GB1575161A

GB1575161A - Sleeve for surgical nails

Info

Publication number: GB1575161A
Application number: GB1112278A
Authority: GB
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 1977-03-25
Filing date: 1978-03-21
Publication date: 1980-09-17
Also published as: FR2384483B1; FR2384483A1; DE2713162A1

Description

(54) SLEEVE FOR SURGICAL NAILS (71) We, MERCK PATENT GESELLSCHAFT MIT BESCH RANKTER HAFTUNG, of 250 Frankfurter Strasse, 61 Darmstadt, Federai Republic of Germany, a Joint-Stock Company organised under the laws of the Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention is concerned with a sleeve for enveloping surgical nails which are to be used for bone stabilising in conjunction with external splints.

Various methods are used for stabilising bone breakages and pseudo-arthroses and for carrying out corrective osteotomias, for example immobilisation by Plaster of Paris bandages or synthetic resin bandages, osteosynthesis by means of nails or plates and the use of external splints and fixing means.

External splints are available in various forms which, however, all function according to the same principle: transversely to the longitudinal axis of the bone, surgical nails are bored in above and below the breakage zone or the osteotomia point and securely connected with one another by a frame construction of metal or synthetic resin parts placed outside of the skin in such a manner that movement in the breakage region can no longer take place.

The main advantage of this procedure is the fact that the breakage region, with the danger of post-operative wound infection and loosening of broken pieces from the periostic tube, does not have to be opened.

However, a frequent and very serious complication is, nevertheless, infection in the region of the point of emergence of the surgical nail through the skin since, in this region, a continuous movement of the skin over the nail takes place and the nail itself, which is, of course, a foreign body, favors the formation of infection. In some cases, it is even more difficult to remove a bore hole infection than, for example, the infected pseudo-arthrosis for which the external splint was originally applied.

Therefore, it is an object of the present invention to provide means by which infections (bore hole osteo-myelitis) can be prevented when using surgical nails.

According to the present invention, this object is achieved by means of a synthetic resin containing an anti-bacterially active material and having the form of a sleeve.

Thus, according to the present invention, there is provided a sleeve for surgical nails to be used for stabilising bones, comprising a physiologically acceptable synthetic resin capable of the protracted liberation of antibacterially active materials and at least one anti-bacterially active material.

The present invention also provides surgical nails covered with such a sleeve.

Surprisingly, we have found that the sleeves according to the present invention effectively prevent or overcome infection in the region of the point of emergence of the surgical nails through the skin. As a result of the suppression of an infection in this region, the sleeves are encompassed, without inflammation, by the tissues and fixed in such a manner that movement of the skin on the surgical nails, which contributes to the infection, is also prevented and thus an encroachment of the infection on to the bones is prevented. The sleeves can be removed, together with the nails, without difficulty.

The sleeves are preferably in the form of a hollow cylinder or tube of about 1-10 cm.

length, depending upon the strength of the soft mantle, with a wall thickness of about 1--3 mm. in the case of an external diameter of about 5-10 mm. Other shapes can, of course, also be made, for example penetrable synthetic resin cylinders or also shapes with non-uniform diameter.

The sleeves consist essentially of physiologically acceptable synthetic resins containing anti-bacterially active materials which are capable of the protracted liberation of anti-bacterially active materials. Examples of synthetic resins which can be used for the production of the sleeves according to the present invention include polyurethane, ethylene vinyl acetate, acrylonitrile fibres and synthetic resins based on polymethacrylates and/or polyacrylates.

It is known to use such synthetic resin materials for surgical purposes. Thus, for example, a bone cement is known which, in a standard pack, contains two sachets, each with about 40 g. of powder, and 2 ampoules, each with 20 ml. of liquid. The powder is a fine pearl methyl methacrylate-methyl acrylate copolymer (particle diameter < 30y), about 0.5 /" dibenzoyl peroxide being added to the powder as catalyst. For identification of the material, traces of chlorophyll can be polymerised in during the production thereof. As X-ray contrast medium, the powder can also contain, for example, zirconium dioxide. The associated liquid consists of monomeric methyl methacrylate to which, as accelerator, is added about 0.70/n dimethyl-p-toluidine, as well as traces of hydroquinone as stabiliser.

As a rule, this liquid is also coloured with traces of chlorophyll for identification purposes. The powder, which is packed into polyethylene sachets, can be sterilised with ethylene oxide. The liquid is sterilised by filtration and filled into glass ampoules.

Upon mixing together 2 parts by weight of powder and 1 part by weight of liquid, the dibenzoyl peroxide reacts with the dimethyl-p-toluidine in the liquid, radical polymerisation thereby being initiated. The mixture is so adjusted that it can be used after only about 1 minute in the form of a paste. This paste remains kneadable for about 4 minutes and then begins to harden, with the evolution of heat. After 6 minutes, the polymerisation is substantially finished.

