RU2843239C1 - Composite implant-endoprosthesis for mandibular defect replacement - Google Patents

Abstract

FIELD: medical science.

SUBSTANCE: invention refers to medicine, particularly to reconstructive maxillofacial surgery. Composite endoprosthesis for replacement of total and subtotal mandibular defect is made of PEEK by 3D printing by means of individual computer model configured to restore original shape and size of lost fragment of mandible. Middle part of the endoprosthesis consists of a jaw body, perforated with four holes under the titanium wire for fixation with the left and right jaw segments, two slots for connection with side parts, two holes for fixation of soft tissues to mental muscle and two perforated sections for fixation of porous structure similar to trabecular structure of jaw. Two symmetrical side fragments of endoprosthesis contain four holes and reverse parts of slots for fixation with middle part, as well as the angle of the jaw, which passes into the condylar process, which has a shape corresponding to the articular fossa, and perforations for fixing a porous structure similar to the trabecular structure of the jaw.

EFFECT: soft-tissue integration of the endoprosthesis with adjacent tissues, glenoid cavity of the skull, interaction with the surrounding tissues is achieved.

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Description

The invention relates to medicine, in particular, to restorative and reconstructive maxillofacial surgery, and is intended to replace total bone defects of the lower jaw that have arisen as a result of pathological processes.

An implant-endoprosthesis for replacing defects of the lower jaw is known [1], consisting of a jaw part made of carbon composite material, which additionally has an articular part made of titanium alloy, consisting of a neck and articular head, replacing the neck and articular head of the condylar process of the lower jaw. The disadvantages of this endoprosthesis are - the complexity of the design, the impossibility of individualizing the endoprosthesis, due to the use of a standard blank, the lack of holes for fixing the periosteum, and the lack of the possibility of further prosthetics of the patient.

Also known is an implant-endoprosthesis for replacing bone fragments of complex shape made of titanium nickelide alloy, containing a shape-changing support structure made in the form of a wire spiral covered along its entire length with a mesh material, and an element of connection with the surrounding tissue attached to it [2]. The disadvantage of this implant-endoprosthesis is the inability to restore its anatomical shape of the defect being eliminated. In addition, the use of this implant-endoprosthesis does not provide functional interaction with tendon-muscle tissues. This causes a change in the spatial relationship of the axes of muscle traction, a change in the moments of forces, and a violation of the biomechanics of the lower jaw. Such defects lead to irreversible severe functional disorders and significantly reduce the quality of life and functional rehabilitation of patients. A significant disadvantage is that these implant-endoprostheses for replacing bone defects of the lower jaw are manufactured in one standard size without clear individualization according to anatomical and topographic parameters.

An implant-endoprosthesis for replacing a volumetric bone defect of the lower jaw is known [3]. The implant-endoprosthesis consists of a monolithic hollow block, a nickel-titanium jaw body with holes for titanium screws, a jaw angle, a jaw branch with a spherical condylar process, a coronoid process with a retainer for the tendon of the temporal muscle with a groove on the outer surface of the body for placing the inferior alveolar vascular-nerve bundle.

Disadvantages of this endoprosthesis: the use of titanium nickelide alloy, which has the phenomena of metallosis, corrosion and bone tissue resorption, high rigidity and electrical conductivity; a connective tissue layer appears between the metal implant and the bone, which ultimately leads to loosening and instability of the implant, reaction to cold, complexity of manufacturing the structure; the design of the endoprosthesis does not provide for holes for fixing the body of the endoprosthesis to soft tissues.

The prototype is an implant-endoprosthesis for replacing a total defect of the lower jaw developed by Xilloc International Publication Number WO 2013/034180 A1 [4]. It is a titanium structure manufactured according to individual patient parameters (additive manufacturing technology). The design of the prosthesis includes recesses and/or through holes for attaching sutures and/or tissue to the implant. The implant is coated with biocompatible hydroxyapatite and has a porous area for better fixation. The endoprosthesis has polished articular processes. The design of the endoprosthesis includes threaded holes for fixing a complete removable denture, which can be closed with plugs. The endoprosthesis has holes (for the mandibular nerve in case of its protection during surgery).

