MX2014000820A

MX2014000820A - Positioning device for screws used to fasten an endomedullary nail.

Info

Publication number: MX2014000820A
Application number: MX2014000820A
Authority: MX
Inventors: Franco Mingozzi; Alan Dovesi; Alberto Scoccianti
Original assignee: Citieffe Srl
Priority date: 2011-08-01
Filing date: 2012-07-31
Publication date: 2014-02-27
Also published as: MX343313B; ITBO20110481A1; BR112014002507A2; CO6862120A2; BR112014002507B1; WO2013018026A1

Abstract

A positioning device for screws used to fasten an endomedullary nail (2) having a principal direction of extension (A2) and presenting at least one hole (DH1, DH2) for the passage of the screws, comprises an arm (5) which is connectable to the nail (2), a bar (6) mounted at a first end of it (6a) to the arm (5) and extending substantially parallel to the principal direction of extension (A2) of the nail (2), an alignment head (7) mounted in the vicinity of a second end (6b) of the bar (6) opposite the first end (6a), the head (7) being made at least partly of a radio-transparent material, having at least one hole (13, 13', 14, 14') for guiding the fastening screws and being movable relative to the nail (2) through the agency of respective adjustment means (8) in order to bring the at least one guide hole (13, 13', 14, 14') into alignment with the at least one passage hole (DH1, DH2).

Description

POSITIONING DEVICE FOR USED SCREWS TO FIX AN ENDOMEDULAR NAIL FIELD OF THE INVENTION The present invention relates to a positioning device for screws used to fix intramedullary nails.

BACKGROUND OF THE INVENTION The use of intramedullary or intramedullary nails to support fractures in long bones is known in the surgical field.

These nails should be fixed in place in relation to the parts of the bone in which they are inserted. This is done by means of screws that pass through the nail at different points along its length.

Although the fixation of the proximal screws (usually the screws closest to the nail insertion end) is relatively simple, the insertion of the distal screws - those used to hold the part of the nail most deeply inserted into the bone - is a much more complex operation.

In order to center the distal screws inside the holes made for them in the nail, the prior art teaches the use of positioning devices which normally comprise a plurality of parts that can be adjusted in such a way that they can be fixed under a configuration of substantial centering with respect to the holes.

In other words, using these positioning devices, the surgeon can identify with a good degree of accuracy the position of the nail and the respective holes in the bone and therefore can insert the screw more easily.

In practice, the positioning devices have marks or holes that must be aligned with the hole in the nail inserted in the bone since, considering the inherent flexibility of the nail, the holes aligned before inserting the nail often become misaligned during the Real insertion, when the nail tends to bend.

To this end, devices known as brightness amplifiers (image intensifiers) are commonly used.

A brightness amplifier is a real-time X-ray direct vision instrument and is therefore available in the operating room. It provides one or more substantially instantaneous images with which the surgeon can align the positioning device with respect to the nail step by step.

The previous patented documents EP 1499249 and EP 1719465, the last one in the name of the same applicant as the present invention, reveal the use of positioning devices, where an external arm is fixed to the nail to be inserted into the bone while the arm itself ride a bar which, in use, extends substantially parallel to the bone and the nail inserted into the bone.

At the distal end, the bar has a head where guide holes are provided for the distal screws to be inserted and which can be adjusted in order to allow the holes to be aligned with the corresponding holes in the nail.

The head is made of a radio-transparent material.

Both of these previous patented documents describe the presence, in the positioning head, of radio-opaque marks adapted to allow initial alignment between the beam emitted by the brightness amplifier and the guide holes in the head.

Both devices described in the previous patents documents EP 1499249 and EP 1719465 are not, however, free of disadvantages.

In particular, because of the very nature of their structure, these solutions can not guarantee an error-free or particularly rapid alignment. In fact, the alignment may involve repeated exposure to radiation (emitted by the brightness amplifier), which is dangerous both for the patient and for the medical staff.

SUMMARY OF THE INVENTION According to the invention, the disadvantages of the prior art are overcome by means of a positioning device comprising the technical characteristics described in one or more of the appended claims.

The technical characteristics of the invention, according to the above-outlined object, can be clearly inferred from the content of the appended claims, in particular claim 1 and, preferably, any of the claims directly or indirectly subordinated to claim 1 .

