WO2004069065A1

WO2004069065A1 - Dynamic epiphysial telescopic screw

Info

Publication number: WO2004069065A1
Application number: PCT/EP2004/001235
Authority: WO
Inventors: Christoph Bertram
Original assignee: Cell Center Cologne Gmbh
Priority date: 2003-02-10
Filing date: 2004-02-10
Publication date: 2004-08-19
Also published as: DE10305348A1; EP1596739A1

Abstract

Device for bridging an epiphysial disk is described comprising a sleeve (1) having a first end and a second end, a stud (5) which is longitudinally movable within the sleeve, wherein the stud has a first end and a second end, wherein the first end of the sleeve comprises a fixing device (4) and a recess (2), wherein by means of said recess a torque is transmittable to the sleeve, the first end of the stud is provided with a recess (8), wherein by means of said recess a torque is transmittable to the stud, the second end of the stud protrudes from the sleeve at the second end of the sleeve, and the second end of the stud comprises a fixing device (6). In particular, telescopic screws are provided that are especially suitable for the treatment of epiphyseolysis capitis femoris.

Description

DYNAMIC EPIPHYSIAL TELESCOPIC SCREW

Field of the Invention

The present invention relates to a device for bridging an epiphysial disk comprising a sleeve having a first end and a second end, a stud which is longitudinally movable within the sleeve, wherein the stud has a first end and a second end, wherein the first end of the sleeve comprises a fixing device and a recess, wherein by means of the recess a torque is transmittable to the sleeve, and wherein the first end of the stud comprises a recess, so that a torque is transmittable to the stud, wherein the second end of the stud protrudes from the sleeve at the second end of the sleeve, and the second end of the stud comprises a fixing device. Furthermore, the invention relates to sleeves and studs of a device according to the present invention as well as to surgical instruments which comprise a device, a sleeve and/or stud according to the present invention.

Background of the Invention

The epiphyseolysis capitis femoris juvenilis, which is a disease pattern of adolescent persons, is a "softening" of the epiphysial disk (growth zone) which etiologically has not yet been completely understood, wherein the epiphysial disk is a still chondric (not yet bony adhered) tissue disk of adolescent persons, which joins the epiphysis, the calotte-shaped head, with the metaphysis, the femoral neck, of the thigh bone. The consequences of this disease are a dis- placement of the caput epiphysis due to loosening and sliding, occasionally tipping in relation to the femoral neck, in most cases in dorsal-medial direction. In all stages the treatment is in principle performed by surgical means, namely with radioscopy (X-ray fluoroscopy) as well as with intraoperative inspection by means of X-ray photography. In case of small dislocation angles (<30°) the caput epiphysis is fixed in situ. In case of larger dislocations the caput epiphysis has to be fixed after a three-dimensional osteotomy. Standardized implants for osteosynthesis, which are used for fracture treatment, serve for fixing operation. These are in particular Kirschner's wires having different thicknesses (d = 1.5 to 2.5 mm), Steinmann's thinner bone nails, triflanged nails, which are considered as being outdated for the present purpose, and bone screws having different thicknesses, which are provided at their head with a cancellous bone thread having a length in the region of 16 to 32 mm and which are provided at their lower end with a screw head. They may be provided with a central hole in order to place the screws exactly by means of guide wires. Such a device for fixing the femoral epiphysis against dislocation due to softening of the epiphysial disk is disclosed, for example, in DE 42 42 866 CI.

It is an object of the present invention to provide relatively simple and cost-effective means for bridging an epiphysial disk of a growing skeleton, and wherein exchange of a screw is unnecessary and a projection of the screw into the soft parts is prevented without interfering a bone growth, and wherein a safe anchorage is provided.

Summary of the Invention

The object of the present invention is achieved by providing a device for bridging an epiphysial disk comprising a sleeve having a first end and a second end, a stud longitudinally movable in the sleeve, wherein the stud has a first end and a second end, wherein the first end of the sleeve comprises a fixing device and a recess wherein by means of the recess a torque is transmittable to the sleeve, and wherein the first end of the stud comprises a recess, wherein by means of said recess a torque is transmittable to the stud, wherein the second end of the stud protrudes from the sleeve at the second end of the sleeve, and the second end of the stud comprises a fixing device.

Brief Description of the Drawings

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

Figure 1 is a longitudinal cross-section of the device in accordance with the present invention; Figur 2a and Figure 2b are two lateral cross-sections of the device in accordance with the present invention.

