WO2010133657A1 - Tool for gripping a rod-shaped implant in a minimally invasive surgical operation - Google Patents

Abstract

The present invention relates to a tool for gripping a rod-shaped implant (4) to be inserted in the body of a patient in the context of a minimally invasive surgical operation, characterised in that said tool includes a body (1) and a system (2, 3) for holding the implant (4) in the body (1) and in that said holding system includes a means for securing the implant (4) by adhesion.

Description

 TOOL FOR PREVENTING A STEM-SHAPED IMPLANT IN A MINIMALLY INVASIVE SURGICAL INTERVENTION

FIELD OF THE INVENTION The present invention relates to a tool for grasping an implant in the form of a rod, said implant being intended to be introduced into the body of a patient as part of a surgical procedure. minimally invasive. This tool is advantageously used in a percutaneous lumbar arthrodesis procedure.

BACKGROUND OF THE INVENTION

Lumbar arthrodesis involves immobilizing a fractured vertebra between two healthy vertebrae.

For this purpose, the intervention is to screw into the fractured vertebra and two healthy vertebrae located on either side of it, three pedicle screws whose U-shaped heads are aligned.

Once the screws are in place, a rod is inserted into the three screw heads, and then the rod is fixed by means of nuts screwed into the screw heads.

So we implant a total of six screws and two rods. In some cases, depending on the size of the fracture, no screws are implanted in the fractured vertebra; then four screws and two rods are used.

Until recently, this procedure was performed in conventional surgery, that is to say by making a long incision in the patient's back allowing the surgeon to manually deposit the rod in the three screw heads. However, because of the size of the incision (typically of the order of 15 cm), this type of intervention poses problems in terms of duration of intervention and convalescence, difficulty of healing and discomfort for the patient.

A percutaneous lumbar arthrodesis technique has therefore recently been developed. This technique is to practice in the patient's back only small incisions of sufficient size to allow the establishment of the screws on each vertebra and then the insertion of the rod in the screw heads.

In this case, the establishment of the rod can no longer be performed simultaneously in the three aligned screws.

It was therefore necessary to design a rod gripping tool allowing the surgeon to manipulate the rod until it is inserted successively into the screw heads, and to separate the rod from the tool at the end of the procedure.

Moreover, the section and the shape of the gripping part of the rod is different according to the manufacturers.

It is thus possible to observe rods having a hexagonal, square end, etc.

It is therefore necessary to provide a gripping tool that fits any existing stem section.

BRIEF DESCRIPTION OF THE INVENTION

According to the invention, there is provided a tool for gripping an implant having the shape of a rod intended to be introduced into the body of a patient in the framework of a minimally invasive surgical procedure, said tool being characterized in that it comprises a body and a system for holding the implant in the body and in that said holding system comprises means for locking the implant by adhesion.

Particularly advantageously, the holding system comprises a clamp adapted to take a so-called free configuration allowing insertion of the implant into the clamp and a locking configuration in which the clamp exerts a clamping force on the implant.

According to a preferred embodiment, the end of the implant-receiving clip has grooves, so that the clip is in its free configuration when the split end is free and in its locking configuration when the split end is compressed radially. The clip is movable in a longitudinal bore of the body between a position where the slotted end is free and a position where the slotted end is in a narrowed conical portion of said longitudinal bore.

Preferably, the clamp is actuated in the body by means of a control screw having a helical connection with the bore of the body.

The control screw and the clamp are rigidly connected; for example, the connection between the control screw and the clamp is provided by clipping the clamp on an eccentric of the screw.

The invention also relates to a percutaneous lumbar arthrodesis device, comprising:

pedicular screws intended to be fixed in adjacent vertebrae, each screw having a recessed head for the passage of an implant in the form of a rod,

- A rod for securing the heads of said screws, and - a tool for gripping the rod as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings in which: FIG. 1 illustrates the implantation of the pedicle screws and of the stem on vertebrae, FIG. A sectional view of the gripping tool according to the invention, in its position of holding the rod, Figure 3 illustrates different views of a preferred embodiment of the control screw.

DETAILED DESCRIPTION OF THE INVENTION

In this non-limiting example, a preferred embodiment of the invention will be described in connection with a percutaneous lumbar arthrodesis intervention. Figure 1 illustrates different stages of the percutaneous lumbar arthrodesis operation: the views 1 to 4 are sections at the level of the patient's spine during the different steps.

The device comprises pedicular screws known in themselves, and a rod diameter adapted to be inserted into the heads of the screws.

The stem can be supplied already cut to a given length, or delivered in the form of a long bar that the surgeon cuts to the desired length.

Typically, the rod has a circular section of 5.5 to 6 mm in diameter.

The view 1 of Figure 1 shows the placement of the pedicle screws 100 in the healthy vertebrae V1 and V2 on either side of a fractured vertebra VF.

For this purpose, it is practical, at the implantation of the screws, incisions in the back of the patient, a dimension adapted for the passage of the pedicle screws.

When the screw is fully screwed into the vertebra, only its head 102 exceeds, and the surgeon therefore uses an extender 101 to be able to handle it. Section 2 of Figure 1 illustrates the lordosis step, in which the surgeon exerts a leverage effect (illustrated by the arrows F1 and F2) on the extensions 101 to return the healthy vertebrae V1 and V2 to the position they occupied before the fracture.

Section 3 of Figure 1 illustrates the establishment of the rod 4 in the successive screw heads. The arrow F represents the insertion direction of the rod 4.

Finally, section 4 illustrates the state of the patient's spine after the procedure. The C mark represents cement possibly injected into the fractured vertebra to consolidate it (vertebroplasty).

