens to a non-fluidic state. Both the expansion mechanism46and the membrane45may initially be unexpanded linearly. The port47may also be used to handle the expandable medical implant41or to guide the implant into a position where it can be effectively deployed.

In other circumstances, it may be preferred to bias the expansion mechanism46toward an expanded state. With such an embodiment, another component, such as but not limit to the elongated member101and the opposite elongated member111, may be used to keep the expansion mechanism46in an unexpanded state while the expandable medical implant41is inserted. Following insertion, the expansion mechanism46may be released and allowed to increase toward its expanded state by releasing one or both of the elongated member101and the opposite elongated member relative to the base2.

As shown inFIGS. 2-5, the cross-sectional shape of some embodiments of the expandable medical implant11is substantially circular. However, the cross-sectional shape of any of the expandable medical implants may be any functional shape, such as but not limited to, generally oval, rectangular, triangular, polygonal, concave-convex, or combinations of these shapes.

In any of the embodiments ofFIGS. 1-10, the expansion mechanisms, bases, expandable ends, telescoping cylinders, or other components that interact with the membranes, may include one or more transfer openings from a component to an interior of the membranes. In some embodiments, the transfer opening is a hole through which a fluid or fill material, or both, may pass. Fluid, fill material, or both may enter the respective expandable medical implants through the ports7,17,27,37,47and pass through one or more transfer openings and into the membrane. In some embodiments, a valve is provided at the transfer opening to control flow to the membrane. The valve may be controlled by direct manipulation or through instrumentation connected through the port7,17,27,37,47.

Fill material may enter the expandable medical implant as a fluid, and then harden or cure in the implant. In some embodiments, a non-hardenable and non-curing fluid is used to expand, or to hold expansion in, the implant or one or some of the components of the implant. A fill material may then be introduced into at least the membrane5,25,35,45to provide support between an upper surface and lower surface of the membrane. The fill material may be a paste, gel, liquid, suspension, granular mixture, or similar substance. Non-limiting examples of fill materials include bone cement, paste, morselized allograft, autograft, or xenograft bone, ceramics, or various polymers. An example bone cement is polymethylmethacrylate (PMMA), which may be made from methylmethacrylate, polymethylmethacrylate, esters of methacrylic acid, or copolymers containing polymethylmethacrylate and polystyrene. Additional non-limiting examples of the fill material include semi-rigid flowable or hardenable material such as silicone or various types of urethane materials. It should further be understood that other types of fill materials which are not necessarily hardenable or curable may be used in association with the present invention. For example, the fill material may comprise beads or small particles or grains of material, some of which may, in aggregate, achieve a harder consistency as a result of interlocking or compaction. In some embodiments, the fill material may also include a bone growth promoting substance. Osteogenic or bone growth promoting substances may include, without limitation, autograft, allograft, xenograft, demineralized bone, synthetic and natural bone graft substitutes, such as bioceramics and polymers, and osteoinductive factors. A separate carrier to hold materials within the device may also be used. These carriers may include collagen-based carriers, bioceramic materials, such as BIOGLASS®, hydroxyapatite and calcium phosphate compositions. The carrier material may be provided in the form of a sponge, a block, folded sheet, putty, paste, graft material or other suitable form. The osteogenic compositions may include an effective amount of a bone morphogenetic protein (BMP), transforming growth factor β1, insulin-like growth factor, platelet-derived growth factor, fibroblast growth factor, LIM mineralization protein (LMP), and combinations thereof or other therapeutic or infection resistant agents, separately or held within a suitable carrier material. Introduction of fluid or fill material into an expandable medical implant embodiment may be through a syringe or similar device, through direct placement, or by any other effective mechanism.

Each of the embodiments disclosed herein may be described as a system for deploying an expandable medical implant. The system includes an expandable medical implant with a base and an expandable end and an enclosed volume between the base and the expandable end. The system also includes a means for pushing apart or pulling together the base and the expandable end.

Embodiments of the implant in whole or in part may be constructed of biocompatible materials of various types. Examples of implant materials include, but are not limited to, non-reinforced polymers, carbon-reinforced polymer composites, PEEK and PEEK composites, low density polyethylene, shape-memory alloys, titanium, titanium alloys, cobalt chrome alloys, stainless steel, ceramics and combinations thereof. If a trial instrument or implant is made from radiolucent material, radiographic markers can be located on the trial instrument or implant to provide the ability to monitor and determine radiographically or fluoroscopically the location of the body in the spinal space. In some embodiments, the implant or individual components of the implant may be constructed of solid sections of bone or other tissues. Tissue materials include, but are not limited to, synthetic or natural autograft, allograft or xenograft, and may be resorbable or non-resorbable in nature. Examples of other tissue materials include, but are not limited to, hard tissues, connective tissues, demineralized bone matrix and combinations thereof.

