Patent Application
20050240181
The present invention relates to spinal instrumentation, and in particular to various connector devices for mating spinal fixation elements, such as spinal rods, to spinal anchoring devices, such as plates, hooks, bolts, wires, and screws, that are implanted in a patient's spinal system.
Treatment of some spinal injuries or disorders may involve the use of a spinal fixation element, such as a relatively rigid fixation rod, that is coupled to adjacent vertebrae by attaching the element to various anchoring devices, such as plates, hooks, bolts, wires, or screws. Often two rods are disposed on opposite sides of the spinous process in a substantially parallel relationship. The fixation rods can have a predetermined contour that has been designed according to the properties of the target implantation site, and once installed, the rods hold the vertebrae in a desired spatial relationship, until healing or spinal fusion has taken place, or for some longer period of time.
A variety of techniques have been developed for attaching a spinal rod to a vertebra, and each technique varies depending on the intended implanted location in the patient's spinal column. When surgery is performed in the cervical spine, for example, the proximal ends of the rods can be attached to the occiput by inserting a bone screw through a flattened, plate-like portion formed on the end of each rod. Other techniques utilize a spinal fixation plate having a yoke or receiver head that seats the spinal rod to attach the rod to the plate. A locking mechanism is utilizes to lock the rod to the plate, and the plate is attached to one or more vertebrae using one or more bone screws inserted therethrough.
While current techniques have been met with success, most do not allow the connection between the spinal rod and the anchoring device to be adjusted. For example, where the spinal rod is connected to a yoke on the fixation plate, the position of the rod is limited to being directly over the plate. Such a connection can also limit use of the device to specific regions of the spinal system, as the yoke does not provide a low-profile connection with the rod.
Accordingly, there remains a need for improved methods and devices for connecting spinal fixation elements, such as spinal rods, to spinal anchoring devices, such as plates, hooks, bolts, wires, and screws.
The present invention provides various embodiments of implantable spinal connectors for mating spinal fixation elements, such as spinal rods, to spinal anchoring devices, such as plates, hooks, bolts, wires, and screws. In one embodiment, an implantable spinal connector is provided having a clamp member with top and bottom portions that are connected to one another at a terminal end thereof. The top and bottom portions are movable between an open position in which the top and bottom portions are spaced a distance apart from one another, and a closed position in which the portions are adapted to engage a spinal fixation element disposed there between. The top and bottom portions also preferably include a bore extending therethrough for receiving a locking mechanism to lock the clamp member in the closed position.
The top and bottom portions of the connector member can be mated to one another using a variety of techniques. In one embodiment, the top and bottom portions can be hingedly connected to one another, and more particularly, a pin member can extend through bores formed in each of the top and bottom portions for allowing the portions to pivot thereabout. In another embodiment, the top and bottom portions can be integrally formed with one another, and they can be adapted to deform around a rod when the portions are in the closed position and the rod is locked therein. The top and bottom portions can also optionally be biased to either an open position or a closed position such that a force greater than the biasing force must be applied to move the top and bottom portions from the open position to the closed position or from the closed position to the open position.
In another embodiment of the present invention, a recess for seating a spinal fixation element is formed between the clamp members, preferably in at least one of the inferior surface of the top portion and the superior surface of the bottom portion, and the recess is adapted to seat a spinal fixation element therein when the top and bottom portions are in the closed position. The recess can have a variety of configurations, and it can be adapted to retain a variety of spinal fixation elements therein. In an exemplary embodiment, a recess is formed in each of the top and bottom portions, and each recess has a substantially concave shape such that the recesses together define a substantially cylindrical recess when the clamp member is in the closed position. In another embodiment, the recesses can have an elongate shape to allow the position of a rod disposed therein to be adjusted.
