WO2013015754A1

WO2013015754A1 - Double compression screw

Info

Publication number: WO2013015754A1
Application number: PCT/TR2012/000075
Authority: WO
Inventors: Olday YILMAZ
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-05-11
Filing date: 2012-05-11
Publication date: 2013-01-31
Anticipated expiration: 2013-11-11
Also published as: TR201104622A1

Abstract

The present invention relates to threaded structure of the tip and head part of double compression screw used for joining two bones in fractures by eliminating the gap between two fractured bones; and application method thereof which can close the fracture gap by placing the said screw within the bone without leaving any part of the screw body out during the operation.

Description

DESCRIPTION

DOUBLE COMPRESSION SCREW

Field of the Invention

The present invention relates to compression screws used for joining two bones in fractures by eliminating the gap between two fractured bones; and application method thereof in the fractured bone .

Background of the Invention

In the large, medium and small bones of the musculoskeletal system, which have a high risk of trauma, fractures in the form of comminuted fracture in the tip part of the bones close to the joints occur as a result of high-energy impacts.

In the current state of the art, bone nails known as intramedullary nails or certain screws are used in orthopedic and trauma surgeries for joining the bones in long bone fractures. An interlocking compression screw is disclosed in the utility model document TR 2010 08521.

In the intra-articular fractures or fractures close to the joint, exact anatomical placement is required for protection of the joint surface. In these type of indications, which make up a large portion of trauma cases, bone shape, its anatomic and biomechanical structure, anesthesia duration, patient's age and implant selection, which allow for the small incision, are the upper limit of physician-patient satisfaction. Headless cannulated compression screws are one of the most important implants offered to the physicians to ensure this satisfaction. These screws can be used in different parts of the body for osteosynthesis, especially in intra-articular and extra-articular or general orthopedic operations. In the comminuted fractures of large joints, these type of headless cannulated compression screws serve as powerful auxiliary tools for the other fracture detection methods. At the same time, it is used in the correction of bone fractures performed in small joints, especially intra-articular and extraarticular fractures of the hand and foot bones; and in the surgical operations of comminuted fracture developing in the tip parts of the said bones.

In the current state of the art, another type of screws used for joining fractured bones are compression screws. These screws are provided with threads at a certain distance from the tip part of ■ the screw body and have a structure with threads at a certain distance from the head part where the screw head will be affixed and screw will be turned. Screw head in the form of a hollow nut, which is provided with threads in the inner and outer part, is affixed onto the threads at the head part of these screws.

In the above-mentioned technique, certain difficulties are experienced in both the usage and the application method within the bones due to the structure of the screws used for joining the fractured bones. For example, screw head, being affixed at a certain distance in the head part of the screw body of the existing screws, is placed so as to hold the two parts of bone, which is split into two pieces through fracturing. Screw body is firmly fixed by being anchored to the bone through the threads thereof. Then, as the screw body is rotated around its own axis by means of the threads thereon with the special screwdriver, which can hold onto the back of the screw head and head part of the screw body provided in the center of the screw head at the same time, it pulls the screw body onto itself and screw head is also fastened by resting against the bone. Thus, the bone on the other side of fracture gap is pulled back in the same direction with the screw body and the fracture gap is closed. However, in this application method, the head part of the screw body often remains out a certain amount and this creates difficulties for both the patient and the physician implementing it. Another issue is that the screw head, which is set at an approximate distance on the screw body without knowing the distance between the fractured bones in advance, is inserted into the bone and as a result the screw head certainly remains out a certain amount after the screw body is retracted by a distance for joining the bones with the screwdriver. In addition, the distance between the threads provided on the screw head and screw body are the same in the currently used screw structures. And this, in turn, prevents making up the necessary precise adjustment for closing the fracture gap.

With the current screws, removing the screw from its location after the joining operation of the fractured bones gives rise to making a fairly large incision the already broken bones. This situation also creates problem for both the patient and the physician who will perform the operation and moreover, it makes the operation more difficult and extends the implementation period.

