Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
1996-10-31
2001-02-20
Prebilic, Paul B. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S017130, C623S017160, C606S064000
Reexamination Certificate
active
06190414
ABSTRACT:
BACKGROUND
1. Technical Field
The present disclosure relates generally to a surgical apparatus for fusing adjacent bone structures, and, more particularly, to an apparatus and method for fusing adjacent vertebrae.
2. Background of the Related Art
The fusion of adjacent bone structures is commonly performed to provide for long-term replacement to compensate for degenerative or deteriorated disorders in the disc. For example, an intervertebral disc, which is a ligamentous cushion disposed between adjacent vertebrae, may undergo deterioration as a result of injury, disease, tumor or other disorders. The disk shrinks or flattens leading to mechanical instability and painful disc translocations or herniation.
Conventional procedures for disc surgery include partial or total excision of the injured disc portion, e.g., discectomy, and replacement of the excised disc with biologically acceptable plugs or bone wedges. The plugs are driven between adjacent vertebrae to maintain normal intervertebral spacing and to achieve, over a period of time, bony fusion with the plug and opposed vertebrae. For example, U.S. Pat. No. 4,877,020 to Vich discloses a cylindrical bone plug having a thread on its exterior, which is screwed into a correspondingly dimensioned cylindrical bore drilled in the intervertebral space. Other bone grafting plugs are disclosed in U.S. Pat. No. 4,950,296.
More recently, emphasis has been placed on fusing bone structures (i.e., adjoining vertebrae) with prosthetic cage implants. One fusion cage implant is disclosed in U.S. Pat. No. 5,026,373 to Ray et al. The Ray '373 fusion cage includes a cylindrical cage body having a thread formed as part of its external surface and apertures extending through its wall which communicate with an internal cavity of the cage body. The fusion cage is inserted within a tapped bore or channel formed in the intervertebral space thereby stabilizing the vertebrae and maintaining a pre-defined intervertebral space. The adjacent vertebral bone structures communicate through the apertures with bone growth inducing substances within the internal cavity to unite and eventually form a solid fusion of the adjacent vertebrae. Other prosthetic implants are disclosed in U.S. Pat. Nos. 4,501,269, 4,961,740, 5,015,247 and 5,489,307.
Both anterior (transabdominal) and posterior surgical approaches are used for interbody fusions of the lumbar spine. Fusions in the cervical area of the spine are primarily performed using a posterior approach. Typically, a plug or fusion cage of the type discussed above is inserted into a preformed cavity inside the interbody, interdiscal space. Since it is desirable in these procedures to promote a “bone to bone” bridge, connective tissue and at least a portion of the distal tissue is removed. Preferably, relatively deep cuts are made in the adjacent bones in order to penetrate into the softer, more vascularized cancellous region to facilitate bone ingrowth across the implant.
More recently, laparoscopic procedures, i.e., an anterior approach through the abdominal cavity, are being utilized to access the spine to perform the discectomy and subsequent fusion procedures. In laparoscopic surgical procedures, the abdominal cavity is insufflated with CO
2
gas. A surgical trocar which includes a cannula and an obturator positioned within the cannula is applied against the abdominal cavity. The whole assembly is advanced in the abdominal cavity to gain access thereto. The obturator is removed to permit the introduction of surgical instruments within the cannula to perform the desired procedure. The laparoscopic approach is characterized by being less invasive to the patient resulting in less patient trauma and improved recovery time.
The laparoscopic approach for discectomy and spinal fusion requires specialized instrumentation to effectively position the implant within the remotely located and relatively inaccessible intervertebral space.
SUMMARY
Accordingly, the present disclosure is directed to a spinal fusion apparatus particularly suited for use in conjunction with laparoscopic or minimally invasive techniques utilized in performing discectomy and spinal fusion. In one preferred embodiment of the disclosure, a prosthetic implant for facilitating fusion of adjacent vertebrae is disclosed. The prosthetic implant includes an implant member dimensioned to be at least partially positioned within an intervertebral space defined between adjacent vertebrae. The implant member includes first and second vertebral engaging plates operatively connected to each other for respectively engaging vertebral end plates of the adjacent vertebrae and having discontinuous surfaces to engage the vertebral end plates and promote bone ingrowth. A displacement member is associated with the engaging plates and is deployable to cause relative movement of the engaging plates to thereby at least laterally displace the engaging plates whereby in a deployed position the engaging plates are in supportive engaged relation with the adjacent vertebrae.
The first and second engaging plates are pivotally connected to each other at respective end portions thereof to define a reduced entry profile to facilitate insertion within the intervertebral space. The implant member may also define an interior cavity for accommodating bone growth inducing substances. The first and second engaging plates preferably include apertures extending therethrough to permit communication with the bone growth inducing substances within the interior cavity. The first and second engaging plates may also include projections for engaging the vertebral end plates to assist retention of the implant within the intervertebral space.
The preferred displacement member is a telescoping jack member which is deployable with a remotely operable applier instrument. The telescoping jack member includes a screw jack having a threaded portion which is cooperatively engageable with a threaded component. The screw jack and the threaded component are disposed between the engaging plates of the implant whereby rotational movement of one of the screw jack and the threaded component causes corresponding telescoping motion of the screw jack and displacing movement of the first and second engaging plates.
The present disclosure is also related to an apparatus for facilitating fusion of adjacent vertebrae. The apparatus includes an elongated member having proximal and distal ends and defining a longitudinal axis, an implant member releasably mounted to the distal end of the elongated member and a manually operable actuator operatively connected to the implant member and moveable to deploy the implant member. The implant member is configured for insertion within an intervertebral space defined between adjacent vertebrae and has first and second vertebral engaging plates adapted for relative movement between a retracted position and an extended position. The first and second engaging plates define an internal cavity for reception of bone growth inducing substances and have contacting surfaces with apertures extending therethrough for communicating with the internal cavity.
The manually operable actuator is operatively connected to a displacement mechanism which moves the implant member between the retracted and extended positions upon movement of the actuator. The displacement mechanism includes a telescopic jack member disposed between the engaging plates and adapted for telescoping movement to deploy the implant.
The present disclosure is also directed to a method for facilitating spinal fusion of adjacent vertebrae. The method includes accessing the intervertebral space defined between adjacent vertebrae, introducing a fusion implant within the intervertebral space and having first and second vertebral contacting plates defining discontinuities to promote bone ingrowth, causing relative movement of the first and second contacting plates such that the contacting plates supportingly engage the adjacent vertebrae, and permitting bone growth into the discontinuities of the vertebral contacting plates to for
Hinchliffe Peter W.J.
Young Wayne P.
Prebilic Paul B.
Surgical Dynamics Inc.
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