Shaping takes place during the elastic phase.

However, the synthetic resins which can be used for the present invention are also available in completely polymerised form.

They are preferably employed in the form of pearl polymers for the production of the sleeves according to the present invention.

According to the present invention, the synthetic resin material contains at least one anti-bacterially active material, optionally together with an appropriate carrier. The carrier can be, for example, the abovedescribed pearl polymer which can be incorporated, for example, into polyurethane or ethylene vinyl acetate. The anti-bacterially active materials used are, in principle, all antibiotics and chemotherapeutic inhibiting materials which are not damaged by the chemical influences or temperatures occurring in the course of the incorporation, the complete hardening or the sintering of the synthetic resin and which are liberated in the desired manner from the synthetic resin.

Furthermore, the anti-bacterially active materials should be chemically stable towards the synthetic resins employed.

Their spectrum of activity is to include gram-positive or gram-negative microorganisms and preferably both groups of micro-organisms. If possible, the microorganisms should have a retarded resistance development with regard to the antibacterially active materials employed. From the large number of antibiotics which can be used, there may be mentioned, by way of example, erythromycin, lincomycin, clindamycin, novobiocin, vancomycin, bacitracin, fusidic acid, rifampicin, polymycins, neomycin, kanamycin, tobramycin, sisomycin, amikacin and, in particular, gentamycin. Penicillins and cephalosporins can also be used. The aminoglycoside antibiotics, such as gentamycin, are especially preferred because of their broad anti-bacterial spectrum and of their heat stability.

The amount of active material to be added can be varied within wide limits and depends essentially upon the activity thereof. In gerieral, about 0.2 to 15 /n by weight of antibacterially active materials, referred to the synthetic resin, are added. In the case of gentamycin, for example, additions of between 1 and 4( by weight (calculated as gentamycin base) have given favourable results. The other antibacterially active materials are preferably also added in amounts which are adequate for their anti-microbial activity. Mixtures of anti-bacterially active materials can also be used.

The synthetic resin materials preferably also contain at least one amino acid because we have found that the liberation of antibacterially active materials from synthetic resin materials is substantially improved in the presence of amino acids, i.e.

independently of a particular production batch, a continuous, slowly decreasing liberation of the active materials takes place over a comparatively long period of time.

Even a small concentration of these physiologically acceptable amino acids has this effect. Furthermore, when the sleeves according to the present invention are produced by injection moulding, the working temperatures thereby necessary can be considerably reduced, making a gentle working up possible, which is desirable from the point of view of the active material.

The amino acids used can, in principle, be all naturally occurring and physiologically acceptable amino acids which have a water solubility of at least about 1 g./100 ml.

Preferred amino acids include aliphatic monoamino-monocarboxylic acids containing up to 5 carbon atoms, for example, glycine, alanine, threonine, valine, serine, hydroxyproline and proline, glycine and alanine being particularly preferred and glycine especially preferred. The synthetic resin material can contain one amino acid or a mixture of several amino acids.

The amount of amino acid to be added can be varied within wide limits and depends at least partly upon the solubility of the amino acid used. In general, about 0.3 to 5 /" by weight of amino acid, referred to the polymer, is added. In the case of glycine, for example, an addition of about 1 /" by weight has proved to be especially favourable.

For the production of the sleeve according to the present invention, into the synthetic resin there is incorporated, for example, an antibiotic and preferably at least one amino acid. This can take place by introducing both components into the synthetic resin before complete hardening thereof, for example a pearl polymer which possibly already contains one of the components is intensively mixed with the missing component or components, whereafter the desired shaping is carried out.

The sleeves or tubes obtained can, if desired, subsequently be sterilised and can then be seal packed as such or after having been drawn on to surgical nails. In the case of a thick soft mantle, tube-shaped sleeves are preferably used which can cover over the whole length of the nail. However, it is to be understood that the sleeves or tubes according to the present invention can be used for covering not only the whole length of the nail but also for covering only a part of the nail, for example in the region of the point of emergence of a surgical nail through the skin. Before use, the tubes can be cut up into appropriate lengths.

The following Example is given for the purpose of illustrating the present invention: Example 40 g. of a sterile, fine pearl polymer (particle diameter < 30y), consisting of a cppolymer of methyl methacrylate and methyl acrylate, which contains about 15% zirconium dioxide as X-ray contrast agent, are well mixed with 0.5 g. gentamycin sulphate and 0.4 g. glycine. The powder obtained is sintered in an appropriate apparatus and shaped into the desired shape, preferably by injection moulding.

