WO2005120403A2

WO2005120403A2 - External fixing device of bone segments for surgical-orthopaedic use

Info

Publication number: WO2005120403A2
Application number: PCT/IB2005/001673
Authority: WO
Inventors: Pietro Mussolin
Original assignee: Mikai S.P.A.
Priority date: 2004-06-09
Filing date: 2005-06-08
Publication date: 2005-12-22
Also published as: WO2005120403A3; ITPD20040051U1; EP1753351A2

Abstract

External fixing device (6) of bone segments for surgical-orthopaedic use, comprising supporting means (7), at least one pair of fixing means (8a, 8b) held by supporting means and a plurality of bone screws (9a, 9b) protruding from the fixing means that are to be inserted into housing holes bored into said bone segments (10a, 10b). The peculiarity of the device consists in that it comprises orienting means (12a, 12b) joined to said fixing means for orienting each bone screw of said plurality of bone screws in an independent way. The device overcomes the drawbacks found in the state of the art and, in particular, is applicable in anatomical areas of considerable morphological complexity and/or in very small areas.

Description

EXTERNAL FIXING DEVICE OF BONE SEGMENTS FOR SURGICAL- ORTHOPAEDIC USE DESCRIPTION This invention refers to an external fixing device of bone segments for surgical-orthopaedic use. The external fixing devices currently used in the surgical-orthopaedic field are used in operations to lengthen bone segments (e.g. phalanges). Said devices are also used in operations for stabilising bone segments after a fracture. In general, the devices used at present comprise a pair of elongated clamps that slide lengthways. These clamps have bone screws at the end to be implanted in the cortex of the bone segments concerned by the operation of lengthening or stabilisation. The device also comprises handling devices consisting of a threaded bar engaged into both clamps. This bar allows the clamps to be moved closer or farther away according to the requirements coming out during the operation and in the following stage. These devices are made in several sizes in order to allow the application of more than one device simultaneously in different anatomical regions. The main drawback posed by these devices lies in the application difficulties found by orthopaedic surgeons. This drawback mainly derive from the fact that the bone screws protruding out of the clamp can only be positioned parallely. This limits the ways in which the device can be applied, especially in anatomical regions that have a particularly complex and/or reduced morphology such as the hand or foot. For instance, these devices establish a minimum implant distance existing between the bone screws. This minimum distance prevents the application of these devices in very small anatomical regions where the screw holes in the stumps/bone fragments are bored at a distance shorter than the minimum distance required by the implant. This drawback also derives from the fact that this type of devices is both large and heavy, thus preventing the simultaneous application of more than one device to the same anatomical region, especially in very small areas such as the space between fingers and toes. Furthermore, the size and weight of these devices significantly worsen the patient's quality of life. In fact, their application prevents patients from performing their habits involving the anatomical region to which one or more of said devices are applied. . The aim of this invention is to provide an external fixing device of bone segments for surgical-orthopaedic use that solves the drawbacks posed by the currently used devices. Within the scope of this aim, an object of the invention is to provide a device that could be applied to anatomical regions of considerable morphological complexity and/or very small areas. Another object of this invention is to provide a device that could allow patients to perform their usual activities involving the anatomical region to which the surgery is applied. Another aim of the present invention is to provide a device that may be manufactured at reasonable costs. This aim, these and other objects that will become better apparent hereinafter, are achieved by an external fixing device of bone segments for surgical-orthopaedic use as claimed in attached claim 1. The fixing device as claimed in claim 1 comprises orienting means of the bone screws in order to orient separately these bone screws, as required by the implant requirements, so that to allow applying the device to anatomical regions of considerable morphological complexity and/or very small areas. Furthermore, the device, according to the other claims, has been made in an easy way and with a reduced number of components in order to limit both its weight and dimension and its manufacturing costs. Further characteristics and advantages will be much more apparent from the description of a preferred but not exclusive embodiment of the external fixing device according to the invention, illustrated only by way of non-limitative example, in the accompanying three attached drawings in which: - figure 1 shows a front perspective view of the device acccording to the invention; - figure 2 shows a first lateral view of the device shown in figure 1 ; - figure 3 shows a plan view from above of the device in figure 1 ; - figure 4 shows a second lateral view of the device in figure 1 ; - figure 5 shows a plan view of the device in figure 1 applied to a bone element schematically shown. With reference to the figures in the drawings, the external fixing device of bone segments for surgical-orthopaedic use, generally designated by the reference number 6, mainly comprises supporting means 7, a pair of fixing means, designated by the reference