WO2013172726A1

WO2013172726A1 - Programmable and autonomous tissue distractor device

Info

Publication number: WO2013172726A1
Application number: PCT/PT2013/000032
Authority: WO
Inventors: Francisco José SANTIAGO FERNANDES AMADO CARAMELO; Francisco José FERNANDES DO VALE; Germano Manuel CORREIA DOS SANTOS VEIGA; Miguel Amaral GOMES MAGALHÃES
Original assignee: Universidade De Coimbra
Priority date: 2012-05-16
Filing date: 2013-05-16
Publication date: 2013-11-21

Abstract

The present invention refers to a mechatronic device of orthopedic correction for the distraction of the bone characterized by: - two engines (4) for the separation of the bone, with two degrees of freedom; - an oscillating piece (5) that transforms the linear motion into the rotating motion of a pin (3) where it is welded one of the anchor rods (1.1), - a power supply (11), - communication system (7, 8) energized by the power supply (1.4), electronic control unit (3) dedicated to regulate the two motors, which is programmed via the communication system and fed by the power supply (1.2, 1.4, 1.5), - an external structure of two parts where are placed the components (1.1, 1.2, 1.3, 1.4, 1.5, 1.6), - an optional anchoring system in the teeth.

Description

DESCRIPTION

"PROGRAMMABLE AND AUTONOMOUS TISSUE DISTRACTOR DEVICE"

Field of Invention

An apparatus and method for the distraction and supporting of tissues that requires two degrees of freedom, which operates in a programmable and autonomous fashion. The programmable and autonomous tissue distractor device (PATDD) comprises the anchoring rods and the body of distraction, which includes the external structure, the electric motors, the control unit that allows progressive and automatic distraction, the communication unit that allows a customizable programming of the device and the power supply required for the operation.

Background of the invention

Mandibular defects can range from isolated segmental defects to large extensive areas of bone loss involving the entire jaw. These defects are often congenital, a result of trauma, infection, or resection of benign and malignant tumors. Many options are available for mandibular reconstruction, including reconstruction plates, particulate bone grafts, block bone grafts, and microvascular free tissue transfer such as a composite fibular graft. Distraction osteogenesis is another option that has proved to be a reliable method for reconstructing missing segments of bone. Because most mandibular defects are composite defects, transport distraction osteogenesis often is an excellent treatment option because both hard and soft tissues are reconstructed.

Originally used for lengthening long bones, this process has gradually been adapted to the maxillofacial region. Distraction osteogenesis in the maxillofacial region has evolved and continues to do so. This evolution has proceeded from bulky external appliances to smaller devices. To eliminate the nonaesthetic scarring caused from the pin "drag, " smaller internal devices have been developed. In 1996, McCarthy stated that the next 2 goals to be achieved are "1) the ability to make Vector changes during the period of distraction, ie, 'interceptive multidimensional distraction;' and 2) the development of an internal or intraoral device to avoid scarring."

A variety of physical conditions involve tissue distraction of two surfaces that, for treatment of conditions, need to be supported away from each other. Such distraction may be to gain exposure to select tissues, to return tissues structures to their anatomic position and form or to promote concomitant growth of new tissue. Depending on the condition being treated, the tissue surfaces may be opposed or contiguous and may be bone, skin, soft tissue, or a combination thereof. An optimal treatment method includes distracting and supporting the tissue surfaces simultaneously. Orthopedic surgeons cannot currently quantitatively predict the optimal tradeoff between

alignment and soft tissue balance.

Bone Distraction and Mandibular Osteogenesis

Bone distraction is a mechanical and physiological process where new bone is formed leading to a measurably changing of the bone size. This process is accomplished by a slow separation of the bone ends that, generally, are originated by an osteotomy of the bone performed to promote osteogenesis and its concomitant growth. The separation of the bone ends is followed by a sufficiently long period of retention that ensures the hardening of the bone matrix. In certain circumstances, this kind of procedure can eliminate the need for bone grafts. The surrounding soft tissues, blood vessels and nerves also undergo stretching in order to accommodate the new bone geometry.