The disadvantages of this design include, first of all, poor integration of the implant with soft tissues and, as a consequence, the formation of a connective tissue layer. Another disadvantage is the relatively large weight of the structure, this problem is especially relevant in cases where endoprosthetics was performed with a long break and a postoperative scar has formed in the area of the postoperative defect, which can subsequently lead to the cutting of the structure through soft tissues. The same problems can be caused by fixing a removable prosthesis to threaded connections in the body of the implant.

The invention is based on the task of creating an implant-endoprosthesis for replacing a volumetric bone defect of the lower jaw, which ensures soft tissue integration with adjacent tissues, the glenoid fossa of the skull, and interaction with surrounding tissues.

The stated problem is solved by the fact that an implant-endoprosthesis is proposed for replacing a total and subtotal defect of the lower jaw consisting of three elements: the body of the jaw -1, two symmetrical fragments containing symmetrical halves of the angle of the jaw, a branch of the jaw with a condylar process and a coronoid process -2. All elements are made of PEEK material (Fig. 1).

Polyetheretherketone Peek (polyetheretherketone), is a semi-crystalline polyaromatic thermoplastic polymer, has many excellent properties such as high heat resistance, high mechanical properties and chemical stability, with self-expressed resistance to most chemicals and solvents, resistance to radiation. [5].

For patients with lost volume and thickness of the jawbone, the ability to compensate for this defect is especially important. Flexible PEEK adapts perfectly to the chewing load and stimulates the formation and growth of mineralized tissue, rather than inhibiting it, like rigid titanium alloys. Composite polymer in the oral cavity is not an obstacle to chemotherapy and radiation therapy. Implants made of it are thin and lightweight, so they allow minimizing the invasiveness of surgical intervention. Composite implants are not subject to corrosion processes. Therefore, they can be trimmed to adapt to a specific patient - corrosion will not appear on the cut.

An Apium M220 extrusion printer (Germany) was used for printing. To improve the biocompatibility and antibacterial properties of the endoprosthesis, nanodispersed cerium dioxide with a particle size of 2-5 nm was added to the extruder at a rate of 1 μg per 10 g of the finished product. Cerium oxide nanoparticles, due to their ability to interact with active forms of oxygen, can act as exogenous antioxidants and perform the functions of natural enzymes in the body, thereby preventing ROS-induced cell damage [6]. PEEK VESTAKEEP i4 3DF filament thread (Evonik, Germany) was used for printing.

The middle part consists of the jaw body (1), perforated with four holes for titanium wire for fixation with the lateral segments (3), grooves for fixation with the left and right segments of the jaw (4), two holes for fixation of soft tissues to the mental muscle (5), two perforation areas for fixation of a porous structure similar to the trabecular shape of the jaw (6) (Fig. 2).

The left and right segments are symmetrical and contain: the body of the symmetrical halves of the jaw angle (2), containing four through holes for fixation with the middle part (3) and the reverse parts of the grooves for fixation with the middle part (4), as well as the jaw angle, passing into the condylar process, which has a shape corresponding to the glenoid fossa (7). In the endoprosthesis of the jaw body there are several perforation holes for tight fixation of the porous structure and soft tissues to the endoprosthesis (6) (Fig. 3).

The holes (3) for the titanium wire on the body and on the segments are made in exact correspondence with the mating parts of these segments. The same exact correspondence, calculated using the computer software of the Apium M220 printer (Germany), have grooves (4) on the middle part and on the corner segments for their exact connection. In addition, the holes on the middle part for fixing the soft tissues to the mental muscle are made strictly indented from the central line to the sides by 5 mm and also from the lower edge of the prosthesis by 5 mm.

A porous structure for integration and ingrowth of soft tissues, similar to the structure of bone trabecula (Fig. 2, 3 (6)), is presented by a multi-cassette matrix complex for replenishment of bone tissue volume in the maxillofacial region in the form of a plastic composition including a mixture of granulated xenogenic or synthetic filler with a fibrin clot L-PRF with particle sizes of 0.25-1.00 mm and a suspension of patient's PRP plasma with nanodispersed cerium dioxide in physiological solution at a concentration of 10-5 M at a ratio of 2:1, wherein the ratio of the components of the composition filler (g): L-PRF (g): PRP with nanodispersed cerium dioxide (ml) is 1:4:2. [7], which was introduced into the pores in the endoprosthesis mechanically using a spatula immediately before using the endoprosthesis. This multi-cassette matrix complex has a porous structure for optimal adhesion to soft tissues.

