US 20070173823 A1
A prosthetic device and method, according to which a member of a relatively flexible, soft material is connected with a member of a relatively stiff material and the connected members are implanted in a spinal column using a non-rigid and a rigid connection.
1. A prosthetic device for insertion in a spinal column, the device comprising:
a first member of a relatively flexible material;
a second member of a relatively stiff material connected to the first member;
means for providing a non-rigid connection of one of the members to a vertebrae of the column; and
means for providing a rigid connection of one of the members to a vertebrae of the column.
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13. A method of implanting a prosthetic device in a spinal column to stabilize the spine, the method comprising:
connecting a first member of a relatively flexible material to a second member of a relatively stiff material;
establishing a non-rigid connection between one of the members and a vertebrae; and
establishing a rigid connection between one of the members and a vertebrae of the spinal column.
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The present invention relates to an intervertebral prosthetic device for stabilizing the human spine, and a method of implanting same. Spinal discs that extend between adjacent vertebrae in vertebral columns of the human body provide critical support between the adjacent vertebrae while permitting multiple degrees of motion.
These discs can rupture, degenerate, and/or protrude by injury, degradation, disease, or the like to such a degree that the intervertebral space between adjacent vertebrae collapses as the disc loses at least a part of its support function, which can cause impingement of the nerve roots and severe pain.
In these cases, intervertebral prosthetic devices have been designed that can be implanted between the adjacent vertebrae, both anterior and posterior of the column and are supported by the respective spinous processes of the vertebrae to prevent the collapse of the intervertebral space between the adjacent vertebrae and provide motion stabilization of the spine. Many of these devices are supported between the spinous processes of the adjacent vertebrae.
In some situations it is often necessary to remove the laminae and the spinous process from at least one of the adjacent vertebrae to get proper decompression. In other situations, the defective disc is removed and two vertebral segments are fused together to stop any motion between the segments and thus relieve the pain. When two adjacent vertebrae are fused, the laminae and the spinous process of at least one vertebrae are no longer needed and are therefore often removed.
However, in both of the above situations involving removal of a spinous process, it would be impossible to implant an intervertebral prosthetic device of the above type since the device requires support from both processes.
According to an embodiment of the invention, an intervertebral prosthetic device is provided that is implantable between two adjacent vertebrae, at least one of which is void of a spinous process, to provide motion stabilization.
Various embodiments of the invention may possess one or more of the above features and advantages, or provide one or more solutions to the above problems existing in the prior art.
With reference to
The lumbar region 12 of the vertebral column 10 includes five vertebrae V1, V2, V3, V4 and V5 separated by intervertebral discs D1, D2, D3, and D4, with the disc D1 extending between the vertebrae V1 and V2, the disc D2 extending between the. vertebrae V2 and V3, the disc D3 extending between the vertebrae V3 and V4, and the disc D4 extending between the vertebrae V4 and V5.
The vertebrae V6 includes five fused vertebrae, one of which is a superior vertebrae V6 separated from the vertebrae V5 by a disc D5. The other four fused vertebrae of the sacrum 14 are referred to collectively as V7. A disc D6 separates the vertebrae V6 from the coccyx 16 which includes four fused vertebrae (not referenced).
With reference to
An intervertebral disc prosthetic device 40 according to an embodiment of the invention is provided which is adapted to be implanted between the spinous processes 22 of the vertebrae V3 and V5. The prosthetic device 40 is shown in detail in
An insert 44 is provided that is dimensioned so as to extend in the channel 42 c with minimum clearance. Tabs 46 a and 46 b extend out from the respective ends of the insert 44 and elongated openings 46 c and 46 d extend through the respective tabs. The length of the insert 44 substantially corresponds to the length of the channel 42 c so that when the insert is inserted in the channel, the tabs 46 a and 46 b project outwardly from the channel.
Two protrusions 48 a and 48 b extend from the sides of the tab 46 a and two protrusions 48 c and 48 d extend from the sides of the tab 46 b. The protrusions are for the purpose of receiving tethers, or the like, to tether the device 40 to the vertebrae V4 and/or V5.