In 1905, Codivilla [1] presented the first practical work of a lengthening of a femur to correct a deficiency being this technique further investigated later (1955) and refined by Ilizarov [2] . The method has evolved and has become a tool of great importance in the lengthening of bones with several applications in different parts of the skeleton and, obviously, in the mandible. The first application in humans was performed by McCarthy et al. [3] in 199.2 employing a mandibular external device. However, the external devices cause facial scars and may result in injury of the facial nerve originated by the transcutaneous pins required for anchoring the device, additionally there is increased risk of infection. The development of intraoral devices [4] made possible the overcome of many of these disadvantages though the difficulty of accessing the bone remains. Furthermore, the existing devices in use in the Clinic are mechanical apparatuses requiring manual activation and the intervention of the physician in a daily basis. This fact associated with the need of two surgical procedures, one for placement and another for removal of the device, imply that patients must remain hospitalized during the distraction. On the other hand, the discontinuity of the manual activation imposed by the nature of the devices besides causing high stress does not promote the best osteogenic activity and hence reduces the maturation of bone .

Recently (2010), Chung et al. [5] presented a proposal to use an electric engine to motorize a distraction device in order to produce a progressive lengthening and thereby reduce stress and increase the osteogenic activity involved. The power supply is the principal matter analyzed in this study, where the distraction device continues to be supported to the mandible by small screws. It should be noted that this project arises after other studies performed in animals, where similar systems are proposed and whose activation is achieved by electrical motors, metal alloys with shape memor or hydraulic pumps [6] . Chung had filled before (2009) a patent claiming a distraction device operated with an electric motor wireless operable, however with only a degree of freedom permitting only a unidirectional movement and with an attachment system based on screws in the bone. The size of the mechanism presented in the patent is not strict defined.

Bone distraction devices in particular mandibular distraction devices that are on the market make its anchorage directly in the bone with small screws independently if it is applied within the body or outside of the body (extraoral or intraorally in the case of the mandible) . In either case an aggressive surgical intervention is general necessary and, for example, it is not possible to avoid the invasion of the mucosal tissue, in the mandible case. On the other hand, these devices require manual activation which is contrary to the ideal of distraction where a continuous and progressive separation of the bone ends is desirable. This issue is partly solved by the devices presented in the mentioned publications. Nevertheless, there are yet two essential aspects to be settled, namely: anchoring and controlling the direction of the distraction.

The PA.BD besides allowing a continuous and progressive distraction as a result of a suitable engine, it also provides to the mandible example a dental anchoring system that is simple to apply. Additionally, the two degrees of freedom allow effective control of the direction of distraction, and therefore ensures that the distraction is performed the best way to the treatment, for example, parallel to the occlusal plane. Note also that PABD is programmable by wireless communication permitting to easily customize case-by-case and adjust its performance during the distraction.

[1] A. Codivilla; On the means of lengthening in the lower limbs, the muscles and tissues Which are shortened through deformity. Am J Orthop Surg, 1905; 2: 353-369.

[2] GA Ilizarov, The Principles of the Ilizarov method.

Bull Hosp Joint Dis Orthop Inst, 1988, 48: 1-11.

[3] JG McCarthy, J. Schreiber, N. Karp, CH Thorne, and BH

Grayson, Lengthening the Human Mandible by Gradual

Distraction, Plast. Reconstr. Am J Orthop Surg, 1992; 89:

1-8.

[4] Swennen G, Schliephake, H., Dempf, R. Schierl, H., and Malevez, C . ; Craniofacial Distraction Osteogenesis: A Review of the Literature. Part I: Clinical Studies; Int J. 89-103.

[5] Chung M.D., Rivera R. D. , Feinberg S.E., Sastry A.M., An Implantable Battery System for a Continuous Automatic Distraction Device for Mandibular Distraction Osteogenesis, Journal of Medical Devices, vol 4, Dec, 2010

[6] Schmelzeisen R. , G. Neumann, and R. von der Fecht, Distraction Osteogenesis in the Mandible With Motor-Driven Plate: A Preliminary Animal Study, Br J. 375-378. [7] Z. Lekston, Drugacz J., and H. Morawiec; Application of Superelastic NiTi Wires for Mandibular Distraction; Mater. Sci Eng, 2004, A, 378: 537- 541.