numbers 8 a and 8 b respectively, which are supported by the supporting means 7 and a pair of bone screws 9 a and 9 b protruding out of the supporting means 8 a and 8 b which are to be inserted in suitable bore holes of the stumps 10 a and 10 b of a bone element generally designated by the reference number 11. The device also comprises orienting means, generally designated by the reference numbers 12 a and 12 b, joined to the fixing means 8 a and 8 b and used for orienting each screw 9 a and 9 b in an independent way. In detail, these supporting means 7 comprise a threaded rod that can be shortened if necessary and provided with a pair of opposite bevels extending lengthwise. In turn, the fixing means 8 a and 8 b are arranged onto the rod as described below. The fixing means 8 a is locked onto one end of the rod 7 while the fixing means 8 b can be moved lengthwise along the rod. Approprietely, there are locking/moving means for locking/moving the fixing means 8 b movable along the rod according to the requirements. These locking/moving means consist of a simple pair of nuts 13 b arranged on both sides of the movable fixing means 8 b to be screwed onto/unscrewed from the rod according to the requirements. The fixing means 8 a and 8 b comprise sleeve members 14 a and 14 b which hold the rod and U-shaped means 15 a and 15 b, which in turn hold the sleeve members 14 a and 14 b and are closed at the front by the orienting means 12 a and 12 b. Sleeve members 14 a and 14 b are advantageously provided with a pair of internal bevels (not shown) complementing the pair of external bevels on the rod 7 so that the sleeve members 14 a and 14 b are prevented from rotating around the rod 7. The curved portions of the U- shaped means 15 a and 15 b hold the sleeve members 14 a and 14 b and the wings of the U-shaped means are provided with coaxial holes bored close to the ends of the wings for inserting the orienting means 12 a and 12 b. The latter consist of screws 16 a and 16 b inserted into these coaxial holes. These screws 16 a and 16 b have crosswise holes bored through the shanks near the heads 17 a and 17 b. The bone screws 9 a and 9 b are inserted in these cross holes. Said screws 16 a and 16 b have tightening nuts 18 a and 18 b fitted in the end opposite the heads 17 a and 17 b. These nuts 18 a and 18 b are necessary for locking the level of protrusion and the orientation of the bone screws 9 a and 9 b. In addition, the heads 17 a and 17 b have opposite bevels 19 a and 19 b suitable for engaging a handling tool not shown. With reference to the figures in the attached drawings, the application of the device 6 onto a bone segment 11 is described below. First, the device insertion holes are bored into the stumps 10 a and 10 b of the bone segment 11. The device 6 is then prepared for the application which is carried out in approximately three steps described hereinafter. The first step consists in adjusting the distance between the fixing means 8 a and 8 b to the distance existing between the insertion holes. This step is carried out by acting with a handling tool on the locking/moving means in order to move the fixing means 8 b in relation to the fixing means 8 a until reaching the desired distance. This distance is then fixed by acting onto the locking/moving means. The second step consists in adjusting the level of protrusion of the bone screws 9 a and 9 b in relation to fixing means 8 a and 8 b according to the surgical requirements. This step is carried out by pulling back or advancing the bone screws 9 a and 9 b in relation to the fixing means 8 a and 8 b until achieving the desired level of protrusion. The third step consists in orienting the bone screws according to the direction of the insertion holes in stumps 10 a and 10 b. This step is carried out by orienting the bone screws 9 a and 9 b separately as required until reaching the desired orientation. The level of protrusion and orientation desired for bone screws 9 a and 9 b are fixed by acting onto the tightening nuts 18 a and 18 b with a handling tool while the locking heads 17 a and 17 b of the bone screws 16 a and 16 b are kept in an locking condition using another handling tool. Once the device 6 is prepared as previously described, the bone screws 9 a and 9 b are inserted into the corresponding insertion holes in stumps 10 a and 10 b. During the operation and in the following stage, the distance between the fixing means 8 a and 8 b-can be increased or decreased by acting onto the locking/moving means as follows. It is sufficient to loosen the nuts 13 b and then fastening the nut 13 b located between the pair of fixing means 8 a and 8 b in order to increase the distance between the pair of fixing means 8 a and 8 b. Or else, it is sufficient to fasten the nut 13 b located on the external side of the pair of fixing means 8 a and 8 b in order to shorten said distance. In order to fix the new positions, both nuts 13 b must be fastened onto rod 7 against the fixing means 8 b. In practice, it has been observed that the device achieves the intended aim and objects, overcoming the drawbacks found in the state, of the art. In fact, the device allows applications also in anatomical regions of considerable morphological complexity and/or very small areas. In addition, the device allows a patient to maintain nearly unchanged his own habits which are performed involving the anatomical region onto which the device has been implanted. Finally, the device can be produced at reasonable costs. In the practice of the invention, the materials used, shapes, dimensions and the executions might be different, yet technically equivalent to the ones herein indicated, without departing from the scope of the present invention.

