RU2334478C2 - Procedure and tools for low-rotation milling without washing with withdrawal and collection of tissue particles - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method of milling is performed on bone or other tissue of patient to form cavity with shape and sizes which allow said cavity to take implant (or for other purposes, when tissue must regenerate). Milling is performed with low rotation frequencies without washing, without tissue heating and without necrosis, which occurs in tissue. Milling tools design allows collecting tissue particles without using sucking-in device. Said particles are in optimal biological state for application in autotransplantation due to the fact that neither overheating nor washing are involved in process of milling. As a result, method is capable of constant self-adjustment according to characteristics of definite section of drilled-out tissue, protecting surrounding tissue, preventing section heating and simultaneously eliminating side effects. Tools have characteristics which are intended for holding particles, without their releasing, when used.

EFFECT: method allows collecting tissue particles and using them further to prepare effective process of autotransplantation.

7 cl, 4 dwg

Description

The invention relates to methods used in drilling or milling of bone, cartilage and other tissues for the required medical purposes, mainly related to the implantation of screws or other prosthetics and osteosynthesis in the knees, hips, spine and other bones or tissues. One of the most important applications is the drilling of the patient’s upper jaw for its preparation under the maxillary dental implant in the fields of dental implantology and maxillofacial surgery.

When used, in particular, in dental implantology, the milling method involves sequentially drilling a bone by sequentially introducing milling heads of increasing diameter to form a cavity adapted to the dimensions of the implant or prosthesis. The milling method includes rotating the tool or milling head with the desired frequency. The exact speed characteristic is determined by many factors, mainly the geometric characteristics of the milling head and the sequence of steps in the milling process.

Milling heads of numerous shapes and sizes are available. This is mainly due to the fact that the design of each implant usually contains specific constructive solutions that require milling by specialized milling heads of cavities that are well adapted to the dimensions of the implant.

The practice of using milling heads with a number of different diameters for the same implant is widespread. This approach ensures that the milling heads used at each stage of the process are precisely sized for the cavity to be drilled.

The wide range of implants and milling heads used in traditional methods implies that rotational speeds are used during milling, varying over a wide range from approximately 800 to 1,500 rpm. This so-called high-speed milling leads to the fact that both the milling head and the bone tissue that the said head processes are heated, while the temperature of the milling head sometimes exceeds 40 ° C. Bone cells are thermosensitive and are characterized by an optimum temperature of 37 ° C. Therefore, any increase in temperature can damage the cells and in many cases cause necrosis.

The thermal damage caused to the tissue surrounding the implant during high-speed milling and to which mechanical damage from the entire milling process can be added has a devastating effect on the initial state of the cavity containing the implant. As a result, more time is required to restore the bone and to integrate the implant into the bone, which are factors that influence the degree of success of the operation.

Therefore, in traditional milling methods, it is widely practiced to supply flushing saline to the milling head and the reaming area to prevent overheating of the milling head and surrounding tissue. However, this wash solution flushes signal proteins and other soluble substances that can perform an active function in bone regeneration.

Mentioned substances are secreted by the tissue in the area where the tissue is damaged in response to damage and as a means of maintaining homeostasis, i.e. preservation of biological and physico-chemical conditions until damage, and are important if tissue repair is required. A special physiological function of signaling proteins is the transmission of activation signals to the cell so that it can respond to degradation that has occurred in the microenvironment. Mentioned proteins are associated with the extracellular matrix. This connection is broken when the milling head impacts the matrix. Said signaling proteins are characterized by low molecular weight and solubility. Wash saline easily dissolves and rinses them and therefore deprives the tissue of the natural resources that the tissue uses for its own healing.

