Patent Description:
The object of the invention is to provide a device which enables an operation as precise as possible, quick, as well as safe for the surgeon, reducing the dependence on the skill of the surgeon, in other words, minimising possible human errors.

Alterations in the extremities are a frequent condition in the general population. It is common for them to go unnoticed or stay hidden in the diagnostic process.

Among these alterations it is worth noting alterations in the frontal or sagittal plane, i.e. deformations with respect to the normal load axis of the limb, which usually occur due to the evolution of developmental processes or as a consequence of the degeneration of the joint and the ligaments which stabilise it.

The correct analysis of these deformities requires a more extensive radiological study than simple radiology, with computed tomography (CT) usually being chosen.

Advances in computer software for processing images enable a complete analysis of the degree of correction desired.

These techniques enable virtual corrections of the alterations on the frontal or sagittal plane to be performed, giving information on the final result of a possible surgical operation.

Likewise, it enables surgical guides to be generated for intraoperative use. The guides adapt precisely to the bone surface and guide the correction of the angle in the frontal or sagittal plane at all times. Until now, said correction had to be performed by taking intraoperative visual references, these techniques being highly dependent on the observer and therefore the results of the correction not being very precise.

In this sense, invention patents <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> describe a series of apparatuses, guides and plates which provide the surgeon with tools that enable them to improve the degree of exactness in the operation but that continue to pose the following problems:.

Trying to prevent the problem of calculating the reference point for the placement of an osteotomy guide, invention patent <CIT>, of which the applicant is joint holder, describes a kit, wherein a surgical guide fundamentally participates which adapts in a personalised manner to the anatomy of the bone of the patient in the areas of interest, made in a single piece with an elongated configuration.

Although this system notably improves osteotomy operations, the configuration of the guide in a single piece makes it impossible to use it in opening osteotomy or tibial addition operations. This type of operation requires a series of additional actions to guide the cutting of the bone, for which reason the guide of <CIT> cannot be applied.

For its part, document <CIT> describes a surgical guide for osteotomy operations, constituted from a body obtained from a personalised 3D model generated by means of computerised axial tomography (CAT) or magnetic resonance of the bone to be operated on, the body having an elongated configuration, with a surface resting on the bone complementary to the physiognomy thereof with the particularity that it has a modular character, wherein three work areas are defined, an upper one, an intermediate one and a lower one, wherein an upper module, an intermediate module and a lower module interact, equipped with means for coupling and unlinking from each other, wherein the upper module includes a pair of protrusions, equipped with axial through holes, intended to guide a pair of upper Kirschner wires which are parallel to each other and the lower module has a pair of parallel protrusions equipped with axial through holes for a pair of lower Kirschner wires, parallel to each other.

Although this structuring allows a precise cut of the bone, it does not provide means for precisely preparing the bone for accommodating the osteosynthesis plate.

The surgical guide for the implantation of osteosynthesis plates in opening osteotomy or tibial addition operations which is recommended solves the aforementioned problem in a completely satisfactory manner, based on a simple but effective solution.

To do so, and more specifically, the guide of the invention is made of a personalised element for each patient obtained by means of an additive manufacturing process based on a 3D model, which is generated from computerised axial tomography (CAT) or magnetic resonance, carried out in the preoperative process on the extremity of the bone to be treated, mainly the tibia, having a vertically elongated configuration, with a surface resting on the bone identical to the physical features thereof by virtue of the aforementioned process.

In accordance with the essential nature of the invention, it has been foreseen that the guide has a modular character, defining three work areas, wherein different modules participate which can be fit together and interchanged.

The upper module includes a pair of protrusions equipped with axial through holes, with an arrangement and inclination calculated beforehand customised for the specific case to be operated, such that said upper module is intended to guide a pair of parallel upper Kirschner wires, at a pre-calculated angle, with the function of maintaining said module of the osteotomy guide in the suitable and pre-calculated position during the operation.

In the intermediate area of the guide, it has been foreseen that two central modules are able to be exchanged, a first central module wherein a pair of protrusions with axial through holes are established, likewise with an arrangement and inclination calculated beforehand customised for the specific case to be operated, axial holes intended to enable a pair of intermediate parallel Kirschner wires to be guided acting as guiding means for the cutting tool in the upper plane of the bisector plane of the osteotomy.

Moreover, the participation of a second central module has been foreseen, interchangeable with the first central module, wherein a pair of holes is established with a diameter, inclination and arrangement calculated beforehand in order to enable them to guide bores which enable the osteosynthesis plate to be accommodated.

