WO2022103306A1 - Device for reconstructing a temporomandibular joint - Google Patents

Abstract

The group of inventions relates to medicine, and more particularly to devices for reconstructing a temporomandibular joint. The present device consists of a mandibular component constructed by the layer-by-layer fusion of a fine metal powder of a titanium alloy in accordance with anthropomorphic data. Said mandibular component represents a portion of the vertical mandibular ramus with a condyle and is configured in the form of a three-dimensional frame that corresponds to the shape of the healthy mandible of the patient and comprises a region for fastening to the unresected part of the mandible, a bed for receiving a bone graft, and a stem with a joint head, which substitutes for the mandibular ramus and is in the form of a bar in the shape of a solid of revolution, expanding toward the base and narrowing closer to the joint head, the latter being in the shape of an ellipsoid.

Description

Temporomandibular Joint Reconstruction Device

The invention relates to medicine and can be used in oncology, maxillofacial, reconstructive plastic surgery when performing resection of the lower jaw with exarticulation of the temporomandibular joint.

One of the important points that largely determine the long-term functional and aesthetic result of the operation is the correct geometric modeling and reliable fixation of the condyle of the reconstructed lower jaw in the articular cavity, as close as possible to the original anatomical position. At the same time, the joint itself acts as a sliding hinge and can move up to 2000 times a day, which means that wear resistance is also an important factor in design. Currently, modern computer programs for 3D planning allow to calculate the required length of the condyle, the position and geometry of the articular cavity with an accuracy of up to a millimeter. However, the issue of fixation of the condyle in the articular cavity remains open to date. The ideal fixation system should be lightweight with minimal metal content (to avoid outward cutting through soft tissues), but still provide a secure and simple fixation of the condyle in the glenoid cavity, without limiting the range of motion.

Total or partial joint replacement has been used since the 1960s of the last century. Materials for the TMJ implant ranged from stainless steel, cobalt-chromium alloys, fiberglass to Teflon coatings. All of these total joint replacements involve condyles and fossae, but fixation designs and methods vary. Most of these constructs have disappeared or ceased to be used due to problems such as bone resorption; proliferation of spongy bone around the implant; low placement success rates; poor wear characteristics.

Implant loosening due to improper screw placement and excessive loads can lead to micro-movement. The ideal method of implant fixation has not yet been developed. One of the significant problems is the reliable fixation of the condyle of the lower jaw in the articular cavity in order to avoid its displacement downwards and to the sides.

There is US Patent Publication US5549680 A [15] D1 which contains an artificial condyle component for attachment to the mandible and an artificial mandibular fossa component for attachment to the temporal bone. The artificial condyle component includes a condylar head having an articular surface, and the articular surface has a spherical surface of the first spherical radius. The temporomandibular joint component has a spherical articular surface of a second spherical radius greater than said first spherical radius.

The proposed model included a 3D computer simulation including the mandible, glenoid fossa, cartilage and articular discs.

The disadvantages of the model are that the head of the condyle can be unexpectedly displaced during surgery, damaging the tympanic plate of the middle ear and causing deafness.

In addition, it is quite difficult to locate the head of the condyle in the fossa component during surgery using a prior art TMJ prosthesis.

There is a prosthesis WO2017075664A1 04.11.2016 to replace the temporomandibular joint, containing: a condylar component for attachment to the lower jaw, a component that includes the head of the condyle having a convex spherical articular surface; a fossa component for attachment to the temporal bone, wherein the fossa component has a concave spherical articular surface defining an alveolar socket that can articulate with the condylar head, with the concave spherical articular surface extending approximately 180°. The fossa component may also be anteroposteriorly symmetrical.

Prosthesis WO2017195022A1 05/11/2017(1) for the lower jaw of the temporomandibular joint, containing the head part (2) for replacing the head of the condyle, in particular, in the anatomical place, and an attachment plate, while the attachment plate has a saddle shape with a lateral part (3) and medial part (4) which have been shaped and designed to fit both sides of the ascending ramus, just below the arcuate notch at the upper end of the ascending ramus.

