Sonic screw

Abstract

A screw for fixation of, for example, a fracture having a hollow shaft, a first outer thread and radial openings at its distal end, and a second outer thread and an inner engagement portion at its proximal end. The second outer thread is adapted to engage with a tissue protection sleeve. The inner engagement portion is adapted to fit to a driving end of a driving tool. By way of this, forces in axial or radial direction may be applied to the screw by the sleeve, and forces in rotational direction may be applied by the driving tool. Therefore, the screw can be installed accurately at the intended site in an object.

Description

BACKGROUND OF THE INVENTION[0001]The invention relates in general to sonic fusion technology. It relates more particularly to a screw and a method for the fixation of fractures, particularly bone fractures. The invention relates to a screw for augmenting within a fractured object, to a system including tools to implement the screw into the fractured object, as well as to the use of the mentioned system. The fractured object might be a bone or a wooden or plastic object like furniture.[0002]Known from U.S. Pat. No. 4,653,489 is a system wherein a fixation cement is introduced through a screw into a portion of a bone afflicted by osteoporosis. Femoral neck fractures as well as distal femoral fractures can be fixated by means of this device.[0003]The system in accordance with prior art comprises a screw having a flow cavity, i.e. an axial through bore through with bone cement can be introduced into the portion at the tip of the screw. The bone cement is advanced by a device which is re...

AI Technical Summary

Benefits of technology

[0007]One aspect of the invention may be to provide a screw and a method by means of which a reliable and even augmentation of the screw in an installation site in an object can be assured.

[0010]At the distal end (the tip portion or leading end of the screw), the first outer thread is capable of cutting into bone (or wood). Therefore, the first outer thread extends along the first few centimeters of the length of the shaft, starting at the tip of the screw in the direction towards the proximal end. According to an exemplary embodiment, the first outer thread might be tapered at the tip of the screw to allow a better introduction of the screw into an object of interest like a bone or a wooden object (for example furniture).

[0011]From the central through bore through the wall of the shaft in the portion of the first outer thread, there is formed at least one opening in radial direction. Providing the tip portion of the screw with a few openings may allow for a better distribution of a suitable material used for augmenting the screw in an object of interest.

[0012]At the other end, the proximal end of the screw, there may be formed a second outer thread, which extends preferably only a few millimeters along the axis of the shaft. This second outer thread is another kind of a thread compared with the first outer thread, since the second outer thread is adapted to engage with a tissue protection sleeve. To avoid negative interdependencies like irritations or lesions, between the second outer thread and tissue surrounding the bone, the outer contour of the windings are flattened or rounded so as to have a smooth contact area.

[0018]With two separate elements, i.e. the sleeve and the driver, each engaging directly at the proximal end of the screw, it is possible to apply forces with different direction precisely onto the screw, so that the screw may be positioned accurately at a appropriate site. With the driver, forces in circumferential direction may be applied to screw in (or out for explanation) the screw. With the sleeve, force in axial or radial direction may be applied to the screw. As another advantage, the screw may be held in place by the screw driver while the tissue protection sleeve is loosened and removed from the proximal end of the screw.

Problems solved by technology

This system has the drawback that the manual pressure applied to the fixation cement varies, not only basically from application to application, but also during the application itself, so that the distribution of the fixation cement within the portion of the bone at the tip of the screw is neither reliable nor even.

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