BRIEF DESCRIPTION OF THE DRAWINGS The benefits of the invention will become more apparent from the detailed description that follows, with reference to the accompanying drawings which illustrate a preferred, non-limiting embodiment of the invention, in which: - Figure 1 is a schematic perspective view illustrating the positioning device according to the invention, in combination with a long bone such as a femur, for example; - Figure 2 is a schematic front view, with some transparent parts in order to better illustrate others, of the device positioning of Figure 1, combined with a femur, which is also illustrated transparent; - Figure 3 is a schematic perspective view of a detail of the positioning device of the previous figures; - Figure 4 is a schematic side view of the detail of the Figure 3; - Figure 5 is a cross-sectional view of the detail of Figure 4 through the line V-V; - Figures 6 and 7 are two plan views, from above and below, respectively, illustrating the detail of Figures 3 to 5; - Figures 8 to 10 illustrate, in respective schematic views with some parts trimmed for clarity, three different stages in the use of the device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to the accompanying drawings, the reference numeral 1 denotes a complete positioning device according to the invention, combined with an intramedullary nail 2 of known type.

As an example, nail 2 is inserted into a femur 3.

The nail 2 is inserted into the femur 3 in a substantially known antegrade manner, for example to support a femur fracture and, as illustrated in Figure 2, it has two proximal fixation screws 4, that is, two screws close to the head 3a of the femur 3, already in place.

As illustrated in Figure 2, the two proximal fixing screws 4 are inserted into holes PH specially made in the nail 2 for the passage of the screws themselves.

The nail 2 has a longitudinal main extension direction A2.

The positioning device 1 comprises an arm 5 that can be connected to the nail 2 and a bar 6 mounted by a first end 6a to the arm 5.

The bar 6 extends substantially parallel to the main extension direction A2 of the nail 2.

The bar 6 has a second end 6b longitudinally opposite the first end 6a.

At the second end 6b the bar 6 mounts a head 7 to align and guide the distal locking screws.

The distal fixation screws, not shown in the accompanying drawings, are designed to fix the end of the nail 2 to the distal part 3b of the femur 3, passing through the respective holes DH1, DH2 made in the nail 2, as illustrated in FIG. Figure 2 The head 7 is connected to the bar 6 by a sliding device 8 designed to slide the head 7 relative to the bar 6 along a direction A7 substantially perpendicular to the direction of extension of bar 6 itself.

The sliding device 8 comprises a screw driving element 9 by means of which the head 7 slides along the direction A7.

For a complete description, both structural and functional, of the sliding device 8, the reader is referred to the aforementioned document EP 1719465 in the name of the same applicant as the present invention.

The head 7 is made of a radio-transparent material and has a substantially cylindrical body 10 and an eye 11 projecting from the body 10.

Through the eye 1 1 the head 7 is connected through a screw element 12 to the bar 6 and, more precisely, to the sliding device 8.

On the body 10 of the head 7 there are two pairs of holes 13, 4 and 13 ', 14', hereinafter referred to as pilot holes because of their dual function of guiding the distal screws during their application and guiding and / or housing the instruments used to position and insert them correctly.

The guide holes 13, 14 and 13 ', 14' are through holes and their longitudinal extension is interrupted by a lighting cavity 10a formed in the body 10.

The guide holes 13, 14 and 13 ', 14' are conveniently arranged symmetrically in a mirror on a median plane (not illustrated) common to the head 7 and bar 6 and perpendicular to direction A7.

More specifically, conveniently, the pairs of holes 13, 14 and 13 ', 14' are arranged in two lines L, L 'which are slightly diverging from one another through an angle equal to the angle of deviation of the distal portion of the nail 2. with respect to the plane mentioned above.

In addition, the distance between the holes 13 and 14 and between the holes 13 'and 14' is equal to the distance between the through holes DH1, DH2 made in the nail 2.

In practice, the choice of using the pair of holes 13, 14 or 13 ', 14' to guide the screws depends on the direction of the deviation angle of the nail, according to whether the nail should be inserted in a right or left bone. .

As illustrated in Figures 1 and 2, placed in one of the guide holes 13, 13 ', 14, 14' there is a removable element 15 which is designed, as explained in detail below, to facilitate the correct alignment of the holes guide 3, 13 ', 14, 14' in relation to the corresponding through holes DH1, DH2 made in the nail 2.

