Surgical nail

The invention relates to a surgical nail, particularly an intramedullary nail, according to the general concept of claim 1.

5 Interlocking of intramedullary nails belongs to state of the art The introduction of the screws or interlocking bolts (hereafter only we will use the concept of interlocking screw that, not However, you must also understand the bolt concept of

10 interlocking) in the nail cross holes intramedullary is done well with the help of a procedure imaging (radiological control), either with a more or less complicated pointing device. In both cases you cannot avoid a certain inaccuracy of aim,

fifteen namely, the screw tip cannot be oriented from exactly coaxial way with respect to the central axis of the transversal drill, but with a slight deviation from the same. To get the interlocking screw, despite of this failure of aim, can lead to the drill

twenty transverse and can pass through it, the outside diameter of the screw is subdimensioned with respect to the diameter of the cross drill. In case the lack of precision in the picture of this subdimensioning, the screw of interlocking can pass through the drill without problems

25 transversal, despite this failure of aim. Nevertheless,

now the interlocking screw presents a certain set with respect to the transversal drill, caused by the subdimensioned.

This game defines the extent to which the fragments main bones that are fixed in the holes of corresponding interlocking by means of the screws interlocking, they can move with respect to the nail and with this, due to the stiffness of the nail, also with respect to the other main bone fragments, fastened with the same nail To ensure the applicability of interlocking for the surgical, this game is indispensable, however, clinically, it is not desired with certain indications (for example in the case of fragments metaphyseals).

Even nails with full cross section that may have an internal thread in the hole interlocking, they are not free game. Internal thread only prevents the nail can move axially on the locking screw.

WO 2004/098424 AESCULAP ​​(basis for the general concept of claim 1) has disclosed a intramedullary nail with a fixation body to receive a locking screw.

For US 6,296,645 HOVER ET AL. a nail is known intramedullary hollow metal that presents in the holes of transverse bore wrap, diametrically opposed and designated as "windows", one or two material inserts

plastic through which you can enter the

locking screw. A disadvantage of this nail known intramedullary is the fact that the inserts of plastic similar to windows can be crushed under the loads that occur in the clinical application, so You miss the desired function. But even during a very prudent handling of the two plastic inserts they should be pushed out of their "window" to be pierced by the interlocking screw, which leads also a loss of function.

The intention of the invention is to remedy this. He object of the invention is to provide a surgical nail, especially an intramedullary nail, whereby the existing clearance between it and the locking screw can be eliminated without risk and a force can be reached improved retention between the locking screw and the intramedullary nail, without the user having to apply a increased precision in your work.

<dl><dt>The </dt><dd>invention solve East object through a nail </dd></dl>

<dl><dt>surgical </dt><dd>what presents the characteristics from the </dd></dl>

<dl><dt>claim 1. </dt><dd /></dl>

This allows the following advantages to be achieved:

a) The accuracy of aiming when inserting the screw interlocking is not altered.

b) The nail and the insert can be packed separately from sterile way and the surgeon can choose if you want use the nail without insert or with insert. If later, the surgeon can introduce the

inserted inside the nail and eventually it can also

take it off. In case the surgical uses the nail without the insert, it is still sterile packed for further use. In this way, the doctor still You can choose during the operation if you want to proceed to an interlock with angular stability of the screw interlocking or not, in which case "angular stability" It means a limitation of certain degrees of freedom.

c) Possibility of fixing with angular stability of the bone fragment in certain directions for a certain amount of cargo. A further preferred embodiment of the invention

it consists in the fact that the insert is made in shape of rod and can be introduced through the drill length of the nail to the area of ​​the holes transversal. The surgeon can insert the insert even after having implanted the nail (without insert), advancing the insert from a position proximal in the longitudinal hole to the area of ​​the cross drills.

The material m of the insert preferably has a lower resistance to pressure fd &lt;Fd, as well as lower tensile strength fZ &lt;FZ than material M.

The modulus of elasticity "e" of the insert is preferably "e" &lt;0.8 E and typically "e" &lt;0.7 E.

In a particular embodiment, the material m of the insert consists of a biocompatible plastic material, preferably of a polyethylene or a polyethylene of

elevated molecule (HMWPE). This has the advantage of not

a disintegration of the plastic material occurs with unknown decay products.