The resulting sleeve has the shape of a hollow cylinder of about 1--10 cm. length and a wall thickness of about 1--3 mm. in the case of an external diameter of about 5-10 mm. Sterilisation, for example by gassing with ethylene oxide, can, if desired, subsequently be carried out. The sleeves are then pushed on to surgical nails for the prophylaxis of infection in the region of the point of emergence of surgical nails through the skin.

WHAT WE CLAIM IS: 1. A sleeve for surgical nails to be used for stabilising bones, comprising a physiologically acceptable synthetic resin capable of the protracted liberation of antibacterially active materials and at least one anti-bacterially active material.

2. A sleeve according to claim 1 in the form of a hollow cylinder or tube of about 1--10 cm. length and with a wall thickness of about 1--3 mm. in the case of an external diameter of about 5-10 mm.

3. A sleeve according to claim 1 or 2, wherein the synthetic resin is a polyurethane, ethylene vinyl acetate, acrylonitrile fibre material or a polymethacrylate and/or polyacrylate.

4. A sleeve according to any of the preceding claims, wherein the antibacterially active material is the antibiotic gentamycin.

5. A sleeeve according to any of the preceding claims, wherein at least one amino acid is additionally present.

6. A sleeve according to claim 5, wherein the amino acid is glycine.

7. A sleeve according to claim 1 for surgical nails, substantially as hereinbefore described and exemplified.

8. Surgical nails, whenever provided with a sleeve according to any of claims 1 to 7.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

Preferred amino acids include aliphatic monoamino-monocarboxylic acids containing up to 5 carbon atoms, for example, glycine, alanine, threonine, valine, serine, hydroxyproline and proline, glycine and alanine being particularly preferred and glycine especially preferred. The synthetic resin material can contain one amino acid or a mixture of several amino acids.

The amount of amino acid to be added can be varied within wide limits and depends at least partly upon the solubility of the amino acid used. In general, about 0.3 to 5 /" by weight of amino acid, referred to the polymer, is added. In the case of glycine, for example, an addition of about 1 /" by weight has proved to be especially favourable.

For the production of the sleeve according to the present invention, into the synthetic resin there is incorporated, for example, an antibiotic and preferably at least one amino acid. This can take place by introducing both components into the synthetic resin before complete hardening thereof, for example a pearl polymer which possibly already contains one of the components is intensively mixed with the missing component or components, whereafter the desired shaping is carried out.

The sleeves or tubes obtained can, if desired, subsequently be sterilised and can then be seal packed as such or after having been drawn on to surgical nails. In the case of a thick soft mantle, tube-shaped sleeves are preferably used which can cover over the whole length of the nail. However, it is to be understood that the sleeves or tubes according to the present invention can be used for covering not only the whole length of the nail but also for covering only a part of the nail, for example in the region of the point of emergence of a surgical nail through the skin. Before use, the tubes can be cut up into appropriate lengths.

The following Example is given for the purpose of illustrating the present invention: Example

40 g. of a sterile, fine pearl polymer (particle diameter < 30y), consisting of a cppolymer of methyl methacrylate and methyl acrylate, which contains about 15% zirconium dioxide as X-ray contrast agent, are well mixed with 0.5 g. gentamycin sulphate and 0.4 g. glycine. The powder obtained is sintered in an appropriate apparatus and shaped into the desired shape, preferably by injection moulding.

The resulting sleeve has the shape of a hollow cylinder of about 1--10 cm. length and a wall thickness of about 1--3 mm. in the case of an external diameter of about 5-10 mm. Sterilisation, for example by gassing with ethylene oxide, can, if desired, subsequently be carried out. The sleeves are then pushed on to surgical nails for the prophylaxis of infection in the region of the point of emergence of surgical nails through the skin.

WHAT WE CLAIM IS: 1. A sleeve for surgical nails to be used for stabilising bones, comprising a physiologically acceptable synthetic resin capable of the protracted liberation of antibacterially active materials and at least one anti-bacterially active material.
2. A sleeve according to claim 1 in the form of a hollow cylinder or tube of about 1--10 cm. length and with a wall thickness of about 1--3 mm. in the case of an external diameter of about 5-10 mm.
3. A sleeve according to claim 1 or 2, wherein the synthetic resin is a polyurethane, ethylene vinyl acetate, acrylonitrile fibre material or a polymethacrylate and/or polyacrylate.
4. A sleeve according to any of the preceding claims, wherein the antibacterially active material is the antibiotic gentamycin.
5. A sleeeve according to any of the preceding claims, wherein at least one amino acid is additionally present.
6. A sleeve according to claim 5, wherein the amino acid is glycine.
7. A sleeve according to claim 1 for surgical nails, substantially as hereinbefore described and exemplified.
8. Surgical nails, whenever provided with a sleeve according to any of claims 1 to 7.