Detailed Description of Preferred Embodiments

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description and drawings the same reference numerals are used to designate the same components and so repetition of the description of the same components will be omitted.

The device according to the present invention is preferably a screw (see Fig. 1), which is used in osteosurgery at a growing skeleton (i.e. with children or adolescent persons) when an epiphysial disk has to be bridged. The device or screw is preferably comprised of two parts: the first part (stud or screw (5)) preferably consists of a metallic cylinder with a thread (6) at a second end of the stud, wherein the thread has a short length and the thread has a larger diameter than the cylinder, and the thread is an external thread. Opposite to the second end of the stud is a first end, which is provided with a recess, preferably with a hexagon socket (8) arranged in longitudinal direction of the cylinder, so that the screw may be fastened or unscrewed by means of an Allen key. The second part (sleeve (1)) usually consists of a tube having an inner diameter, which is preferably only slightly larger than outer diameter of the first part, i.e. the stud, having the consequence that the stud is movable or slideable in longitudinal direction of the sleeve. At the first end of the tube an external thread (4) having a short length is provided for fixing the first end of the tube with a corresponding bone. Furthermore, the first end of the tube is provided with a screw head having a recess (2) for receiving an Allen key. According to a preferred embodiment of the present invention the stud is provided with a central small hole (3) for passing e.g. a thin metallic wire, which may serve as a guide wire. The device according to the present invention provides steady osteosynthesis for parts of a skeleton still having a growth potential, whereas there is no risk of an interruption of the growth of the skeleton.

A typical indication for application of the device according to the present invention is e.g. epiphysiolysis capitis femoris (femoral head slipping), which is characterized by a slipping of the femoral head on the femoral neck. As described above, this disease is treated either with so-called Kirschner's wires or with a common screw for osteosynthesis application, which projects about 1.5 cm from the bone into the soft parts. Though common screws also allow a growth they have to be exchanged in 50 % of patients concerned, namely when the corresponding screw head "touches" with the associated bone. The treatment with Kirschner's wires does not allow a permanent fixation since the wires become slack and may loose off the bone. In this kind of treatment, exchange operations of the corresponding wires are necessary in case of further growth. In applying the device according to the present invention with bone fractures concerning the epiphysial disk a steady servicing is assured as well, allowing a further growth out of the epiphysial disk.

An essential advantage of the device according to the present invention is that no exchange of a screw is necessary and no troubling projection of a screw into the soft parts occurs and nevertheless a safe fixation and anchorage without disturbance of bone growth is achieved.

A further advantage of the device according to the present invention is for instance that in contrast to the system described in the patent document DE 42 42 866 C2 the device according to the present invention is not only provided for fixing a slipped femoral head of an epiphysis but may be additionally used in case of epiphysial injuries of other epiphysial disks, such as epiphyseal fractures. The device according to the present invention allows furthermore, due to its simple configuration without technically complex piston guide in "closed casing", an arbitrary combination of both parts, sleeve and stud, with each other and therefore allows in a simple manner sliding paths having different lengths at growing bones. Furthermore, the device according to the present invention is provided at the sleeve with a thread as a fixing device thus a potential coming out of this sleeve into the soft parts is prevented. Other devices, as described e.g. in the patent document DE 42 42 866 C2, have no such fixing devices. Furthermore, the piston guide as described in the patent document DE 42 42 866 C2 may inhibit further growth of the bridged epiphysial disk when reaching final position of the sliding path. However, the device according to the present invention does deliberately not feature such an inhibition. A potential disadvantage of a dislocation of both components is less important with respect to medical reasons than an inhibition of growth of bones.

The Figures schematically illustrate an embodiment of the device according to the present invention, namely in a longitudinal cross-section (Figure 1) and in two essential lateral cross- sections (Figure 2a and Figure 2b). In the Figures, a preferred embodiment of the device according to the present invention is illustrated, wherein the stud (5) and the sleeve (4) have the shape of a cylinder. It is further preferred that the fixing device of the movable stud (5) consists of a self tapping spongiosa thread (6) and that the fixing device at the first end of the sleeve (1) consists of a corticalis thread (4).