[8] Implantable distraction osteogeenesis device and methods of using same, Feinberg S.E.,

Sastry A.M., Chung M. , US Patent 2009/0192514 Al

Summary of the invention

An apparatus and method for the distraction and supporting of tissues that require two degrees of freedom, as is the case of the osseous distraction.

In this case, the device is placed intraoral preferably fixed in the 1st molar and in the 1st premolar teeth and whose goal is to, autonomous and automatically, perform the distraction of the mandible parallel to the occlusal plane. The distraction is a mechanical process that promotes the lengthening of the bone aiming at the formation of new osseous tissue essential to the reconstruction and correction of some deficiencies such as craniofacial.

The PABD comprises the anchoring rods and the body of distraction which includes the external structure, the motors, the control unit that allows progressive and automatic distraction, the communication unit that allows a customizable programming of the device and the power supply required for the operation. One of the anchor rods is fixed whereas the other is driven by motors and adjustable to ensure, preferably, two degrees of freedom which will allow to performing the distraction parallel to a plane defined by the user, such as in the mandible case where the distraction can be performed parallel to the occlusal plane .

Programmable and Autonomous Tissue Distractor Device (PATDD)

The described invention is a mechatronic device aimed at the correction of pathologies by a distraction process. It is a device design to preferentially correct craniofacial deficiencies which promotes autonomous, automatic and controlled distraction of the mandible while ensuring, through two degrees of freedom, that the direction of the bone separation is controllable.

The device comprises six main parts:

a. external structure (1, 2) where all the components are located in;

b. two engines (4) with gearbox and lead screw to produce the necessary translation;

c. two transmission elements of motion (5) with a surface with involute profile that enclose the nuts of the lead screw; d. one oscillating piece (3) and respective pin that transforms linear to rotation motion;

e. electronic control unit (9, 10),

f . remote communication unit (7, 8 ) ,

g. battery suitable fox the operation of the device (11) .

The invention may be implantable and in the case of the mandible is applied intraorally and its anchoring is done directly on the teeth, preferably, between the first molar and the first premolar. The teeth anchorage is preferably obtained using metal bands that are frequently used in clinical practice for supporting other devices. The rods of the distractor are welded to these metal bands in the most convenient way for attaining the best results for each case of craniofacial correction. This procedure is directly followed by a specialist who optimizes the positioning of the distractor to the patient. The intraoral placement will be made preferably close to the gum in the vestibular side which significantly limits the physical dimensions of the device. Thus, the dimensions of the distractor at rest with no activation has to be less than 30x14x10 mm, which implies the use of components of appropriate size.

Currently, the surgery needed to initiate the distraction involves the bilateral osteotomy at a specific section and attaching the distractor to the bone. This implies, on one hand, an important invasion of the surrounding tissue and, on the other, the placement of mounting screws on the bone that is not absent of risk. For the mandible case, _. anchoring the distractor to teeth eliminates the requirement for placing (and removal) the device using screws, thereby the surgery is considerably simplified reducing also the risk of Subsequent complications. Moreover, as the device is applied intraoraly facial scars are avoided and when implantable close to other bones scars is may also be minimized. When craniofacial deficiencies are corrected by bone distraction generally the mandible is sectioned, according to the conditions that the clinician decides, the distractor is anchored to teeth in order to connect the two bone ends and to carry out its separation. The separation is then performed continuously and autonomously. This movement is performed by the two small engines (4), preferably DC and brushless, which in a preferential arrangement are placed parallel to each other. This geometrical arrangement of the engine not only allows a translational movement essential for bone distraction but also it promotes a torque on the oscillating piece (5) . This degree of freedom associated to the rotation will permit that the bone growths parallel to the plane that optimize the treatment, such as parallel to the dental occlusion plane or if necessary in other plane to achieve further correction. Without the possibility of rotating the direction of distraction would be limited to a single direction which occurs with the existing devices.

