Hinged expandable corpectomy device

The present invention is directed to an adjustable corpectomy device which fits within the intervertebral distracted channel. The device includes a means for engaging an extendable member to accommodate the distracted channel. The corpectomy implant device is defined by a main body, a first expandable plate, and an opposing second expandable plate. Each expandable plate is adapted to fit within the main body in a compressed state, and extends away from the main body in a non-compressed, expanded state.

FIELD OF THE INVENTION

The invention generally relates to improvements to vertebral implants and, more particularly, to a longitudinally expandable vertebral implant including telescoping sections configured for incremental expansion by a ratchet expander for ease of securement at any desired increment in situ.

BACKGROUND OF THE INVENTION

The spine consists of vertebrae that are categorized into sections known as the cervical, thoracic and lumbar section in a flexible arranged column. The vertebrae are separated by small cartilaginous cushions known as intervertebral discs. Intervertebral discs are oblate spherical structures that maintain the space between adjacent vertebrae. Each intervertebral disc consists of an outer annulus fibrosus, which surrounds the inner nucleus pulposus. The annulus fibrosus consists of several layers of strong annular fibrocartilage to contain the nucleus pulposus and distribute pressure evenly across the disc wherein a mucoprotein gel serves to absorb shocks.

Deterioration of an intervertebral disc results in limited mobility and can cause severe pain. For instance, normal aging causes the nucleus pulposus to lose fluid and contract in volume resulting in a reduction in the intervertebral space. Any reduction of space between adjacent vertebrae may put pressure on the nerves of the spinal column. Further, a reduction in volume of the nucleus pulposus reduces the disc's ability to absorb shock which can result in disc herniation. The bulge of a herniated disc may also put pressure on nearby nerve structures resulting in pain as well as diminished range of motion.

Surgical options are available including laminectomy and discectomy combined with vertebral fusion and/or dynamic stabilization. However, these surgical options are highly invasive and require prolonged hospitalization and recovery. More recently, artificial disc replacement prosthetics have been used to replace or augment all or part of the removed or resected intervertebral disc.

In order to reduce the pain associated with the movement of the intervertebral joint, surgical intervention is often indicated as a means to alleviate pressure upon the spinal cord while concomitantly stabilizing the associated vertebrae. This involves a surgical procedure to distract the disc and or vertebra, or portions thereof, and the insertion of bone fusing material into the cavity of the opposing vertebra. Corpectomy devices have been developed to help support the spine and maintain the normal spacing between opposing vertebrae. Some of these devices may be packed with fusing material to ensure solid bone growth between the two vertebrae. Typically, corpectomy devices are manufactured at various heights requiring that a cavity between opposing vertebrae to be distracted to a dimension corresponding to the sized corpectomy device. The surgical procedure to prepare the implant site can be difficult and lengthy. Moreover, the procedure can increase risk of trauma to the tissues surrounding of the implant site.

SUMMARY OF THE INVENTION

The present invention is a longitudinally adjustable corpectomy device which fits within the intervertebral distracted channel. The device includes a means for engaging an extendable member to accommodate the distracted channel. An expanding member moves in relation to a main body in accordance with a hinged operation.

An objective of the instant invention to provide a corpectomy device that may be adjusted within the intervertebral cavity or adjusted in situ within the cavity.

It is a further objective of the instant invention to provide an expandable corpectomy which can be expanded by use of a hinged mechanism.

Yet another objective of the instant invention is to provide vertebra engagable endplates which are arranged to pivot and self adjust.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the Figures, set forth is a hinged, expandable corpectomy implant device, referred to generally as10. The corpectomy implant device10is defined by a main body12, a first expandable plate14, and an opposing second expandable plate16. Each expandable plate14and16is adapted to fit within the main body12in a non-expanded state, seeFIG. 1. Referring toFIGS. 2A and 2B, in an expanded state, each expandable plate14and16moves a distance from the main body12. The expandable plate14contains an upper surface18which can be smooth. In a preferred embodiment, the upper surface18contains surface configurations, such as ridges or teeth20. The teeth20are sized, shaped, and orientated to grip and secure to a surface, such as a vertebral bone. A side wall22extends away form the upper surface18and is set back to allow for at least a portion of the upper surface18to overhang. The first expandable plate upper side wall22is inserted into the main body12so that in the non-expanded position, the upper surface lies flush with the top end24of the main body12. Two slotted regions26and28are sized to receive an expansion member to be described later.

The second expandable plate16contains an upper surface30which can be smooth. In a preferred embodiment, the upper surface30contains surface configurations, such as ridges or teeth32. The teeth32are sized, shaped, and orientated to grip and secure to a surface, such as a vertebral bone. A side wall34extends away form the upper surface30and is set back to allow for at least a portion of the second expandable plate upper surface to overhang. The second expandable plate upper wall side wall34is inserted into the main body12so that in the non-expanded position, a portion of the second expandable plate16lies flush with the bottom end36of the main body12. Two slotted regions38and40are sized to receive an expansion member to be described later.

To provide for the expandable plates14and16to traverse between an expanded position and non-expanded position, the corpectomy implant device10comprises an expansion member42, illustrated as a toggle. The expansion member42is defined by a screw44inserted in a threaded aperture60formed along a pivot hinge52which adjoins a proximal end62of an upper expansion member plate46to a proximal end64of a lower expansion member plate48. The screw head50is shaped to receive a rotation generating device, such as a drill bit or other driving tool, such as a screw driver, to provide the necessary rotational force to move the expansion member plates46and48relative to each other. The first plate14includes a notch66formed in a bottom edge wall68and the second plate16includes a notch70formed in a top edge wall72. The notches66and70are constructed to allow passage of the screw shank45when the implant is in a compression position.

In use, as the screw44is rotated, the expansion member plate46and the expansion member plate48pivot about hinge52from a first position in which the expansion member plates46and48from a generally V shaped orientation to an expandable state in which the expansion member plates46and48form a linear structure. Depending on the degree of expansion required, the expansion member plates46and48may assume a position in-between the non-expanded state and the fully expanded state. The expansion member42is designed so that the degree of expansion when the expansion member plates46and48are in the non-expansion state is greatest. As such, during the first few rotations, the degree of member plate separation is greatest. As the expansion member plates46and48reach their most distal heights, i.e. formation of a liner structure, plate separation is more difficult. Such feature allows the surgeon the capability to make fine adjustments at this point.

Positioned at the distal end of each expansion member plate46and48are generally cylindrical bars54and56. The cylindrical bar54is sized and shaped to slidably engage slotted region28. The cylindrical bar56is sized and shaped to slidably engage slotted region38. As such, when screw44is engaged and rotates causing each expansion member plate46and48to pivot about hinge52, bar54slides within slotted region28. As the bar contacts the closed end58, the first expandable plate14moves. Concurrently, as bar56slides within slotted region38and contacts closed end60, the second expandable plate16moves, causing overall expansion.

FIGS. 7-10are pictorial views depicting the corpectomy implant device10between vertebra62and64.FIG. 8illustrates the corpectomy implant device10in the compressed state.FIG. 9illustrates the use of a driver66.FIG. 10illustrates the corpectomy implant device10in the expanded state.