The connector mechanism can also include a locking mechanism that is adapted to lock the top and bottom portions in the closed position to retain a spinal fixation element there between. In one embodiment, at least a portion of the locking mechanism can extend through the bore formed in the top and bottom portions to lock the top and bottom portions in the closed position. The bore can have various shapes and sizes, but it preferably has either an elongate slotted configuration or a cylindrical shape. The locking mechanism can be, for example, a fastening element having a head and a threaded shaft. The threaded shaft can mate to corresponding threads formed within the bore in one or the top or bottom portions, and in an exemplary embodiment the threads on each of the shaft and in the bore in one of the top and bottom portions are left-handed threads. More preferably, the bore formed in the top portion is non-threaded for freely rotatably receiving the threaded shaft of the fastening element, and the bore formed in the bottom portion is threaded for mating with the threaded shaft of the fastening element. In an alternative embodiment, the threaded shaft can mate with a receiving element.
The present invention also provides an installation device for implanting a spinal connector. In one embodiment, the installation device includes first and second opposed arms that are pivotally coupled to one another and that are movable between an open position, wherein a distal portion of each arm is spaced a distance apart from one another, and a closed position, wherein the distal portion of each arm is adapted to seat and engage a spinal connector disposed there between. The distal portion of each arm can be substantially C-shaped to define a connector-receiving recess formed there between when the arms are in the closed position, and the distal portion of each arm can also include a connector-engaging member formed thereon and adapted to engage a connector positioned there between. The connector-engaging member can be, for example, a ridge that is adapted to extend between top and bottom portions of the spinal connector. The installation device can also include a locking mechanism coupled to each of the first and second arms and adapted to lock the arms in a fixed position relative to one another.
In another embodiment, an installation device for implanting a spinal connector is provided having an elongate shaft with a connector-receiving member formed on a distal end thereof and adapted to seat a spinal connector, and a driver shaft rotatably disposed through the elongate shaft and including a mating element formed on a distal end thereof and adapted to mate with a fastening element to rotate the fastening element relative to a spinal connector coupled to the elongate shaft, thereby mating the fastening element to the connector. The connector-receiving member can be, for example, a housing having a recess formed therein for seating a spinal connector. The mating element on the driver shaft preferably extends through and distally beyond the housing, and in one embodiment, the mating element can be in the form of an elongate shaft. At least a portion of the shaft is preferably asymmetrical for extending into a socket formed in a fastending element. The shaft that forms the mating element can also include threads formed thereon for mating with corresponding threads formed on a spinal connector.
The present invention also provides a spinal fixation kit that includes a spinal clamp having top and bottom portions adapted to seat a spinal fixation element there between, and a fastening element having a head and a shaft. The top and bottom portions of the clamp member each include a bore extending therethrough and axially aligned with one another for receiving a fastening element, and the bore in the top portion includes left-handed threads formed therein. The threads are configured to mate with left-handed threads formed on at least a portion of the shaft of the fastening element. In a further embodiment, a distal-most end of the shaft of the fastening element can include a socket formed therein for receiving a driver tool. The kit can thus also include an installation device having a hollow elongate shaft with a distal, connector-receiving portion adapted to seat the connector, and a driver tool rotatably coupled to the shaft and including a distal end that is adapted to extend through the bores in the connector and into the socket in the fastening element such that rotation of the driver tool is effective to mate the fastening element to the connector. The kit can also include a spinal anchoring element having at least one thru-bore formed therein. The fastening element is preferably removably matable to the at least one thru-bore in the spinal anchoring element.
The present invention also provides a spinal fixation system that includes a spinal fixation plate having at least one thru-bore formed therein, and a spinal connector having top and bottom portions that are connected to one another at a terminal end thereof and that are adapted to retain a spinal rod there between. A locking mechanism can be provided for locking the top and bottom portions of the spinal connector in a fixed position with respect to one another to engage a spinal rod there between. The locking mechanism is also preferably adapted to mate the spinal connector to the spinal fixation plate.
In other aspects of the present invention, a medical connector device is provided in the form of a substantially J-shaped connector body having a first, substantially planar portion with a thru-bore formed therein, and a second, substantially curved portion that extends in a direction substantially transverse to the first portion and that defines a recess for seating a spinal fixation element. The thru-bore in the first portion is positioned to receive a fastening element such that a head of the fastening element is effective to contact a spinal fixation element seated within the recess in the second portion and to lock the spinal fixation element within the recess.
