Surgery – Instruments – Orthopedic instrumentation
Patent
1990-10-09
1992-07-14
Apley, Richard J.
Surgery
Instruments
Orthopedic instrumentation
411385, 411393, A61F 500
Patent
active
051293889
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device to contain, reduce and re-establish physiological curves to the spine of a patient by implanting a diapason screw spinal instrument. The screws have U-shaped heads for receiving on element integrally connecting the various screws with one another.
BACKGROUND OF THE INVENTION
Normally, pedicular screws joined by plates are implanted. However, this implantation depended on the spatial requirement of the holes of the plates, hence requiring a correct setting but small reduction.
Hooks are also implanted laid on the posterior arches moving around on rods with complex blocking systems. These systems allow for a correct setting and reduction but firstly require observance of the posterior vertebral arches and secondly delicate to-and-fro manoeuvres, dangerous for the patient and scarcely practical for the operator.
SUMMARY OF THE INVENTION
The device of the invention makes it possible to overcome all these drawbacks. In effect, it comprises several screws composed of three segments: particular head/body point, a bolt, a cap and a homolateral joining element.
The structure and adaptation of this equipment has been specially created to this effect.
The screw is made of homologous materials for use in surgery so as to avoid the equipment breaking when it penetrates into the vertebral body.
The point of the screw has an inverted pyramidal square shape. The body of the screw is conical and bears a standard cortical thread which allows for improved blocking of the implant in the most fragile region of the vertebral pedicule.
Moreover, this conicity reinforces the solidity of the body of the screw at the screw head.
The head of the screw has a a U-diapason shape for receiving the element for rendering the various screws integral with one another. The bottom of the U is slightly rounded so as to enable the joining element to be fixed in several positions, which also facilitates the blocking of the joining element.
The U is threaded at the internal section of the branches so as to allow for screwing in situ of a bolt locking the joining element. As the risk of this system concerns the spatial requirement of the branches of the U at the time of screwing, this risk can be avoided by placing a cap able to fit exactly on the outer smooth section of the branches of the U. This cap comprises a circular orifice to allow for the tightening and definitive blocking of the bolt blocking the joining rod.
The bolt is characterized by a threaded cylindrical shape bearing at its extremity a male conical point able to be fit perfectly into the female conical notches of the joining rod. The opposing section of the bolt comprises a hexagon-shaped cavity enabling it to receive a chuck key.
The joining element is made of a homologous material for surgical implantation. This is a rod with a cylidrical section and having a sufficient diameter so as to resist the stresses and forces of the spine, said rod being notched to allow for a micrometric adjustment of the various screws in relation to one another. Each notch has a female conical shape so as to receive the point of the bolt. Depending on the adjustment to be obtained, the notching shall have one variable pitch.
The diameter of the joining element is sufficient so to render it resistant whilst allowing for easy shaping so as to be adapted to or re-establish the physiological curves of the spine. In addition, its circular section enable it to be rotated prior to being locked, this being effected after a correct positioning of the joining element by tightening the bolt of the various homolateral screws.
This rod is easily placed owing to the adaptation of the head screws as it may be positioned directly at the bottom of the U without requiring any forced movement or the need for any to-and-fro sliding.
The structure in itself of the diapason implant, by modifying the size of the screw or by adapting the screw head to other osteosynthesis posterior arch systems, makes it possible to make vertebral fixings over the entir
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patent: 4743260 (1988-05-01), Burton
patent: 4763644 (1988-08-01), Webb
patent: 4815453 (1989-03-01), Cotrel
patent: 4913134 (1990-04-01), Luque
patent: 4946458 (1990-08-01), Harms et al.
patent: 4950269 (1990-08-01), Gaines, Jr.
Lapresle Philippe
Missenard Gilles
Sacriste Jean-Francois
Vignaud Jean-Louis
Apley Richard J.
Weinhoffer Susan L.
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