Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-03-29
2001-01-09
Smith, Jeffrey A. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S053000
Reexamination Certificate
active
06171310
ABSTRACT:
The present invention relates to the subject matter disclosed in German patent application 198 14 564.0 of Apr. 1, 1998, the entire specification of which is incorporated herein by reference.
The invention relates to a device for handling an implant which can be placed against a contact surface of a bone and thereby covers a tunnel in the bone and fixes in position at least one thread extending in the tunnel.
During the insertion of ligament replacement implants in the knee area, a ligament replacement implant is inserted in a tunnel passing through the head of the femur and the head of the tibia and is fixed on the bone via threads attached to it. For the purpose of fixing, disk-like or button-like implants are used which close the tunnel in the bone on the outside. The ligament replacement implant must be inserted into the tunnel in the bone with an exactly defined tension, and for this purpose it is known to vary the tension by turning the implants fixing the threads in position about the longitudinal axis of the bone tunnel. This turning leads to a twisting of the threads holding the ligament replacement implant and thus to an alteration in the tension.
The object of the invention is to propose a device for the handling of an implant of this type, with which the tension of the ligament replacement implant may be varied in the bone tunnel in a controlled manner.
This object is accomplished in accordance with the invention by a device of the type described at the outset which is characterized by releasable holding means on the device, with which the device can be connected to the implant in a locking position of the holding means in such a manner that as a result of rotation of the device the implant can be turned in relation to an axis defined by the tunnel and in addition lifted away from its contact surface in the direction of this axis.
Such a device can thus be temporarily connected to the implant such that any turning of the device leads to turning of the implant and therefore to a change in the twisting of the threads in the bone tunnel, i.e. to an alteration in the tension. Since the implant is pulled forcefully against the contact surface by the threads and since means for securing against rotation are customarily provided in the case of such implants in order to maintain tension once this has been reached, it is also possible with the new device to lift the implant slightly away from the contact surface for turning and thus make the turning possible. The implant is placed against the contact surface again only after the desired tension has been set; by releasing the holding means the connection between implant and device can be released again.
In a preferred embodiment it is provided for the holding means to comprise spreading elements which in their locking position engage the back of recesses on the implant.
The recesses can be formed, in particular, by the edges of openings in the implant. With such a solution, the spreading elements are guided through the openings of the implant and then spread apart so that, as a result, a form-locking connection results which enables the operator not only to lift the implant away from the contact surface of the bone but also to turn it in the desired manner as a result of movement of the device.
It is favorable when the spreading elements are spring arms which extend parallel to one another and may be moved away from one another at their free ends by means of a spreading member insertable between them.
The spreading member can, in particular, be displaceable on the device in longitudinal direction of the spring arms.
In a particularly preferred embodiment it is provided for the device to have an elongated, essentially cylindrical housing and for the spreading member to be connected to an actuating rod which is mounted in the housing for displacement in longitudinal direction and exits from the housing at its end remote from the spreading elements.
This actuating rod can have a grip at its free end.
It is particularly advantageous when it is provided in a preferred embodiment for the spreading elements to be connected via an elastic spring element to a pulling handle, with which a force lifting the implant away from the contact surface of the bone can be transferred to it. The lifting of the implant away from the contact surface thus takes place with a spring element as intermediate element.
This may be utilized, in particular, for the fact that a marking is provided for indicating the distance between the spreading elements and the pulling handle so that the operator can establish from this marking the force which is necessary to lift the implant away from the contact surface. This force is a measurement for the tension of the threads and the ligament replacement implant in the bone tunnel and thus gives the operator immediate information on whether the desired setting has been reached or not.
It may be provided, in particular, for the spreading elements to be mounted on a first housing portion of the device, for the pulling handle to be securely connected to a second housing portion of the device and for the two housing portions to be adapted to be pulled apart from one another contrary to the force of a spring connecting them.
In a preferred embodiment, the second housing portion can be designed in the shape of a sleeve and accommodate the first housing portion in it at least partially.
In this respect, it is advantageous when the spring is arranged in the interior of the second housing portion.
It is favorable when the spring is detachably connected to the second housing portion; the two housing portions can then be separated from one another simply by detaching the spring and so cleaning of all the parts of the device is possible without further ado.
A fixing element, in particular, in the shape of a U-shaped clip which can be inserted into the second housing portion through lateral openings therein can be provided for the detachable connection of the second housing portion and the spring.
It is, in addition, favorable when the spring is a helical spring, into which threaded connection pieces are screwed at its ends for the connection with the first and/or the second housing portion. These can also be screwed out of the spring so that a complete dismantling of the device for cleaning purposes can be achieved.
The application of the pulling force necessary for checking the tension of the ligament replacement is made easier when laterally projecting gripper bars are arranged on the second housing portion.
The marking can comprise, in particular, a window in the second housing portion and an indicator element on the first housing portion which is visible through the window.
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Eichhorn Juergen
Giordano Nicola
Kienzle Karl-Ernst
Aesculap AG & Co. KG
Lipsitz Barry R.
Smith Jeffrey A.
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