Finally, the lower module has a pair of protrusions equipped with axial through holes, with an arrangement and inclination calculated beforehand customised for the specific case to be operated, such that said lower module is intended to guide a pair of lower parallel wires with the functions of acting as a stop for said cutting tool when the cutting plane of the tibia is being obtained, as well as the function of maintaining said lower module of the osteotomy guide in the suitable and pre-calculated position during the operation.

This lower module in turn ends on the bottom in a lateral bend or arm which acts as positioning and stabilising means for the guide when it rests on an area of the bone that is smoother and easier to perform the deperiostisation. In this manner, it is not necessary to remove the periosteal tissue covering the head of the tibia, the most irregular area and where the periosteal tissue is thicker, which would need a much more complicated and intrusive operation.

In this manner, the aforementioned lateral arm wherein the lower module is angled enables a perfect positioning and immobilisation of the total assembly of the guide on the area to be treated, minimising and simplifying, as said, the deperiostisation operations.

From this structuring, it is not necessary to think or debate about the exact location of the guide or the angle to cut, since the wires used determine it, almost completely reducing the risk of human error in the placement of the guide and calibration of the same since this guide does not require calibration during the operation. This implies that with the help of the 3D models obtained in the preoperative period and the preoperative calculations supported by the computer tools, we were able to obtain a personalised osteotomy guide for each patient by means of additive manufacturing, which considerably improves the degree of accuracy of the operation and significantly reduces the time of the surgical operation, with all that it entails: less probability of infection, less time for anaesthesia, etc..

In the same manner, this modular structure makes it possible to use the intermediate modules in a different order, enabling the steps of the surgery to be reversed, i.e. the holes can be made first in order to accommodate the plate and finally insert the wires in order to guide the cut or choose the opposite order.

This change in order with respect to the initially described process enables holes to be made on uncut bones, such that, depending on the health thereof, it will enable holes to be made with less risk of breaks or fissures being produced in the bone to be treated.

Finally, it is worth noting the fact that with the guide system of the invention, since all the parameters are pre-calculated by a computer, it is not necessary to continuously supervise the work being performed by means of X-ray equipment, unnecessarily radiating the surgeon's hands.

As a complement to the description provided below, and for the purpose of helping to make the features of the invention more readily understandable, in accordance with a practical preferred embodiment thereof, said description is accompanied by a set of plans which, by way of illustration and not limitation, represent the following:.

In light of the mentioned figures, it can be seen how the surgical guide for the implantation of osteosynthesis plates in osteotomy operations is constituted from a modular body, wherein three work areas are defined, an upper one, an intermediate one and a lower one, linked through an upper module (<NUM>), two intermediate modules (<NUM>-<NUM>') and a lower module (<NUM>), equipped with means for coupling to each other, such as complementary ribs (<NUM>) and grooves (<NUM>), lockable by means of transverse pins (<NUM>), such that these modules can be made independent when this is deemed convenient.

Moreover, the assembly formed by these modules is obtained by means of an additive manufacturing process starting from a 3D model, which is generated from computerised axial tomography (CAT), carried out in the preoperative process on the extremity of the bone (<NUM>) to be treated, having a vertically elongated configuration, with a surface resting on the bone complementary to the physical features thereof by virtue of said process.

The upper module (<NUM>) includes a pair of protrusions (<NUM>) equipped with axial through holes, with an arrangement and inclination calculated beforehand customised for the specific case to be operated, such that said upper module is intended to guide a pair of parallel upper Kirschner wires (<NUM>) the function of which is to maintain said module (<NUM>) of the osteotomy guide in the suitable and pre-calculated position during the operation.

The first central module (<NUM>) has a pair of protrusions with axial through holes, and likewise has an arrangement and inclination calculated beforehand as customised for the specific case to be operated, axial holes intended to enable a second pair of parallel Kirschner wires (<NUM>) to be guided, acting as guide means for the cutting tool in the upper plane of the bisector plane of the osteotomy.

The second central module (<NUM>'), the one shown in <FIG>, can be easily replaced by the first central module (<NUM>), fitting equally in the upper (<NUM>) and lower modules (<NUM>), having a pair of holes (<NUM>) with a diameter, inclination and arrangement calculated beforehand in order to enable it to act as a guide for bores which enable the osteosynthesis plate to be accommodated.

As will be explained later, the structure of the device enables different modes of operation, making it more versatile.

As for the lower module (<NUM>), it has a pair of protrusions (<NUM>) equipped with axial through holes, with an arrangement and inclination calculated beforehand customised for the specific case to be operated, such that said lower module is intended to guide a pair of lower parallel Kirschner wires (<NUM>) intended to act as a stop for said cutting tool when the cutting plane is being obtained, as well as the function of maintaining said lower module of the osteotomy guide in the suitable and pre-calculated position during the operation. All of this is shown in <FIG>.