The invention also incorporates a control mechanism that is based, preferably, in an electronic microcontroller (9) that activates the motors, and in sensors (10) that monitor the position. These controllers can be . programmed to perform a given protocol of distraction and optionally programmed to adjust their performance during the distraction using information obtained from the sensors . The communication with the device required for its initial activation and for programming is performed by an appropriate electronic unit, preferably, an integrated wireless circuit (8) and an antenna (7) .

The power supply is provided by one or more batteries, preferably of 3.0 V, that can deliver an average power of 0.3 W during the activating pulses and can hold a sufficient charge to maintain the operation for 10 days.

Distraction Device and Procedure Applied to programmed and automatic tissue distraction

Brief Description of the drawings

Figure 1 shows an schematic representation of the views (front view, right side and top) and perspective of the exterior structure of the distractor. The exterior structure of the distractor has essentially a support function of the mechanism being composed of two parts (1, 2) that penetrate in each other while sliding. In the perspective view it is visible the pin (3) where it will be supported one of the anchor rods that allows the rotation movement .

Figure 2 shows an schematic representation in cutaway view of the parts 1 and 2 referenced in Figure 1, the inner pin (3) also referenced in Figure 1 and some components inside. The motors with gearbox and lead screw (4) are shown, arranged parallel to each other. The motors activate, through transmission elements (5), the oscillating part that causes the rotation of the pin (3) .

Figure 3 shows an schematic representation in cutaway view of the components referenced in Figure 2 and the board

(6) on which are mounted the electronic components responsible for the control and communication. The components responsible for communication are the antenna

(7) and the wireless chip (8) . The components responsible for controlling the motors are the control integrated circuit (9) and the position sensor (10) .

Figure 4 shows an schematic representation in cutaway view of the components referenced in Figure 1 and of the bottom view of the board (6) referenced in Figure 3 where it is placed on the battery (11) which supplies the power needed by the whole mechanism.

Figure 5 - Chart that roughly represents the profile achieved with an actual distractor device. The x axis represents the time during the distraction procedure whereas in the y axis the displacement occur in the distraction direction is represented. The rate of distraction is not uniform in the sense that for each activation different displacements are obtained. The activation period is nearly constant and long corresponding to the rotation of the^' screw required for permforming the distraction .

Figure 6 - Chart representing the example for 3 different profile, that can be obtained using the PAB.DD.. The x axis represents the time during the distraction procedure whereas in the y axis the displacement occur in the dist action direction is represented, _: The rate of distraction may ne uniform or variable (line 2 and line 3) . On the other hand, several activation periods may be programmable from a relatively long and constant period showed by line 1 and continuous distraction represented by line 2 and 3.

Claims

- 1 - CLAIMS

1. Mechatronic device of orthopedic correction for the distraction of the bone characterized by:

- two engines (4) for the separation of the bone, with two degrees of freedom;

- an oscillating piece (5) that transforms the linear motion into the rotating motion of a pin (3) where it is welded one of the anchor rods (1.1),

- a power supply (11)/

- communication system (7, 8) energized by the power supply (1,4) ,

- electronic control unit (3) dedicated to regulate the two motors, which is programmed via the communication system and fed by the power supply (1.2_/ 1.4_/ 1.5)_/

^ aft external structure of two parts where are placed the components (1.1, 1.2, 1.3, 1.4, 1.5, 1.6).

- an optional anchoring system in the teeth.

2. Mechatronic device according to claim 1 characterized by the engines be arranged optionally parallel to each other-.

3. Mechatronic device according to previous claims characterized by the engines perform a torque on an oscillating piece capable of rotating a pin .

4. Mechatronic device according to previous claims, characterized by the external structure consist of - 2 -

two components (1, 2), penetrable to each other, to allow the slide that occurs during the separation.

5. Mechatronic device according to previous Claims, characterized by the electronic communication be wireless .

6. Mechatronic device according to previous claims, characterized by the control electronics (3) be programmed to drive the distraction in the occlusal plane or in other plane considered more convenient.

7. Mechatronic device according to previous claims, characterized by the data communication can be made between similar devices placed bilaterally in the mandible.

8. Mechatronic device according to previous claims, characterized by the control unit acting together with the electronic control can adjust the bilateral distraction during the clinical protocol.