GB1593440A - Intramedullary nails - Google Patents

Abstract

A thigh and lower leg locking nail having a principal portion (2) and a proximal end portion (3) is designed as a hollow cylinder having a rounded, distal tip (4) and a conically flared proximal end (8) provided with an internal screw thread (7) and having two lateral inner surfaces (9) in the flared end. A slot (6) which is narrower at the distal end (4) than over the remainder of its length reaches from the tip (4) to the region of the proximal end portion (3). Both in the principal portion and in the final portion there are pairs of through-holes (10, 11, 12) as transverse and diagonal bores. <IMAGE>

Description

(54) IMPROVEMENTS IN OR RELATING TO INTRAMEDULLARY NAILS (71) We, HOWMEDICA INTER NATIONAL, INC., of Professor-Kiintcher- Str. 1-3, 2301 Schönkirchen tiber Kiel Germany, a Federal German company do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an intramedullary nail, for a thigh (femur) or tibia, comprising a hollow, cylindrical, longitudinally-slotted member having a straight or curved major portion, a proximal end portion, preferably bent at an angle with respect to the major portion, a generally conically-enlarged portion and an internallythreaded portion for cooperation with an insertion and extraction instrument.

Such nails are known and are predominantly used in the case of fragment fractures, fractures near joints, correction osteotomies and various forms of pseudarthrosis. It has, however, been found that these known nails do not optimally meet the requirments a surgeon expects as regards a high stability and a quick knocking in and out so that the duration of an operation may be kept short.

The invention is based upon the problem of providing an intramedullary nail which is adapted to be knocked into a bone and knocked out of it again with a high degree of transverse and rotational stability and no problem occuring and with which, after having been knocked in, the necessary transverse and oblique bores may be performed through the bone without difficulty.

In accordance with the invention, there is provided an intramedullary nail, for femur or tibia, comprising a hollow, cylindrical, longitudinally-slotted member having a straight or curved major portion, and a proximal end portion, which has a generally conically-enlarged end portion and an internally-threaded portion for cooperation with an insertion and extraction instrument, wherein the wall of the member is provided with a plurality of openings serving to accommodate fastening means and the threaded portion is located inwardly from the generally conically-enlarged end portion.

A nail formed in accordance with the invention is distinguished from the known construction of the proximal end portion, with resulting high transverse and torsional stability. With an embodiment having further improved stability properties, the portion of the length of the longitudinal slot nearer the distal end portion is of a narrower width than over the remaining length thereof. In this manner a high transverse and torsional stability is obtained both at the proximal and distal end portions of the nail.

The inner threaded portion fulfils two functions: it serves, on the one hand, to cooperate with the instrument for knocking the nail in and out, on the other hand, serves to fasten an aligning apparatus after the nail has been knocked into the bone. The aligning apparatus in this operation is fastened on the generally conically-enlarged end portion with the aid of a screw driven into the threaded portion. It is then possible with the aid of this arrangement, to perform the transverse and oblique bores through the bone without any difficulty and centrally with respect to openings in the wall of the nail.

The aligning apparatus makes possible a short, simple and safe method of operation and enables the surgeon to work free of radiation.

The generally conically-enlarged end portion of the nail serves to engage the nail with respect to the aligning apparatus and preferably comprises two smooth lateral inner surfaces. The angle of inclination of these surfaces is suitably smaller than the angle of inclination of the upper and lower surfaces interconnecting the lateral surfaces with each other and these, in general are likewise of a curved design in adaptation to the hollow cylindrical shape of the member.

The interlocking nail according to the invention is particularly well suited as an implantation for the femur or tibia. An intramedullary nail suitable for the tibia is suitably designed in such a manner that it comprises a straight major portion and a proximal end portion bent at an angle with respect to the major straight portion. A nail suitable for the femur preferably has a curved major portion and a proximal end portion extending approximately as an extension of the curvature axis. Naturally, in this arrangement, the proximal end portion may also be slightly bent at an angle with respect to the major portion but the latter may, perhaps, also be sraight. The embodiments described above for tibia and femur, however, are in general preferred. Usually, a nail suited for a femur has a diameter of 12, 13 or 14 mm, while a tibia nail has a diameter of 11 or 12 mm. The length of the nails varies and must be adapted to the circumstances.

In a further preferred embodiment of the invention, the nail is provided in a distal end portion and the proximal end portion with two respective pairs of openings, each pair forming a transverse or oblique bore extending through the hollow cylindrical member. The femur nail, in this case, is preferably provided with a transverse and an oblique bore in the proximal end portion, while the tibia nail is provided with two transverse bores in this portion. In the distal end portion, there are provided two transverse bores. If the nail has been knocked into the bone, it is possible, without difficulty with the aid of the aligning apparatus fastened at the generally conically-enlarged end portion, to form the bores through the bone centrally with respect to respective trans verse and oblique bores in the nail, in order to fit the corresponding fastening means.

