Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-04-08
2001-04-24
Buiz, Michael (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S057000, C606S059000
Reexamination Certificate
active
06221072
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention relates to a device for fixing bone sections relative to each other, comprising a support bar for lateral application along the bone sections to be fixed, said support bar having at least two bone pin looking blocks being slidable across and securable on said support bar, each of two opposite sides of said blocks being provided with a protruding portion for fastening pivotably adjustable clamping beds, in which bone pins can be pressed against said clamping beds by means of clamping plates to be secured on the clamping beds, said clamping beds and clamping plates being engaging planes for the bone pins and both clamping beds can be secured relative to each other in such a way that their engaging planes for the bone pins enclose a sharp angle.
2. Description of Related Art
In professional circles, such a device is called an “external fixator” and is applied to assist in the healing of bone fractures. A device of the type described above is known from WO 95/10240.
With this device, after applying the pins in the bone sections and securing them to the support bar through the bone pin locking blocks, the bone sections can be pressed towards each other or be spaced apart across a certain distance. This occurs by sliding the bone pin locking blocks across the support bar.
A difficulty is that after mounting the device, the bone sections can only perform the movement described above and that other movements of the bone sections relative to each other are hardly possible.
BRIEF SUMMARY OF INVENTION
The object of the invention is to remove this difficulty and to that end provides for, that a sliding piece fixable on the support bar is mounted between each bone pin locking block and the support bar, and said sliding piece is provided with a spherical portion, whereas the bone pin locking block is provided with a cup-shaped portion which is matingly received on the spherical portion of said sliding piece, in such a way, that the bone pin locking block, after having been pivoted into the desired position, can be fixed on the sliding piece.
In this way, it is achieved that the two bone pin locking blocks have much more freedom of movement relative to each other before they are fixed onto the sliding piece and thus through the latter onto the support bar. Therefore, in certain cases, the bone sections connected with it can be brought into a more suitable position relative to each other as a result of which the healing process can be accelerated.
It is possible to provide a cavity in the bone pin locking block, in which the spherical portion of the sliding piece can be received in such a way that it will contact a stop surface. The cavity can then be closed by an externally threaded ring to be screwed into the block.
However, it is important that the dimensions of the sliding piece be kept as small as possible and that securing the bone pin locking block onto the sliding piece is as simple as possible. To that end, according to the invention it will be provided for, that each bone pin locking block is divided in two parts according to a plane going through the axis of the support bar in the centre position of said block, the parts at one side being pivotably connected to each other and at the opposite side being able to be pulled towards each other by a bolt in such a way that the parts can enclose the spherical portion of the sliding piece and can be clamped thereon.
Thus, a simple construction and an easy connection between the bone pin locking block and the sliding piece is achieved. The block can also be clamped onto the sliding piece in a simple way and thus be fixed relative to the support bar through said sliding piece.
With the known device mentioned above, the contact planes for the bone pins are partially constituted by two parallel grooves made in a clamping plate.
According to a further development of the invention, each clamping bed can now be provided with at least two clamping plates which can be pressed against the clamping bed in any angular position by means of one bolt, each of which being provided with contact planes for one bone pin.
In this way it is achieved, that the two bone pins to be clamped onto a clamping bed need not be parallel but can enclose an angle. Thus, two bone pins, together with the bone, can form a triangle as a result of which a more rigid structure is achieved than when the bone pins are parallel. Furthermore, the locations where the bone pins are secured in a bone can be situated wider apart.
In order to be able to press the bone sections connected by means of a fixator continuously against each other, one of the sliding pieces can be brought under an adjustable compressive load by means of a length-adjustable compression spring.
Now in certain cases it is desirable that after a certain time, the sliding pieces are moved slightly towards each other or moved slightly apart. The latter is the case e.g. when a bone must be extended and the bone sections growing towards each other must be moved slightly apart repeatedly.
In order to be able to realize this in a simple way, according to the invention, one can employ an adjustment member consisting of a bush being slidable on the support bar and comprising means for clamping it onto at a certain position on the support bar, said bush being provided with an external thread on which a set screw can be screwed, said screw being rotatably connected to a sliding piece, said sliding piece being connected to a blade spring extending towards a portion of the circumferential surface of the set screw, said surface being provided with a number of flat sides mounted circumferentially.
By rotating the set screw in one or the other direction the sliding piece can be moved in the desired direction. By the presence of the blade spring and the flat sides on the set screw it is known across which distance a sliding piece is moved when the blade spring, on rotating the set screw, will get from its one flat side onto its next flat side.
REFERENCES:
patent: 2238870 (1941-04-01), Haynes
patent: 4620533 (1986-11-01), Mears
patent: 5098432 (1992-03-01), Wagenknecht
patent: 5746741 (1998-05-01), Kraus et al.
patent: 5769851 (1998-06-01), Veith
patent: 5921985 (1999-07-01), Ross, Jr. et al.
patent: 424 292 (1991-04-01), None
patent: 699 419 (1996-03-01), None
patent: 2 665 353 (1992-02-01), None
patent: 2 024 632 (1980-01-01), None
patent: 95/10240 (1995-04-01), None
Buiz Michael
Foley & Lardner
King Anthony S.
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