Plate arrangement for osteosynthesis

Details Plate arrangement for osteosynthesis Plate arrangement for osteosynthesis

1999-06-25

2001-02-06

Buiz, Michael (Department: 3731)

Surgery

Instruments

Orthopedic instrumentation

Reexamination Certificate

active

06183476

ABSTRACT:

FIELD OF THE INVENTION
The invention concerns a plate arrangement for osteosynthesis of fractured hollow bones by means of two plate parts, each of which is connectable by fastening screws with an associated bone section and which plate parts are connected with one another by a telescope arrangement allowing an axial relative movement of the plate parts.
BACKGROUND OF THE INVENTION
One such plate arrangement is, for example, known from DE-A-41 32 021. The axial moveability of the plate parts relative to one another allows the introduction of controlled micromovements in physiologically loaded directions so that the growth of the bone is promoted.
Since bones, such as, for example, the upper leg bones neither all have the same shape and size nor exhibit a uniform geometric form, the assembly of the plate parts to the bone fragments is not always without problems.
The invention has as its object the provision of a plate arrangement of the above-mentioned kind whereby the assembly of the plate parts to the bone sections or fragments is simplified.
SUMMARY OF THE INVENTION
The above object is solved in accordance with the invention in that the openings of the plate parts intended for the passing through of the fastening screws are formed by elongated holes, each of which has its longitudinal dimension directed perpendicular to the telescope axis.
The orientation of the elongated holes with their longitudinal dimensions perpendicular to the telescope axis assures that the introduced micromovements can be transmitted without play to the bone fragments. On the other hand, the elongated holes make possible the insertion of the screws at a given angle relative to the hole axis, so that for each screw a most favorable position in respect to fastening effect can be chosen. Moreover, the elongated holes of the plate arrangement permit a certain swivel motion about the telescope axis, and surprisingly it has been shown that a controlled amount of such swiveling movement can also have a favorable influence on bone growth.
Preferably, the longitudinal dimension of the elongated holes relative to the thickness of the associated plate parts is so chosen that the screw axis can take on an angle relative to the elongated hole axis up to about 15° to both sides of its hole axis, so that the angular displacement between the two extreme positions can amount to about 30°.
To assure a good engagement of the screw heads with the associated plate part, even if the screws are positioned inclined to the hole axis, the screw shaft near the underside of the screw head is preferably a spherical shape, with the elongated hole advantageously being surrounded by a concavely curved support surface complementary to the spherical-shaped underside of the screw head. The underside of the screw head thereby forms a kind of ball joint head which can be rotated in the support surface serving as a ball joint socket.
To give the operator the possibility to easily adapt the plate parts at the operation site to the shape of the bone in question, the plate parts in a preferred embodiment of the invention have a reduced cross section in a middle area between each two screws holes. This gives the possibility of bending the plate parts in these areas without weakening the fastening areas.
Advantageously in each of the plate surfaces facing the bone a recess is formed which extends parallel to the telescope axis. Thereby, and especially in connection with the previously mentioned cross sectional diminishment, there results on the side of each plate part intended for engagement with the bone several small feet, through which feet the plate part lies onto the bone. This enables a stable multiple point support of the plate parts on the bone.
In order on one hand to rotatably guide the plate parts relative to one another and on the other hand to improve the moveability of the plate parts relative to one another, the sections of the telescope arrangement which are inter-engageable with one another, in a preferred embodiment of the invention, are of non-circular shape, and more preferably of a polygonal cross section, so that the parts slide relative to one another by means of lands running parallel to the telescope axis. These lands can be formed on one or the other of the inter-engageable telescope sections. Thereby on one hand a secure guiding and on the other hand a reduced friction of the parts on one another is assured. Further features and advantages of the invention will be apparent from the following description which describes the invention in connection with the accompanying drawings by way of exemplary embodiments.


REFERENCES:
patent: 3604414 (1971-09-01), Borges
patent: 4493317 (1985-01-01), Klaue
patent: 5733287 (1998-03-01), Tepic et al.
patent: 335797 (1959-03-01), None
patent: 566 767 (1975-09-01), None
patent: 41 32 021 A1 (1993-04-01), None
patent: 196 36 309 (1998-01-01), None
patent: 1239266 (1960-12-01), None
patent: 85 888 (1986-01-01), None

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