In addition, it is common practice to remove and collect tissue particles removed during milling and to use them in autotransplantation. This method makes it unnecessary to use alternative and much less useful methods proposed for this purpose, for example, such as allotransplantation (homologous transplantation of tissue obtained from a bank of human tissues) or xenotransplantation (the process of transplanting tissue from one species of animal to another). As part of this process, a suction device equipped with a filter collects all bone particles. After repeated analysis of high-speed milling methods, it was found that in these particles cell death already occurred as a result of thermal and mechanical damage caused during the process.

The main objective of the present invention is to provide a milling method that protects the tissue surrounding the drilling site as much as possible, prevents the heating of the site and at the same time eliminates the side effects caused by the use of flushing saline, mainly washing off the own cellular signals that help the tissue heal faster and become biologically stronger .

Another objective of the present invention is to provide a milling method that allows the collection of tissue particles captured during milling, and then used to prepare an effective autograft process. As a result, this invention aims to characterize tools that are designed to hold and not release particles, and the use of these tools.

Another objective of the present invention is to provide a milling method that is constantly self-adjusting according to the characteristics of a particular area of the fabric being drilled. This goal, the achievement of which all milling methods must ensure, is based on the fact that the outer surface of the tissue (the cortical layer when milling is started) is harder and contains fewer cells. After drilling said layer, the tissue becomes less dense and contains more cells. If this goal is achieved, it will be easier to make the implant stable at the initial stage and, thus, to support the integration of the implant into the tissue.

In order to achieve the aforementioned objectives, the characteristics of the method for milling a patient's tissue to form a cavity for receiving an implant or prosthesis are determined. This method includes low speed milling without washing. As a result of the process, tissue particles of high biological quality are obtained and subsequently used as autografts after mixing, preferably with PRGF (plasma rich in growth factors) obtained according to the invention WO 0044314, for which the patent is granted to the present applicant.

For the formation of a cavity containing the implant, the milling method in accordance with the present invention contains mainly three stages of milling:

1) The initial stage

2) The intermediate stage

3) Countersink stage

The initial stage involves cutting through the cortical tissue, which is the first layer of tissue and usually has a very solid consistency. This initial stage is already included in other methods. To ensure the correct implementation of this stage, a conical “tapping milling head” should be used. This head is specially designed to pass through the cortical tissue and facilitate the start of cavity milling, even in small areas of the tissue. Therefore, the tip of the milling head must be very sharp so that the drilled hole can be made exactly in the right place. A suitable milling head to be used at this stage is described in international application PCT / ES03 / 00443, also filed by the present applicant.

Milling at the initial stage is usually performed at high speeds, preferably in the range of 800-1200 rpm. This is due to the design of the milling head, which has a very sharp apex, and the fact that the milling head should create a very small drilled hole in the hard fabric without circular slippage nearby. At this initial stage, plentiful amounts of washing physiological serum solution should be supplied to prevent tissue heating as a result of high-speed milling.

The purpose of the intermediate stage is the formation of almost the entire cavity containing the implant, with depth, width and other main parts determined during the process. As described in the introduction of the present description of the invention, milling heads of various shapes and sizes are required for milling a cavity that is precisely sized and shaped like an implant. As a result, at the intermediate stage, several types of milling heads are used until they form the desired cavity.

In accordance with the present invention, the intermediate milling step is characterized by two main factors.

- Milling is carried out at low speeds from 20 to 80 rpm and without supplying a flushing saline solution.

- Tissue displaced or released at this intermediate stage of cavity formation is removed or collected. The invention provides the specified through the use of specially designed milling heads, which allow the holding of biased tissue in the milling head during milling and, thereby, facilitate extraction. The following method is often used: milling is interrupted for a short time when the device detects that the milling head contains a sufficient amount of tissue particles, or whenever it is considered necessary to pause. The milling head is then removed from the cavity and a spatula or other tool is used to remove tissue from the head before the fabric is placed in a small container made of glass or similar sterile material. Then the milling is resumed. This means that tissue particles can be collected without the need for suction filters or other additional tools.

