WO2007085716A2

WO2007085716A2 - Device for the magnetic detection of the holes in an orthopaedic plate

Info

Publication number: WO2007085716A2
Application number: PCT/FR2007/000101
Authority: WO
Inventors: André JOLY; Thierry Le Tiec; Valentin Valdes
Original assignee: Joly Andre; Thierry Le Tiec; Valentin Valdes
Priority date: 2006-01-24
Filing date: 2007-01-19
Publication date: 2007-08-02
Also published as: FR2896399A1; FR2896399B1; WO2007085716A3

Abstract

Magnetic detection device for percutaneously measuring the positions of the locking screw holes for an orthopaedic plate. The device according to the invention makes a direct measurement, using magnetic and percutaneous detection, of the position of the locking-screw holes for orthopaedic plates. The method of detecting the position of the holes relies on the fitting of pads (20) in the middle of the holes to be measured on the plate (0). These pads (20) are equipped at their centres with a magnetic pellet (21) the ferromagnetic properties of which are quite different from those of the metals used to make the plates (0). A measurement unit (10) equipped with a magnetic detector can percutaneously determine the position of the pellets in the holes once the plate is installed. The device according to the invention is particularly intended for identifying the position of the fixing holes of orthopaedic plates used for osteosynthesis operations.

Description

ORTHOPEDIC PLATE

The present invention relates to a magnetic sensing device for the percutaneous measurement (thickness of the skin and soft parts simply) of the positions of the passage holes of the locking screws of an orthopedic plate. This invention makes it possible to locate the position of the holes and thus to accurately perform the incision necessary for the placement of a drill sleeve. The socket when self-centered on the plate allows the drilling and setting of the locking screw.

Orthopedic plates have many holes to allow optimal locking on the operated bone. The surgeon can choose inoperative holes to be used for locking the plate, before its placement on the patient. Current methods of locating the positions of the locking screw holes are based on large incisions where the entire plate is viewed or on external viewing frames. Large incisions increase blood loss and risk of infection, are painful, promote skin adhesions and are not aesthetic. The implementation of external sight frames is complicated, time-consuming and constraining for the surgeon.

The device according to the invention makes it possible to remedy the risks and inconveniences associated with the method of large incisions as well as the constraints related to the use of an external sight frame. Indeed, the device according to the invention measures directly percutaneously, by magnetic detection, the position of the holes for passing the locking screws of the plates. The method of detecting the position of the holes is based on the placement of studs in the center of the holes to be measured. These studs are provided at their center with a magnetic tablet whose properties Ferromagnetic materials are quite distant from those of the metals used for plate construction. A measuring box, equipped with a magnetic detector, can percutaneously determine the position of the pellets in the holes. This simple device of implementation makes it possible to determine with a sufficient precision the position of the holes of the plates. The installation of the locking screws can thus be optimal, without the need to install external sighting frames or to resort to too large incisions.

The use of the device according to the invention is simple and fast. The surgeon can install the pads in the course of intervention, according to his analysis of the holes necessary for the locking of the plate. Plates with studs installed during their manufacture can also be considered. Once the plate is put in place with its studs, the surgeon uses the magnetic measurement box to percutaneously locate the position of the magnetic pellets under the skin. Once detected, it can mark the position with a marker or light beam (laser) on the skin through the measuring box through a hole provided for this purpose. The measuring box has the advantage of being lightweight and compact, manipulable with one hand, operating on battery or battery. In order to make it usable in an aseptic environment, the casing will be covered with a sterile cover allowing its protection and manipulation, a sterile cannula will also be introduced into the central orifice of the casing. The result of the magnetic sensing measurement is presented to the surgeon in a simple and unambiguous manner by visual or sound means. At the marked position, the surgeon can make a small incision and remove the pellet, using a suitable extraction system (corkscrew type), to free the hole. Once the pad removed, the drill sleeve is positioned and centered for drilling and setting the locking screw. The pads and the measuring box are compatible for use in a sterile environment.

An orthopedic plate (0) consists of a metal plate (stainless steel, titanium, chromium or cobalt for example) pierced with numerous holes. A plate measures about fifteen centimeters long for a few centimeters wide and two to three millimeters thick. The holes are arranged over the entire surface according to a diagram specific to the use of the plate. The holes allow the passage of locking screws which allow to fix the plate on the operated bone. Depending on the bone operated, different holes may be used at the discretion of the surgeon.

The accompanying drawings (Figures I to VIII) illustrate a possible embodiment of the device according to the invention. In the accompanying drawings, the orthopedic plate elements (0) are presented as examples and are not representative of a particular model.

- Figure I shows a general view of the device according to the invention in the XY plane. A typical plate

(0) is shown from the front in the XY plane after installation. In order to lighten the drawing, neither the bone nor the tissues are represented. Similarly, the length of the plate (0) is fictitious and truncated. Two holes for the locking screws are equipped with studs (20), the others are left free. The measuring box (10) is shown in its operative position, outside the operated member, the detection unit being placed opposite of the theoretical position of a hole equipped ^'with a pad. The recessed arrows show the possible movements of the measuring box (10) around the theoretical position of the holes to be measured.