In an alternative embodiment, the hard material reduced, inserted into the longitudinal nail drill hollow, it consists of a bioresorbable plastic material that is preferably a polylactide. With this realization it turns out in a first time a transversal interlocking without play of the intramedullary nail which is then reduced successively with the increase in polymer resorption, of way that the cross locking screw, and also the provisioned bone fragments, return to be able to move with respect to the intramedullary nail. Thus performs a dynamization of bone fragments, then of fracture consolidation.

An additional advantage of bioresorbable material is that the chips generated by screwing the interlocking screw through the nail can be catabolized by the body.

In an additional embodiment, the nail it comprises at least two transverse holes, so preferably at least three cross drills.

One of the cross holes can be configured also as an elongated hole with the section profile transverse F, the longest dimension "a" being arranged of the elongated hole in the axial direction of the nail.

Preferably, the material "m" of the insert also it has a lower density p1 than material M with

a density p2, preferably p1 &lt;0.8 p2.

The nail may comprise an interlocking screw or interlocking bolt that can be inserted into the hole transverse (with the transverse profile F) and through the insert, and whose outer thread, or respectively whose stem without thread, has an outside diameter "d" that meets the condition a&gt; d &lt;b.

The diameter of the longitudinal nail drill in direction of its central axis can be performed so variable and the longitudinal drill can comprise preferably a circular stop.

In an additional embodiment, the insert in rod shape can also comprise a deepening that extends radially, transversely with with respect to its longitudinal axis. Thanks to this deepening, an interlocking screw or interlocking bolt can focus more easily and be screwed through the insert, and less shavings of material "m" are generated.

The insert can also comprise several deepening which are arranged identically to the drills transverse of the nail.

In an additional embodiment, the insert in Rod shape can be made in conical shape. Thank you in this way, the insert can be introduced more easily from the distal position in the longitudinal bore of the nail, and also a pressed adjustment is possible.

In an additional embodiment, the insert in rod shape and nail wall have a means

complementary, preferably in the form of a groove and a

corresponding protuberance, which fixes the insert so rotary in a predetermined position with respect to nail.

The rod-shaped insert may comprise one or several bumps that extend in the radial direction, transversely with respect to its longitudinal axis. These bumps may be arranged identically to the cross holes in the nail. The bumps they have a transverse extension “x” that, in a way advantageously, it is in a relation 1 &lt;x / q &lt;2, being "q" the diameter of the insert (7). The advantage of this embodiment it consists in the fact that, when the insert is introduced in the longitudinal nail drills, the bumps are interlock in the cross holes, so that the insert is positioned securely and strictly in the nail. Additionally, the increase in the volume of displacement leads to an improved retention force, to know, greater angular stability.

The nail can be made available to the surgeon already with an insert inserted in its longitudinal hole, to the area of ​​the transversal drills, or alternatively in the form of pieces packed so separated.

The nail can be used together with a screw

<dl><dt>from </dt><dd>interlocking with a stem from screw and a thread </dd></dl>

<dl><dt>Exterior, </dt><dd>applying for he diameter d from the thread the </dd></dl>

<dl><dt>condition </dt><dd>a&gt; d &lt;b, being "D" preferably to the less 5% </dd></dl>

<dl><dt>less than the smaller of the two dimensions a, b. </dt><dd /></dl>

For the manufacture of the nail, from the tip top or bottom of the nail (of material M) can introducing a solid body of a material "m" into the longitudinal nail drill, so that the solid body get to rest at least in the area of ​​one of the drills transverse of the nail.

Next, the invention and further embodiments of the invention are described in detail with reference to the partially schematic representations of several examples of realization. In the drawings:

Figure 1 shows a longitudinal section through a hollow intramedullary nail, partially filled with a softer material;

Figure 2 shows a cross section of the nail intramedullary in the area of ​​the transverse drill;

Figure 3 shows an insert of a subject biocompatible plastic for introduction from the position distal in a hollow intramedullary nail with countersunk radial, respectively drills, according to the

<dl><dt>position </dt><dd>from the drills transversal in he nail </dd></dl>

<dl><dt>intramedullary; </dt><dd /></dl>

<dl><dt>Figure 4 </dt><dd>sample a cut cross of the nail </dd></dl>

<dl><dt>intramedullary </dt><dd>in the zone of the drill cross with a </dd></dl>

rotary lock insert;