In yet another embodiment of the present invention, a spinal fixation system is provided having a spinal plate with at least one thru-bore formed therein, and at least one anchoring device having a distal hook portion adapted to engage bone and a proximal receiver head adapted to receive an elongate spinal fixation element. The receiver head is positionable within the at least one thru-bore formed in the spinal plate such that a spinal fixation element disposed within the receiver head can be coupled to the spinal plate, and the spinal plate can be mated to bone. In an exemplary embodiment, the spinal plate is an occipital plate having first and second opposed thru-bores formed therein, and the system includes a first anchoring device having a receiver head disposed within the first thru-bore formed in the occipital plate, and a second anchoring device having a receiver head disposed within the second thru-bore formed in the occipital plate. A locking mechanism can be disposed within the receiver head of the at least one anchoring device to lock a spinal fixation element therein.
The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
The present invention provides various methods and devices for mating spinal fixation elements, such as spinal rods, to spinal anchoring devices, such as plates, hooks, bolts, wires, and screw. One of the many advantages of the connector devices is that they provide a low-profile connection between a spinal fixation element and spinal anchoring devices. Some of the connector devices also provide an adjustable connection, such that a position of the spinal fixation element with respect to the spinal anchoring device to which it is mated can be adjusted.
The top and bottoms portions 12, 14 of the clamp 10 can have a variety of configurations, shapes and sizes, but they should be adapted to retain a spinal rod 30 there between, and to mate the rod 30 to a spinal plate 32. In an exemplary embodiment, as shown, each portion 12, 14 has a substantially elongate shape and includes superior and inferior surfaces 12s, 12i, 14s, 14i, first and second opposed sides 12s1, 12s2, 14s1, 14s2, and first and second opposed terminal ends 12t1, 12t2, 14t1, 14t2. The second terminal end 12t2, 14t2 of each portion is preferably mated to one another, or integrally formed with one another, such that the inferior surface 12i of the top portion 12 is positioned on the superior surface 14s of the bottom portion 14. The mated ends 12t2, 14t2 allow the top and bottom portions 12, 14 to be moved between an open position in which the portions 12, 14 are spaced apart from one another, as shown in
The top and bottom portions 12, 14 can optionally be biased to either a closed position or an open position such that a force greater than the biasing force is necessary to move the top and bottom portions 12, 14 from the closed position to the open position to insert a spinal rod there between, or from the open position to the closed position to engage a spinal rod positioned there between. In an exemplary embodiment, the top and bottom portions 12, 14 are biased to an open position, and they are formed from a material that allows the portions 12, 14 to deform around a spinal rod 30 positioned there between to provide a secure connection between the spinal rod 30 and the clamp 10. Suitable materials include, by way of non-limiting example, nitanol, titanium, and stainless steel. To facilitate deformation of the clamp 10 around a spinal rod 30, the inferior surface 12i of the top portion 12 and the superior surface 14s of the bottom portion 14 can tapered away from one another toward the first ends 12t1, 14t1 thereof, as shown in
In order to seat the spinal rod 30 between the top and bottom portions 12, 14, at least one recess is preferably formed on at least one of the inferior surface 12i of the top portion 12 and the superior surface 14s of the bottom portion 14. While the position, shape, size, and configuration of the recess(es) can vary, in an exemplary embodiment, as shown, the recess 16 is formed in the second terminal ends 12t2, 14t2 of the top and bottom portions 12, 14. Such positioning of the recess 16 facilitates formation of a hinge-type connection between the top and bottom portions 12, 14, allowing the portions 12, 14 to be moved between the open and closed positions. The shape and size of the recess 16 can also vary, but it preferably defines a substantially cylindrical cavity extending between the opposed sides 12s1, 12s2, 14s1, 14s2 of the top and bottom portions 12, 14. The cylindrical cavity 16 can be formed from opposed concave recesses 16a, 16b formed in each of the inferior surface 12i of the top portion 12 and the superior surface 14s of the bottom portion 14. The recess 16 preferably does not extend beyond the inferior surface 14i of the bottom portion 14 to allow the inferior surface 14i to have a substantially planar configuration. Such a configuration allows the inferior surface 14i of the clamp 10 to engage and rest against a spinal anchoring device, such as a spinal fixation plate, without interference from the spinal rod 30 disposed within the recess 16. In another embodiment, the recess 16 can have an elongate shape to allow the spinal rod 30 to be positioned at various locations within the recess 16, and to allow an angle of the spinal rod 30 with respect to an axis A of the recess 16 to be adjusted.
