Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-03-17
2001-10-23
Reip, David O. (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S064000, C606S064000
Reexamination Certificate
active
06306139
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to intervertebral connection devices designed to correct a weakening, a fracture of the vertebrae, or a defective posture of the spine.
It relates more precisely to devices for connecting the cervical vertebrae, preferably intended to be fixed on their anterior face.
BACKGROUND OF THE INVENTION
An anterior intervertebral connection device generally comprises a rigid osteosynthesis plate adapted to cover at least partially two consecutive vertebrae, in order to join them together. This osteosynthesis plate presents an anterior face and an opposite posterior face intended to be applied against the anterior face of the vertebrae. This plate is generally provided with two pairs of through holes, designed each to receive a screw intended to be anchored in the body of the vertebrae.
After implantation of such osteosythsis devices in patients, a phenomenon of avulsion or of partial extraction of the anchoring screws has been observed. This results in a risk of lesion or injury, particularly of the oesophagus and the pharynx.
The need is therefore felt to ensure blocking of the anchoring screws in order to avoid their leaving the osteosynthesis plate.
In an attempt to satisfy this need, document FR 2 740 321 has proposed an osteosynthesis device comprising, as means preventing extraction of the screws, a rigid counter-plate intended to be fixed on the anterior face of the osteosynthesis plate. The shape of this counter-plate is substantially similar to that of the osteosynthesis plate, so as to totally to cover all the anchoring screw heads. The counter-plate is fixed on the osteosynthesis plate with the aid of a screw adapted to screw in a tapping made on the osteosynthesis plate. The counter-plate thus constitutes a stop for the heads of the screws.
It must be considered that the operation of positioning these anti-extraction means is relatively long to carry out due to the phase of positioning of the counter-plate, followed by a phase of screwing the counter-plate on the osteosynthesis plate. Furthermore, the screw for fixing the counter-plate on the osteosynthesis plate risks unscrewing, resulting in the counter-plate moving away from the plate and thus in an avulsion of the anchoring screws. Moreover, it must be considered that the use of a rigid counter-plate presents relatively large dimensions capable of causing injuries or lesions.
It is therefore an object of the invention to overcome the drawbacks set forth hereinabove by proposing an intervertebral connection device designed to present an efficient and reliable means for blocking the anchoring screws, while being easy and quick to place in position.
SUMMARY OF THE INVENTION
The invention relates to an intervertebral connection device comprising a rigid osteosynthesis plate adapted to cover outer faces of at least two consecutive vertebrae at least partially. The plate comprises an anterior face and an opposite posterior face. The posterior face is positionable against outer faces of at least two consecutive vertebrae. The plate further comprises at least one pair of through bores each adapted to receive an anchoring screw arranged to anchor the plate on a vertebrae. The anchoring screws each comprise a screw head. An anti-extraction device is adapted to prevent extraction of the anchoring screws. The anti-extraction device is mounted on the anterior face of the plate and acts as stops for the screw heads of the anchoring screws. The anti-extraction device comprises at least one mobile flap mounted on the plate by a guide device. The anti-extraction device is movable between a first position that permits access to the through bores and a second position that obturates access to the through bores at least partially to act as stops for the screw heads.
REFERENCES:
patent: 4794918 (1989-01-01), Wolter
patent: 5951558 (1999-09-01), Fiz
patent: 0 599 640 A1 (1994-06-01), None
patent: 2 740 321 (1997-04-01), None
patent: WO 98/34553 (1998-08-01), None
Bacon & Thomas PLLC
Reip David O.
Scint'x
Woo Julian W.
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