The objective of the invention is to create a prosthesis of the temporomandibular joint, which would provide reliable fixation of the condyle in the joint while maintaining the full range of motion.

Modern designs continue to face a number of challenges, including: pathological reactions from wear residue; destruction of metal from fatigue and loosening of the screw; and the difficulty of placing implants on the skull (Quinn, 2000). It was also noted that the service life of the implant is insufficient, given the young age. many patients. This means that improved wear rates and more comprehensive fatigue testing are required (van Loon et al, 1995; van Loon et al, 1999).

The natural temporomandibular joint allows both rotation and horizontal movement of the mandibular condyle. Translation is controlled by the lateral pterygoid muscles attached to the mandibular condyle. The function of these muscles is lost when the mandibular condyle to which they are attached is replaced with part of a mandibular prosthesis. Therefore, the most important value of the prosthesis of the temporomandibular joint is the repetition and preservation of the functional characteristics of the joint, rotational movements. It is also necessary to exclude the risk of dislocation.

Invention W02016014006A1, July 22, 2015, includes a fossa implant (1), a condylar apparatus and an insert placed between the fossa implant and the condylar device. The Fossa implant includes locking sets for maximum insert movement. The condylar apparatus includes the head of the condyle. Insert; different seating condylar head, retaining ring, and seat retaining ring. When applying the present invention to a patient suffering from incurable temporomandibular joint defects, the deformed parts are first removed by surgery. The fossa implant, which can be applied to each patient, is fixed on the zygomatic bone. Then an individual temporary condylar apparatus is fixed on the lower jaw. The appropriate insert for the patient is selected by measuring the distance between the fossa implant and the head of the condyle with a measuring device. After the measurement is completed, the apparatus of the temporary condyle is removed from the lower jaw. The permanent condylar apparatus is inserted into the mandibular bone. The ring is put on the head of the condyle. Then the condylar body of the special insert is installed on the condylar head of the condylar apparatus. The ring is installed in the ring socket using a bracket.

The disadvantage of the invention is the multi-stage process of combining all the elements into one single working design, which increases the time of surgical intervention and therefore affects the clinical result of implantation.

There is an invention US5405393A A prosthesis of the temporomandibular joint, containing a part of the prosthesis of the skull, containing a supporting surface adapted for installation on bone tissue in the area and / or near the natural glenoid fossa and / or articular eminence, and a part of the prosthesis of the lower jaw with the possibility of rotation relative to the part cranial prosthesis in an implanted state. The prosthesis provides a natural combination of rotation and translation of the condyle of the mandible, despite the loss of function of the lateral pterygoid muscles.

Known endoprosthesis from the condyle of the lower jaw (patent SU No. 1805933, M.cl. A 61 F 2/02), containing a head and a plate with mounting holes made of porous titanium nickelide, an annular groove in which a wire ring of cast titanium nickelide is placed, while the surface and articular part of the head of the endoprosthesis is covered with a layer of composite material (plastic).

Disadvantages - the complexity of manufacturing and its individual fit.

Adaptation of the proposed jaw prosthesis is very difficult due to the individual variability of the structures of the pits. This situation forces the doctor to work longer and also causes some difficulties in adapting the jaw prosthesis.

The prosthesis should have a design that can enable surgeons to adapt the prosthesis to the jaw in the shortest possible time and with comfort during surgery.

The technical result of the proposed invention is to achieve the maximum functional result by providing movement as close as possible to the normal physiological movement of the lower jaw. The individual approach to the manufacture of the device allows patients to use the prosthesis with full functionality for longer.

The device is the condyle of the mandible together with the temporomandibular joint.

A distinctive feature of the device is that the device consists of two parts - the jaw component and the articular capsule.

