RU2265417C2 - Implant for substituting extended bone fragments of complex shape - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has support base of variable shape and a member attached to it for making connection to surrounding tissue. The support base is manufactured as cylindrical wire spiral covered with wire net allover its length. Cylindrical spiral lumen is filled with porous permeable titanium nickelide granules as connection member to surrounding tissue.

EFFECT: simplified manufacturing process.

4 cl, 3 dwg

Description

The invention relates to medical equipment and can be used to replace elongated and complex bones with extensive resection or total extirpation.

The human skeleton, containing more than 200 bones, performs many functions: supporting, protective, locomotor, shaping, etc. Therefore, the anatomical structure of bones, the properties of the tissues that form them, are extremely complex and extremely expediently organized. The search for artificial materials, the development of devices and techniques for replacing defective bones for these reasons is difficult and to date have not achieved significant success in the complex requirements of adequacy. The tasks of prosthetics of bones or their fragments are limited by the restoration of support and shape-forming functions. And even in such a reduced search volume, any promotion should be perceived as a result worthy of official protection.

Of the long-known analogues of bone implants, autoimplants — bone fragments from donor sites of the human skeleton that are functionally similar and least traumatic — are still used.

Additional trauma is a significant disadvantage of autobone. A high percentage of insolvency of various etiologies. A great technical difficulty for the surgeon is modeling the shape, especially the elongated bones of complex geometry. With the development of organic chemistry and metallurgical materials science, new biocompatible materials have appeared that are functionally suitable for solving this problem.

Known bone implant made of polymethyl methacrylate, covered with nylon fabric [1]. Made in the form of an oblong plate, it is used for prosthetics of the ribs, i.e. spongy bones carrying a sufficiently large load in combination with flexural mobility. The disadvantages of this analogue, characteristic of polymer implants, are low biocompatibility, low mechanical strength and cycle resistance.

Developed for medical purposes, an alloy based on titanium nickelide surpasses previously known analogues in all of the above properties.

A known implant for replacing bones and bone fragments of an oblong shape from such an alloy. It was used for prosthetics of the ribs of the chest [2] and lower jaw resected in a large area for a malignant tumor [3]. The implant contains a basic support element made in the form of an oblong plate, and layers of porous permeable titanium nickelide located on both surfaces of the plate, fastened together with it with the possibility of micromotion (figure 1). The latter is necessary to ensure bending deformation without destroying the porous layers. The analogue [3] by the greatest similarity is selected as a prototype of the proposal.

When prosthetics of a limited quasilinear portion of the lower jaw is limited, individual modeling of its shape does not have particular difficulties. However, for large areas of resection or extirpation with separation along the joint space (exarticulation), when the shaping becomes three-dimensional, the manufacture of an adequate prosthesis is technologically difficult. In practice, this leads to a defect in the anatomical form, i.e. functional and cosmetic mismatch, which is the disadvantage of the prototype.

The technical result of the invention is to simplify the technology of manufacturing the implant.

The specified technical result is achieved in that in the implant for replacing extended bone fragments of complex shape made of a superelastic alloy based on titanium nickelide and containing a moldable support base and an element of communication with the surrounding tissue bonded to it, the support base is made in the form of a cylindrical wire spiral, sheltered along the entire length of the wire mesh, the lumen of the cylindrical spiral is filled with granules of porous permeable titanium nickelide as an element of communication with the surrounding tissue.

The preferred shape of the guide cylinder of the wire spiral in the form of a circle.

The preferred shape of the guide cylinder of the wire spiral in the form of an oval.

The preferred shape of the guide cylinder of the wire spiral in the form of a closed broken line.

The attainability of the technical result is due to the entire set of essential features, of which the structure and form of the support basis are the main ones in the chain of causal relationship. The spiral form of this element has sufficient basic strength in the postoperative period and increases in the long term, when the whole structure is integrated as a matrix with body tissues. Three-dimensional deformation ability of the spiral minimizes labor costs when modeling a complex bone shape during the operation itself.

The matrix function is performed by the volume of granules of porous permeable titanium nickelide filling the lumen of the wire spiral, and the wire mesh covering the spiral. The latter, in addition, serves as a limiter of the volume of granules.

The proposed device is universal in its use for replacing spongy bones of an extended and complex shape. Versatility is ensured by the possibility of varying the cross-sectional shape of the cylindrical spiral, i.e. spiral cylinder guide forms. The most technologically simple form is a circle. For flattened bones such as ribs of the rib cage or branches of the lower jaw, an oval (for example, elliptical) shape with an appropriate anatomy size ratio is more suitable. A variety of forms of replaced bones is complemented by the possibility of manufacturing an implant with a guide shape in the form of a closed broken line with the number of angles from three or more.

