US 20050203625 A1
A method for performing percutaneous interbody fusion is disclosed. The method includes the steps of inserting a guide needle posteriorly to the disc space, inserting a dilator having an inner diameter slightly larger than the outer diameter of the guide needle over the guide needle to the disc space to enlarge the disc space, and successively passing a series of dilators, each having an inner diameter slightly larger than the outer diameter of the previous dilator, over the previous dilator to the disc space the gradually and incrementally increase the height of the disc space. Once the desired disc height is achieved, the guide needle and all the dilators, with the exception of the outermost dilator, are removed. An expandible intervertebral disc spacer is then passed through the remaining dilator and positioned in the disc space. Th disc spacer is expanded to the required disc height, and then a bone matrix is passed through the dilator to fill the disc space. The dilator is then removed. An expandible intervertebral disc spacer is also disclosed, having a tapered bore that causes greater expansion of one end of the spacer with respect to the other. A kit for performing the percutaneous interbody fusion procedure is also disclosed.
1. A method for performing a percutaneous interbody fusion procedure following a percutaneous discectomy procedure, comprising the steps of:
inserting a guide needle through an incision in a patient's body to a position in the disc space between a first and second vertebra;
inserting a dilator over the guide needle to enlarge the disc space to a first desired height;
removing the needle from the dilator;
inserting an expandible intervertebral disc spacer into the disc space through the dilator;
expanding the disc spacer to enlarge the disc space to a second desired height;
inserting a bone matrix compound into the disc space through the dilator;
removing the dilator and
closing the incision.
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7. A method for performing a percutaneous interbody fusion procedure after removal of a disc, comprising the steps of:
inserting a guide needle through an incision in the patient's body to a position in the disc space between a first and second vertebra on a first lateral side if the patient's spine;
inserting a first dilator having an inner diameter that is slightly larger than an outer diameter of the guide needle over the guide needle to the disc space to enlarge the disc space;
determining if the disc space is at a first desired height;
if the disc space is not at the first desired height, successively inserting a plurality of dilators over the first dilator and guide needle, each successive dilator having an inner diameter that is slightly larger than an outer diameter of a previous dilator to enlarge the disc space to the desired first height;
if the disc space is at the first desired height, removing the guide needle and each dilator except for an outermost dilator;
inserting an expandible intervertebral disc spacer through the dilator to the disc space;
expanding the disc spacer to enlarge the disc space to a second desired height;
inserting a bone matrix compound through the dilator to the disc space;
removing the dilator; and
closing the incision.
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11. An expandible intervertebral disc spacer for implantation in a disc space to enlarge the height of the disc space and restore lordosis in a spine of a patient during interbody fusion procedures, comprising:
a top portion having an inner surface and an outer surface, and having a first end and a second end;
a bottom portion having an inner surface and an outer surface, and having a first end and a second end, the inner surface of the bottom portion facing the inner surface of the top portion;
a plurality of pins joining the top portion to the bottom portion to permit vertical movement of the top portion with respect to the bottom portion;
the inner surface of the top portion and the inner surface of the bottom portion defining a tapered bore having a diameter at a first end that is greater than a diameter at a second end; and
a rod for insertion into the tapered bore to expand a distance between the top portion and the bottom portion, the second end of the top portion moving a greater distance with respect to the second end of the bottom portion than the first end.
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16. A kit for performing percutaneous interbody fusion surgical procedures, comprising:
at least one expandible intervertebral disc spacer;
at least one guide needle;
a plurality of dilators, a first dilator having an inner diameter that is slightly larger than an outer diameter of the guide needle, and each dilator having an inner diameter successively larger than an outer diameter of a previous dilator; and
a package including a top cover and a bottom cover, the top cover and the bottom cover forming a package containing the at least one disc spacer, the at least one guide needle, and the plurality of dilators.