The gripping tool is not shown in Figure 1, but it is used for the percutaneous placement of the rod 4 and its maintenance during the clamping steps in the screw heads 100.

Referring to Figure 2, the gripping tool has a body 1 having a handle for a good grip by the surgeon.

Inside the body 1 are arranged a control screw 3 and a clamp 2 which cooperate with the body 1 to allow the locking of the rod 4. The body 1 has a central bore whose inner diameter is slightly greater than the outer diameter of the control screw and the clamp. However, at the proximal end of the body 1, that is to say on the side where the rod 4 is inserted, the outside of the body has a rounded portion 10 narrowing. The clamp 2 has a generally cylindrical shape with a bore on the side of the rod 4 with a diameter slightly greater than that of the rod 4.

The clamp 2 further comprises longitudinal grooves 21 distributed around its periphery which allow easy deformation of the clamp 2, thus allowing easy insertion of the rod 4 when the clamp 2 is in a so-called "free" configuration, that is to say ie not constrained.

For example, the grooves 21 have a length of the order of 24.5 mm.

The control screw 3 is movable in translation and rotation in the body 1 by means of a helical connection provided by a thread 31 on the screw and a complementary thread in the body 1.

The screw 3 fits into the clamp 2.

In the example illustrated in Figures 2 and 3, the screw has at its end 32 an eccentric tip 33. It is housed in the clamp 2 which comprises, on the side of the screw 3, longitudinal slots 22 allowing its deformation for a clipping on the eccentric 33.

For example, the slots 22 have a length of the order of 15 mm.

The screw 3 and the clamp 2 are clipped together outside the body 1, prior to the use of the tool.

The screw 3 - clamp 2 assembly is then threaded into the bore of the body 1 side handle.

Of course, one could consider any other mode of connection between the screw and the clamp without departing from the scope of the present invention.

Before clamping and before insertion of the rod 4 into the clamp 2, the control screw 3 and the clamp 2 are slightly offset to the left with respect to the configuration of FIG. 2. In this preliminary situation, the grooves 21 are not tightened and the clamp 2 has sufficient clearance inside the bore of the body 1: the rod 4 can then be easily inserted into the clamp 2 on the side of the body endpiece 1.

The surgeon then performs a screwing of the screw 3 which has the effect of driving in translation the screw / clamp assembly, until the conical end of the clamp 2 comes into abutment against the conical inner portion 11 of the end of the body 1, which has the effect of tightening the bore of the end of the clamp 2 around the rod 4 by deformation of the grooves 21, thereby causing the locking of the rod 4.

The surgeon can proceed with the placement of the rod in the pedicle screws, then disengage the rod of the gripping tool by unscrewing the control screw 3.

As can be understood, this tool allows the gripping of any form of rod, as the latter has a circular section at least locally (not specifically at its end). For rods that do not have a circular section, it is easy to manufacture a specific clamp adapted to this other section of rod. The other elements of the gripping tool remain the same.

The modular nature of the tool then makes sense.

Moreover, it is of a particularly simple design and low cost.

The body 1, the clamp 2 and the screw 3 are chosen from rigid materials and biocompatible, sterilizable, for example as stainless steel.

Moreover, in order to limit the wear of the clamp, it will be advantageously realized in a harder material than that of the rod, for example stainless steel hardened and ground.

Thus, it is advantageous to use a stainless steel M390 ISOMATRIX hardened and ground for the clamp and not hardened for the rest of the tool.

Finally, it goes without saying that the examples that we have just given are only particular illustrations in no way limiting as to the fields of application of the invention. In particular, the intended medical field is not limited to percutaneous lumbar arthrodesis, but more broadly relates to any minimally invasive surgical procedure in which it is necessary to introduce a rod into the body of a patient. Thus, when introducing a centromedullary implantable device in a long bone, using a gripping tool as described above.

By way of example, current applications are stable elastic medullary nailing (ECMES) or Metaizeau nailing, osteosynthesis by proximal and diaphyseal femur, proximal and diaphyseal humerus, diaphyseal tibia, distal radius .

All implantations in long bones are potentially concerned by this application.

Claims

1. Tool for gripping an implant (4) having the shape of a rod intended to be introduced into the body of a patient as part of a minimally invasive surgical procedure, comprising a body (1) and a system (2, 3) for holding the implant (4) in the body (1), said holding system comprising means for locking the implant (4) by adhesion, characterized in that the holding system comprises a clamp (2) adapted to take a so-called free configuration allowing insertion of the implant (4) in the clamp (2) and a locking configuration in which the clamp exerts a clamping force on the implant, the clamp ( 2) being actuated in the body (1) by means of a control screw (3) having a helical connection with the bore of the body (1), and in that the connection between the control screw and the clamp is ensured by clipping the clamp (2) on an eccentric (33) of the screw (3).

2. Tool according to claim 1, characterized in that the end of the clamp receiving the implant (4) has grooves (21), so that the clamp is in its free configuration when the split end is free and in its locking configuration when the slotted end is radially compressed.

3. Tool according to claim 2, characterized in that the clamp is movable in a longitudinal bore of the body (1) between a position where the slotted end is free and a position where the slotted end is in a narrowed conical portion of said longitudinal bore.

4. Percutaneous lumbar arthrodesis device, comprising:

pedicular screws intended to be fixed in adjacent vertebrae, each screw having a recessed head for the passage of an implant in the form of a rod,

- A rod (4) for securing the heads of said screws, and - a tool for gripping the rod (4) according to one of claims 1 to 3.