Surgery – Instruments – Orthopedic instrumentation
Patent
1991-10-04
1994-03-01
Brown, Michael A.
Surgery
Instruments
Orthopedic instrumentation
606 69, 606 73, A61B 1756
Patent
active
052902889
DESCRIPTION:
BRIEF SUMMARY
This invention is relative to a device permitting an osteosynthesis of rachis from the rear by means of implants, a portion of which is intended for bone anchorage in vertebral pedicles and another portion is intended to accommodate either a plate or a rod in order to connect the screws together.
As a rule, pedicular screws are implanted, that are connected solely either through plates or through rods.
The purpose of the invention is to provide an instrument of simple design, permitting a specially accurate and reliable positioning and locking of a plate as well as a rod, in order to facilitate the osteosynthesis of rachis, regardless of the anatomical conditions and deformations caused by kyphosis, scoliosis or scolio-kyphosis.
To this purpose, one object of the invention is a device for rachis osteosynthesis with pedicular screws of the type comprising an ogival-shaped threaded point and a threaded head, that are separated by a hexagonal body, said screws being connected by a connection member, characterised in that it also has one fixing part provided with a hole for the passage of said threaded head on which a locking nut is screwed for the assembly consisting of the fixing part and the connection member on said head, one of either the fixing part or the connecting member being shaped on its inner face in order to provide a groove to accommodate said hexagonal body and locking it against rotation, said part, in form of a U-shaped part, being also striated on its face opposing the plate.
According to an application of the device, more particularly to the fixing of a rod, the device is characterized in that said fixing part comprises, at its upper face, a groove in the bottom of which said hole is provided, one flank of which forms a shoulder, whereas the other flank defines a concave-shaped surface for the accommodation of said rod, said locking nut being provided ats lower face with a truncated portion capable of abutting against said shoulder on the one hand, and against said rod on the other hand and in that the lower face of said fixing part comprises said groove for accommodating and locking the hexagonal body.
According to an application of the device, more particularly to the fixing of a plate, the device is characterized in that said fixing part is a U-shaped part overlapping the upper face of said plate provided with said passage hole and flanked by two lateral parallel protusions, in that said plate comprises oval-shaped holes and is provided with transversal striae on its upper face and with said accommodation and locking groove for the hexagonal body on its lower face.
FIG. 1 of the drawing is an exploded view of an embodiment of the device of the invention for fixing a rod,
FIG. 2 is a cross section view of the device of FIG. 2 in an assembled condition,
FIG. 3 is an exploded view of an embodiment of the device for fixing a plate,
The device of the invention comprises pedicular screws of a known general type, consisting of three parts: a point 1, a body 2, a head 3.
The screw is made from materials approved for surgical uses in order to be bio-compatible and to eliminate any breaks of the materials when it enters the vertebral body.
The screw point 1 is threaded and ogival-shaped and it is advantageous that the conicity of thread bottom and thread top is different.
The head of the screw 3 is cylindrical-shaped with a threading compatible for a locking nut (4,4') for either a rod 5 (FIG. 1) or a plate 6 (FIG. 3) by means of one auxiliary part (7 or 8) provided with a smooth hole 9 at its central portion and threaded onto the head 3.
Nuts (4,4') have an extension at their top in form of a cylindrical tubular part 10 provided with slots 11 permitting the nuts to be locked whereas the opposing parts 10 are slightly moved closer to each other by means of a plier prior to the insertion of the screw head 3 into the auxiliary part 7,8.
Besides, means are provided on either the sole auxiliary part or the connecting member for pedicular screws, in order to provide a seat for accommodation of and a lo
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Henry Patrick
Vignaud Jean-Louis
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