NZ555699A - Intramedullary nail - Google Patents

Abstract

The disclosure relates to an intramedullary nail (1), especially for the tibia, which comprises a proximal end part (2), a distal end part (3) adapted to be introduced into the medullary space and a center axis (6). Said intramedullary nail has A) an overall length L ranging from 200 to 500 mm; B) a first curved section (4) having a length G1 = L and a radius of curvature R1; and C) a second curved section (13) having a length G2 = G1 and a radius of curvature R2 < R1 which is arranged between the proximal end part (2) and the first curved section (4); and D) the tangents in the two end points of a center section comprising the two curved sections (4; 13) form a total angle gamma between 9 DEG and 12 DEG .

Description

555699 English translation of the specification of the International Patent Application No. PCT/CH2004/000758 "Intramedullary nail" in the name of Svnthes GmbH INTRAMEDULLARY NAIL The invention relates to an intramedullary nail, particularly for the tibia, of the introductory portion of claim 1.

US patent 6,020,506 of GOSNEY discloses a generic intramedullary nail, which has a proximal end part, which can be pressed on, and a distal end part, which are at an angle relative to one another by means of several curved segments, which are disposed between the end parts. In addition, the proximal end part, which can be pressed on, is bent at right angles, so that a relatively large angle is formed between the tangents to the central axes at the axial ends. It is a disadvantage of this known intramedullary nail that it is not suitable for use in relatively linear, tubular bones, especially the tibia.

The invention is to provide a remedy here. It is an object of the invention to create an intramedullary nail, which has a central section, comprising several curved sections, the tangents at the two end points of this central section, enclosing a relatively small angle, that is, an angle, which is suitable particularly for linear, tubular bones, or to at least provide a useful alternative.

Pursuant to the invention, this objective is accomplished with an intramedullary nail, which has the distinguishing features of claim 1, The advantages, which are achieved by the invention, are seen to lie essentially therein that, due to the inventive intramedullary nail: • the intramedullary nail has a central section, comprising two curved sections and, because of the two curvatures, which have a different radius, the intramedullary nail can be adapted optimally to the medullary canal; INTELLECTUAL PROPERTY OFFICE OF N.Z. l 14 JAN 20D9 RECEIVED 555699 • the tangents at the end points of this middle section enclose an angle gamma of between 9° and 12° and the intramedullary nail is therefore suitable for relatively linear tubular bones, especially for the tibia, and • because of the small angle gamma, it is possible to insert the intramedullary nail into the medullary space without using much force.

In different embodiments, the intramedullary nail has the following distinguishing features, depending on the application: • the length G3 of the proximal end part ranges from 1/6 L to 1/3 L, L being the total length of the intramedullary nail; • the tangents at the two end points of the first curved section enclose an angle alpha ranging form 7° to 10° and preferably from 8° to 9°; • the tangents at the two end points of the second curved section enclose an angle beta ranging from 1° to 3°; • the first curved end section of length Gi has a radius of curvature ranging from 300 to 1,300 mm, • the ratio L/Ri ranges from 0,2 to 0,8; • the length "I" of the straight, distal section ranges from 0,20 L to 0,55 L and preferably from 0,25 to 0,50 L; • the length Gi of the first curved section ranges from 0,2 L to 0,4 L and • the radius of curvature R2 of the second curved section ranges from 10 to 50 mm.

In a further embodiment, the proximal end part axially adjoins the second curved section and is formed as a straight proximal section.

INTELLECTUAL PROPERTY OFFICE OF N.Z.

I 4 JAN 2009 RECEIVED 555699 In a different embodiment in turn, the distal end part is constructed as a straight section.

Due to the formation of one or both end parts as straight sections, the advantage can be attained, that the curvature of the intramedullary nail is slight, as a result of which the intramedullary nail is particularly suitable for straight, tubular bones.

In a different embodiment, the intramedullary nail has a longitudinal borehole, which is coaxial with the central axis.

In yet another embodiment, there is at least one locking hole, which extends transversely to the central axis and is suitable for accommodating a screw, in the region of the proximal end part.