The implant-endoprosthesis is used as follows. In patients with a defect of the lower jaw and disarticulation of the temporomandibular joint, spiral computed tomography of the facial skeleton with volumetric reconstruction of the image is performed. Using a computer model of the patient's lower jaw, a design of an individual endoprosthesis is simulated that restores the original shape and size of the lost fragment of the lower jaw. A virtual placement of the lower jaw endoprosthesis is carried out, in accordance with the position of the heads and glenoid fossae, in the correct anatomical position. Based on the resulting computer model, 3 parts of the individual endoprosthesis are made from PEEK VESTAKEEP i4 3DF material (Evonik, Germany) using the 3D printing method in an Apium M220 printer (Germany). The first stage of the operation is performed on the patient. Under intubation anesthesia, the endoprosthesis containing the median element of the mental section is made a semi-oval incision of the soft tissues and adjusted to the soft tissues. The endoprosthesis is sutured to the chin muscles through the holes in the mental section. The wound is sutured layer by layer with catgut and silk, and drains are installed.

Two months after integration with the soft tissues of the middle part of the implant, two symmetrical incisions are made in the projection of the angles of the lower jaw on the left and right, the soft tissues are dissected, the bed for the implants is separated, the left and right parts of the composite implant-endoprosthesis are installed in the correct anatomical position, fixed to the grooves with wire sutures made of titanium wire with a diameter of 1.5 mm. The wound is sutured layer by layer and drained.

List of figures.

Fig. 1. Scheme of a composite implant-endoprosthesis.

Fig. 2. Diagram of the middle part of the composite implant-endoprosthesis.

Fig. 3. Diagram of the lateral (left) part of the composite implant-endoprosthesis.

Clinical example

Patient R., 36, applied to the Makeyevka City Clinical and Surgical Department, Donetsk region, complaining of facial deformation, difficulty chewing and swallowing. According to the patient, he has been ill for 10 years, when after taking necrotic drugs (desomorphine for 12 years), the teeth on the lower jaw began to loosen and fall out, the tooth sockets did not heal for a long time. Diagnosis: chronic toxic osteomyelitis of the lower jaw. He has undergone multiple surgeries at the Makeyevka City Clinical and Surgical Department (6 times). The last time in November 2020, a necrectomy operation was performed under general anesthesia, removing necrotic areas of the body and branch of the jaw and the articular process on the right. Hospitalized for the next stage of surgical treatment. At the time of examination: the face is asymmetrical due to postoperative deformation of the lower jaw. There is a bone tissue defect on the left: absence of the body of the branch and articular process on the left and right. In the submandibular region on the left and right there are postoperative scars, pale pink, soft elastic consistency. Mouth opening is limited to 2.5 cm, the lower jaw is shifted to the right. Upon examination of the oral cavity, teeth on the lower jaw are missing. The patient underwent spiral computed tomography of the facial skeleton with volumetric reconstruction of the image. Using a computer model of the patient's lower jaw, we simulated the design of an individual lower jaw endoprosthesis that restores the original shape and size of the lost fragment of the lower jaw. We carried out a virtual placement of the lower jaw endoprosthesis in accordance with the position of the heads and glenoid fossae in the correct anatomical position. Based on the resulting computer model, 3 parts of the individual endoprosthesis were made of PEEK VESTAKEEP i4 3DF material (Evonik, Germany) using the 3D printing method in an Apium M220 printer (Germany). Immediately before the operation, the perforation holes of the endoprosthesis to the right and left of the harmful line were filled with a multi-cassette matrix complex with a porous structure based on granulated xenogenic or synthetic filler with nanodispersed cerium dioxide. The first stage of the operation was performed - under intubation anesthesia, an endoprosthesis containing a median element of the mental section was inserted. For this, a semi-oval incision of the skin and subcutaneous fat was made. Soft tissues and stumps of the submental muscles were isolated. Through the holes in the mental section, the endoprosthesis was sutured to the submental muscles. The wound was sutured layer by layer with catgut and silk. Tape drains were installed. Two months after the integration of the endoprosthesis with the soft tissues of the middle part of the implant, two symmetrical incisions were made in the projection of the body and bordering the angles of the lower jaw on the left and right, the soft tissues were dissected, the bed for the implant was separated on the left and right. After that, the left and right parts of the complex implant-endoprosthesis were installed in the correct anatomical position, which were fixed to the grooves in the middle part with wire sutures. The perforation holes of these parts of the prosthesis were also filled before the operation with a multi-cassette matrix complex with a porous structure based on granulated xenogenic or synthetic filler with nanodispersed cerium dioxide. The wound was sutured layer by layer with drains. The patient's sutures were removed on the 12th day. A control examination was performed after 6 months. At the time of the examination, the patient has no complaints from the dentoalveolar system. The facial configuration is correct. The function of the lower jaw is not impaired, the movements of the articular heads are free and instantaneous. There is no pathological bone mobility.

