WO2014013517A1

WO2014013517A1 - Fixing device for a bone fracture at the wrist

Info

Publication number: WO2014013517A1
Application number: PCT/IT2012/000228
Authority: WO
Inventors: Filippo LAURENTI
Original assignee: Assut Europe S.P.A.
Priority date: 2012-07-20
Filing date: 2012-07-20
Publication date: 2014-01-23

Abstract

An external bone fixator (1) for wrist fractures, comprising two or more Kirschner wires (41, 42), which are introduced through the wrist joint to connect the two bone stumps of the fracture (F), so that each wire exits percutaneously at an end section thereof so as to be bendable in a direction substantially orthogonal to its own direction of extension into the wrist joint. The fixator (1) further comprises an L-shaped external fixation bar (2), on the arms (21, 22) of which two pairs of jaw-like locking devices (51, 52) are applied, wherein the devices of one pair clamp, in use, the end sections of the Kirschner wires (41, 42), and the devices of the other pair clamp surgical screws, pins or half-pins inserted percutaneously into bone (Fig. 1).

Description

FIXING DEVICE FOR A BONE FRACTURE AT THE WRIST

DESCRIPTION

Field of the Invention

The present invention refers to an external bone fixator for wrist fractures, suitable for use for compound and displaced fractures.

Background of the Invention

A wrist fracture is a very common lesion involving a long and tedious immobilization for the patient, with an entailed relevant socio-economic impact.

In particular, currently this type of fracture can be treated by applying a plaster cast, which however is very uncomfortable for the subject who has to carry it, above all in terms of weight and encumbrance.

Alternatively, wrist fractures can be treated with bridge-like external fixators, so called as characterized by two half-pins proximal to the fractures and two distal half-pins (metacarpus II) locked with one or two external rods, completely immobilizing the wrist joint for the whole consolidation period.

Known fixators, besides being maximally invasive also due to the number of screws needed, require anyhow a non-negligible intervention time to be applied.

Summary of the Invention

The technical problem set and solved by the present invention is that of providing an external bone fixator for wrist fractures which allows overcoming the drawbacks mentioned hereto with reference to the known art.

Such a problem is solved by a bone fixator according to claim 1. The present disclosure further refers to a method of treating a wrist bone fracture according to claim 7.

Preferred features of the fixator of the invention and of the above-mentioned method are set forth in the dependent claims.

The present invention provides some relevant advantages.

One of the main advantages of this invention lies in that the fracture stabilization, through two or more Kirschner wires, enables immediate motion of the wrist joint, therefore enabling the patient to maintain a certain independence in everyday life.

Moreover, by virtue of the use of elongated and bendable connecting elements for the bone stumps concerned by the fracture, the invention allows immediate mobilization of the wrist. In a particularly effective embodiment, such connecting elements are flexible, in particular Kirschner wires.

Moreover, the fixator of the invention and the associated method for the applying thereof allow very quick intervention times, typically of the order of 15- 20 min, and a very low infective risk.

With respect to the treatment with a bridge-like external fixator, the method proposed herein allows an interfragmentary stabilization of the fracture, something that in a bridge-like external fixation can be performed, yet with the use of two or more Kirschner wires (besides the four half-pins proximal and distal to the fracture itself); in fact, a feature of the bridge-like stabilization is that of stabilizing the fracture only through articulation distraction and the entailed ligamentotaxis.

Compared to the treatment with a volar plate, the synthesis by external fixation with two Kirschner wires and two proximal half-pins, all introduced percutaneously, appears clearly less complex, shorter in its implementation, but above all definitely reduces complications due to the surgical approach and the opening up of the fracture site (arterial lesions, nerve lesions, deep infections).

Other advantages, features and the operation steps of the present invention will be made apparent in the following detailed description of some embodiments thereof, given by way of example and not for limitative purposes.

Brief description of the figures

Reference will be made to the figures of the annexed drawings, wherein:

^■ Figure 1 shows a perspective view of a preferred embodiment of the fixator device of the invention, applied by way of example on a wrist affected by a compound fracture F;

^■ Figures 2A and 2B show each a perspective view referring to a respective first or second step of a preferred implementation of the method of applying the device of Figure 1 , which steps are related to the inserting of flexible connecting elements into the body district of interest according to a process of reduction and percutaneous synthesis with two Kirschner wires;

^■ Figure 2C shows a schematic depiction of the arrangement of the flexible elements of Figures 2A and 2B into the body district at the end of the above-mentioned inserting steps;

^■ Figures 3A and 3B show each a schematic depiction of a respective third or fourth step of a preferred implementation of the method of applying the device of Figure 1 , which steps refer to the inserting of surgical screws or equivalent elements into the body district of interest;

^■ Figure 4A shows a perspective view illustrating a fifth step of a preferred implementation of the method of applying the device of Figure 1 , which step obtains the bending of the end sections of the flexible connecting elements which exit percutaneously;

^■ Figures 4B and 4C show each a schematic depiction, respectively in a side view and in a front view, of the arrangement of the flexible elements of Figures 2A and 2B into the body district at the end of the above-mentioned bending step; and ^■ Figure 5 shows a perspective view referring to the device of Figure 1 once applied at the fractured wrist joint.