The removable element 15, clearly illustrated in Figures 3-7, comprises a substantially cylindrical central body 16 made of a radio-transparent material and having a central axis A16.

The removable element 15 has a first and second flange, called 17 and 18 respectively, which extend radially from the central body 16 and are separated from each other along the direction defined by the arrow A16.

The first flange 17 is disposed at an intermediate position between two longitudinally opposite ends 15a, 15b of the removable element 15 and designed to define a reference stop against the alignment head 7, as clearly illustrated in Figures 1 and 2.

The second flange 18, on the other hand, is disposed at the end 15a of the farthest element 15 of the bone 3 and of the nail 2.

Conveniently, at its end 15b closest to the bone 3, the removable element 15 has a rounded tip adapted to come into contact with the patient's skin, if necessary, without causing abrasions or injuries of any kind.

Conveniently, although not necessarily, to facilitate its production, the removable element 15 is made in two parts connected together, for example by screwing, as clearly illustrated in Figure 5.

The cavities filled with a radio-opaque material in the removable element 15 form a plurality of radio-opaque portions that define visible marks through the images obtained from the brightness amplifier.

More specifically, a first radiopaque portion 19 is formed near the end 15b with the rounded tip.

Conveniently, the shape of the first radiopaque portion 19, and as a result of the respective image visible through the brightness amplifier, it is substantially punctate.

A second radiopaque portion 20 is formed on the first flange 17.

Conveniently, the shape of the second radiopaque portion 20, and consequently of the respective image visible through the brightness amplifier, is approximately circular, with a plurality of projections projecting from the respective circumference.

A third radiopaque portion 21 is formed on the second flange 18.

Conveniently, the shape of the third radiopaque portion 21, and consequently of the respective image visible through the brightness amplifier, is substantially circular.

The three radio-opaque portions 19, 20 and 21 have a single central axis, axis A16, common to all three, and consequently appear concentric to an observer at a point in line with axis A16 proper.

In use, thanks to the positioning device 1 according to the invention, a guide hole 13, 13 ', 14, 14' for the distal screws can be aligned quickly and effectively with the matching passage holes DH1, DH2 formed in the nail 2 .

More specifically, once the nail 2 has been inserted into the Femur 3 and the proximal screws 4 have also been inserted, it is necessary to proceed to align the brightness amplifier (not illustrated) in relation to the removable element 15 that has already been inserted in one of the guide holes 13, 13 ', 14, 14 'in the head 7.

In the example illustrated in the accompanying drawings, the guide holes 13, 14 must be aligned with the matching passage holes DH1, DH2.

As illustrated for example in Figure 8, which represents in schematic form a first image obtained from the brightness amplifier, the removable element 15 is arranged in a random position, misaligned with the main emission direction of the brightness amplifier.

For this reason, the three radio-opaque portions 19, 20, 21 present at different points of the removable element 15 are not concentric.

By suitably adjusting the position of the emission head (not shown) of the brightness amplifier, it is possible to adjust the image (Figure 9) so that after three radio-opaque portions 19, 20, 21 are arranged in a concentric configuration. This image represents the position where the direction of emission of the rays of the brightness amplifier is aligned with the central axis A16 of the removable element, the axis in relation to which the three radio-opaque portions 19, 20, 21 are concentric.

Figure 9 illustrates a condition of substantial parallelism between the direction of emission of the brightness amplifier beams and the guide holes 13, 13 ', 14, 14' present in the head 7. This situation minimizes the positioning problems of the distal screws due to the parallax error, that is, in other terms, the measurement error due, in the specific case, to the non-coplanar position of the holes to be aligned.

Starting from the aligned configuration illustrated in Figure 9, the operator (in practice, the surgeon) must adjust the sliding device 8 to fix the head 7 so that the three radio-opaque portions, now concentric with each other, are aligned with , for example, the through hole DH1.

More specifically, in the described embodiment, in order to arrange the distal screws correctly, the punctate radiopaque portion 19 should be aligned with the center of the through hole DH1. This configuration is illustrated in Figure 10.

Thus, for the positioning device 1, the sliding device 8 constitutes the adjustment means for aligning at least one guide hole 13, 13 ', 14, 14' with at least one matching passage hole DH1, DH2.