At the countersink stage, if necessary, a base surface is created for receiving the implant or prosthesis. The purpose of the countersink stage is to drill the top of the cavity to create enough space to accommodate the implant head when it is inserted into the cavity. The shape of the implant determines the point at which the countersink step is performed, if necessary. In some cases, the countersink is performed at the end of the intermediate stage or when a cavity is formed, while in other cases, the countersink is performed during the intermediate stage.

In the same way as at the intermediate stage, milling at the countersink stage is performed at low revolutions from 20 to 80 rpm and without supplying a washing saline solution. In addition, fabric displaced or released at this countersink stage is removed or collected through the use of specially designed milling heads that allow the displaced fabric to be held in the milling head during milling and thereby facilitate removal. The design of these milling heads used in the countersink step in accordance with the present invention has characteristics similar to the design of tools used in the intermediate milling step.

Although milling at the initial stage should preferably be performed at high speeds, low-speed milling is also allowed, as at the intermediate stage and the countersink stage, if necessary for a special application or case.

As for the tools or milling heads used in the method according to the invention and mentioned above, the invention provides the characterization of special milling heads for milling in the intermediate and countersink stages. These milling heads have a retarding structure that allows the accumulation and retrieval of displaced or extracted tissue.

All milling heads used in the intermediate and countersink stages are preferably thin cylindrical parts containing a smooth, standard-sized portion on top for attaching the head to a rotation motor. Secondly, the head contains a milling section, consisting of spiral grooves, which are cut so as to create the angle necessary for the release or extraction of the cut material, and, at the same time, to create spaces for the accumulation of the extracted tissue. Thirdly, the milling head contains a sharp tip or tip in the case of milling heads for the intermediate step and a blunt tip or tip in the case of milling heads for the countersink step.

Spaces accumulating the extracted tissue, or sites for holding tissue formed between continuous loops of spiral grooves on the inner concave surface between these loops. The structural elements of this section of the milling head described below provide its holding ability or the ability of these areas to accumulate the extracted tissue.

- Firstly, the spiral grooves are cut at an angle of inclination of 25-40 degrees relative to the longitudinal axis of the milling head, in contrast to traditional milling heads, in which the spiral is usually inclined at an angle of 6 degrees and sometimes up to 15 degrees.

- Secondly, the concavity of the holding sections in the rod of the milling head or to the longitudinal axis is more pronounced than in traditional non-holding milling heads. In particular, in the cross section of a given section of the milling head, the curvature or concavity of the holding sections has approximately the same shape as a semicircle, and may be even more or more closed.

Determination of characteristics and the use of milling heads with the above characteristics ensures that the fabric extracted during milling is sent to the holding areas and, since the washing solution is not supplied, accumulates in them.

However, it should be noted that in the present invention, the holding property of the milling head and the fact that the milling is performed at low revolutions and without washing, facilitate the preparation of tissue particles that can be used for autotransplantation. Therefore, the fact that milling is performed at low speeds improves the quality of the resulting tissue, since the particles become larger and contain significantly more living cells than the particles obtained as a result of high-speed milling. This is due to the fact that the milling head performs significantly more revolutions at a high speed of rotation than at a low speed of rotation, but at the same time it moves at the same distance, the fabric is crushed to a greater extent with the formation of a kind of powder, which, as the analysis showed, does not contain living cells. In addition, the fact that there is no supply of flushing saline to cool the milling head and surrounding area means that signal proteins and other substances that accelerate and support tissue regeneration and contribute to the rapid stabilization of the implant are not removed from the surrounding tissue.

In addition, all milling heads, except for the milling milling head, which is characterized by a shorter milling section, may contain bands cut or etched on the outer surface that indicate different milling depths in accordance with the heights of the implants. Since the milling head rotates at low speeds, these strips remain visible and therefore can be used to indicate the point at which the corresponding depth for each particular milling head has been reached, and therefore the point at which the milling should be stopped or continued using the next milling head .

