ES2267358A1 - Compression screw for osteo-synthesis of mini bone fragments, has four-lobed track, defined at screw head, which forms threaded orifice for fixation to threaded inner rod of screwdriver - Google Patents

Abstract

A compression screw includes two notches extending from a sharpened, spiral distal end to a conical proximal end, and a head defining a four-lobed track. The track defines a threaded orifice extending into the screw interior. The threaded inner rod of a screwdriver is inserted and fixed into the screw interior via the orifice. The screw also defines two threaded zones of different passes for inter-fragmentary compression.

Description

Compression screw for osteosynthesis minifragments

Object of the invention

The compression screw for osteosynthesis of minifragments of the present invention consists of a compression screw for stabilization of osteotomies in forefoot surgery and in general for minifragment surgery, this being solid having both threaded ends, and being self-tapping and self-drilling, with screwdriver assembly system to facilitate handling and insertion into the bone in a single maneuver without drilling or tapping
previous.

Background of the invention

The screws that are currently used are cannulated and require drilling prior to insertion, and if they are not self-tapping, they also require pre-tapping. They are double threaded, proximal and distal or also with a single threaded area such as mini-rings for osteosynthesis. Also the current screws have a union by adjustment with the screwdriver so they must be handled carefully, to prevent them from loosening, and when they are inserted into the bone and when starting to thread, and therefore to apply a force quite large, the screwdriver shows a slight movement with respect to the screw so that its stability is lost and the energy used for tightening must be greater. The adjustment increases with tightening, making it difficult to release the screwdriver without moving the screw
llo.

To solve the problems that exist in the currently the compression screw has been devised to osteosynthesis of minifragments that we will describe to continuation.

Description of the invention

The compression screw for osteosynthesis of minifragments of the present invention consist of a screw that It has the following characteristics:

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Is solid with two threaded zones of different pitch for compression interfragmentary

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Is self-drilling, thanks to its tip-shaped distal end sharp.

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Is self-tapping thanks to the two notches in its thread distal and conical shape of the proximal thread, whose profile of the tooth increases as the screw is introduced.

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He screw is hidden in the bone by having its proximal area threaded

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In the head (proximal area) has a "four lobes" footprint that avoids the risk of tool wear and provides a good tightening torque and distribution of efforts. At the bottom of the footprint there is a threaded hole for fixing the screw to the screwdriver

The screwdriver joins the screw through this hole so that the screw is attached to the screwdriver, this is inserted into the screw head and threaded the inner rod that has the screwdriver inside the zone screw thread located at the bottom of the four footprint lobes So the fixation is secure and the screw does not fall off or making sudden movements of the screwdriver.

With the screw already implanted, the screwdriver unscrewing the inner rod and removed Easily screw head.

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Compression screw thanks to the different steps of the two threaded zones. Threaded head penetrates the bone faster than the distal thread, having a step minor thread, causing the two fragments to approach and Creating compression The profiles of the proximal and distal part they are symmetrical to ensure that the compression.

Description of the drawings

To complement the description that is being performing and in order to help a better understanding of the characteristics of the invention, is accompanied herein descriptive, as an integral part of it, of a game of drawings, where illustrative and non-limiting nature has been represented the following:

Figure 1 shows the screw object of the invention.

Figure 1a shows the screw with a cut in your distal area

Figure 1b shows the screw seen from its distal area

Figure 1c shows the screw seen from its proximal area

Figure 2 shows the screwdriver with the inner rod

Figures figures 3, 4, 5 and 6 show how to it makes the connection between screw and screwdriver

Preferred Embodiment of the Invention

We start from a screw that is inside of a container specially designed for this purpose. In first place the pressing rod (1) into the screwdriver (2). The assembly is simple and the rod does not fall or have possibility of accidentally letting go.

The screwdriver (2) is inserted into the head of the screw (3), placed in its container in an upright position and a Once the pressing rod (1) is threaded, the screw of the container. The fixing is secure, the screw (3) does not fall off with sudden movements of the screwdriver (2).

The screw (3) is stuck in the bone inserting the tip in its entirety with some ease. One time after the tip is exceeded, the threading of the distal zone (32) begins and continue this until the compression begins with the threading of the proximal area (31) of the screw (3) because it has a minor passage that the distal thread, the conical thread acts as a self-tapping and due to the different thread pitch the compression is achieved when they contact the two bone fragments and there is no risk of entering excess the screw (3) leaving this screw (3) completely hidden in the bone.

It is not considered necessary to extend this description so that any subject matter expert understands the scope of the invention and the advantages derived therefrom. The terms in which this report has been written must be taken always in a broad and non-limiting sense.

The materials, shape, size and layout of the elements will be subject to variation as long as it do not involve an alteration of the essential characteristics of the invention claimed below.

Claims (6)

1. Compression screw for osteosynthesis of minifragments, of the type used for stabilization of osteotomies in forefoot surgery and in general for minifragment surgery, characterized in that it is a solid screw with double proximal and distal threads. 2. Screw according to the preceding claim, characterized in that the profiles of the proximal and distal part are symmetrical to ensure that their compression is facilitated. 3. Compression screw for osteosynthesis of minifragments, according to the preceding claims, characterized in that it is self-drilling due to its very sharp tip-shaped distal end. 4. Screw, according to the preceding claims, characterized in that it is self-tapping because it has a proximal conical thread, whose initial thread anchoring coincides with the diameter of the screw shank as well as the external thread profile, whose tooth profile increases to as the screw is introduced, and a distal thread with two notches at its end. 5. Screw according to the claims previous because in the head it has a footprint of "four lobes "that avoids the risk of wear of the tool, greater torque and effort distribution, with a threaded hole at the bottom of it for the connection with the screwdriver. 6. The screwdriver according to the claim, characterized in that it joins the screw through the threaded hole, so that the screw is integral with the screwdriver because it is inserted into the screw head and the inner rod having said screwdriver is threaded into the threaded area of the screw located at the bottom of the four-lobe footprint, thus making the fixation secure and preventing the screw from falling by sudden movements of the screwdriver.