FI83729C - SURGICAL IMPLANTS. - Google Patents

Description

83729

Surgical implant

The invention relates to a surgical implant as further defined in the preamble of claim 1.

In particular, the invention relates to the so-called spike parts used in connection with the external fik-5 means.

The major drawback in the surgical use of external fixation devices is the high infection rate. Typically, about 4-30% of surgeries result in in-10 infection formation (see, e.g., LDAnderson, WC Hudchins et al., Clin. Orthop. 105: 179, 1979; F. Bunny, Hoffman External Hart Frame Fixation: Current Con cepts of External Fixation of Fractures ", Springer-Werlag, Berlin, BRD, 1982). A high infection rate of 15 is caused e.g. that microorganisms enter the body from outside it along fixation peaks through a skin ulcer present in the fixed limb around the peak. 1 2 3 4 5 6 7 8 9 10 11 In the present invention, it has surprisingly been found that when, according to the characterizing part of claim 1, the fixing tines 4 of the soft tissue piercing 4 forming the core layer of the external fixation means 4 are coated with at least the soft tissue piercing part 6 containing a surface of 7 layers of antimicrobial agent or combination of agents released under tissue conditions, such as anti 9 antibiotics or a mixture of antibiotics, can significantly reduce infection by 10% in external fixation. This is due to the fact that the antimicrobial agent released from the surface of the spikes of the devices according to the invention effectively prevents the migration and propagation of microorganisms from the ulcer deeper into the tissues. Likewise, said antimicrobial agent effectively inhibits the infectious effect of the microorganisms present in the implant or the microbes entering the wound during surgery.

The spikes of the external fixation means according to the invention may also have a porous surface structure, consisting, for example, of a metallic core material. The open porosity of the surface of the peaks is then preferably filled at least in part with an antimicrobial agent released under tissue conditions or with an organic or inorganic substance containing an antimicrobial agent which is released into the tissues. When such devices are used, the antimicrobial agent released into the tissue provides an effective anti-infective effect.

The invention and its further advantages are further illustrated in the following description and in the examples, which refer to the application examples shown in the accompanying drawings. In the drawings, Fig. 1a schematically shows a part of an external fixation means for a tibial fracture 25 installed, Fig. Ib schematically shows an external fixation device for use in the wrist area, Fig. 2 schematically shows a spike of an external fixation means according to the invention, Fig. 3 shows a fixation according to Example 1.

3,83729

In external fixation means for fractures, the invention can be applied e.g. as follows. The external fixation means consist of a) fixation spikes, i.e. pins, attached to the bone through the soft tissue, and 5 b) out-of-body support structures to which the spikes are attached. Such known external fixation means are shown schematically in Figures 1a and Ib. Fig. 1a shows schematically in longitudinal section a part of, for example, an external fixation means used in the fixation of the tibial fracture 1, both sides. Their number may vary depending on the type of fracture. Figure Ib schematically shows, for example, an external fixation device used in the wrist area, in which the fixation spikes 4 penetrate the soft tissues 3 only at one end and are attached to one support structure 5.

Fig. 2 schematically shows a fixing spike 4 (core layer II) coated with an antimicrobial agent-containing coating 6 according to the invention, forming a surface layer I, which passes through the soft tissue 3 and the fixable bone 2 and the adhesive. linked to the external support structure 5. 1

According to a preferred embodiment, the surface layer I and the core layer II (core-forming material) of the spike part of the external fixation means are the same substance, and the core layer II may also contain an antimicrobial agent. Antimicrobial agents can be added to such implants made of polymeric materials 4,83729 or their components already in the polymerization step, in the processing of the polymer raw material into a semi-finished product or product, or after the manufacture of the implant, e.g. by impregnating the antimicrobial agent inside the material. When such an implant is placed in the body, an antimicrobial agent dissolves in the surrounding tissue from its surface layer, which effectively prevents infection. Implants made from such a material or combination of materials can deliver an antimicrobial agent under tissue conditions for many months when the concentration of the antimicrobial agent in the surface layer is high enough and / or its diffusion from the surface layer to the surrounding tissues is sufficiently slow and / or in place of the fusible antimicrobial agent, a new antimicrobial agent diffuses from the continuous core material. When such polymeric spike portions of the invention are made of a biodegradable polymer, copolymer, polymer blend, or composite, they support the tissues to be fixed for the required time while gradually losing their strength as the bone tissue heals. At the same time, such spike portions of the external fixation device deliver antimicrobial agents to the surrounding bone tissue and / or soft tissue, effectively preventing infections. Once the fracture has healed, the biodegradable spike parts do not need 30 removal surgeries because the body uses the biodegradable spike parts for food. Thus, upon removal of the external fixation means, the fixation spike portions within the bone can be left in place because the body uses them as its cellular nutrients at a later stage.

