Surgery – Instruments – Orthopedic instrumentation
Patent
1998-05-28
1999-11-30
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
606 70, A61B 1756
Patent
active
059934492
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a device for the fixation of bones.
BACKGROUND
For the anterior fusion of vertebra segments (fractures, tumors, infections, congenital and post traumatic kyphoses, deformities) a wide variety of plate- as well as rod-systems are available.
Some of the advantages of plate systems such as the one disclosed in PCT/US93/08433, are the relatively small dimensions and the generally easy handling. Important disadvantages of these known plate-system consist therein that the area of fusion cannot actively be set under compression, a great assortment of expensive plate implants, and in the case of deformities no possibilities of correction.
Rod systems, such as the ones disclosed in PCT/US93/10908 or PCT/EP94/01606, do not have the above mentioned disadvantages of the plate-systems, but they are naturally larger in their dimensions and more difficult to handle.
U.S. Pat. No. 4,289,123 discloses an orthopedic appliance which includes a pair of brackets anchored to bone and connected by a pair of rods. However, the disclosed device is bulky and cumbersome to use.
SUMMARY OF THE INVENTION
The present invention provides a device which combines the advantages of the known plate- and rod-systems easy handling, platelike dimensions, an assortment favourable in costs as well as possibilities of compression and correction.
The device according to the present invention comprises a block, a bone plate associated with the block and having a bone-contact surface and at least one plate hole, and first and second parallel guide channels associated with the block for accommodating first and second longitudinal carriers. Each of the guide channels has a longitudinal axis lying in a plane which is parallel to the bone-contact surface and an imaginary cylinder defined by the first guide channel does not intersect an imaginary cylinder defined by the bone plate hole while an imaginary cylinder defined by the second guide channel intersects the imaginary cylinder defined by the bone plate hole.
The first guide channel extends completely through the block while the second guide channel extends partially through the block to form an opening in the block opposite the bone plate. At least one of the guide channels can extend to the side of the block opposite the bone-contact surface to facilitate insertion of a longitudinal carrier. Alternatively, at least one of the guide channels can extend to the top of the block to facilitate insertion of a longitudinal carrier.
The bone plate comprises at least two plate holes having centers which lie on a common connecting line. In one preferred embodiment, the connecting line is disposed at an angle of +10.degree. to +50.degree. with respect to the longitudinal axes of the first and second guide channels. In another preferred embodiment, the connecting line is disposed at an angle of -10.degree. to -50.degree. with respect to the longitudinal axes of the first and second guide channels.
Each guide channel includes a bore hole positioned orthogonal to its longitudinal axis to accommodate a fastener for removably securing a longitudinal carrier to the guide channel. The bone-contact surface includes a cylindrical segment having a cylinder radius of between 25 and 35 mm and a longitudinal axis which is parallel to the longitudinal axes of the first and second guide channels. Preferably, the plate holes have longitudinal axes lying in parallel planes which are perpendicular to the longitudinal axis of the cylindrical segment of the bone-contact surface.
The bone plate holes have a multiple-threaded threads preferably having a planar thread bottom. In a further preferred embodiment, the planar thread bottom forms an angle of between 20.degree. and 40.degree. with respect to the thread longitudinal axis. The plate holes can be spherical.
An apparatus for the fixation of bones according to the present invention includes first and second devices each comprising: a block; a bone plate associated with the block and having a bone-contact surface and at leas
REFERENCES:
patent: 4289123 (1981-09-01), Dunn
patent: 5324290 (1994-06-01), Zdeblick et al.
patent: 5702395 (1997-12-01), Hopf
patent: 5713898 (1998-02-01), Stucker et al.
Hatebur Alexander
Schlapfer Fridolin
Buiz Michael
Goldberg Jonathan D.
Synthes (USA)
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