Once the spinal rod 30 is positioned within the recess 16 between the top and bottom portions 12, 14, the portions 12, 14 are preferably locked in the closed position using a locking mechanism 20. The locking mechanism 20 can also be used to attached the clamp 10 to a spinal plate 32. While a variety of techniques can be used to lock the clamp 10 in the closed position and to mate the clamp 10 to a spinal plate 32, in an exemplary embodiment, each portion 12, 14 includes a bore 18a, 18b formed therein for receiving a portion of the locking mechanism 20. The location of each bore 18a, 18b can vary depending on the intended use, and depending on the location of the spinal rod 30 within the clamp 10. In the illustrated embodiment, however, each bore 18a, 18b is formed in a substantial mid-portion of the clamp 10 to prevent the locking mechanism 20 from interfering with the spinal rod 30. The shape of the bores 18a, 18b can also vary, and in one embodiment the bores 18a, 18b can be substantially cylindrical to prevent sliding movement of a locking mechanism 20 therein. Alternatively, the bores 18a, 18b can be in the form of elongate slots 18a, 18b, as shown, which allow the clamp member 10 to slide with respect to the locking mechanism 20. As a result, when the clamp member 10 is mated to a spinal plate 32, the clamp member 10 can translate relative to the plate 32, thus allowing the position of a rod 30 engaged by the clamp member 10 to be adjusted with respect to the plate 32. One or both slots 18a, 18b can also optionally include a recess formed therein for seating a portion of the locking mechanism 20, which will be discussed in more detail below. As shown in
The locking mechanism 20 that is used to lock the clamp member 10 in the closed position, and to mate the clamp member 10 to a spinal plate 32, can also have a variety of configurations, and virtually any locking mechanism known in the art for use with spinal fixation devices, including polyaxial and monoaxial bone screws, hooks, plates, rods, etc., can be used. In the illustrated embodiment, however, the locking mechanism 20 includes a threaded member 20b that is integrally formed on and extends from a surface of the spinal fixation plate 32, and a locking nut 20a that is adapted to mate to the threaded member 20b. While not shown, the threaded member 20b can be separate from and disposed through a thru-bore formed in the spinal fixation plate 32. In use, the clamp member 10 is positioned with the threaded member 20b extending through the slot 18a, 18b in each of the top and bottom portions 12, 14 thereof, and the nut 20a is threaded onto the threaded member 20b to close the clamp member 10, thereby engaging the spinal rod 30 within the recess 16, and locking the clamp member 10 to the spinal plate 32.
A person skilled in the art will appreciate that a variety of other techniques can be used to lock the clamp member 10 in the closed position. By way of non-limiting example, the clamp member 10 can include gripping features and/or anti-rotation features formed within the recess 16 thereof to facilitate engagement of the spinal rod 30. In other embodiments of the invention, as shown in
Referring to
The fastening element 60 includes a head 62 and a shaft 64. The head 62 has a size that prevents passage thereof through a thru-bore formed in a spinal anchoring device, such as thru-bore 72 formed in plate 70, and the shaft 64 is configured to extend through the thru-bore 72 in the plate 70 and through each of the top and bottom portions 52, 54 of the clamp 50. A distal portion 64a of the shaft 64 includes threads 65 formed thereon for mating with the corresponding threads 59 formed within the bore 58a in the top portion 52 of the clamp 50. Thus, in use, when the shaft 64 of the fastening element 60 is positioned through the thru-bore 72 in the plate 70 to threadably mate to the clamp 50, the fastening element 60 engages the top portion 52 of the clamp 50 to lock the top and bottom portions 52, 54 in a fixed position relative to one another, thereby locking a spinal fixation element there between and locking the clamp 50 to the plate 70.