In the current applications, desired compression can not be produced due to the structure of the screwdriver and the short distance in the workspace during the compression of the compression washer provided on the screw head and it doesn't allow for calculating the amount of compression to be made. Another occurring problem is that the desired compression by means of the screw tightening head can not be produced as the said head leaves the thread area after being rotated two turns due to the shortness of the tightening head. In the current applications, the compression nut provided on the upper part of the screw as fixation piece (2) can not meet the desired compression amount during the implementation due to the screwdriver and the application method thereof, moreover, it doesn't allow for setting the predetermined compression distance on the screw before the implementation. At least 6 mm of compression can be produced by means of the application method described and the product used according to the present invention when compared with the previous products and methods.

The above-mentioned problems are overcome by the double compression screw and application method thereof according to the invention. This is achieved by producing the compression by means of the screw body instead of the screw head in the application according to the invention. On the other hand, in the application method according to the invention, the distance of compression can be set outside and the area to be compressed can be planned before the operation. Besides, insertion of the screw in one goes with one screwdriver and removal thereof from its place are facilitated due to the structure of the double compression screw according to the invention. Purpose of the Invention

The purpose of the invention is to provide exact anatomical placement for the protection of the joint surface especially in the intra-articular fractures or fractures close to the joint.

Another purpose of the invention is to enable complete burial of the head part of the screw body, which is placed in the fractured bones, within the bone; to prevent it from remaining outside .

A further purpose of the invention is to perform and end the procedure with a much smaller incision compared to the current applications .

A further purpose of the invention is to enable setting the desired distance outside and planning of the area to be compressed before the operation.

Compression is performed by means of determining the measurement of the distance between the fractured bones and tightening the screw head by the determined distance.

A further purpose of the invention is to facilitate the insertion of the screw in one go with one screwdriver due to the structure of the screw.

Description of the Figures

The views of the double compression screw according to the invention from different angles are given below:

Figure 1, Side view of mounted screw body and fixation piece in vertical position.

Figure 2, Cross view of mounted screw body and fixation piece. Figure 3, Sectional front view of fixation piece mounted on screw body.

Figure 4, Side view of the fractured bone of ankle.

Figure 5, View of double compression screw placed within fractured ankle bones. Figure 6, View of double compression screw joining fractured ankle bones.

The pieces in the figures are numbered individually and the said pieces corresponding to these numbers are given below:

1. Screw body

1.1. Screw body tip part threaded section

1.2. Screw body head part threaded section

1.3. Screw body head part

1.4. Distance between two threads in the tip part of the screw

1.5. Distance between two threads in the head part of the screw

2. Fixation piece

2.1. Fixation piece head part

2.2. Distance between two threads on the fixation piece

3. Fractured bone number 1

4. Fractured bone number 2

Description of the Invention

The double compression screw according to the invention is characterized in that it, as shown clearly in Figure 1, comprises screw body tip part threaded section (1.1), which enables superior holding of the screw body (1) when inserted in the bone structure; screw body head part threaded section (1.2), which aids in the movement of the screw within the bone during the compression operation at the screw body head part; screw body head part (1.3), which is the section in the screw body (1) where the screwdriver holds; fixation piece (2), which provides anchoring of the screw within the bone during the^' rotation of the screw for joining the fractured bones, with inner and outer parts thereof having threaded structure, which can be moved forwards by being rotated clockwise and backwards by being rotated counter-clockwise around its own axis over the screw body head part threaded section (1.2) by means of the threads therein and hence provides the insertion of the screw body into the bone and anchoring of the said screw; and fixation piece head part (2.1) on which the outer part of the special screwdriver, used for providing the movement of the fixation piece, will be placed. In the insertion of the screw body into the bone during the compression process, the fixation piece (2) provided on the screw body head part threaded section (1.2) will advance more rapidly than the screw body tip part threaded section (1.1) thanks to the screw structure, which is formed by having the distance between two threads in the tip part (1.4) of the double compression screw described in the said invention as, for instance, 1 unit; the distance between two threads in the head part threaded section of the said screw as 0.5 unit; and the distance between two threads on the fixation piece as 1 unit. More clearly, the distance advanced by the threaded part of the fixation piece (2) within the bone is half of the distance advanced by the screw body moving forwards when the alien tip of the screwdriver is rotated one turn after it is fixed on the screw body head part (1.3) while the outer tip of the screwdriver holds the fixation piece (2) . Fractured bone number 1 advances towards fractured bone number 2 and the gap is closed, screw body doesn't remain out of the bone.

