Surgery – Instruments – Orthopedic instrumentation
Patent
1998-09-25
2000-06-27
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
606 63, A61B 1756, A61B 1758, A61F 230
Patent
active
060801573
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device that dynamically stabilises the lamina after a laminoplasty.
BACKGROUND
Cervical spinal stenosis is a condition in which the opening for the spinal cord that runs through the vertebrae of the spinal column is not quite wide enough to comfortably accommodate the spinal cord. The result is that when the ligaments thicken or there is some bulging of the cervical discs (a natural product of wear and tear through life) the person who is affected begins to experience pressure on their spinal cord. This causes three types of symptoms:
As a result of these symptoms, some people find that their mobility and their ability to undertake a normal day's work is severely affected. The obvious solution is to make more room for the spinal cord so that the pressure will not happen. There are two methods of creating more room in the cervical spinal canal. The first is a laminectomy in which the bony structures forming the back of the canal and the associated ligaments are removed. This can lead to the swan neck deformity so that although it is a very safe operation and usually quite effective it can result in swan neck deformity which is a very difficult problem to correct and which itself causes a lot of discomfort in the neck and shoulders. This is due to the lack of the supporting structures at the back of the vertebrae which normally perform some of the work of keeping the neck in the right shape.
The alternative and increasingly popular way of doing the operation is called a laminoplasty. In this operation the back of the spine is exposed but instead of the bony structures being removed, they are altered in shape. When the bone has been weakened it is bent outwards opening the canal and providing more room for the spinal cord. The traditional problem has always been to stabilise the lamina in this new position.
One way of stabilising the lamina is to take a bone graft from the hip in the form of a rectangular plate of bone and wedge it in position to try and hold the lamina in its new, more open shape. This is generally effective but because it is not a firm arrangement can lead to some slippage and recurrent narrowing of the spinal canal. It also involves making a separate wound in the area of the hip and taking a bone graft.
It is an object of the present invention to provide a prosthesis device to dynamically stabilise the lamina after laminoplasty.
PRESENT INVENTION
Accordingly the invention consists in a device for dynamically stabilising the lamina of the spine after a laminoplasty comprising spacing means shaped to engage between the severed edges of the lamina and retaining means attached to said spacing means and shaped to maintain the spacing means in an operable position.
This invention also consists in a method of dynamically stabilising reshaped lamina after a laminoplasty comprising the steps of positioning a spacing means between the severed edges of the lamina and positioning a retaining means attached to said spacing means to maintain the spacing means in an operable position.
The invention consists in the foregoing and also envisages constructions of which the following gives examples only.
DRAWING DESCRIPTION
One preferred form of the invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 is a cross section through the back bone;
FIG. 2 is a rear view of a section of the back bone;
FIG. 3 is a section of the back bone with modifications made;
FIG. 4 is a cross section of the back bone illustrating the modifications made in a laminoplasty;
FIG. 5 shows the modified back bone with the device according to the present invention in place;
FIG. 6 is a perspective view of a device according to the present invention;
FIG. 7 is an elevation of the device according to the present invention; and
FIG. 8 shows a back view with the device fitted in place.
PREFERRED EMBODIMENT
FIGS. 1 and 2 illustrate a section through a joint in the back bone 1 with the vertebrae body 2, spinal cord 3, lamina 4 and spine 5. FIG. 2 shows a rear vie
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Derwent Abstract Accession No. 85-005046/01, Class P31, SU, A, 1091916 (Moscow Medical Institute) May 15, 1984.
Form PCT/ISA/210, International Search Report, dated Feb. 10, 1998 for PCT/NZ96/00096, International Filing Date Sep. 11, 1993.
Cathro Richard Andrew
Gillett Grant Randall
Bui Vy Q.
Buiz Michael
CG Surgical Limited
Johnston Michael G.
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