Since the fastening element 60 is bottom loading relative to the plate 70, the fastening element preferably includes a mating element formed on a distal-most end 64c of the shaft 64 to allow the fastening element 60 to be engaged by a driver mechanism and rotated to thread the shaft 64 into the clamp 50. While a variety of mating elements can be used, in an exemplary embodiment, the mating element is an asymmetrical socket 68 that is adapted to receive a complementary asymmetrical driver mechanism. The illustrated socket 68 has a six-pointed star shape, but virtually any shaped socket can be used. In use, after the fastening element 60 is inserted through the thru-bore 72 in the plate 70, and the clamp 50 is positioned over the shaft 64, a driver mechanism is inserted into the socket 68 and it is rotated to thread the fastening element 60 into the clamp 50, thereby mating the clamp 50 to the plate 70.
In order to further facilitate mating of the fastening element 60 to the clamp 50, the fastening element 60 also preferably includes a feature that at least temporarily attaches the fastening element 60 to the plate 70. This will allow the fastening element 60 to be maintained in a fixed, but freely rotatable position relative to the plate 70 while a driver mechanism is used to rotate the fastening element 60 to threadably mate with the clamp 50. The fastening element 60 can also optionally be freely translatable relative to the plate 70, depending on the configuration of the thru-bore 72 in the plate 70. While various techniques can be used to at least temporarily mate the fastening element 60 to the plate 70, as shown in
The present invention also provides an installation device 80, shown in
In general, the installation device 80 includes first and second opposed arms 82, 84, each having a proximal handle 82a, 84a and distal, clamp-engaging end 82b, 84b. The arms 82, 84 are pivotally mated to one another such that the arms 82, 84 are movable between an open position, in which the distal ends 82b, 84 are spaced a distance apart from one another, and a closed position, as shown, in which the arms 82, 84 are effective to engage and retain the clamp 50 there between. In the illustrated embodiment, the arms 82, 84 are mated to one another at a substantial midpoint M thereof, such that the arms 82, 84 pivot about the midpoint M. A locking mechanism, such as the illustrated pawl-and-ratchet mechanism 88, can be coupled to the arms 82, 84 to lock the arms 82, 84 in the closed position. A person skilled in the art will appreciate that virtually any type of locking mechanism can be used. The arms 82, 84 can also include at least one angle or bend B formed therein to facilitate use of the device, as will be described in more detail below.
In use, the installation device 80 can engage the clamp 50 between the clamp-engaging member 83, 85 on each arm 82, 84. With the arms 82, 84 preferably in a locked position, using the pawl-and-ratchet mechanism 88, the installation device 50 can be manipulated to slide the clamp 50 over a spinal rod (not shown), and then to position the clamp 50 over the shaft 64 of the fastening element 60 (
The driver shaft 94 is rotatably disposed through the hollow elongate shaft 93 and it includes a proximal handle 94a and a distal mating element 94b formed thereon. The distal mating element 94b is configured to extend through the clamp 50 positioned within the recess 93c of the clamp-engaging portion 93b, and to extend into the socket 68 in the fastening element 60. The mating element 94b therefore preferably has a shape that is complementary to the shape of the socket 68 such that the mating element 94b can be used to rotate the fastening element 60, thereby threading the fastening element 60 into the clamp 50. Rotation of the mating element 94b on the driver shaft 94 can be achieved by rotating the handle 94a of the shaft 94, which is connected to the mating element 94b.