- Figure II shows a view from outside the measuring housing (10) in three orientations: main face (a), side (b), side (d) and bottom (c). The switch (13) for turning on the detection unit is placed on one side (d). The pushbutton (12) calibration is placed on the side (b). On the main face (a), the light strips (15) make it possible to unambiguously display the result of the magnetic measurement. The face (c) has the orifices (11) along the main axis of the detection unit. Finally, on each of the orientations (a, b and d), an arrow (14) materializes the main axis of the orifice (11) of the center of the detection unit.

- Figure III shows a sectional view of the measuring case (10) according to plans (a), (b) and (c). The section along the plane (a) makes it possible to visualize a potential assembly of the magnetic detector (16), the associated acquisition and processing electronic card (17), in order to allow a presentation of the results on the light strips (15) . An independent power source (18) supplies the magnetic detector (16) and the electronic card (17). The cuts along the planes (b) and (c) make it possible to realize the interest of the proposed assembly for the magnetic detector (16) in order to preserve an orifice (11) through the entire measurement box (10) according to the detection axis.

- The present TV picture is seen in the XY plane (left part) and the details in the XZ plane (right part) of the plate (0) equipped or not with two pads (20). The studs

(20) are inserted into the holes, so that the magnetic pads (21) are in the center of the holes in the XY plane (left side). The studs (20) inserted into the holes do not form over-thickness with respect to the plates along the Z axis (left side).

- Figure V. shows a stud (20) in detail in the XY plane (top part) and in the YZ plane (bottom part). The magnetic pellet (21) of toroidal shape is placed in the center of the stud in the XY plane and close to the upper surface of the stud along the Z axis. The hole (22) is in the center of the stud. In the case of different magnetic pellet shapes (21), different hole positions (22) could be considered. Finally, the position of the fins (23) are indicated relative to the plate (0). Depending on the shape of the hole in the plate (0), different fin configurations (23) could be envisaged.

- Figure VI shows two situations of use of the device according to the invention in the XZ plane. To simplify the drawing, neither the bone nor the soft tissues are represented. The recessed arrow indicates the possible movements of the measuring box. Two holes of a plate (0) are equipped with studs (20), a hole is left free. In the upper part of the figure, the measuring box (10) is placed in front of the hole which is not equipped with a stud (20). The result of the detection indicated on the light strips (15) is negative. In the lower part of the figure, the measuring box (10) is placed in front of a plate portion (0) which has no hole and is far from a hole equipped with a stud (20). The result of the detection indicated on the light strips (15) is negative.

Figure VII shows two other situations of use of the device according to the invention in the XZ plane. To simplify the drawing, neither the bone nor the soft tissues are represented. The recessed arrow indicates the possible movements of the measuring box. Two holes of a plate (0) are equipped with studs (20), a hole is left free. On the upper part of the figure, the measuring box (10) is placed close to a hole equipped with pad (20). The result of the detection presented on the light strips (15) indicates this proximity. In the lower part of the figure, the measuring box (10) is placed in alignment with the hole equipped with a stud (20). The result of the detection indicated on the light strips (15) is positive and determines an alignment between the position of the orifice (11) and the magnetic chip (22), along the Z axis.

FIG. VIII shows a situation of use of the device according to the invention similar to that presented in the lower part of FIG. VII. To clarify the understanding of use, a portion of bone (32) and soft tissue (31) are shown. Only one hole of the plate (0) is equipped with a stud (20), the other holes are left free. In the upper part of the figure, in the XZ plane, the measuring box (10) is placed facing the hole equipped with the stud (20). The result of the detection indicated on the light strips (15) is positive and indicates an alignment between the position of the orifice (11) and the magnetic chip (22), along the axis Z. A marker (30) can therefore to be introduced into the orifice (11) in order to locate on the skin (31) the measured position. On the part bass of the figurative, in the XY plane, the measuring case

(10) is removed, as is the marker (30). The mark, a cross on the skin (31), is clearly visible and allows the surgeon to make a precise incision to discover the stud (20 /) and remove it before placing a drill sleeve.

With reference to these drawings, the device according to the invention consists of two parts: a measuring box (10) and pads (20).

The measuring box (10) consists of a magnetic detection unit whose measurement result is unambiguously presented to the surgeon by light strips (15). Indeed, if a single bar is illuminated, the detection unit is on and calibrated, but detects nothing: no magnetic pellet. If, against all bars are illuminated, this ^indicates a maximum of magnetic detection, thus detecting a magnetic chip. In a variant of the device according to the invention, a sound code could also indicate the result of the measurement; serious sounds: low measurement so no lozenge; acute sound: maximum measurement, so detection of a pellet. The measuring housing is traversed by a cylindrical orifice (11), from one side, along the main axis of the detection unit (16). On each of the faces of the housing, an arrow (14) materializes the main axis of the orifice (11).