The method and tools for low-speed milling without washing according to the invention, used for the extraction and collection of tissue particles, not only achieve the stated objectives, but also provide other proven advantages and positive characteristics, a detailed description of which is given below.

The analyzes showed that the milling method according to the invention does not increase the temperature of the milling heads by more than 5 ° C, which, taking into account the summation with the ambient temperature, means that the temperature is maintained below 40 ° C, i.e. temperature at which damage and even necrosis occurs.

Analyzes using optical and electron microscopes also showed that bone particles extracted during milling retain their osteogenic (originating from bone-forming tissue), osteoinductive (inducing bone formation by other cells) and osteoconductive (providing structural support during bone regeneration) properties. Therefore, bone particles are ideally suited for use in autotransplantation. Autotransplantation can, for example, be carried out by mixing bone particles with PRGF (plasma rich in growth factors according to the invention WO 0044314, for which the patent is granted to the present applicant). Another possible autograft method involves storing particles in physiological serum or blood of a patient. The mixture can later be used in autotransplantation.

The method of low-speed milling without washing in accordance with the invention can be applied not only in implantology, but also in orthopedic surgery and traumatology, special fields in which methods of very aggressive surgery are traditionally used, based on high-speed milling and mechanical criteria that do not take into account biological damage, applied fabric.

In this regard, technical innovations aimed at reducing damage can be a significant contribution to improved clinical development and shortening the recovery period (as already proven by the application of the method described in detail in patent WO 0044314 to the present applicant for this type of operation). These innovations also make it possible to obtain a large amount of live bone for use in autotransplantation. In the case of hip and knee prostheses, the use of the low-speed milling method without rinsing allows you to restore a large amount of bone for use as a graft for the prosthesis. The graft can be installed using rods or pins, screws or microplates for osteosynthesis in case of bone fractures.

A detailed description of the present invention is given with reference to the accompanying drawings, although the drawings do not disclose the entire content of the invention:

Figure 1 is a first example of a low-speed milling method in accordance with the invention.

Figure 2 is a second example of a low-speed milling method in accordance with the invention.

Figure 3 - a possible design of a milling tool in accordance with the invention.

4 is a possible construction of another milling tool in accordance with the invention.

Figure 1 presents an example of a method of low-speed milling, where the method is used to form a cavity or cell (5) in the tissue (6) of the patient. In this particular case, the tissue is the upper jaw, and a cavity is formed to accommodate the maxillary dental implant (4). In this method, the cortical layer or the hardest outer section of the bone (6) is drilled at the initial stage (1). This is followed by an intermediate stage (2) of milling, on which a cavity (5) is formed. And, finally, the method is completed by a countersink step (3), in which the cavity (5) is expanded to accommodate the head (18) of the maxillary dental implant (4).

As already indicated in the present description of the invention, at each stage of milling, the required tools are used to exert the desired effect on the cavity, etc. In this regard, the cutting milling head (7), used at the initial stage (1), contains a very sharp conical tip (19), allowing this head to begin cavity milling. In addition, the countersink milling head (9) used in the countersink step (3) is shorter and wider than other milling heads, since its purpose is to drill the top of the cavity (5). The shape of the intermediate milling heads (8) used in the intermediate step (2) is shown in detail in FIG. 3. Figure 1 shows the location of the marks (16) on the surface of the milling head (8), which indicate the depth to which each tool should drill or mill. These marks serve as a guide for the milling technician.

FIG. 2 shows another example of a method in accordance with the present invention for the same application as that shown in FIG. 1, which serves to demonstrate how the countersink step (3) can be performed in the intermediate step (2), i.e. an option that may be useful for maxillary dental implants (4) of certain types, depending on the types of existing instruments.

Figure 3 presents an example of an intermediate milling head (8) used in the intermediate stage of the method, which form the bulk of the cavity in the patient’s tissue. This intermediate milling head (8) consists mainly of three parts or zones. The top of the milling head contains a smooth, essentially cylindrical section (13) of standard sizes. Secondly, there is a milling section (14) containing spiral grooves (11) cut in the mill. Thirdly, the cutter contains a sharp tip or apex (15).