17. The kit of
18. The kit of
19. The kit of
20. An expandible intervertebral disc spacer, comprising:
a split cylinder having a top half and a bottom half joined by a plurality of pins to permit movement of the top half with respect to the bottom half, an inner surface of the top half and an inner surface of the bottom half facing each other defining a tapered bore extending from a first end of the cylinder towards a second end of the cylinder; and
a piston screw insertable into the tapered bore to expand the cylinder by moving the top half away from the bottom half;
wherein the piston screw moving into the taperd bore causes the second end of the cylinder to expand a greater distance than the first end.
1. Field of the Invention
The present invention relates to a device and method for performing interbody spinal fusion, stabilization and restoration of the disc height in the spine, and in particular to a device and method for performing percutaneous, minimally invasive interbody fusion of the lumbar spine.
2. Discussion of the Related Art
Many devices exist to assist in maintaining the position of the lumbar vertebra in conjunction with lumbar fusion surgery. Fusion is the joining together of the vertebra of the spine. The underlying concept of the known devices is to maintain the relative position of the vertebral bodies with respect to each other, while the bone that has been placed between the vertebra to form the fusion of the vertebra, has an opportunity to heal and mature. These devices employ different strategies and philosophies, and can include devices which utilize the pedicles, as well as devices which are placed in to the disc space to promote fusion across the disc space. The latter devices and techniques associated with these devices are known as “interbody fusion”. While no single technique has been universally accepted as the most optimum method, there is growing evidence that interbody fusion may be the preferred method.
The interbody fusion procedure may be performed via an anterior or posterior approach. Initially, all interbody fusion procedures were accomplished using the posterior approach. The procedure was performed by first performing a laminectomy, removing the disc space, and then packing the disc space with pieces of bone, which were then permitted to heal over time. The hope was that the inserted bone pieces would grow and fuse together with the vertebra above and below that disc space, forming a bridge of bone between the two vertebral bodies, thus accomplishing the interbody fusion.
Posterior interbody fusion procedures are accomplished via a variety of techniques. Most procedures attempt to restore proper disc height, i.e. the space between the adjacent vertebra. The patient benefits from restoring the proper disc height, particularly where there has been deterioration, degeneration or collapse of the disc.
More recently, the anterior interbody fusion procedure has gained popularity, due to the availability and improvements made in devices that enable the anterior approach for lumbar interbody fusions. These devices typically provide for a retroperitoneal or transperitoneal technique to be used for approaching the lumbar disc, removing some or all of the disc, and placing either bone or a metallic device into the disc space. These devices also typically provide a means for distracting the disc space, i.e. making the space between the discs wider. Presently, this aspect of lumbar interbody fusion procedures are considered to be an important step in the procedure because of its effects on the neural foramina, or areas from which the nerve roots exit through the vertebra. It is generally accepted that enlarging the disc space consequently enlarges the neural foramina, thus decompressing the exiting nerve roots.
The current techniques, due to the present equipment available, particularly for anterior interbody fusion, suffer the disadvantage in that they are major surgeries and require large incisions with the manipulation of both tissue and organs. While attempts have been made to perform anterior interbody fusions laparoscopically, these procedures are often complicated and are typically performed under general anesthesia.
Therefore, a need exists for a method for performing interbody fusions that reduces the trauma to the patient, and consequently reducing recovery time. A device is also needed to facilitate the interbody fusion procedure to enable the procedure to be performed percutaneously, enabling the surgeon to distract the disc to restore disc height, maintain the distraction, and promote the growth of the bone placed in the disc space between the two vertebral bodies, thus accomplishing the interbody fusion.
It is, therefore, an object of the present invention to provide a minimally invasive, percutaneous surgical procedure for performing interbody fusion which reduces the trauma to the patient and reduces recovery time.
It is also an object of the present invention to provide a percutaneous interbody fusion procedure which accomplishes the interbody fusion through small incisions in the body of the patient and utilizes a minimum of incisions to complete the procedure.
It is a further object of the present invention to provide a device which facilitates the percutaneous interbody fusion procedure.
