BACKGROUND OF THE INVENTION

Spine surgeons have articulated a desire not to insert a plate on the anterior surface of a vertebral body and then place fixation devices such as bone screws through that plate. Often times, the plate may be considered to be too proud and its profile can sometimes cause patient discomfort and may be related to dysphasia.

PCT Published Patent Application WO 02/013732 (Bramlet) discloses an apparatus and method for fusing opposing spinal vertebrae. The implant includes a body assembly and a retention member coupled to the body assembly. The retention member includes a tang where the tang is extendible from the body assembly. The method includes the step of inserting an implant between adjacent vertebrae with a retention member of the implant in a first retracted configuration. The method also includes the step of configuring the retention member in a second extended configuration wherein the retention member is in its second extended configuration, a portion of a tang of the retention member extends from the implant and into at least one of the adjacent vertebrae.

U.S. Pat. No. 6,336,928 (DePuy France) discloses a device for joining at least two vertebral bodies, which comprises at least one plate equipped at each end with anchoring parts which can be introduced substantially vertically into seats previously established in the vertebral bodies to be joined, and then, after introduction, can be folded back at an angle towards one another in order to exert a constant compression of the vertebral bodies and to ensure perfect anchoring, wherein each anchoring part is connected to the ends of the corresponding plate via a central connection zone delimiting two profiled notches in order to permit deformation of the zone, in such a way that each pair of anchoring parts permits a compression, both at the level of the plate and at the level of its ends, and in such a way that the anchoring parts at each end of the plate permit a clamping which prevents any extraction.

U.S. Pat. No. 7,594,931 (LDR I) discloses an intervertebral arthrodesis for insertion in an intervertebral space separating opposite faces of two adjacent vertebrae has a ring shaped intervertebral cage having a bar that extends perpendicular to the axis of the spine. The bar has a height less than the rest of the cage. A surface of the cage contacting the vertebrae has an undulating shape for limiting sliding of the cage in a plane parallel to the vertebrae faces.

PCT Published Patent Application WO2008/149223 (LDR II) discloses an intersomatic cage, an intervertebral prosthesis, an anchoring device and an instrument for implantation of the cage or the prosthesis and the anchoring device, as well as a system and a method for implanting spinal implants and anchoring devices in vertebrae. An intersomatic cage or an intervertebral prosthesis fit closely to the anchoring device, which includes a body of elongated shape on a longitudinal axis, of curved shape describing, along the longitudinal axis, an arc whose dimensions and radius of curvature are designed in such a manner that the anchoring device may be implanted in the vertebral plate of a vertebra by presenting its longitudinal axis substantially along the plane of the intervertebral space, where the anchoring device is inserted, by means of the instrument; through a slot located in at least one peripheral wall of the cage or on at least one plate of the intervertebral disc prosthesis to penetrate into at least one vertebral plate

PCT Published Patent Application WO2010/028045 (Synthes) discloses an intervertebral implant for insertion into an intervertebral disc space between adjacent vertebral bodies or between two bone portions. The implant includes a spacer portion, a plate portion operatively coupled to the spacer portion and one or more blades for securing the implant to the adjacent vertebral bodies. The blades preferably include superior and inferior cylindrical pins for engaging the adjacent vertebral bodies. The implant may be configured to be inserted via a direct lateral trans-psoas approach. Alternatively, the implant may be configured for insertion via an anterior approach

US Patent Publication No. 2005-0149192 & 2005-0149193 (Zucherman I and II) disclose an intervertebral implant has a fusion body with at least one keel that anchors the implant into cancellous bone of at least one vertebral body. A method for implantation includes lateral implantation of the implant.

US Patent Publication No. 2004-0260286 (Ferree) discloses intradiscal components associated with Total Disc Replacements (TDRs), for example, are maintained in a disc space with keels having attributes that resist extrusion, pull-out, and/or backout. In the preferred embodiment, the keel is curved to resist extrusion, particularly anterior or posterior extrusion. The invention may include a TDR with a pair of endplates, each with a keel extending into a different vertebral body, and wherein the keels are angled or curved in different directions to resist extrusion. In alternative embodiments, the keel may include one or more members that extend outwardly to resist extrusion. Such members may be spring-biased, composed of a shape-memory material, or extend outwardly in response to an applied mechanical force, as might be applied by turning a screw. The keel may further include a bone-ingrowth plug or coating or ‘teeth’ to resist extrusion. Keels according to the invention may also be configured to resist extrusion through the addition of an elongate member that penetrates a vertebral body and the keel. Such a member may be a secondary keel or screw.