The milling head in accordance with the present invention contains holding sections (17) that correspond to the inner surface of the spiral grooves (11) and to which the fabric is removed, which is removed during the milling process before it is finally inside them. The holding capacity of these holding sections (17) is increased in that the spiral grooves (11) in the intermediate milling head (8) are made so that the angle (10) at which the said grooves are inclined to the longitudinal axis (12) of the milling head is 25 -40 degrees and the fact that the curvature (20) of the cross-section of the holding sections has approximately the same shape as a semicircle and can be even more or more closed.

As can be seen in figure 3, the milling head (8) also contains marks (16), which indicate the depth to which each tool should drill or mill and, thus, serve as a guide for the specialist performing the milling.

Figure 4 shows an exemplary embodiment of a milling head (9) to be used in the method in the countersink stage because of its wider section (14), which provides a wider hole at the top of the cavity and thus creates space for the implant head to be accommodated. This milling head (9) for the countersink stage consists mainly of two parts or zones: a smooth, essentially cylindrical section (13) of standard sizes and a milling section (14) containing spiral grooves (11) cut in the mill.

The milling head (9) for the countersink step in accordance with the invention contains holding sections (17) that correspond to the inner surface of the spiral grooves (11) and to which the fabric removed during milling moves, is attracted and finally enclosed within them. The holding ability of these holding sections (17) is enhanced by the fact that the spiral grooves (11) in the milling head (9) for the countersink stage are made so that the angle (10) at which the said grooves are inclined to the longitudinal axis (12) of the milling head, is 25-40 degrees and the fact that the curvature (20) of the cross section of the holding sections has approximately the same shape as the semicircle, and may be even more or more closed.

Claims (7)

1. A milling method to be performed on a bone, cartilage or other tissue of a patient to form a cavity with a shape and size that allows the cavity to accommodate an implant or prosthesis, or to form a cavity for other purposes, including the repeated use of various rotating milling tools on the fabric, moreover, the said method contains an intermediate stage, which sets the depth, width and other basic characteristics of the cavity, while the tools used in the intermediate stage work on in the range of 20-80 rpm, and tissue particles displaced or released as a result of the milling process are collected and accumulated in the milling tool and removed from it when the tool is removed, so that these particles can be stored and used for others surgical applications. 2. The milling method according to claim 1, in which the countersink stage is carried out to expand the throat of the cavity, the tools used in the countersink stage operate at revolutions in the range of 20-80 rpm. 3. The milling method according to claim 1, in which the initial stage for cutting through the cortical tissue is carried out, while the tools used in the initial stage operate at revolutions in the range of 20-80 rpm. 4. The milling method according to any one of the preceding paragraphs, in which the washing solution is not supplied to the tools, released tissue particles or tissue surrounding the milled hole or cavity during the milling process. 5. The milling method according to claim 1, in which tissue particles collected during the milling process are mixed with plasma rich in growth factors or other biological materials for the required medical purposes. 6. Milling tools for use in a milling method to be performed on a bone, cartilage, or other tissue to form a cavity with a shape and size that allows the cavity to hold an implant, or for other purposes, wherein said milling tools are essentially , elongated tools that contain a section containing spiral grooves, between the spiral grooves there are made fabric retention zones for the accumulation of tissue extracted during milling, the spiral being spiral GOVERNMENTAL grooves formed at an angle of inclination of 25-40 ° to the longitudinal axis of the milling tool and / or retention zones are concave or curved inwards so that when viewed in cross-section said curvature or concavity forms approximately the shape of semicircle. 7. Milling tools according to claim 6, in which the tools have at least one visually noticeable horizontal mark, made in the form of a relief or other suitable form, to perform the function of an indicator in the milling process.

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