RU236848U1 - PERSONALISED CONTOURED ANGLE IMPLANT - Google Patents

Abstract

The utility model relates to the field of maxillofacial surgery, reconstructive medicine and aesthetic surgery, in particular to individualized implants for correcting the shape and contours of the angles of the lower jaw, and can be used for aesthetic or functional reconstructions in the lower third of the face, aimed at replacing existing defects and harmonizing the overall facial profile of the patient. The technical result achieved when using the utility model consists in increasing the effectiveness of prosthetics of the angle of the lower jaw, expressed in increasing stability. The technical result is provided by a contour implant of the angle of the lower jaw, comprising a housing including an inner surface and an outer surface, wherein the inner surface of the housing repeats the outer and lower surfaces of the bone of the angle of the lower jaw of the patient, and the outer surface forms the required outer contour of the angle of the lower jaw, characterized in that the housing, made individually in accordance with the CT data of the patient, additionally contains a positioning process made with the possibility of supporting on the bone in the region of the oblique line of the lower jaw, and the outer surface contains a recess made with the possibility of placing the tip of a surgical instrument in it and exerting a pressing effect on the implant, wherein the implant housing contains at least one opening made with the possibility of placing a pressing screw in it, the axis of which is made perpendicular to the inner surface of the implant housing. 2 c.p. phyl., 2 fig., 1 table.

Description

The utility model relates to the field of maxillofacial surgery, reconstructive medicine and aesthetic surgery, in particular to individualized implants for correcting the shape and contours of the angles of the lower jaw, and can be used for aesthetic or functional reconstructions in the lower third of the face, aimed at replacing existing defects and harmonizing the overall facial profile of the patient (A61F 2/02, A61F 2/28, A61F 2/76).

State of the art

In modern maxillofacial, reconstructive and aesthetic surgery, implants of the angles of the lower jaw (mandibular angles) are quite widely used, for example, in cases of their congenital hypoplasia (underdevelopment), asymmetry, post-traumatic deformities, as well as for aesthetic correction of the shape or volume of the lower third of the face.

However, due to the limited view of the surgical field, the lack of precise external landmarks and the complex anatomy of the mandibular angle zone, there is a possibility of incorrect implant placement. Implant positioning in the vertical and frontal planes, as well as rotational displacements, can significantly affect the symmetry, aesthetics and stability of the result. At the same time, the vast majority of implants used are designed for fixation by gradual ingrowth of the patient's bone tissue into the porous structure of the implant, made of a biocompatible material.

The prior art includes mandibular angle implants fixed with screws, for example, http://www.centrplastiki.ru/o_chelustno-licevaya_s09.h™l?ysclid=mclorggjh0366977913. However, during their installation, displacements along the vertical and in the frontal plane are possible, the absence of fixed external support elements increases the risk of incorrect orientation or rotation of the implant, the accuracy of positioning often depends on the subjective landmarks of the surgeon, and deviation when screwing in the screws can lead to "protrusion" of the implant (in this case, we use the term "protrusion" to denote a clearly localized, palpable and often visible protrusion in the area of the installed implant, in contrast to the "norm", in which the implant should be indistinguishable from the natural bone during palpation and visually, and the contour of the jaw should be smooth and natural, without local protrusions).

Also known from the prior art are craniofacial implants (US 9895211 B2, published 20-02-2018), on the inner surface of which mounting flanges are located, which are in contact with the bone landmark of the lower jaw, preventing displacement of the implant relative to the lower jaw in at least one direction, wherein each flange protrudes practically perpendicularly from the inner surface of the corresponding part of the body.

The disadvantage of this solution is insufficient fixation of the implant in the frontal plane and low resistance to rotational loads, as well as the dependence of the correct positioning of the implant during installation on the skill of the surgeon.

The same disadvantages are also found in the known implant system for augmentation of the lower jaw (US 2023285152 A1, published 09/14/2023), in which the implant body additionally contains one or more protrusions protruding from the inner surface of the body and intended for additional fixation of the implant from displacement.

