Instrument for placing spheres of biomaterial in bone cavity comprises hollow cylindrical body with guide rod and piston

The present invention relates to a device for placing inside a given part of a bone small spheres of a biomaterial.

For the placement of certain implants or orthopedic fixtures such as a screw-plate system in a localized part of a bone, for example, in the head of the femur (femoral metaphysis), it is first necessary to with the aid of an auger, the housing which the implant or the orthopedic assembly will occupy subsequently, that is to say the screw and the barrel of the plate, in the particular example considered. To ensure the maintenance of the implant or the orthopedic assembly in its housing, it is necessary to introduce therein a biomaterial before introducing the screw or the implant, in order to stabilize the orthopedic assembly.

Currently, the filling of the housing with the biomaterial is carried out manually using a curette. The curette is handled in such a way that the existing bone defect is gradually filled. The biomaterial is pushed with a graft punch in different directions in order to better distribute this material in the housing. The arrangement of the material in the housing is controlled by an image intensifier.

We then slide the screw on the spindle which will then progress in the middle of the biomaterial risking either a conflict with the biomaterial (friction, pulverization of the material, metal particles which can become detached from the screw) or the entrainment of this material in the femoral head. , which is not desirable. In addition, the duration of the filling of the housing using the biomaterial by this technique is around 15 minutes.

It is therefore understood that this technique of placing the biomaterial in the housing using a curette and a graft stripper has many drawbacks. In particular, it increases the duration of the surgical intervention, in particular because of the checks to be carried out. In addition, the good distribution of the biomaterial in the housing is difficult to ensure.

There is therefore a real need for a device for placing the biomaterial in a predetermined part of a bone which makes it possible to accelerate the filling of the housing with the aid of the biomaterial and which makes it possible to improve the distribution. biomaterial inside the home.

To achieve this goal, according to the invention, the device for placing small spheres of a biomaterial in a given part of a bone is characterized in that it comprises:

. a cylindrical hollow body of internal diameter D1 having a first filling end and a second end provided with clipping means;

. a guide rod forming a closure comprising a cylindrical main portion of external diameter D2 and having, near its second end, an enlarged cylindrical portion capable of cooperating with the clipping means of the body to temporarily secure said rod in the body; and. a piston constituted by a cylindrical part having an external diameter D3 and an axial bore D4, the diameter D3 being slightly smaller than the internal diameter D1 of the body and the internal diameter D4 being slightly greater than the diameter D2 of the rod so that, after unclipping, said rod can slide in a sealed manner to the spheres inside said piston and that the piston can slide in a sealed manner to the spheres in the annular space between said rod and said body.

It is understood that thanks to the possibility of displacement of the body of the device relative to the rod and more precisely relative to its enlarged cylindrical part forming a shutter, it is possible to locate with precision the zone in which the spheres will be placed in the housing. It is also understood that thanks to the action of the piston, the external diameter of which is smaller than that of the body and therefore that of the housing, it is possible to obtain a good distribution of the spheres of the biomaterial against the wall of the housing.

According to a preferred embodiment, the rod has an axial bore opening into its second end without a portion which is widened over at least part of its length.

The axial bore of the rod makes it possible to guide the whole of the device during its introduction into the housing using a spindle which has been put in place beforehand.

Also preferably, said first filling end of the hollow body is extended by a part having a frustoconical recess opening into the axial bore of said body. This flared portion makes it possible to facilitate filling with the spheres of the annular space between the body and the rod in the manner of a funnel.

More preferably, said clipping means disposed at the second end of said body comprise longitudinal slots formed at the second end of said body and raised portions formed at the second end of said body and projecting into said axial bore, and said portion enlarged cylindrical rod has a substantially cylindrical side face in which is formed a groove suitable for receiving the raised portions of said body.

Other characteristics and advantages of the invention will appear better on reading the following description of a preferred embodiment of the invention given by way of non-limiting example. The description refers to the appended figures in which:

FIG. 1 is a top view of the body of the device for placing the biomaterial;

Figure 1A is a side view of the body of Figure 1;

FIG. 2 is a top view of the piston;

FIG. 2A is a side view of the piston of FIG. 2;

FIG. 3 is a top view of the rod with its shutter;

Figure 3A is a side view of the rod of Figure 3;

FIG. 4 shows the first phase of use of the device consisting in placing the biomaterial spheres;

FIG. 5 shows the next step consisting in the positioning of the piston inside the body of the device;

FIG. 6 shows the next step of use in which the body is moved away from the end of the rod to allow the exit of the biomaterial spheres; and FIG. 7 shows the final state of the device when the piston drives out the spheres in the housing made in the bone.

Referring firstly to FIGS. 1 to 3, the various parts of the device for placing spheres of biomaterial will be described.