At this point, the removable element 15 can be extracted from the guide hole 13 where it was inserted. The hole 13 itself is released so that it can guide and accommodate the surgical instruments necessary to prepare for the insertion of the distal screw (not shown) into the hole DH1.

Once the distal screw has been inserted into the DH1 hole, a second distal screw may, if necessary, be inserted into port DH2 simply using port 14 as a guide for surgical instruments and the distal screw itself, obviously provided that the distance between centers between ports 13 and 14 in the head 7 be compatible with the real distance between holes DH1, DH2.

The described invention has important advantages.

A first benefit is that since the removable element 15 extends beyond the head 7, to and from the patient's body (see Figure 1), the precision obtained in aligning the guide hole with the brightness amplifier is greater that achievable with prior art devices, where the radio-opaque portions are disposed exclusively in the head.

Another inherent benefit of the device 1 according to the invention lies in the presence, in the removable element 15, of an extension towards the patient's body. This extension considerably allows the position of the radio-opaque portions - at least of the first portion 19 - to the actual position of the nail 2 (and of the holes DH1, DH2 therein) considerably. This circumstance, also, contributes to increase the positioning accuracy of the guide hole in relation to the through holes in the nail.

Conveniently, on the other hand, the removable element 15 can also be used, depending on the size of the patient's member, to apply a certain amount of pressure on the patient's skin - thanks to its rounded tip - in order to get very close to the bone where the nail is placed.

Conveniently, the positioning device 1 has removable elements 15 of different lengths to adapt to different body structures of the patient. In other words, according to the amount of soft tissue in the limb subject to the surgery, it is possible to select a removable element 15 of the most suitable length to get as close as possible to the bone.

In the present description, the term "flange" is used exclusively to indicate a zone of greater diameter projecting from the central body of the removable element and substantially coaxial with it, that is, without any reference to the possible connection between two or more lashes, as could be inferred by considering the word "tab" in its broadest sense.

The disclosed invention has obvious industrial applications and can be modified and adapted in various ways without departing from the scope of the inventive concept. On the other hand, all the details of the invention can be replaced by technically equivalent elements.

Claims

1. A positioning device for screws used to fix an intramedullary nail (2) having a main extension direction (A2) and having at least one hole (DH1, DH2) for the passage of the screws, comprising an arm (5) ) that can be connected to the nail (2), a bar (6) mounted by a first end (6a) to the arm (5) and extending substantially parallel to the main extension direction (A2) of the nail (2), an alignment head (7) mounted near a second end (6b) of the bar (6) opposite the first end (6a), the head (7) is made at least partially of a radio-transparent material, possesses at least less a hole (13, 13 ', 14, 14') to guide the fixing screws and can be moved relative to the nail (2) by means of the respective adjustment means (8) in order to align at least one hole guide (13, 13 ', 14, 14') with the at least one through hole (DH1, DH2), characterized in that it comprises u a removable element (15) extending longitudinally along its central axis (A16), adapted to be inserted in the guide hole (13, 13 ', 14, 14') and emerge from the alignment head (7) in directed to the nail (2), the removable element (15) has at least two concentric radio-opaque portions (19, 20, 21) arranged at different points along the central axis (A16), at least one of the portions (19, 20, 21) is external to the head (7).

2. The positioning device according to claim 1, characterized in that the removable element (15) comprises a central body (16) and a first flange (17) extending from the central body (16) and adapted to define a stop for the head (7).

3. The positioning device according to Claim 2, characterized in that one of the concentric radio-opaque portions (19, 20, 21) is formed on the first flange (17).

4. The positioning device according to any of claims 1 to 3, characterized in that one of the radio-opaque portions (19, 20, 21) has a pointed shape and is disposed at the end (15b) of the element (15) closest to the nail (2).

5. The positioning device according to any of claims 1 to 4, characterized in that the removable element (15) comprises, near its end (15a) furthest from the nail (2), a second flange (18).

6. The positioning device according to the Claims 3, 4 and 5, characterized in that the three radio-opaque portions (19, 20, 21) present on the removable element (15), respectively on the two flanges (17, 18) and near its end (15b), they have a shape such as to be concentric for an observer in line with the central axis (A16) of the removable element itself (15).

7. The positioning device according to any of claims 1 to 6, characterized in that it comprises a plurality of removable elements (15) of different lengths.