Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1998-06-17
2000-02-01
Willse, David H.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
A61F 244
Patent
active
060197935
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a surgical prosthetic device, and in particular to an invertebral implant.
BACKGROUND
It is a well-known surgical procedure to remove a damaged disc in the spine between two adjacent vertebrae of patient and to replace it by inserting into the resulting disc space one or more implants having a combined width approximating the height of the disc space. The implant must be able to maintain the space between the two adjacent vertebrae.
Implantation of the surgical prosthetic device in the intervertebral space involves a considerable invasiveness with loss of or damage of anatomical structures.
The invention as claimed aims at solving the above described problems.
SUMMARY OF THE INVENTION
The surgical prosthetic device according to the present invention is adapted for placement between two adjoining vertebrae for total or partial replacement of the disk from between the vertebrae and has two plates with: interior surfaces facing each other and held at a distance by connecting means made of a shape-memory alloy; and exterior surfaces configured and dimensioned for contacting the end plates of the two adjoining vertebrae.
Preferably, the connecting means are wires and the two plates are also made of a shape-memory alloy. The transition temperature of the shape-memory alloy is in the range of 5.degree. C. to 30.degree. C., preferably between 15.degree. C. to 25.degree. C. The shape-memory alloy can be nitinol.
In one embodiment, the two plates have a hollow cylindrical configuration with concave sides connected by the connecting means. In a preferred embodiment, the exterior profile of the device is generally circular when the device is at a temperature below the transition temperature of the shape-memory alloy and generally rectangular when the device is at a temperature above the transition temperature of the shape-memory alloy. In a further preferred embodiment, the exterior shape of the device at a temperature below the transition temperature of the shape-memory alloy is such that the device is introducible between the two adjoining vertebrae endoscopically.
The two plates can be provided with perforations for allowing bony ingrowth and teeth to provide initial stability of the device. Preferably, the two plates are closer to each other when the device is below the transition temperature of the shape-memory alloy than when the device is above the transition temperature.
The method of maintaining the space between two adjacent vertebrae of a patient after removal of the disk from between the vertebrae according to the present invention comprises the steps of inserting a spacing device made at least partially from a shape-memory alloy into the space between the two adjacent vertebrae after removal of the disk from between the two vertebrae at a temperature below the transition temperature of the shape-memory alloy; and allowing the spacing device to reach the transition temperature and a predetermined configuration suitable to its spacing function.
In one embodiment, the method further comprises the step of configuring the spacing device to have a generally circular exterior profile when the spacing device is below the transition temperature of the shape-memory alloy and to have a generally rectangular profile when the spacing device is above the transition temperature of the shape-memory alloy. In a preferred embodiment, the method further comprises the step of endoscopically introducing the spacing device into the space between the two adjacent vertebrae. For the better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings, examples and descriptive matter in which are illustrated and described preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of a device according to the invention at a temperature below the transition temperature of the memory alloy;
FIG. 2 is a perspective view of a mo
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patent: 5888227 (1999-03-01), Cottle
Higgins Tom
Perren Stephan M.
Stewart Alvin
Synthes
Willse David H.
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