It is yet another object of the present invention to provide a device which distracts the disc space and which may be inserted through a tube to effect the percutaneous interbody fusion procedure.
It is a further object of the present invention to provide a collapsible and expandible interbody fusion spacing device that facilitates the percutaneous interbody fusion procedure.
It is still a further object of the present invention to provide a kit for performing a minimally invasive percutaneous interbody fusion procedure.
The above and other objects of the present invention may be achieved by providing a collapsible and expandible interbody fusion spacer device that may be inserted through a small diameter tube to the disc space that is being fused, so that the procedure may be performed in a minimally invasive manner. The spacer is preferably constructed in two halves that are connected by pins located on the sides of the spacer. The outer surface may be flat to engage the end plate of the vertebra above and below the spacer, and the outer surface may be scored, have ridges, points, tabs, detents, or the like to enhance gripping of the end plates of the vertebra to resist movement of the spacer once it is in place. The interior surfaces of the halves that make up the spacer include a semicircular hollowed portion that is preferably threaded along at least a portion of its length that is aligned with a similar semicircular threaded hollowed portion on the other half of the spacer. When the spacer is assembled, the threaded portion forms a canal for acceptance of a piston screw. Preferably, the threaded canal is tapered from one end to the other, particularly from the end which will be positioned posteriorly in the disc space to the end which will be positioned anteriorly in the disc space. When the piston screw is inserted, the anteriorly positioned end will expand a greater distance in the disc space than the posterior end, due to the tapered threaded canal. This will cause the disc height, i.e. the distance between the vertebra, to be greater anteriorly than posteriorly, which more closely mimics the natural curve of the spine, particularly in the lumbar spine, thus restoring lordosis, the natural curve of the lumbar spine.
A method for performing percutaneous interbody fusion is also provided, in which the disc space is enlarged in the craniocaudal direction following percutaneous discectomy. Following the discectomy, a guide needle is passed through the incision to the disc space between the vertebra. Over the needle, a series of tubularly shaped dilators are passed, with each successive dilator having an inner diameter that is slightly larger than the outer diameter of the dilator that is in place. As each successive dilator is inserted in the disc space, it forces the vertebra apart, increasing the disc space, until a desired height between the vertebra is achieved. Once a desired height is reached, which is only a desired height and not necessarily the maximum height, the outer dilator is left in place, while those inside the outer dilator are removed. The maximum height does not have to be achieved by the dilators because the expandible intervertebral disc spacer of the present invention is then inserted into the disc space through the outer dilator. Once in place, the spacer is expanded to increase the disc height to the maximum distance. After the spacer is in place on one side of the vertebral body, the procedure is repeated on the other side. After the two spacers are in place, a bone matrix, which encourages fusion, is passed through the dilators, filling the space with bone. The dilators are then removed and the procedure is complete.
A kit for performing percutaneous interbody fusion is also provided, which includes a plurality of expandible intervertebral disc spacers, which preferably expand the disc space a greater distance anteriorly than posteriorly, at least one dilator for expanding the disc height and having a hollow interior for allowing passage of the disc spacers to the disc space, and a guide needle. A curette for performing percutaneous discectomies may be provided, and a bone matrix for fusing the vertebra together may also be provided.
The above and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings, in which:
Referring now to the drawings, in which like reference numerals identify similar or identical elements throughout the several views, and inn particular to
Screw 20 is provided for insertion into bore 18 to expand the disc spacer 10. As seen in
While the above procedure has been described for only one set of dilators, and for enlarging the disc space for placement of a disc spacer on one side of the disc space 62, it is understood that the procedure is performed on both sides of the disc space to raise the disc height evenly, and that two disc spacers 10 are inserted. After the bone matrix is inserted, the dilators are then removed and the procedure is complete.
While the invention has been shown and described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and modifications in form and detail may be made therein without departing from the spirit and scope of the invention, as defined by the appended claims.