The application method of the double compression screw according to the invention within the fractured bone comprises the following process steps:

^ Firstly, the path through which the double compression screw will pass is opened by means of a wire; Then, the cannulated drill is sent into the bone through the same path and forms the cavity where the screw will be placed and fastened;

The screw length to be implemented is measured by means of a screw gauge;

> The cavity where the screw head will be placed is formed by using a proximal reamer;

The gap distance in the fractured area is determined based on the x-ray film taken before the operation and this measurement is set by rotating the fixation piece in the forward direction on the threads of the screw body head part ;

Double compression screw is placed so as to be inserted into the fractured bone number 1 and fractured bone number 2, passing through the gap in between them, after the fixation piece is fixed on the screw body, fixation piece is buried in the bone number 1; ·

Screwdriver is rotated clockwise by means of affixing the outer part of the screwdriver on the fixation piece (2) and at the same time fixing the alien tip of the screwdriver on the screw body head part (1.3);

Pushing movement in the forward direction is achieved by means of the screwdriver, which rotates the screw body and fractured bone number 1 (3) approaches fractured bone number 2 ( 4 ) ;

Compression is produced through the screw body;

> As can be clearly seen in Figure 6, the gap between two fractured bones is closed when the compression is completed and at the same time no screw remains out of the bone thanks to the movement of the screw body in the forward direction;

Since the distance between the threads in the tip part of the screw body (1.4) is two times the distance between the threads in the head part of the screw body and in the inner part of the fixation piece (1.5) as well, the screw body advances 2 units by the screwdriver motion while the fixation piece advances 1 unit on the head part of the screw body. Thus, precise adjustment of the screw body's placement within the bone can be done, ankle bone and fixation piece are evened.

With the screw according to the invention and application method thereof, compression can be produced from the screw body and not from the fixation piece, compression distance of the screw can exceed 10 mm and most importantly the compression distance on the screw can be set before the operation.

At least 6 mm of compression can be produced by means of the application method described and the product used according to the present invention when compared with the previous products and methods.

Claims

Double compression screw comprising screw body tip part threaded section (1.1), which enables superior holding of the screw body (1) when inserted in the bone structure, in the tip part; screw body head part threaded section (1.2), which aids in the movement of the screw within the bone during the compression operation, in the screw body head part; screw body head part (1.3) on which the screwdriver holds, in the screw body (1); fixation piece (2), which provides anchoring of the screw within the bone during the rotation of the screw for joining the fractured bones, with inner and outer parts thereof having threaded structure, which can be moved forwards by being rotated clockwise and backwards by being rotated counter-clockwise around its own axis over the screw body head part threaded section (1.2) by means of the threads therein and hence provides the insertion of the screw body into the bone and anchoring of the said screw, characterized in that the fixation piece head part (2.1) on which the outer part of the special screwdriver, used for the movement of fixation piece (2), will be placed, is formed by having the distance between two threads in the tip part (1.4) of screw as, for instance, 1 unit; the distance (2.2) between two threads in the head part threaded section of the said screw and in the inner part of the fixation piece (2) as 0.5 unit; and the distance between two threads on the fixation piece as 1 unit.

The application method, for joining the fractured bones within the bone, of the double compression screw according to claim 1, wherein the said method comprises the following process steps: The gap distance in the fractured area is determined based on the x-ray film taken before the operation and this measurement is set by rotating the fixation piece in the forward direction on the threads of the screw body head part (1.5);

Double compression screw is placed so as to be inserted into the fractured bone number 1 (3) and fractured bone number 2 (4), passing through the gap in between them, after the fixation piece (2) is fixed on the screw body, fixation piece is buried in. the bone number 1;

Screw body is rotated and pushed in the forward direction by the screwdriver, fractured bone number 1 (3) approaches fractured bone number 2 (4) and compression is achieved through the screw body;

The gap between the two fracture bones, which is determined before the operation, is closed fully upon the completion of the compression as the distance covered by the movement of the screw body in the forward direction is the same as the distance of the gap, hence no part of the screw is left outside;

The screw body (1) advances 2 units by the screwdriver motion while the fixation piece (2) advances 1 unit on the head part of the screw body (1.2) due to the distance between the threads in the tip part of the screw body

(1.4) being two times the distance between the threads

(1.5) in the head part of the screw body and in the inner part of the fixation piece (2) as well, ankle bone is flushed with fixation piece.