In the case of the tibia nail, the proximal end portion, in accordance with a preferred embodiment of the invention, is provided with an additional pair of openings forming a further bore. One opening of this bore, in this case, is preferably formed as an elongate hole.

Suitably, the major portion of the nail designed in accordance with the invention is provided with oppositely arranged lateral depressions extending approximately the entire length of the major portion. Through these depressions the knocking in and out of the nail is facilitated.

In the following, two embodiments of nail according to the invention will be described by way of example and in connection with the accompanying drawing, in which: Fig. 1 shows a lateral elevational view of an intramedullary nail for a femur; Fig. 2 shows a horizontal sectional view of a portion of the nail shown in Fig. 1; and Fig. 3 shows a partial lateral elevational and partial sectional view of an intramedullary nail for a tibia.

In the following, reference will be made firstly to the intramedullary nail for a femur, as shown in Figures 1 and 2. As may be seen from Figures 1 and 2 the nail 1 consists of a hollow, cylindrical, longitudinallyslotted member having a straight major portion 2 and a proximal end portion 3 slightly bent an an angle with respect to the major portion. The major portion 2, may, however, be slightly curved but this optional feature is not shown in Figure 1. The nail 1 is provided at its distal end portion with a rounded tip 4 which is essentially open and from which a longitudinal slot 6 extends (Figure 2) in a direction towards the proximal end portion 3. This longitudinal slot 6 terminates approximately in a region in which the proximal end portion 3 begins. The slot 6 is of a narrower width in the region of the distal end than over the remaining length thereof, so that the hollow cylindrical member is almost closed at the distal end.

The major portion 2 is provided with oppositely-disposed lateral depressions 5 extending approximately the entire length of the major portion.

Turning now to Figure 2, it will be seen that the proximal end portion 3 is provided with an inner threaded portion 7 and a generally conically-enlarged end portion 8 adjoining it. The end portion 8 in this arrangement is designed in such a manner that two smooth lateral inner surfaces 9 are formed, while the upper and lower surfaces interconnecting them are adapted to the curvature of the hollow cylindrical member.

The threaded portion 7 can cooperate with an instrument for knocking in and out the nail and, furthermore, serves, after the nail has been knocked into the bone, as a fastening means for an aligning apparatus fixed on the generally conically-enlarged end portion 8 of the nail. With such an aligning apparatus, the necessary bores may be made in the bone without difficulty for the insertion of fastening means.

The nail 1 is furthermore provided at the distal and proximal end portions, respectively, with two pairs of openings 10, 11 and 12 associated with each other and forming transverse or oblique bores extending through the hollow cylindrical member.

In the case of the femur nail, shown in Figures 1 and 2, there are two pairs of openings 12 arranged in the distal end portion for transverse bores, while the proximal end portion is provided with a pair of openings 11 for a transverse bore and a pair of openings 10 for an oblique bore.

The pairs of openings 10 and 11 are best recognizable in Figure 2.

Figure 3 shows an intramedullary nail 23 suited for a tibia. This nail, as in the case of the femur nail shown in Figures 1 and 2, comprises a straight major portion 21 and a proximal end portion 22 bent at an angle with respect to the major portion. The angle included between the maior portion and the end portion, however, in this case is wider.

Apart from the fact that the main portion 21 is designed to be shorter than the main portion 2, both portions are essentially identical. So, the portion 21 is also provided with lateral depressions 23, as well as with two pairs of openings 25 at the distal end forming respective transverse bores. A rounded tip 24 is likewise provided.

The proximal end portion 22 also essentially resembles the proximal end portion 3 of the femur nail 1. It is provided with an inner threaded portion 26, as is the femur nail 1, and a generally conically-enlarged end portion 27 adjoining it, which end portion comprises two smooth lateral inner surfaces 28 and two rounded upper and lower surfaces 29. In the juncture region between the major portion and proximal end portions, two pairs of openings 30 are arranged to form a transverse bore extending through the hollow cylindrical member. There is no oblique bore provided in the case of the tibia nail.

In addition to the pairs of openings 30 for the transverse bores, the proximal end portion 22 is provided with another pair of openings 31, 32 forming a further bore.

In this arrangement, the opening 31 is formed as a round bore and the oppositely disposed bore 32 as an elongate hole. As can be seen from Figure 3, the axis through the pair of openings 31, 32 extends normally to the axes extending through the pairs of openings 25 and 30.