The closest technical solution (prototype) to the claimed utility model can be considered OMNIPORE® implants for mandibular plastic surgery (Design Y™ Mandible Onlay, https://pdf.medicalexpo.com/pdf/matrix-surgical-usa/omnipore-surgical-implant/107545-259497-_5.html), made of porous high-density polyethylene and having orientation "tongues" to improve the accuracy of installation. Implant stabilization is carried out with suture material, Kirschner wires or screws for rigid fixation, and when tightening the screw, the implant is pressed against the bone, and the screw is screwed in until its head is flush with the surface of the implant.

The disadvantages of the prototype include serial production in three sizes that do not take into account the individual characteristics of the patient, requiring adjustment and trimming of the implant in place after installation, as well as the possibility of “bulging” (partial distortion) of the implant body when tightening the fixing screws.

Disclosure of the essence of the utility model

The objective of this utility model is to eliminate the shortcomings of analogues and the prototype, namely, to create a personalized contour implant for correcting the mandibular angle, which has high positioning accuracy and is reliably fixed from axial displacement and rotation, and also eliminates “bulging” during installation.

The technical result achieved when using the utility model consists in increasing the efficiency of prosthetics of the angle of the lower jaw, expressed in increasing the stability of the implant used. The consequence of the stability of fixation is an increase in the reliability and durability of the implant.

This technical result is provided by a contour implant of the angle of the lower jaw, comprising a housing including an inner surface and an outer surface, wherein the inner surface of the housing repeats the outer and lower surface of the bone of the angle of the lower jaw of the patient, and the outer surface of the implant forms the required outer contour of the angle of the lower jaw, characterized in that the housing, made individually in accordance with the CT data of the patient, additionally contains a positioning process made with the possibility of supporting on the bone in the region of the oblique line of the lower jaw, and the outer surface of the implant contains a recess made with the possibility of placing the tip of a surgical instrument in it and exerting a pressing effect on the implant, wherein the implant housing contains at least one opening made with the possibility of placing a pressing screw in it, the axis of which is made perpendicular to the inner surface of the implant housing.

In particular, the positioning appendage contains at least one opening designed to accommodate a fixing screw.

In particular, the notch is made in a boat-shaped form.

Brief description of the drawings

Fig. 1. - Digital model of the patient's skull with personalized contour implants installed on both sides of the lower jaw angles (frontal projection).

Fig. 2. - Digital model of the patient's skull with an installed personalized contour implant of the angle of the lower jaw (lateral projection).

The figures show: 1 - implant body; 2 - positioning process (paw); 3 - hole for fixing screw; 4 - hole for pressure screw; 5 - recess for instrument.

The claimed personalized contour implant of the angle of the lower jaw contains a housing 1 made by 3D printing from a biocompatible thermoplastic material, preferably polyetheretherketone (PEEK), corresponding to medical standards (for example, ISO 10993). In this case, the inner (facing the bone of the lower jaw) surface of the housing 1 is made in precise anatomical correspondence with the outer and lower surface of the bone of the patient's lower jaw according to CT/MSCT data, and the outer (facing the skin) surface of the housing 1 is made in accordance with a digital 3D model adapted to the specific anatomy of the patient, including areas of the body, angles and branches of the jaw, as well as landmarks necessary for precise placement of the implant.

The inner side of the body 1 contains a positioning process 2 (paw), oriented inward from the external oblique line, which ensures the correct orientation of the implant in the frontal and vertical planes and the stability of its fixation. Optionally, the paw may contain openings 3 for fixing screws, for example, titanium ones, made with the possibility of fixing the paw 2 to the bone tissue of the lower jaw in the area of the oblique line.

The body 1 contains at least one hole 4 for a clamping screw, for example, a titanium one, and the axis of the hole 4 is made strictly perpendicular to the mating surface, which prevents the structure from protruding when clamped, increasing the stability of the fixation.

In order to facilitate the positioning of the clamping screw in the opening 4 and to eliminate the risk of displacement of the implant during fixation, i.e. to ensure the stability of the implant during fixation, the outer side of the housing 1 also contains a recess 5, preferably of a boat-shaped shape, intended for inserting the tip of a surgical instrument, such as tweezers or a spatula, to exert a pressing effect on the housing 1 of the implant during screwing the clamping screw(s) into the opening 4.