Claims

1. External fixing device of bone segments for surgical-orthopaedic use comprising supporting means, at least one pair of fixing means held by said supporting means and a plurality of bone screws protruding from said fixing means that are to be inserted into housing holes bored into said bone segments, said device being characterized in that it comprises orienting means joined to said fixing means for orienting each bone screw of said plurality of bone screws in an independent way in order to allow applications of the device in anatomical areas of considerable morphological complexity and/or in very small areas.

2. The device, according to claim 1 , characterized in that said supporting means comprise a threaded rod provided with a pair of opposite longitudinal bevels.

3. The device, according to the claims 1 or 2, characterized in that said pair of fixing means comprise a fixing means fixed to an end of said rod and a fixing means movable lenghtwise along said rod.

4. The device, according to one or more of the foregoing claims, characterized in that it comprises locking/moving means for locking/moving the position of said fixing means movable along the rod, as required.

5. The device, according to one or more of the foregoing claims, characterized in that said locking/moving means comprise a pair of nuts on both sides of said movable fixing means, said pair of nuts can be screwed into/unscrewed from said rod as required.

6. The device, according to one or more of the foregoing claims, characterized in that said fixing means comprise a sleeve member holding said rod, a U-shaped body holding said sleeve member and closed at the front by said orienting means.

7. The device, according to one or more of the foregoing claims, characterized in that said sleeve member comprises a pair of internal bevels complementary to said pair of external bevels in order to prevent the sleeve member from rotating around the rod.

8. The device, according to one or more of the foregoing claims, characterized in that the curved portion of said U-shaped body holds said sleeve member and the wings of said U-shaped body have coaxial holes bored close to the ends of the wings housing the orienting means.

9. The device, according to one or more of the foregoing claims, characterized in that said orienting means comprise a screw inserted in said coaxial housing holes.

10. The device, according to one or more of the foregoing claims, characterized in that said screw comprises a crosswise hole, bored into the shank near the head of the screw, into which at least one bone screw is inserted.

11. The device, according to one or more of the foregoing claims, characterized in that said screw has a tightening nut at the end opposite to the head for fixing the orientation of said bone screw.

12. The device, according to one or more of the foregoing claims, characterized in that said head of said screw has a pair of laterally opposed bevels in order to engage a handling device.

13. The device, according to one or more of the foregoing claims, characterized in that said rod can be shortened using a hand-nippers, as required.