Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
1999-05-11
2001-04-10
Isabella, David J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
Reexamination Certificate
active
06214050
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an expandable implant capable of providing inter-bone stabilization (e.g., intervertebral spinal stabilization) and also capable of extruding materials, such as osteogenic material, upon expansion. The present invention also relates to a method of stabilizing bones (e.g., spinal vertebrae) with respect to one another while extruding osteogenic material.
There are several situations where it becomes desirable to stabilize one bone with respect to another. One exemplary situation arises in patient's who suffer from chronic low back pain. Chronic low back pain is one of the most common and perplexing problems facing the field of orthopedic surgery. In addition to patient discomfort, chronic low back pain has several adverse societal impacts, including lost income and possible chronic dependence on drugs, alcohol and public relief programs.
In many cases, low back pain can be avoided by preventing relative motion between spinal vertebrae. This treatment is commonly referred to as intervertebral stabilization. To abate low back pain, stabilization is directed to stabilizing contiguous vertebrae in the lumbar region of the spine.
Surgical techniques are known for use in spinal stabilization. These techniques seek to rigidly join vertebrae which are separated by a degenerative disk. Ideally, the surgery effectively replaces the vertebra-disk-vertebra combination with a single rigid vertebra. Various surgical techniques have been developed which attempt to approach or approximate this ideal.
One technique known in the art is to partially remove a degenerated disk and insert a bone graft into the void formed by the removed disk. Other techniques involve use of a surgical prosthetic implant which, acting alone or in combination with bone fragments, replaces the use of bone grafts. Such implants have been provided in the form of an implant that is placed between two adjacent vertebrae. The implant may contain bone fragments to facilitate bone growth. The implant contacts adjacent vertebral plates and achieves vertebral fusion after a sufficient amount of bone growth occurs, thus treating or preventing back pain in patients that have discogenic pain.
While conventional implants can be filled with bone fragments to expedite bone growth, it is believed that the mere presence of the bone fragments is not enough to achieve the rate of bone growth that would be provided if the bone fragments or other osteogenic material were extruded from the implant. There is consequently a need for an expandable implant which is adapted to extrude osteogenic material during its expansion and which thereby is adapted to expedite the bone growth and fusion process. By expediting the bone growth and fusion process, it is possible to reduce the amount of time between surgery and the patient's ability to return to work or perform physically demanding activities.
There also is a need for an expandable implant which can be repositioned in the event that the stabilization provided by the initial positioning of the implant creates an undesirable vertebral alignment.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to satisfy the foregoing needs by providing an expandable implant capable of extruding osteogenic material during expansion, to thereby expedite bone growth.
Another object of the present invention is to provide a method of stabilizing vertebrae with respect to one another while extruding osteogenic material.
Still another object of the present invention is to provide an expandable implant which can be contracted after expansion in order to facilitate repositioning of the implant.
To achieve these and other objects, the present invention provides an expandable implant comprising an anchor structure and a movable structure. The anchor structure is adapted to be inserted at least partially into a bone or between two bones, and is adapted to be secured thereto by expansion. The movable structure is operatively connected to the anchor structure so that movement of the movable structure with respect to the anchor structure causes expansion of the implant and at least partial extrusion of material contained within the implant.
Also provided is an expandable implant comprising an anchor structure, a movable structure, and an actuation device. The anchor structure is adapted to be inserted at least partially into a bone or between two bones, and is adapted to be secured thereto by expansion. The anchor structure has a cavity which contains osteogenic material. The movable structure delimits aspects of the cavity and is operatively connected to the anchor structure so that movement of the movable structure with respect to the anchor structure causes expansion of the implant and at least partial extrusion of the osteogenic material. The actuation device connects the anchor structure to the movable structure and is adapted to move, in response to mechanical manipulation, the movable structure with respect to the anchor structure in a first predetermined direction which causes expansion of the implant and reduces the volume of the cavity. As a result of the reduction in volume, the osteogenic material is extruded at least partially from the cavity.
The present invention also provides a method of stabilizing first and second bones with respect to one another. The method comprising the steps of inserting at least one expandable implant between the bones, expanding the implant, and extruding an osteogenic material from the implant during expansion thereof.
The above and other objects and advantages will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.
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Isabella David J.
Liniak, Berenato, Longacre & White LLC
LandOfFree
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