List of references.

1. Patent. 2493797 Russian Federation, IPC A61C 8/00, A61B 17/58, A61F 2/28. Implant-endoprosthesis for replacing a volumetric bone defect of the lower jaw / Rapekta S.I., Astashina N.B., Rogozhnikov G.I., Antsiferov V.N. - No. 2012120544/14; declared 17.05.2012; published 27.09.2013, bulletin No. 27.

2. Patent 2265417 Russian Federation, IPC A61F 2/28. Implant for replacing extended bone fragments of complex shape / Dyuryagin N.M., Gunter V.E., Sysolyatin P.G., Dyuryagina E.N., Nivikov V.A., Proskurin A.V. - No. 2004101307/14; declared 15.01.2004; published 20.06.2005.

3. Patent. 2491899 Russian Federation, IPC A61C 8/00, A61B 17/58, A61F 2/28. Implant-endoprosthesis for replacing a volumetric bone defect of the lower jaw / Sirak S.V., Sletov A.A. - No. 2012118101/14; declared 04.05.2012; published 10.09.2013, bulletin No. 25.

4. Pat. WO 2013/034180 A1, WHO, IPC A61F 2/28 2006.1, A61F 2/30 2006.1, Mandibular implant / Xilloc Medical B.V. Beerens, Maikel Michael Adrianus, Poukens, Jules Maria Nikolaas. - PCT/EP 2011/065462; International Filing Date 09/07/2011; Publication Date 03/14/2013.

5. Patel P., Hull T.R., McCabe R.W., Flath D., Grasmeder J., Percy M. Mechanism of thermal decomposition of poly (ether ether ketone) (PEEK) from a review of decomposition studies. Polym Degrad Stab 2010;95(5):709-718.

6. Nanomaterials based on cerium dioxide: properties and prospects for use in biology and medicine / A.B. Shcherbakov, N.M. Zholobak, V.K. Ivanov et al. // Biotechnology. 2011. - V.4. - No.1. - P. 9-28.

7. Russian Federation Patent for Invention No. 2793324 Nanodispersed plastic bioengineered composition based on cerium dioxide for replenishing bone tissue volume / Yanushevich O.O., Bazikyan E.A., Chunikhin A.A., Volozhin G.A., Prokopov A.A., Ivanov V.K., Abrahamyan K.D. / applicant and patent holder FSBEI HE MGMSU named after A.I. Evdokimov of the Ministry of Health of the Russian Federation - application No. 2021136649 dated 12/13/2021, published 03/31/2023 Bulletin "Inventions. Utility Models" - 2023. - No. 10. - 10 p.

Claims (2)

1. A composite endoprosthesis for replacing a total and subtotal defect of the lower jaw, made of PEEK material using the 3D printing method using an individual computer model, designed with the ability to restore the original shape and size of the lost fragment of the lower jaw, and consisting of three elements: the middle part, which consists of the body of the jaw, perforated with four holes for titanium wire for fixation with the left and right segments of the jaw, two grooves for connection with the lateral parts, two holes for fixation of soft tissues to the mental muscle, two perforated areas for fixation of a porous structure similar to the trabecular structure of the jaw, and two symmetrical lateral fragments containing four holes and reverse parts of the grooves for fixation with the middle part, as well as the angle of the jaw turning into the condylar process, which has a shape corresponding to the glenoid fossa, and perforation holes for fixation of a porous structure similar to the trabecular structure of the jaw. 2. An endoprosthesis according to item 1, characterized in that the two perforated sections of the middle part and one section on each side part are filled with a porous structure similar to the trabecular structure of the jaw, made from a multi-cassette matrix complex based on a granulated xenogenic or synthetic filler with nanodispersed cerium dioxide.