In Figures 1 and IA, the body of the device is shown. This body 10 is formed by a tubular part 12 therefore having an axial bore 14 of internal diameter Dl. This tubular part has a first end 16 which is provided with longitudinal slots such as 18, defining between them elastically deformable tongues 20. On their internal face 20a, the tongues are provided with a raised portion forming a lug 22 intended to constitute, as will be explained later, clipping members. Preferably, the second end 24 of the body 10 is provided with a flared extension 26 which defines a frustoconical recess 28 in the form of a funnel opening into the axial bore 14 of the body 10.

In FIGS. 2 and 2A, there is shown the second element of the device for placing spheres in biomaterial constituting the piston 30. The latter is also essentially constituted by a tubular part 32 therefore having an axial bore 34. The diameter of the axial bore 34 is referenced D4 while the external diameter of the piston 30 is equal to D3. The diameter D3 is slightly smaller than the diameter Dl to allow the sliding of the piston in the body while ensuring a seal against the biomaterial spheres. At its first end 36, preferably the piston 30 is provided on its outer face with grooves such as 38 extending over part of its length. At its other end 40, the piston 30 is provided with an operating part 42. The length L3 of the piston 30 is greater than the length L1 of the body 10.

In Figures 3 and 3A, there is shown the rod of the device of the invention. This rod has a common part of external diameter D2 and it has a length L2 substantially greater than the lengths L1 and L3 of the body and of the piston. Preferably, the rod 50 has an axial bore 52 which extends over at least part of its length and preferably over its entire length. Near its end 54, the rod comprises an annular-shaped portion 56 having a diameter D'2 substantially greater than the diameter D2 of the rod 50. Preferably, the annular portion 56 has an annular groove 58, the function of which will be explained later. . The end part 60 of the rod 50 also has an increased diameter but less than the diameter D'2 of the widened part 56. The diameter D2 is slightly less than the diameter D4 of the axial bore of the piston in order to ensure a seal against the biomaterial spheres.

Preferably, these various elements constituting the device for placing the biomaterial are made of a steel having the qualities required for surgical instruments.

Referring now to FIGS. 4 to 7, we will describe the mode of use of the device for placing small spheres of biomaterial in the housing made in the part of the bone concerned.

In Figure 4, there is shown the rod 50 in place in the body 10 of the device. In this position, the enlarged part 56 forming the shutter of the rod 50 is clipped onto the body 10 of the device by means of the clipping lugs 22 cooperating with the groove 58 of the enlarged portion 56. This assembly thus defines an annular volume 70 between the wall of the body 10 and the external part of the rod 50, this volume being closed at its lower part by the shutter 56 of the rod 50. Is introduced into this annular space 70 using the funnel 28, the necessary amount of small spheres of biomaterial 72. Then, as shown in Figure 5, the piston 30 is put in place, the latter being engaged by its axial bore 34 on the rod 50. The piston 30 is introduced into the axial bore of the body 10 such that the spheres of biomaterial 72 are slightly compressed.

In the next step, partially shown in Figure 6, the entire device in the state in which it is shown in Figure 5 is introduced into the housing made in the bone. The end 60 of the rod constitutes a limitation on the insertion of the device into this housing and thus ensures correct positioning thereof. In the next step, one causes the separation of the body 10 relative to the shutter 56 of the rod 50, the latter remaining stationary. This causes the rod to unclip relative to the body 10 and obtain an opening 74 between the shutter 56 and the lower edge 12a of the body 10. This opening 74 allows the biomaterial spheres 72 to exit the volume in which they were initially confined. By maintaining the body 10 in its position and by causing the piston 30 to be pushed in relative to the latter, the transfer of the spheres 72 inside the housing is facilitated. The depression of the piston also makes it possible to cause the application of the spheres 72 against the internal wall. It should be added that by causing the piston 30 to rotate around its axis, the grooves 38 formed on its external face make it possible to improve the positioning and the distribution of the spheres 72 on the wall of the housing. '

It should also be noted that the axial bore 52 provided in the rod 50 serves to guide the device on the guide rod-pin previously placed in the housing.

In a preferred embodiment of the device, the internal diameter Dl of the body is of the order of 13 mm. Its length L1 is of the order of 145 mm.

As regards the piston 30, its external diameter D3 is of the order of 12.4 mm, so that it is greater than the internal diameter D1 of the body 10, its axial bore has a diameter which is of the order of 5 mm such that it is slightly greater than the external diameter D2 of the rod 50 which is of the order of 4.4 mm.

It goes without saying that the different diameters D1, D2, D3 and D4 are imposed by the external diameter of the body 10 of the device, the external diameter of the body itself being fixed by the diameter of the housing made in the bone, this housing most often being a diameter of 14 mm.