The mating element 94b on the driver shaft 94 can also optionally be threaded to mate with the threads 59 formed within the bores 58a, 58b in the clamp 50. This will allow the mating element 94b to engage the clamp 50 and retain the clamp 50 within the recess 93c prior to mating the clamp 50 to the plate 70 using the fastening element 60. Thus, in use, the clamp 50 can be loaded onto the installation tool 92 by positioning the mating element 94b on the driver shaft 94 through the bores 58a, 58b in the clamp 50. The handle 94a on the driver shaft 94 can then be rotated, preferably while holding the gripping portion 93a of the hollow shaft 93, to thread the mating element 94b into the bores 58a, 58b in the clamp 50. The installation tool 92 can then be manipulated to slide the clamp 50 over a spinal fixation element, e.g., a rod, by inserting the rod through the recess 56 (
As previously described with respect to clamp member 10, a locking mechanism can be used to lock the top and bottom portions 112, 114 in a fixed position with respect to one another. By way of non-limiting example,
As previously stated with respect to
The thru-bore 213 is preferably positioned relative to the curved portion 214 such that a portion of the locking mechanism, which will be discussed in more detail below, comes into contact with the spinal rod 230 seated within the recess 216. As a result, when the locking mechanism is in a locked configuration with the connector member 200, the locking mechanism will create an interference or friction fit with the spinal rod 230, thereby locking the spinal rod 230 within the recess 216.
While a variety of locking mechanism can be used, in the embodiment shown in
In use, two connector members 300, 300′ are preferably used to mate two spinal rods to a spinal plate 330 having at least two thru-bores or slots 332, 334 formed therein, as shown. The receiving member 302, 302′ on each connector member 300, 300′ is preferably configured to be position within a slot 332, 334 formed in the spinal plate 230 to mate two spinal rods (not shown) to the plate 230, and the hook portion 304, 304′ on each connector member 300, 300′ is used to engage bone. Depending on the configuration of the thru-bores 332, 334 in the plate 330, each receiving member 300, 300′ can optionally be adapted to allow rotatable and/or slidable movement thereof with respect to the plate 330. For example, in the illustrated embodiments, the plate 300 includes elongate slots 332, 334 formed therein, and the receiving member 302, 302′ on each connector member 300, 300′ includes opposed flattened side surfaces 306, 306′ (only one side is shown) formed thereon. The flattened sides 306, 306′ prevent rotation of the receiving members 302, 302′ within the slots 332, 334, yet they allow slidable movement of the receiving members 302, 302′ therein. This allows a spinal rod coupled to the receiving member 302, 302′ of each connector 300, 300′ to be positioned as desired with respect to the spinal plate 330. Once a rod is properly positioned relative to each connector 300, 300′, a closure mechanism 303, 303′ can be threaded into the receiver members 302, 302′ to lock the rods therein. As a result, when the closure mechanism 303, 303′ bears against the rods to lock the rods within the receiving members 302, 302′, the rods also preferably bear against the spinal fixation plate 300, thereby locking the connector members 300, 300′ to the plate 330. A person skilled in the art will appreciate that the connector members 300, 300′ can have a variety of configurations. By way of non-limiting example, the plate 330 can be telescoping and each connector member 300, 300′ can be integrally formed on opposed ends of the plate 330.
In use, the receiving head 402 can be positioned through the thru-bore or slot 406 formed in the lateral extension 404, and a spinal rod 430 locked in the receiving head 402 can be used to prevent removal of the receiving head 402 from the slot 406. A retaining member, such as a split o-ring 408, can optionally be disposed around a portion of the receiving head 402 on an opposed side of the slot 406 from the flange 402a to help retain the receiving head 402 within the slot prior to locking the rod 430 therein. The receiving head 402 can also be configured to prevent passage thereof through the slot 406 when positioned in a first orientation, and to allow passage through the slot 406 in the lateral extension 404 when position in a second orientation. This can be achieved by providing opposed, substantially flattened sides 403a, 403b on the receiver head 402 that define a width wr2 that is less than a width w of the slot 406 to allow the receiving head 402 to pass through the slot 406 in the second orientation, as shown in
In another embodiment, opposed sides 403a, 403b on the receiver head 402 can be adapted to rest against the head portion 442 of the spinal screw 440 that is attached to the lateral extension 404. For example, the sides 403a, 403b can be substantially concave, as shown in
In use, as shown in
One of ordinary skill in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.