The nails must, of course, have different dimensions in adaptation to the different sizes of bones. As guide values, an overall length of about 400 mm and a diameter of 12, 13 or 14 mm may be stated for the femur nail. The corresponding values for the tibia nail are 330 mm and 11 or 12 mm. For the femur nail, there are two types for right and left which differ by the direction of the oblique bore as provided. With the tibia nail, only one type is needed. The nails are made of materials well known to an expert but, preferably, stainless steel.

WHAT WE CLAIM IS: 1. An intramedullary nail, for femur or tibia, comprising a hollow, cylindrical, longitudinally-slotted member having a straight or curved major portion, and a proximal end portion, which has a generally conically-enlarged end portion and an internally-threaded portion for cooperation with an insertion and extraction instrument, wherein the wall of the member is provided with a plurality of openings serving to accommodate fastening means and the threaded portion is located inwardly from the generally conically-enlarged end portion.

2. A nail according to claim 1, wherein the proximal end portion is bent at an angle with respect to the major portion.

3. A nail according to claim 1 or 2, wherein a portion of a length of the longitudinal slot nearer the distal end is of a narrower width than over the remaining portion of the length thereof.

4. A nail according to claims 1, 2 or 3, wherein the generally conically-enlarged end portion comprises two smooth lateral inner surfaces.

5. A nail according to any preceding claim comprising, in a distal end portion and the proximal end portion, two respective pairs of openings, each pair of openings forming a transverse or oblique bore extending through the hollow cylindrical member.

6. A nail according to any preceding claim, wherein the proximal end portion comprises an additional pair of openings forming a further bore.

7. A nail according to claim 6, wherein one of the additional pair of openings is an elongate hole.

8. An intramedullary nail substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. suited for a tibia. This nail, as in the case of the femur nail shown in Figures 1 and 2, comprises a straight major portion 21 and a proximal end portion 22 bent at an angle with respect to the major portion. The angle included between the maior portion and the end portion, however, in this case is wider. Apart from the fact that the main portion 21 is designed to be shorter than the main portion 2, both portions are essentially identical. So, the portion 21 is also provided with lateral depressions 23, as well as with two pairs of openings 25 at the distal end forming respective transverse bores. A rounded tip 24 is likewise provided. The proximal end portion 22 also essentially resembles the proximal end portion 3 of the femur nail 1. It is provided with an inner threaded portion 26, as is the femur nail 1, and a generally conically-enlarged end portion 27 adjoining it, which end portion comprises two smooth lateral inner surfaces 28 and two rounded upper and lower surfaces 29. In the juncture region between the major portion and proximal end portions, two pairs of openings 30 are arranged to form a transverse bore extending through the hollow cylindrical member. There is no oblique bore provided in the case of the tibia nail. In addition to the pairs of openings 30 for the transverse bores, the proximal end portion 22 is provided with another pair of openings 31, 32 forming a further bore. In this arrangement, the opening 31 is formed as a round bore and the oppositely disposed bore 32 as an elongate hole. As can be seen from Figure 3, the axis through the pair of openings 31, 32 extends normally to the axes extending through the pairs of openings 25 and 30. The nails must, of course, have different dimensions in adaptation to the different sizes of bones. As guide values, an overall length of about 400 mm and a diameter of 12, 13 or 14 mm may be stated for the femur nail. The corresponding values for the tibia nail are 330 mm and 11 or 12 mm. For the femur nail, there are two types for right and left which differ by the direction of the oblique bore as provided. With the tibia nail, only one type is needed. The nails are made of materials well known to an expert but, preferably, stainless steel. WHAT WE CLAIM IS:

1. An intramedullary nail, for femur or tibia, comprising a hollow, cylindrical, longitudinally-slotted member having a straight or curved major portion, and a proximal end portion, which has a generally conically-enlarged end portion and an internally-threaded portion for cooperation with an insertion and extraction instrument, wherein the wall of the member is provided with a plurality of openings serving to accommodate fastening means and the threaded portion is located inwardly from the generally conically-enlarged end portion.

2. A nail according to claim 1, wherein the proximal end portion is bent at an angle with respect to the major portion.

3. A nail according to claim 1 or 2, wherein a portion of a length of the longitudinal slot nearer the distal end is of a narrower width than over the remaining portion of the length thereof.

4. A nail according to claims 1, 2 or 3, wherein the generally conically-enlarged end portion comprises two smooth lateral inner surfaces.

5. A nail according to any preceding claim comprising, in a distal end portion and the proximal end portion, two respective pairs of openings, each pair of openings forming a transverse or oblique bore extending through the hollow cylindrical member.

6. A nail according to any preceding claim, wherein the proximal end portion comprises an additional pair of openings forming a further bore.

7. A nail according to claim 6, wherein one of the additional pair of openings is an elongate hole.

8. An intramedullary nail substantially as herein described with reference to the accompanying drawings.