The recess (2) of the first end of the sleeve (1) and the recess (8) of the first end of the stud (5) which both allow a torque transmission are each preferably designed as a socket which is hexagonal-shaped or slot-shaped or Phillips-shaped or square-shaped, wherein a hexagonal- shaped socket is most preferred, see Figure 2a. It is further preferred that in the device according to the present invention the stud and/or the first end of the sleeve is provided with a hole (3), see Figure 1 and Figure 2b.

According to another embodiment of the device according to the present invention it is preferred that the first end of the sleeve (1) has a reduction (7) for preventing the stud (5) from passing through the first end of the sleeve (1).

Preferred materials for the device according to the present invention are medically appropriate materials such as steel alloys consisting of chromium, nickel, molybdenum, or especially the material titanium. In case of special indications possibly special resorbable systems for osteosynthesis applications may be used, if, for instance, children are to be treated. In this case, the screws may be comprised of e.g. a polymer such as poly-L-lactite and/or poly-L-glycolyte. This material is degraded in the course of approximately 12 months in the human body, thereby a growth inhibition may be prevented and thus a second surgery for removal of said material is not necessary.

In order to keep a variety of different possibilities of application of the device according to the present invention devices, especially screws of different diameter and length are recommended with respect to the Association of Osteosynthesis (AO), Switzerland. According to the AO screws with following dimensions are preferred:

Screw (5) thread (mm): 1.5 2.0 2.7 3.5 4.0 4,5 root of thread (mm): 1.0 1.3 2.0 2.4 3.0 3.5 length of thread (mm): ranging from 20 to 130 mm The sleeve (1) should preferably have the following dimensions: inner diameter: corresponding to root of thread of the screw (5) outer diameter: approx. 1-4 mm larger than the inner diameter (corresponding to a wall thickness of 0.5-2 mm) thread (mm): 2.7 3.5 4.0 5.0 diameter of sleeve head (mm): 3.0 4.0 5.0 6.0 length of sleeve (1): ranging from 20 to 130 mm

A choice of the dimension may also be made for instance by means of a template at a standard anterior-posterior X-ray photography.

Furthermore, the present invention relates to sleeves and studs of the device according to the present invention described above and to its use for manufacturing of a device according to the present invention as well as to a surgical instrument comprising a device, sleeve and/or stud, especially screw, according to the present invention.

Further literature concerning any one of the materials, methods, uses and compounds to be employed in accordance with the present invention may be retrieved from public libraries and databases, using for example electronic devices. For example, the public data base "Medline" may be utilized, which is hosted by the National Center for Biotechnology Information and/or the National Library of Medicine and National Institutes of Health. The contents of all cited references (including literature references, issued patents, published patent applications as cited throughout this application and manufacture specifications, instructions, etc.) are hereby expressly incorporated by reference; however, there is no_. admission that any document cited is indeed prior art as to the present invention.

Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

ClaimsWhat is claimed is:

1. Device for bridging an epiphysial disk comprising:

- a sleeve having a first end and a second end;

- a stud which is longitudinally movable within the sleeve, wherein the stud has a first end and a second end;

wherein

- the first end of the sleeve comprises a fixing device and a recess wherein by means of said recess a torque is transmittable to the sleeve;

- the first end of the stud is provided with a recess, wherein by means of said recess a torque is transmittable to the stud;

- the second end of the stud protrudes from the sleeve at the second end of the sleeve, and the second end of the stud comprises a fixing device.

2. Device according to claim 1, wherein the stud and/or sleeve are cylinder-shaped.

3. Device according to claim 1 or 2, wherein the fixing device of the movable stud consists of a self tapping spongiosa thread and the fixing device on the first end of the sleeve consists of a corticalis thread.

4. Device according to any one of claims 1 to 3, wherein the recess for torque transmission is a socket, which is hexagonal-shaped or slot-shaped or Phillips-shaped or square- shaped.

5. Device according to any one of claims 1 to 4, wherein the first end of the sleeve consists of a reduction for preventing the stud from passing through the first end of the sleeve.

6. Device according to any one of claims 1 to 5, wherein the stud and/or the first end of the sleeve are provided with a hole passing through the stud/sleeve.

7. Device according to any one of claims 1 to 6, wherein the stud and the sleeve consist of a metal.

8. Sleeve of the device according to any one of claims 1 to 7.

9. Stud of the device according to any one of claims 1 to 7.

10. Surgical instrument comprising of a device according to any one of claims 1 to 7, a sleeve according to claim 8 and/or a stud according to claim 9.