Thus, when using the at least partially biodegradable fixation devices according to the invention, the complications which may occur to the patient in connection with the removal of the spike part 5 of the external fixation device, possibly breaking it and remaining partially inside the bone tissue, can also be eliminated.

According to a preferred embodiment, the spike portions of the invention may also contain one or more cavities or the like substantially filled with an anti-microbial agent or mixture of agents released under tissue conditions. In this case, the total amount of antimicrobial agent contained in the spike parts can be increased. As the spike diffuses through its outer surface into the tissues surrounding the antimicrobial agent, new material diffuses from the cavity / cavities in place of the effluent so that the concentration of antimicrobial agent in the spike portion, its surface layer I and thus in the surrounding tissue remains. The contact of the cavity with the surface layer can be closed with a substance which, under tissue conditions, is at least partially biodegraded and / or rapidly dissolves, whereby the contact with the surface layer is opened.

25

The invention is illustrated by the following example.

EXAMPLE

A research-type fixation device of the type shown in Figure Ib, consisting of an external support structure and supported bone fixation spikes 6,83729 (so-called "half-pins"), was used for external fixation of a rabbit distal femoral theotomy as follows.

The steel spikes (1.6 mm thick) of the fixation devices 5 of the study set (20 rabbits) were coated with a 0.3 mm thick layer of poly-DL-lactide (Mw 100,000) containing 10 wt.% Of the soft tissue-permeable portion and 10 mm of the extracorporeal portion. % Kefalo-10 spores.

Instruments from the control set (20 rabbits) were not coated.

All fixatives were sterilized with ethylene oxide.

anesthetized rabbit hair from the lateral aspect of the distal thigh area was shaved, the skin was washed with Neo-Amisept solution 20 and the distal portion of the femur was exposed with a longitudinal incision. On the distal side of the planned osteotomy level, two small skin incisions were made above the knee joint, on which the fixation spikes were pressed into the bone contact, after which the tips threaded by the tip-25 were screwed into the bone so that they pierced both cortexes. The same was done for the proximal side of the osteotomy plane using three fixation peaks. The fixation spikes were attached to the support structure. The femur was osteotomized with 30 diamond discs at a height of about 2 cm above the knee joint in the pumice area. The bone surfaces were brought into compression contact by adjusting the distance between the proximal and distal peak groups from the support structure. The opening was closed with a biodegradable om-35 game (fixation shown schematically in Figure 5).

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In a control series with uncoated fixation peaks, four infections in the area of fixation peaks in the tissues occurred during healing. In a series of studies using spikes coated with a polylactide-anti-5 biotic mixture, only one superficial infection occurred in the skin-penetrating region of the spike during healing.

Claims (4)

A surgical implant, in particular an implant for fixing a bone fracture, which has at least one core layer (II) made of metal, metal blend or polymeric material or combination of these materials, ie. composition and a core layer (II) at least partially covered, surface layer (I) formed in the tissue conditions at least partially absorbent polymer, polymer or polymer blend, characterized in that said surface layer (I) is intended in a manner known per se to act as a carrier (matrix) in the tissue conditions releasable anti-microbial material or material compound, and the said surface layer (I) and the core layer (II) are constructed as a spigot for an external fixative to penetrate the skin, so that at least some of the implants are present. outside tissue while the surface layer (I) is arranged for the implants, so that it stands at least 20 in the soft tissue dk the implants are in place. Implant according to claim 1, characterized in that at least their surface layer (I) contains open porosity. 25 Implant according to claim 1, characterized in that the surface layer (I) consists of at least partially porous or fibrous material, the pores or spaces of the fibrous structural units being at least partially filled with organic or inorganic material, which are intended to function as carrier (matrix) in at least tissue conditions releasable antimicrobial or other chemotherapeutic material. 35 Implant according to claim 1, characterized in that said implants comprise at least one cavity or similar present in the nuclear layer, which is intended for release in the tissue conditions antimicrobial or other chemotherapeutic material or material compound and said at least one cavity or material. at least in the tissue conditions provided in association with the surface layer (I).