US Patent Publication No. 2008-0167666 (Fiere) discloses equipment including at least one U-shaped clip whose lateral branches have sections and widths such that they may be inserted in the vertebral bodies of two vertebrae by impaction on the intermediate branch of the clip, so as to rest along the cortical bones of the vertebral bodies, and whose intermediate branch is deformable in such a way as to allow a reduction of the distance between the lateral branches; the intermediate branch, before implantation, has a length such that one of the lateral branches may be positioned slightly above the cortical bone forming the plate of the subjacent vertebra while the other lateral branch may be positioned slightly below the cortical bone forming the plate of the subjacent vertebra, and has, after deformation, a length such that the two lateral branches may be brought closer to each other.

U.S. Pat. No. 6,773,437 (Ogilvie) discloses a fusionless method of correcting spinal deformities in growing adolescents, utilizing a shape memory alloy staple. Various embodiments of the shape memory alloy staple include features such as barbs on the inner and outer surfaces of the prongs in the shape memory alloy staple as well as the use of notches on the crossbar or cross plate connecting the prongs to the shape memory alloy staple. In some embodiments, the shape memory alloy staple has an aperture defined through the cross plate for receiving a bone screw or other bone anchor which in turn allows the interconnection of a longitudinal member.

US Patent Publication No. US 2010-0004747 (Lin) discloses a trans-vertebral and intra-vertebral plate and a rectangular cage with a slot for the plate of spinal fixation device are for neutralizing intervertebral movement for the spinal interbody fusion. The rectangular cage with a vertical or oblique slot is inserted into the intervertebral space from the lateral or anterior side of the spinal column and then the plate is inserted through the slot of the cage and hammered into and buried inside two adjacent vertebral bodies, to achieve three-dimensional intervertebral fixation.

US2010-0204739 (Bae) discloses a system for spinal surgery including a prosthesis comprising a plurality of bone anchors which engage an intervertebral construct for fusion or motion preservation. The fusion construct comprises a spacer optionally encircled by a jacket. The motion preservation construct may comprise an articulating disc assembly or an elastomeric disc assembly. Any of the constructs may occupy the intervertebral disc space between adjacent vertebrae after removal of an intervertebral disc. The anchors slidingly engage the construct to securely fix the prosthesis to the vertebrae. The anchors and jacket of the fusion construct provide a continuous load path across opposite sides of the prosthesis so as to resist antagonistic motions of the spine.

SUMMARY OF THE INVENTION

The present invention relates to fixing an intervertebral fusion cage to its adjacent vertebral bodies with a single staple, wherein each tyne of the staple traverses the anterior wall of the cage at an angle so that the staple enters both of the vertebral bodies. The staple is designed to be a zero-profile staple.

Generally, the present invention relates to methods for securing the cage to one or more levels of the spine with fixation. The fixation, which is typically a staple, is intended to be driven perpendicular to the proximal face of the cage, and in-line with the inserter. After the cage is placed and positioned according to surgeon preference, a single piece fixation clip is then deployed and fixed in a manner that produces a zero-profile device.

The staple's shape may be designed to provide compression onto the cage once placed in its desired location.

The device of the present invention allows for a smaller incision and access site, and the in-line nature of the staple also frees the surgeon from having to insert the staple at a high angle through sometimes challenging approaches.

Therefore, the present invention is advantageous because it allows for fixation of the cage to each of the vertebral bodies via a single staple. The staple is preferably designed to provide an essentially zero-profile device. This staple may be inserted fully through or partially through a side wall of the cage and into the adjacent vertebral bodies. Further, these staples may be designed to provide compression to the graft held within the cage and thereby promote fusion.

In certain embodiments, the staple is designed to be tapped flush to the vertebral body. The staple may also provide compression onto the graft using a shape memory or spring material. In certain embodiments, the staple may allow for independent cage insertion and staple insertion, with the option to either insert the staple in-line with the cage or to disengage the staple from the cage and place it anywhere about the cage.