Some embodiments may also include supplemental fixation devices in addition to or as part of the expandable medical implant for further stabilizing the anatomy. For example, and without limitation, rod and screw fixation systems, anterior, posterior, or lateral plating systems, facet stabilization systems, spinal process stabilization systems, and any devices that supplement stabilization may be used as a part of or in combination with the expandable medical implant.

An embodiment of the invention is a method of implanting an expandable medical implant. The method embodiment includes providing the expandable medical implant with a base and an expandable end and an enclosed volume between the base and the expandable end. The expandable medical implant may also include an elongated member with a distal end and a proximal end. The distal end is coupled to the expandable end of the expandable medical implant and the elongated member is in contact with the base of the expandable medical implant. The method may also include introducing the expandable medical implant through an incision in a patient. Introduction through an incision of some embodiments is conducted while the expandable medical implant is an unexpanded or less than fully expanded state. Consequently, a smaller, less invasive incision is possible.

Method embodiments of the invention may also include applying a compressive force to the elongated member to push apart the base and the expandable end of the expandable medical implant. The base and the expandable end may be pushed apart partially or temporarily to properly locate the expandable medical implant while imaging or alignment procedures are accomplished. For example, and without limitation, portions of the base and the expandable end may be pressed against vertebrae on one or both sides of the expandable medical implant. If proper alignment is confirmed, the expandable medical implant may be secured in place. If proper alignment is not achieved, tensile force may be applied to the elongated member, or compressive force released, to reduce the expansion of the expandable medical implant while the expandable medical implant is repositioned or removed.

Another method embodiment includes providing the expandable medical implant with a base and an expandable end and an enclosed volume between the base and the expandable end. The expandable medical implant may also include an elongated member with a distal end and a proximal end. The distal end is coupled to the expandable end of the expandable medical implant and the elongated member is in contact with the base of the expandable medical implant. Method embodiments of the invention may also include applying a tensile force to the elongated member to pull together the base and the expandable end of the expandable medical implant. The method may additionally include introducing the expandable medical implant through an incision in a patient. Introduction through an incision of some embodiments is conducted while the expandable medical implant is an unexpanded or less than fully expanded state. Consequently, a smaller, less invasive incision is possible.

The tensile force on the elongated member may be released to allow the base and the expandable end of the expandable medical implant to separate. In some embodiments, elasticity in components of the expandable medical implant, or a separate biasing member, may be included with the expandable medical implant to urge the base away from the expandable end. The base and the expandable end may be allowed to expand partially or temporarily to properly locate the expandable medical implant while imaging or alignment procedures are accomplished. For example, and without limitation, portions of the base and the expandable end may be pressed against vertebrae on both sides of the expandable medical implant. If proper alignment is confirmed, the expandable medical implant may be secured in place. If proper alignment is not achieved, tensile force may be applied to the elongated member to reduce the expansion of the expandable medical implant while the expandable medical implant is repositioned or removed.

A fill material may be introduced into the enclosed volume between the base and the expandable end of some embodiments. The fill material may serve as a supplement to mechanisms of the expandable medical implant that otherwise secure the implant in place, or the fill material may be a primary component to secure the expandable medical implant in place. The fill material may occupy only a portion of the volume between the base and the expandable end, or it may be used to further expand portions of the expandable medical implant such as the membrane5,25,35,45, one or both linearly and laterally.

Some portion of the elongated member may extend from the expandable medical implant after the expandable medical implant is secured in place. Therefore, an additional act of some methods embodiments is to remove at least a portion of the elongated member from the expandable medical implant. The elongated member may be cut or twisted off with an instrument, released from its connection to the expandable end of the implant. The elongated member may, at any position along its length, include a release mechanism, portion of reduced strength, or other characteristic that facilitates removal of all or a portion of the elongated member.

The expandable medical implant shown inFIGS. 1-10presents a small profile in its unexpanded state so that it is well-suited for implantation from a generally posterior approach. However, embodiments of the invention may include implantation from any surgical approach, including but not limited to, posterior, lateral, anterior, transpedicular, lateral extracavitary, in conjunction with a laminectomy, in conjunction with a costotransversectomy, or by any combination of these and other approaches.

Various method embodiments of the invention are described herein with reference to particular expandable medical implants. However, in some circumstances, each disclosed method embodiment may be applicable to each of the expandable medical implants, or to some other implant operable as disclosed with regard to the various method embodiments.

Terms such as lower, upper, anterior, posterior, inferior, superior, lateral, medial, contralateral, and the like have been used herein to note relative positions. However, such terms are not limited to specific coordinate orientations, but are used to describe relative positions referencing particular embodiments. Such terms are not generally limiting to the scope of the claims made herein.

While embodiments of the invention have been illustrated and described in detail in the disclosure, the disclosure is to be considered as illustrative and not restrictive in character. All changes and modifications that come within the spirit of the invention are to be considered within the scope of the disclosure.