The lower module (<NUM>) in turn ends on the bottom in a lateral bend or arm (<NUM>) which acts as positioning and stabilising means for the entire assembly of the guide.

From this structuring, the operation, as mentioned previously, can vary depending on what the surgeon wants as far as the order of the cutting and performing holes for the adaptation of the osteosynthesis plate and is as follows:
In a process prior to surgical operation, specifically in the preoperative process, a personalised guide is prepared for the specific patient.

The protrusions (<NUM>) of each module will be provided with a different marking for the specific identification thereof and the sequence of use thereof, just like the wires (<NUM>), each of which bears a personalised identification in correspondence with marking of the respective protrusion of the guide wherein it must be placed, likewise including a depth marking, for the operative placement thereof at the exact depth.

First, the approach will be made and the bone (<NUM>) will be prepared, making an incision at the height of the osteotomy, until the operation area is opened.

Subsequently, the surgical guide is then placed with the modules thereof assembled together, adapting it to the bone, being especially applicable the arm (<NUM>) wherein the lower module (<NUM>) ends, which acts as positioning and stabilising means when resting on an area of the bone that is smoother and easy to perform the deperiostisation, stabilising the assembly formed by the three modules in the implantation thereof.

Once the guide has been stabilised, the Kirschner wires (<NUM>) are then placed, which must be inserted into the surgical guide in a certain order and position, and with a certain depth: wherein both the order and the depth of placement are defined beforehand in the Kirschner wires (<NUM>) and in the protrusions (<NUM>) of the different modules of the guide.

With the Kirschner wires (<NUM>) placed in the correct position thereof, the first intermediate module (<NUM>) is then removed. At this point, it could be interesting to cut the excess portion of the wires (<NUM>) in order to prevent different collisions between them in the successive phases.

Once the intermediate module has been removed, the cut of the osteotomy is performed, using a surgical cutting saw using the intermediate Kirschner wires as a guide and cutting until reaching the stop which establishes the contact with the lower Kirschner wires (<NUM>) and cutting limit of which is clearly perceived since the collision between the intermediate and lower Kirschner wires (<NUM>) prevents the saw from being able to continue to cut.

Next, the two intermediate wires (<NUM>) are taken out.

Subsequently, the second intermediate module (<NUM>') is placed, such that through the holes (<NUM>) thereof, bores can be made in the bone which enable the bone to be conditioned to the osteosynthesis plate.

Once these conditioning holes have been made, the guide is removed module by module and all the wires are taken out, then the space (<NUM>) of the sectioned bone is opened until the osteosynthesis plate (<NUM>) can be accommodated therein, which is fastened to the bone by means of through screws through the holes which had been drilled beforehand using as a guide the holes of the osteosynthesis plate through which the screws pass.

Then, the gap generated after opening the sectioned bone is filled by using any of the usual techniques used to do so.

Finally, the wound made is closed, with the approach used in the usual surgical procedures.

Claim 1:
A surgical guide for osteotomy operations, it is constituted from a body obtained from a personalised 3D model generated by means of computerised axial tomography (CAT) or magnetic resonance of the bone to be operated on, a body which has an elongated configuration, with a surface resting on the bone complementary to the physiognomy thereof with the particularity that it has a modular character, wherein three work areas are defined, an upper one, an intermediate one and a lower one, wherein an upper module (<NUM>), a first central module (<NUM>) and a lower module (<NUM>) are configured to interact, equipped with means for coupling and unlinking from each other, such that the upper module (<NUM>) includes a pair of protrusions (<NUM>), equipped with parallel axial through holes configured to guide a pair of upper Kirschner wires (<NUM>), and the lower module (<NUM>) having a pair of parallel protrusions (<NUM>) equipped with parallel axial through holes configured to guide a pair of lower Kirschner wires (<NUM>), characterized in that the surgical guide further comprises a second central module (<NUM>') interchangeable with the first central module (<NUM>), wherein the first central module (<NUM>) has a pair of protrusions with parallel axial through holes configured to guide a pair of intermediate Kirschner wires (<NUM>) as guide means for a tool, the lower Kirschner wires (<NUM>) that pass through the lower module (<NUM>) constituting stop means for the cutting tool during the guiding thereof along the intermediate wires, and wherein the second central module (<NUM>') has a pair of holes acting as a guide for bores (<NUM>) configured for accommodating an osteosynthesis plate.