The jaw component is a section of the vertical branch of the lower jaw with a condyle. The component is made in the form of a spatial frame, if possible, repeating the geometry of the patient's healthy jaw. The frame has three characteristic areas - the area of attachment to the unresected part of the lower jaw bone, the bed for placing the bone graft and the stem with the articular head.

The difference is that the bed is a volumetric spatial L-shaped power frame, having a J-shaped profile in cross section, made in the form of power points connected by beams, through the holes in which, with the help of fasteners (screws, screws), the graft is fastened to frame.

The attachment site is similar in design to the bed, but has a U-shaped profile in cross section and tightly wraps around the lower part of the lower jaw under molars 36, 37. The frame is fastened to the lower jaw by fasteners (screws, screws) through the holes in the frame.

Another difference is that the stem replaces the branch of the lower jaw, and is a beam in the form of a body of rotation, expanding towards the base and narrowing closer to the articular head. The leg ends with a polished articular head in the shape of an ellipsoid.

The device is made taking into account the anthropometric data obtained on the basis of the preoperative examination (CT) and accurately repeats the anatomical features and geometry of the lower jaw. The design and modeling of the jaw component, the selection of the graft, the installation technology is carried out in a computer environment according to the models obtained from the patient's CT scan.

The device is individual with sufficient accuracy repeats the anatomical contours of both the lost bone, to achieve an aesthetic effect, and the contours of the bones with which the frame is fastened (attachment area) and the geometry of the grafts, achieving the maximum fit of the frame to them.

Frame manufacturing technology - three-dimensional printing from metal powder of titanium alloy Ti64ELI GOST R ISO 5832-3.

The articular capsule is a cylindrical body with one end of which there is a hole with an internal cavity, into which the articular head of the jaw component is placed, and the edge is smoothed. The shape of the hole and the cavity are such that after inserting the articular head into it, its free movement within the anatomical limits of the jaw stroke is ensured, but at the same time preventing its dislocation. From the other end of the cylinder, a supporting surface is made in the form of a "wing" resting on the articular cavity and temporal bone. Through the hole in the “wing”, the capsule is attached to the skull with the help of fasteners (screws, screws).

The supporting surface is made on the basis of the anatomical model obtained from the patient's CT scan and completely repeats the contours of the bone in the interface area, which makes it possible to achieve a sufficiently tight fixation of the component.

The manufacturing technology of the joint capsule is milling from ultra-high molecular weight polyethylene UHMWPE.

To implement the method, a device for replacing the temporomandibular joint is proposed, including a device consisting of two parts: a jaw component made using the technology of layer-by-layer fusion of a finely dispersed metal powder according to anthropometric data, consisting of an attachment site to the unresected part of the lower jaw bone, a bed for placement of a bone graft and a stem with an articular head, as well as an articular capsule made using milling technology from ultra-high molecular weight polyethylene, containing a cylindrical body with a hole and an internal cavity at one end, in which the articular head of the jaw component is located, from the other end of the cylinder, a supporting surface is made in the form of a "wing" resting on the articular cavity and the temporal bone. “The wing contains holes through which the capsule is attached to the skull with the help of fasteners - screws, screws.

The essence of the claimed method and the device for its implementation are shown in Figs. 5 shows the location of the fasteners from the inner and outer sides, Fig.6 General view of the installed prosthesis of the temporomandibular joint with the installed condyle, Fig. 7-9 shows a fragment of a surgical intervention, which shows the capsule of the temporomandibular joint, in which a titanium condyle of the prosthesis of the lower jaw branch is installed; artery, transplant vein.

The main essential distinguishing feature of the device is an articular capsule with a cylindrical body, one end of which has a hole with an internal cavity, into which the articular head of the jaw component is placed, and the edge is smoothed. The shape of the hole and the cavity are such that after inserting the articular head into it, its free movement inside is ensured within the anatomical limits of the jaw stroke.

The difference is that the structure is designed individually for a particular patient, the screws are guided in the direction of the most pronounced bone mass specified during design, the length of the screws is planned depending on the bone thickness.