Detailed description of preferred embodiments

Referring initially to Figure 1 , a device for bone fixation of wrist fractures from the outside - hereinafter for simplicity's sake referred to as bone fixator - according to a preferred embodiment of the invention is generally denoted by 1.

The bone fixator 1 comprises an external fixation bar 2 shaped so as to have a first arm 21 and a second arm 22 angled the one with respect to the other. In the present example, the fixation bar 2 is substantially L-shaped and has the first arm 21 of lesser extension and the second arm 22 of greater extension. Moreover, always in the present example, such arms 21 and 22 are substantially orthogonal the one to the other.

Furthermore, the bone fixator 1 comprises a first pair of locking devices 31 and 32 applied or applicable at the first arm 21 of the rod 2, and a second pair of locking devices 33 and 34 applied or applicable at the second arm 22 of the rod 2.

Each locking device 31-34 is apt to clasp thereinside an element to be locked, and moreover is selectively positionable on the rod 2 in an absolute and relative adjustment, by sliding the device 31-34 on the rod itself.

Locking devices of the type considered herein are known per se (they may be, e.g., jaw-like) therefore a further description thereof will be omitted.

The locking devices 31 and 32 of the first pair are intended to lock each a respective flexible elongated element 41 , 42 which will be described hereinafter.

The locking devices 33 and 34 of the second pair are intended for locking each a respective surgical screw, half-pin, pin or equivalent element. In the present example two surgical screws are provided, respectively denoted by 51 and 52. As mentioned above, the bone fixator 1 comprises, according to the invention, a first and a second elongated and flexible connecting element, respectively denoted by 41 and 42.

As will be better explained hereinafter with reference to the operation modes of the fixator 1 and in connection with Figures 2A and 2B, each connecting element 41 , 42 is apt to be introduced longitudinally through the wrist joint to connect the two bone stumps concerned by the fracture. By "longitudinal direction" herein it is meant substantially the direction of development of the bone segments concerned by the fracture (line L in Figure 1).

Always as will be explained hereinafter, each element 41 , 42 is applied so as to exit percutaneously at an end section 411 , 421 thereof, so as to be bendable in a direction substantially orthogonal to its own direction of extension into the wrist joint and locked by a respective device 31 , 32.

Advantageously, each connecting element 41 , 42 has a substantially wire- shaped configuration. Based on a particularly effective embodiment, such connecting elements 41 and 42 are Kirschner wires.

The implantation modes for implanting the bone fixator 1 into the body district of interest will presently be illustrated with reference to Figures 2A to 5.

The patient's position is supine on a surgical bed, with the arm concerned by the fracture supported on a transparent table or panel, in turn resting on the dish of a brilliance amplifier positioned perpendicularly to the operating table.

Preliminarily, the surgeon performs a fracture reduction under brilliance.

As shown in Figure 2A, in a first step of the method of applying the bone fixator 1 , the first Kirschner wire 41 is inserted percutaneously so as to cross the bone stumps concerned by the fracture and be arranged bridge-like therebetween.

In the present exemplary intervention, the first wire 41 is inserted from the radial styloid.

A first end of the wire 41 , which for simplicity's sake will be referred to as distal, remains inserted in situ inside the body, whereas a proximal section 411 thereof exits percutaneously at the insertion port, to be then locked by the device 31.

As shown in Figure 2B, the second Kirschner wire 42 is inserted through a front port, in the present example at the ulnar end of the radial epiphysis (IV-radius line), in a position adjacent to that of the first wire 41 and according to analogous modes.

Of course, different fractures may require a different positioning of the wires 41 and 42. E.g., the first wire 41 may be introduced from the radial styloid and the second wire 41 in a dorsal position at the basis of the Lister's tubercle.

Referring to Figure 2C, preferably the two wires 41 and 42 are arranged between the bone stumps so that the related directions of extension cross (so- called X-crossing arrangement). Thus, the wires 41 and 42 exert a more effective tractive action and allow a stabilization of the fracture fragments.

Alternatively, the wires 41 and 42 may also be arranged substantially parallel the one to the other, typically with endomedullary transit into the two stumps.

Intervention needs different from the ones considered herein may further require the applying of flexible connecting elements additional with respect to the two wires considered herein.

As shown in Figures 3A and 3B, the two surgical screws 51 and 52 are then inserted dorsally, in a direction substantially orthogonal to that of development of the bone segments and onto an intact bone portion. Such screws 51 and 52 are inserted preferably under brilliance.

In the present example, the first screw 51 is arranged about 2 cm proximally to the fracture, with a tilt of about 25 - 30° with respect to the line orthogonal to bone development. The second screw 52 is positioned about 2 cm proximally to the first screw 51 , parallelly to the latter.

It will be understood that intervention needs different from the ones considered herein may envisage different tilts.