Implementation of a utility model

The declared personalized contour implant of the angle of the lower jaw is implemented as follows:

A multispiral computed tomography (MSCT) scan of the patient is performed, covering the lower jaw and surrounding anatomical structures.

Then, based on the MSCT data, a digital 3D model of the patient’s lower jaw is created, which includes areas of the body, angles and branches of the jaw, as well as landmarks necessary for precise placement of the implant.

Using CAD systems, virtual modeling of the implant shape is performed, adapted to the specific anatomy of the patient. The design includes:

- body 1, repeating the bend of the outer and lower surfaces of the angle of the lower jaw,

- positioning process 2, oriented inwards from the external oblique line, which ensures the correct orientation of the implant in the frontal and vertical planes and the stability of its fixation,

- technological elements: a perpendicular hole 4 for a screw and a recess 5 for a tool on the outer surface of the implant for pressing during installation (optionally also holes 3 for fixing screws), which ensures stability during fixation (and screws in a particular case ensure stability after installation);

The implant is made using 3D printing from a biocompatible thermoplastic material - preferably polyetheretherketone (PEEK) - that meets medical standards (e.g. ISO 10993).

A physical 3D model of the patient's jaw is made using the same CT data used for fitting. The accuracy of fit, geometry of the positioning process, volumetric ratios and compliance with anatomical landmarks are checked.

The implant is installed through intraoral access, which minimizes trauma and eliminates external incisions. Positioning process 2 ensures automatic installation of the implant in the desired position along the oblique line and stability of the position during fixation. Optionally, the implant is fixed with screws through holes 3, which provides additional stability after installation.

A pressing effect is exerted on the body 1 of the implant in the direction of the bone structure of the lower jaw with the tip of the surgical instrument placed in the recess 5, and the body 1 is fixed to the bone of the lower jaw with at least one screw through the hole 4, while the direction of the screws is strictly perpendicular to the contact surface, which prevents the structure from protruding.

Postoperative monitoring and recovery

The position of the implant is controlled relative to anatomical landmarks. Dynamic monitoring of the structure's engraftment and soft tissue restoration is carried out. Full restoration of the functional and aesthetic result is usually achieved within 2-3 weeks.

Example of implementation

Patient G. (57 full years old). Indications for implantation - age-related resorption of the lower jaw bones, reduction of the severity of the angles and lines of the lower jaw, restoration of the aesthetic appeal of the lower third of the face.

Symmetrical (right and left) implants were installed through incisions in the oral cavity and each was fixed with one screw to the oblique line of the jaw and two screws into the bone tissue of the lower jaw. As a result, the overall aesthetic perception of the lower third of the face improved, an improvement in the appearance of the neck was observed, a significant reduction in ptosis (jowls), while neither a facelift nor platysmoplasty was performed.

By taking into account CT data, increased accuracy of modeling of the chin area is achieved, taking into account the individual characteristics of the patient, in particular:

The exact position of the mental foramen and the course of the mandibular canal are determined with an accuracy of fractions of a millimeter. This is absolutely necessary for the safe positioning of the implant and to avoid the risk of nerve damage, which can lead to permanent numbness of the lip and chin.

In addition, CT accurately measures the thickness and height of the bone in the area of the proposed implant placement, reveals bone tissue deficiency (atrophy), cysts, sclerotic areas that may affect the stability of the implant and require preliminary bone grafting.

Also, the use of CT (MSCT) allows us to see the tuberosities, depressions, and irregularities of the bone surface, which must be accurately repeated in the implant design for an ideal fit, since the ideal correspondence of the implant shape to the recipient bed ensures the maximum area of “implant-bone” contact and optimal mechanical stability from the moment of installation.

When using the claimed implant with a positioning process, there is a significant simplification and acceleration of the stages of surgical planning and the operation itself. In particular, due to the anatomically oriented process, resting on the external oblique line, the implant occupies an unambiguous position in three-dimensional space without the need for multiple fitting or manual adjustment of the position in the surgical field.

A comparative clinical study of two groups of patients was conducted:

Study design:

Type: Prospective randomized controlled trial (RCT).

Patients: 200 patients (100 per group) with indications for aesthetic mandibuloplasty (modeling of the contour of the angle of the lower jaw). The groups are comparable in age, gender, initial anatomy and bone density.