The technical result is achieved due to the fact that in the preoperative period the patient undergoes computed tomography of the lower jaw, additional software processing of the obtained scans is performed, the shape and size of the bone defect of the lower jaw is determined (Fig. 1-2). On the edge of the bone defect, a lightweight device (figure 2) of the jaw component is designed according to anthropometric data, covering the defect and absolutely repeating the anatomy along the edge of the defect, the leg of the jaw component with the articular head is designed (figure 1, 3), and the length of the fixing screws is determined when commits device to bone tissue (figure 5). The articular head of the jaw component must fit into the articular capsule (FIGS. 3-5), which is also designed from CT-derived models.

Holes, fasteners and their proposed size depending on their location are shown in Fig.5.

As a result of individual design, the screws are inserted safely and as accurately as possible into the most pronounced bone mass during fixation of the device. Also at the design stage, their length is planned.

Thus, the operation time and traumatism are reduced, providing a movement that is as close as possible to the normal physiological movement of the lower jaw, eliminating the risk of dislocations.

As an example, we present a clinical case of using the device.

Patient A., Diagnosis "Ameloblastoma of the lower jaw on the right with damage to the body and branch of the lower jaw on the right." A patient with such a prevalence is shown to perform surgery in the amount of "Segmental resection of the lower jaw with exarticulation in the temporomandibular joint, defect plasty with a revascularized peroneal autograft on microvascular anastomoses." At the first stage, 3D computer modeling of the lower jaw was performed, localization, character, etc. were determined. the length of the defect n/jaw (Fig. 1-2). Using special software, the resulting defect was reconstructed with a peroneal graft, taking into account the anatomical features and geometry of the resected fragment of the lower jaw (Fig. 3), an individual mesh plate was modeled for fixing the graft (Fig. 1-2).

According to a prefabricated template, a resection of the lower jaw was performed. The use of a pre-modeled template allows for maximum contact between the resected areas of the lower jaw and the fibular graft at the reconstruction stage.

Then, according to a prefabricated template, a peroneal graft was modeled, the latter was fixed with 4 x 8 mm fasteners (screws, screws) to the manufactured plate, which was fixed to the edges of the sawdust of the lower jaw. Next, an incision was made in the preauricular region. The navicular fossa was skeletonized, the remnants of the capsule of the temporomandibular joint were resected. Using 4 screws to the zygomatic bone, a capsule of the temporomandibular joint, in which the titanium condyle of the prosthesis of the lower jaw branch is installed (Fig. 7, 8, 9). Under optical magnification, microanastomoses were placed between the facial artery, vein and peroneal artery, the transplant vein. (Fig. 10)

Claims

CLAIM L Device for the reconstruction of the temporomandibular joint, consisting of a jaw component made using the technology of layer-by-layer fusion of a fine metal powder of a titanium alloy according to anthropometric data, which is a section of the vertical branch of the lower jaw with a condyle, made in the form of a spatial frame that repeats the geometry of the patient's healthy jaw, including an attachment site to the unresected part of the lower jaw bone, a bed for placing a bone graft and a stem with an articular head replacing the lower jaw branch in the form of a beam in the form of a body of rotation, expanding towards the base and tapering closer to the articular head, which has the shape of an ellipsoid. 2. A device for the reconstruction of the temporomandibular joint, consisting of an articular capsule in the form of a cylindrical body, made using milling technology from ultra-high molecular weight polyethylene, containing a hole at one end of the cylindrical body and an internal cavity in which the articular head of the jaw component is located, the shape of the hole and the cavity provides placement and free movement of the lower jaw within the anatomical limits, containing from the other end of the cylindrical body a support surface in the form of a "wing" resting on the articular cavity and temporal bone and containing holes through which the articular capsule is attached to the skull with the help of fasteners, length and the location of which is pre-planned depending on the thickness of the bone. nine