Since the spinous process of the vertebrae V4 has been removed, the device 40 is implanted between the spinous process 22 of the vertebrae V3 and the spinous process 22 of the vertebrae V5. In the implanted position shown in
Then, two screws, one of which is referred to by the reference numeral 49 in
Although not shown in the drawing, tethers can be tied between the protrusions 46 a-46 d and the vertebrae V3, V4, and/or V5 to provide additional support and resistance.
As examples of the materials making up the spacer 42 and the insert 44, the spacer can be of a relatively soft material, such as soft plastic, including silicone, while the insert can be of a relatively stiff material, such as hard plastic or rubber. In the latter context, the surgeon could be provided with several inserts 44 that vary in stiffness, and once the condition of the vertebrae V4 and V5 (
When the device 40 is implanted in the manner discussed above, the relatively flexible, soft spacer 42 provides non-rigid connections to the vertebrae V3 and V5 that readily conforms to the processes 22 of the vertebrae V3 and V5 and provides excellent shock absorption, while the insert 44 adds stiffness, compressive strength and durability, and the screws 49 provide a rigid connection to the vertebrae V4.
A prosthetic device 50 according to another embodiment is shown in detail in
A spacer 54 is also provided which is substantially rectangular in shape with the exception that a curved notch 54 a is formed in one end portion and a tab 54 projects from the other end of the spacer 52.
A connector 56 is designed to fit over the tabs 52 b and 54 b of the spacers 52 and 54, respectively, to connect them. To this end, the connector 56 has a through opening 56 a with a cross section slightly greater than the cross sections of the tabs 52 b and 54 b.
Two tabs 56 b and 56 b extend out from the respective ends of the connector 56, and elongated openings 56 c and 56 d extend through the respective tabs for receiving screws, for reasons to be described.
Two protrusions 58 a and 58 b extend from the sides of the tab 56 b and two protrusions 58 c and 58 d extend from the sides of the tab 56 c. The protrusions are for the purpose of receiving tethers, or the like, to tether the device 40 to the vertebrae V4 and/or V5.
To connect the spacers 52 and 54, their respective tabs 52 b and 54 b are inserted into the opening 56 a of the connector 56 from opposite ends of the opening until the corresponding shoulders of the spacers 52 and 54 engage the corresponding ends of the connector 56. The spacers 52 and 54 and the connector are sized so that the tabs 52 a and 54 a engage the inner wall of the connector 56 in a friction fit so as to retain the spacers 52 and 54 in the connector.
Since the spinous process of the vertebrae V4 has been removed, the device 50 is implanted between the spinous process 22 of the vertebrae V3 and the spinous process 22 of the vertebrae V5. In the implanted position, the spinous process 22 of the vertebrae V3 extends in the notch 52 a of the spacer 42, and the spinous process 22 of the vertebrae V5 extends in the notch 52 b. The dimensions of the device 50 are such that, when it is implanted in this manner, the elongated openings 56 c and 56 d extend over the pedicles 26 a and 26 b (
Although not shown in the drawing, tethers can be tied between the protrusions 58 a-58 d and the vertebrae V3, V4, and/or V5 to provide additional support and resistance.
The spacers 52 and 54 could be fabricated from a relatively soft material, such as soft plastic, including silicone, while the connector 56 could be fabricated from a relatively stiff material, such as hard plastic or rubber. In the latter context, the surgeon could be provided with several connectors 56 that vary in stiffness. Thus, once the surgeon ascertains the condition of the vertebrae V3, V4, and V5 (
Thus, when the device 50 is implanted between the processes 22 of the vertebrae V3 and V5 in the manner discussed above, the relatively flexible, soft spacers 52 and 54 provide a non-rigid connection to the vertebrae V3 and V5 that readily conforms to the processes 22 of the vertebrae V3 and V5, and provides excellent shock absorption. Also, the connector 56 adds stiffness, compressive strength and durability, and the screws 49 provide a rigid connection to the vertebrae V4.
It is understood that other variations may be made in the foregoing without departing from the invention and examples of some variations are as follows:
The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, therefore, that other expedients known to those skilled in the art or disclosed herein, may be employed without departing from the invention or the scope of the appended claims, as detailed above. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts a nail and a screw are equivalent structures.