The spiraled structure of the spiral wire provides greater elasticity, i.e. the best form-forming properties. When the transverse dimension is the same as with a monolithic wire, the spun wire has a more developed surface, which is important for increasing the contact area and integration with surrounding tissues.

The main properties of the material (titanium nickelide), such as superelasticity, biocompatibility, cycle resistance, consumer properties of the porous structure, are used in the proposal in full, as in the prototype. The advantage of granular porous permeable titanium nickelide as a matrix of reconstructed tissue, in comparison with that in massive form (prototype), is more energetic dynamics of impregnation with liquids and further processes and greater resistance to deformation fractures of the formed prosthesis. The type of attachment of the implant to the stumps of the resected bone depends on medical indications, is designed and performed specifically in each case according to anthropometric data.

The drawings show:

Figure 1. An implant for replacing long bone fragments of complex shape is a prototype.

Figure 2. An implant to replace a fragment of the lower jaw of the patient: 1 - a cylindrical spiral, 2 - a wire mesh, 3 - granules of titanium nickelide.

Figure 3. Photo of a patient with a restored lower jaw.

Achievability of the technical result is confirmed by specific examples of the use of the implant when replacing the removed fragments in the lower jaw.

Example:

Patient A., 63. Diagnosis of the disease: plexiform ameloblastoma of the lower jaw with damage to the right lateral, frontal, left lateral, posterior left segments of the lower jaw. The patient underwent resection of a fragment of the lower jaw within the specified limits with exarticulation of the left temporomandibular joint (TMJ) and reconstruction of the removed area with an implant (Fig. 2), which, in accordance with the signs of the proposal, had the following characteristics in a static state: strength basis 1 was designed according to preoperative anthropometry and manufactured in the form of a cylindrical spiral with an elliptical cross-sectional shape (cylinder guide) with dimensions of 5 and 20 mm, a spiral pitch of 4 mm from nickel-titanium wire diameter 1.5 mm. Wire mesh 2 is made using textile technology of nickel-titanium wire with a diameter of 1.0 mm The cell size is 1.5 mm. The grid is made in the form of a tape 25 mm wide and superimposed on a support basis by spiral winding with an overlap of 1/3 of the tape width on the previous turn. The formed spiral lumen is filled with titanium nickelide granules with a predominant transverse size of 0.5-6.0 mm.

The device during the operation works as follows.

Check and, if necessary, adjust the length of the implant "in place", shape the contours of the resected portion of the jaw. The ends of the implant are equipped with attachment devices - an endoprosthesis of the joint head of the TMJ on the one hand and a connection plate for attachment to the lower jaw stump on the other hand. The implant is immersed in a prepared bed in soft tissues, covered and sutured. The TMJ endoprosthesis is firmly ligated to the elements of the joint capsule and the surrounding soft tissues. The second end of the implant is attached to the stump of the remaining fragment. Tissues of the anterior and lateral parts of the bottom of the oral cavity, chin-hyoid, anterior biceal muscles are ligated to it. Sutured the mucous membrane of the oral cavity, a skin incision of the submandibular region. Impose active drainage.

The postoperative period was uneventful. Examination of the patient after 60 days revealed the absence of changes in the shape and location of the implant, inflammation of the surrounding tissues, restored all the functions of the lower jaw, except chewing. A good cosmetic effect was achieved (photo of FIG. 3).

The degree of readiness of the implant for clinical use is sufficient to meet the criterion of "industrial applicability".

Sources of information

1. I.G. Nazarenko. Alloplasty of the chest wall after measuring excision of the ribs due to the tumor. // Clinical surgery, No. 7, 1967, S. 60-62.

2. Bone implant. RF patent No. 2157151.

3. P. G. Sysolyatin, V. E. Gunter and others. New technologies in maxillofacial surgery. STT, Tomsk, 2001, p. 162-163 (prototype).

Claims (4)

1. An implant for replacing long bone fragments of complex shape from a superelastic alloy based on titanium nickelide, containing a form-adjustable support base and an element of communication with surrounding tissue fastened to it, characterized in that the support base is made in the form of a cylindrical wire spiral sheathed along the entire length of the wire mesh, the lumen of a cylindrical spiral is filled with granules of porous permeable titanium nickelide as an element of communication with the surrounding tissue. 2. The implant according to claim 1, characterized in that the guide of the cylindrical wire spiral is made in the form of a circle. 3. The implant according to claim 1, characterized in that the guide of the cylindrical wire spiral is made in the form of an oval. 4. The implant according to claim 1, characterized in that the guide of the cylindrical wire spiral is made in the form of a closed broken line.

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