Then, as shown in Figures 4A, 4B and 4C, the proximal section 411 , 421 of each Kirschner wire 41 , 42 which exits percutaneously is bent in a direction substantially orthogonal to its own direction of extension into the wrist joint, and then clasped, as shown in Figure 5, within a respective locking device 31 , 32.

Similarly, the portions of screws 51 and 52 which exit percutaneously are clasped within the corresponding locking devices 33 and 34, before, after or concomitantly with the corresponding locking of the wires 41 and 42.

The bending of the wires 41 and 42 and their locking within the devices 31 and 32 can also occur prior to a percutaneous insertion of the screws 51 and 52.

In this connection, consider that it is not strictly necessary for the screws 51 and 52 inserted into the bone to intercept the distal portions of the wires 41 and 42 in order to secure them. Such distal sections are held even merely by virtue of their fitting into the bone and of static friction with the surface thereof .

Therefore, in the end arrangement the first arm 21 of the rod 2 is arranged substantially orthogonal to the longitudinal direction of the bone, whereas the second arm 22 is arranged substantially parallel to such direction.

Finally, the surgeon can check, under examination with optical instruments, reduction effectiveness and fixation stability.

The invention does not apply to Goiran-type (reversed Colles) fractures and to meta-epiphyseal comminuted (C3) fractures with volar fragments.

The present invention has been hereto described with reference to preferred embodiments thereof. It is understood that other embodiments might exist, all falling within the concept of the same invention, as defined by the protective scope of the claims hereinafter.

Claims

1. An external bone fixator (1) for wrist fractures, comprising:

- a pair of elongated connecting elements (41 , 42), each apt to be introduced longitudinally into the wrist joint to connect the two bone stumps of the fracture and apt to exit percutaneously at a proximal section thereof (411 , 421) so that it can be bended in a direction substantially orthogonal to its direction of extension within the wrist joint;

- an external fixation bar (2), having a first arm (21) and a second arm (22) substantially angled the one with respect to the other; and

- a first (31 , 32) and a second (33, 34) pair of locking devices, arranged or apt to be arranged each at a respective first (21) or second (22) arm of said fixation bar (2), wherein the overall arrangement is such that, in use, the bent end sections (411 , 421) of said connecting elements (41 , 42) are clasped each within a respective locking device (31 , 32) of said first pair arranged at said first arm (21) of said fixation bar (2), whereas each locking device (33, 34) of said second pair is arranged at said second arm (22) of fixation bar (2) and clasps a surgical screw, pin or fiche (51 , 52).

2. The bone fixator (1) according to claim 1 , wherein each of said elongated connecting elements (41 , 42) has a substantially wire-shaped configuration and is preferably flexible.

3. The bone fixator (1) according to the preceding claim, wherein said elongated connecting elements are Kirschner wires (41 , 42).

4. The bone fixator (1) according to any one of the preceding claims, wherein said external fixation bar (2) is substantially L-shaped.

5. The bone fixator (1) according to any one of the preceding claims, wherein said first (21) and second (22) arm of said fixation bar (2) are substantially orthogonal the one to the other.

6. A fixator assembly for wrist fractures, comprising a bone fixator (1) according to any of the preceding claims and one or more surgical screws, fiches or pins (51 , 52).

7. A method of treatment of a wrist fracture, providing the steps of:

(a) introducing longitudinally a first (41) and a second (42) elongated connecting element percutaneously into the wrist joint, so as to connect by such elongated elements (41 , 42) the two bone stumps of the fracture and so that a proximal section (41 , 421) of each of such elongated elements (41 , 42) exits percutaneously;

(b) bending said proximal sections (411 , 421) of said elongated elements (41 , 42) in a direction substantially orthogonal to the direction of extension of the elements (41 , 42) into the wrist joint;

(c) percutaneously fixing a pair of surgical screws, pins or fiches (51 , 52) onto a sound bone portion; and

(d) locking into a predetermined relative position the bent end sections (41 1 , 421) of the connecting elements (41 , 42) and the portion of the screws, fiches or pins (51 , 52) which exits percutaneously, wherein said steps (b) and (c) can be carried out in any order.

8. The method according to claim 7, providing the use of wires, preferably Kirschner wires (41 , 42), as connecting elements.

9. The method according to claim 7 or 8, wherein said step (a) provides the connecting elements (41 , 42) to be arranged crossed within the joint.

10. The method according to claim 7 or 8, wherein said step (a) provides the connecting elements (41 , 42) to be arranged substantially parallel, preferably endomedullarly, within the joint.

11. The method according to any one of the claims 7 to 10, wherein said step (a) provides the first connecting element (41) to be inserted from the radial styloid and the second connecting element (42) to be inserted at the ulnar end of the radial epiphysis.

12. The method according to any one of the claims 7 to 1 1 , wherein said step (c) provides the surgical screws, pins or fiches (51 , 52) to be arranged with a tilt of about 25 - 30° with respect to the line orthogonal to bone development.

13. The method according to any one of the claims 7 to 12, providing the use of a bone fixator (1) according to any one of the claims 1 to 6.