Groups:

Group 1 (Control): OMNIPORE® (Design Y™ Mandible Onlay) screw-retained implant (prototype).

Group 2 (Research): Claimed implant with positioning appendage (“paw”) and perpendicular screw.

Observation: 24 months.

Evaluation: Clinical examination, standardized radiography (OPTG), MSCT (cone beam computed tomography) at 1 week, 6, 12 and 24 months. Evaluation of stability, position of the implant, signs of bone resorption (osteolysis), complications, need for revision interventions.

Main evaluation criteria:

Positional stability: Measurement of implant displacement from the initial position (mm) using MSCT.

Additionally assessed:

Implant survival: The percentage of implants that remain stable and functional without revision.

Complication rate: Percentage of patients with complications that required or did not require intervention.

Peri-implant osteolysis (bone resorption): Presence and degree (mild, moderate, severe) of bone loss around the implant/screws on CT.

Revision Rate: The percentage of patients requiring surgery to correct the position, replace, or remove the implant.

The results of the study are presented in Table 1.

Table 1. Summary results of the clinical study.

Evaluation parameter Group 1 Control Group 2 Research Statistical significance
(p-value) Mean vertical displacement (mm) at 24 months 1.8 ± 0.7 0.4 ± 0.3 p < 0.001 Mean rotational displacement (°) at 24 months 5.2 ± 2.1 1.3 ± 0.9 p < 0.001 Overall implant survival at 24 months (%) 88% 98% p = 0.005 Complication rate (total) after 24 months (%) 26% 7% p < 0.001 Including clinically significant "bulging" 12% 0% p < 0.001 Including loosening/migration of screws 15% 3% p = 0.001 Incl. Persistent swelling/discomfort 8% 4% p = 0.20 (NS) Peri-implant osteolysis (any degree) after 24 months (%) 42% 18% p < 0.001 Incl. Moderate/severe osteolysis 18% 4% p = 0.002 Revision rate at 24 months (%) 14% 3% p = 0.003

The lower values of vertical and rotational displacement in Group 2 (by 4-4.5 times) directly confirm the effectiveness of the “paw” in preventing these types of displacements due to mechanical locking and support, that is, the stability of fixation.

The overall complication rate in Group 2 was 3.7 times lower. Particularly critical is the complete absence of "bulging" and a sharp reduction in the frequency of screw loosening (5 times). This is a direct consequence of the tight fit due to the "paw", the recess for the instrument and the perpendicular screw, as well as better load distribution.

The 2.3 times lower incidence of any osteolysis and 4.5 times lower incidence of moderate/severe forms in Group 2 indicate better biomechanical integration. This is the result of reduced micromobility, absence of “bulging”, i.e. direct confirmation of implant stability.

Rare need for revisions: 4.7 times fewer patients in Group 2 required reoperation. This is the most clinically significant result, showing that the advantages in stability lead to a reduced need for complex and expensive corrections, increasing patient satisfaction and reducing overall treatment costs.

All the data presented in the table indicate an achieved and statistically confirmed increase in the efficiency of prosthetics, achieved through increased stability, which results in increased reliability and durability.

Claims (3)

1. A contour implant of the angle of the lower jaw, comprising a housing including an inner surface and an outer surface, wherein the inner surface of the housing repeats the outer and lower surfaces of the bone of the angle of the lower jaw of the patient, and the outer surface of the implant forms the required outer contour of the angle of the lower jaw, characterized in that the housing, made individually in accordance with the CT data of the patient, additionally contains a positioning process made with the possibility of supporting on the bone in the region of the oblique line of the lower jaw, and the outer surface of the implant contains a recess made with the possibility of placing the tip of a surgical instrument in it and exerting a pressing effect on the implant, wherein the implant housing contains at least one opening made with the possibility of placing a pressing screw in it, the axis of which is made perpendicular to the inner surface of the implant housing. 2. A contour implant of the angle of the lower jaw according to claim 1, in which the positioning process comprises at least one opening made with the possibility of placing a fixing screw therein. 3. A contour implant of the angle of the lower jaw according to claim 1, in which the recess is made in a boat-shaped form.