Figure 5 shows a view of an insert with rotary lock of a biocompatible plastic material for the introduction from the distal position in a nail

intramedullary hollow with radial bulges according to

<dl><dt>the </dt><dd>position from the drills transversal in he nail </dd></dl>

<dl><dt>intramedullary; </dt><dd /></dl>

<dl><dt>Figure 6 </dt><dd>shows a longitudinal section through </dd></dl>

an insert of a biocompatible plastic material for introduction from the proximal position in a nail intramedullary hollow;

Figure 7 shows a rotated longitudinal section of 90º through the insert of figure 6, and

Figure 8 shows a view of an insert for the introduction from the proximal position in a nail intramedullary hollow.

The surgical nail 1 shown in Figure 1 is a intramedullary nail for long bones with a central axis 2 consisting of a material M (metal or metal alloy) and It presents three transversal drills 5 with a diameter D and a transverse axis 6 and extending transversely with with respect to the central axis 2.

A fourth cross drill is arranged so proximal and configured as elongated hole 20, being arranged the longest dimension in axial direction. Two of the three transverse holes 5 are arranged in the distal part of the intramedullary nail 1.

The intramedullary nail comprises a longitudinal bore 3 extending in coaxial direction with respect to the axis central 2, and a wall 4 therethrough. In this drill longitudinal 3, from the distal position, a rod-shaped insert 7 (figure 3) in the form of a

solid one-piece body consisting of a

resorbable polylactide, so that the longitudinal drill 3, in the area of ​​the two distal transverse drills 5, be filled with precision adjustment of a material m of a reduced resistance, particularly a module of reduced elasticity (compared to material M of intramedullary nail). However, a pressed material adjustment m.

As shown in Figure 1, a screw of interlocking 21 with rod 22 and external thread 23 it can be screwed into the cross hole 5, and with it through insert 7.

The insert 7 comprises a longitudinal bore 8 continuous, coaxial with respect to its longitudinal axis 13, and which in its distal limb comprises an enlargement 11 in hemisphere shape, with a stop 10 in the proximal direction. The stop 10 of the extension 11 guarantees a axial safe positioning of the insert 7 in the hole longitudinal 3 of the intramedullary nail.

Insert 7 comprises four radial deepening 12 that extend transversely with respect to the axis longitudinal 13 and are arranged axially in such a way they get to rest at the same height as the drills cross-sections 5 of the intramedullary nail when insert 7 is inserted as far as the stop 10 in the longitudinal bore 3. So that the deepening 12 are aligned with the holes 5 also radially, the insert 7 has a profile 15, as depicted in figure 2, which

corresponds to a profile 16 in the longitudinal bore 3 of the

intramedullary nail, so that insert 7 can enter the longitudinal hole 3 only in one certain rotary position.

As shown in Figure 4, the insert 7 and the longitudinal drill 3 of the intramedullary nail, instead of profiles 15, 16 in the form of flattening, can also comprise two nerves / grooves 17, 18 that have the same rotation blocking effect.

An alternative of insert 7 is illustrated in Figure 5 of Figure 3, in which, instead of the deepening 12, 14 bumps are present which, thanks to their elasticity, can be embedded in the openings of the cross holes 5 on wall 4, so that you can also obtain an axial and rotary locking of the insert 7. The protuberances have a transverse extension x that is in a relation 1 &lt;x / q &lt;2, being "q" the diameter of insert 7.

In figures 6 and 7 another insert 7 is shown alternative that can be introduced into the drill longitudinal 3 of the intramedullary nail from a position proximal instead of distal. The insert comprises a drill

<dl><dt>longitudinal </dt><dd>axial 8 A) Yes as a elongated hole 19 what </dd></dl>

<dl><dt>corresponds </dt><dd>with he hole elongate twenty in he nail </dd></dl>

<dl><dt>intramedullary </dt><dd>1. He hole elongate 19 has shape </dd></dl>

approximately elliptical with a long axis a and a short axis b. An additional form of realization of an insert 7 presenting approximately the

same length as the intramedullary nail and, with it, covers

all cross drills 5 (drills of interlocking) of the intramedullary nail from proximal to distal The insert 7 is fixed by means of a thread 24 in the proximal area of ​​insert 7 in the hollow intramedullary nail.

5 If necessary, the insert 7 can also be cut during operation -. -