The detection unit of the measurement box (10) consists of a magnetic detector (16) which is supplied with electrical energy (18) θt, the acquisition and processing of the signal of which are provided by a card electronic (17). The 'shape of the magnetic detector (16) ^is defined about a central hollow axis (port 11) which allows the passage of a marker through the measurement casing. The inside diameter of the orifice (11) is typically of the order of one centimeter. The magnetic detector (16) itself consists of four soft iron cylinders each surrounded by a coil and all interconnected. The magnetic detection maximum is thus achieved in the center of the orifice (11).

A typical voltage of the order of ten volts, delivered by the power supply (18) is sufficient for the proper functioning of the magnetic detector (16). The measuring case (10) consists of a rigid shell pierced with two orifices (11) and provided with the various instruments (12, 13, 14 and 15). Typical dimensions of the measuring case (10) are: length about twelve centimeters, width about five centimeters and thickness about two centimeters. The measuring case (10) can be placed in a disposable sterile envelope, adapted to its dimensions. A sterile disposable cannula can be placed in the port 11 to complete the sterile isolation of the measurement housing (10). These features make it possible to ensure optimal use of the measurement box (10) in the context of an operating room, while preserving great flexibility of manipulation for the surgeon.

The pads (20) are made of a material that is neutral from a magnetic point of view, for example polyethylene, and compatible with their use for "plugging" temporarily the holes of the orthopedic plates. The studs are small cylinders (24) whose thickness is equivalent to that of the plates (a few millimeters) and _ Q _ whose diameter is compatible with their insertion into the holes of the plates. Perimetric fins (23) keep the studs (20) in position within the hole. In the center of the studs, a magnetic chip (21) is arranged in such a way that the magnetic field emission is maximum in the center of the studs (20). The magnetic chip (21) may consist of a magnet shaped torus around the central axis (22) of the pads (20). Finally, a hole (22) is left free in the center of the studs (20) to allow the removal of the studs (20) with a pointed tip and threaded. After determining their positions, the studs (20) must be removed, after making an incision in the skin and soft tissues, and before the placement of the drill sleeves.

In a variant of the device according to the invention, the pads (20) can be replaced by washers, equipped with magnetic pads (21) on their perimeter and inserted into the screw holes on the plates. The washers allow the detection of the position of the through holes of the plate locking screws and may possibly not be removed, the screws passing through. This variant is particularly suitable for deep operations.

The device according to the invention is particularly intended for locating the position of the orthopedic plate fixation holes used for osteosynthesis operations.

Claims

Device for the magnetic detection and the percutaneous measurement of the position of the holes for the passage of the locking screws of an orthopedic plate, characterized in that it comprises a measurement box (10) equipped with a detection unit magnet (16) and pads (20) equipped with magnetic pads (21) intended to be placed in the center of holes of the plate to be detected.

2- Device according to claim 1, characterized in that the measuring housing (10) is autonomous (operating on batteries or batteries - 18), manipulated with one hand and that its operation is compatible with use in sterile environment by the addition of a sterile disposable envelope adapted to its dimensions and a sterile cannula in the orifice (11) to complete its sterile insulation.

3- Device according to any one of the preceding claims, characterized in that the magnetic detection unit (16) is designed around a hollow central tube

(11) which allows the detection of the maximum magnetic flux at its center and the passage of a marker or any other instrument, and in that the measuring box (10) itself has orifices along the axis of the tube central (11) of the magnetic detection unit (16).

4- Device according to any one of the preceding claims, characterized in that it is equipped with light strips (15) and / or a sound code system presenting the surgeon the result of the measurement magnetic flux in a simple and unambiguous manner in visual (15) and / or auditory mode.

5. Device according to any one of the preceding claims, characterized in that the measuring box (10) is equipped with a push button (12) which gives access in a simple manner to a function for calibrating (12) the unit. detection and a start function (13).

6. Device according to claim 1, characterized in that the studs (20) consist of a material which is neutral from a magnetic point of view and in that they serve as a support for magnetic pads (21) arranged in such a manner that they are in the center of the holes to be measured, once the studs inserted in the holes the orthopedic plates.

7- Device according to any one of the preceding claims, characterized in that the pads (20) can be inserted into the holes of an orthopedic plate and are held in place by fins (23) of suitable shape.

8- Device according to any one of the preceding claims, characterized in that the studs (20) are equipped with a hole (22) for removing them from a plate set up, after making an incision in the soft tissues. .

9- Device according to any one of the preceding claims, characterized in that the pads (20) are made of a material compatible with use in a sterile medium. 10- Device according to claim 1, characterized in that the pads. (20) may optionally be replaced by washers equipped with magnetic pads on their perimeter and which have the same properties as the pads (20).