In a further embodiment, there is at least one locking hole, which extends transversely to the central axis and is also suitable for accommodating a screw, in the region of the distal end part.

In yet a further embodiment, there are two locking holes, which extend transversely to the central axis and enclose with one another an angle preferably of 45° to 90°, in the region of the distal end part.

In another embodiment, the distal end part has four locking holes, the distance of the proximally located central locking hole to the other two locking holes being different.

The implantation method is described briefly in the following by means of a cannulated intramedullary nail: Step A: Bringing about and maintaining the optimum setting, depending on the type of fracture INTELLECTUAL PROPERTY OFFICE OF N.2. 1 4 JAN 2009 RECEIVED 555699 Step B: Opening the medullary canal with the help of an opening instrument, so that the entry angle and the orientation with respect to the medullary canal are correct, depending on the surgical technique used.

Step C: Introducing a guide wire up into the distal, future end position of the intramedullary nail and determining the length of the intramedullary nail required.

Step D: The intramedullary nail, pre-mounted on the insertion handle, is brought by means of the guide wire through the opening channel into the medullary space.

Step E: After the axial position of the intramedullary nail is checked and repositioned, the intramedullary nail is locked over its locking options.

The invention and further developments of the invention are described in greater detail in the following by means of the partially diagrammatic representations of an example. In the drawing Figure 1 shows a longitudinal section through an embodiment of the inventive intramedullary nail, Figure 2 shows a section along the line ll-ll of Figure 1 and Figure 3 shows an enlarged section in the region of the second, curved section of the embodiment of the inventive intramedullary nail shown in Figures 1 and 2.

The intramedullary nail 1, shown in Figures 1 to 3, comprises essentially a central axis 6, a proximal end part 2, a distal end part 3 suitable for introduction into the intramedullary space and two curved sections 4; 13, which are disposed axially one behind the other. Axially, the proximal end part 2 adjoins the second, curved section 13 and is constructed as a straight, proximal section 8 of length G3 < L, whereas the distal end part 3 is constructed as a straight, distal section 5 with a length "I". The first curved section 4 has a length Gi < L and a radius of curvature Ri, whereas the second curved section 13, disposed between the proximal end part 2 and the , INTELLECTUAL PROPERTY 4 OFFICE OF N.Z.

H JAN 2009 555699 first curved section 4, has a length G2 £ Gi and a radius of curvature R2 < Ri-The tangents t5,4 and t13,2 at the two end points of a middle section, enveloping the two curved section 4; 13, enclose an angle gamma here of 10° and coincide proximally with the central axis 6 of the straight, proximal section 8 and distally with the central axis 6 of the straight, distal section 5.

Furthermore, the tangents t5,4 and t},i3 at the two end points of the first curved section 4 enclose an angle alpha of 8° here and the tangents t4,i3 and ti3,2 at the two end points of the second curved section 13 enclose an angle beta of 2°.

Both curvatures of the intramedullary nail lie in the plane of the drawing, which, after the implantation of the intramedullary nail 1, corresponds to the anatomical medio-lateral plane, that is, the intramedullary nail, when implanted, is bent in the antero-posterior direction.

Moreover, the intramedullary nail has a continuous longitudinal borehole 7, which is coaxial with the central axis 6 (fig. 2).

In the region of the proximal end part 2 of the intramedullary nail 1, there are four locking holes 9, which extend transversely to the central axis 6 and of which one is constructed as an elongated hole, in order to be able to carry out a compression. For the locking of the intramedullary nail 1, five screws (not drawn) are provided in the region of the proximal end part 2.

In the region of the distal end part 3, there are four locking holes 10, 12, 10, 12, which extend transversely to the central axis 6, are disposed in different radial directions and enclose different angles with one another. Moreover, the distances between the central locking hole 12 and the other two locking holes 10 are different.

INTELLECTUAL PROPERTY OFFICE OF N.2. 1 4 JAN 200S 555699

Claims (20)

Claims

1. Medullary nail, especially for the tibia, with a proximal end part, a distal end part, suitable for introducing the intramedullary nail into the medullary space, and a central axis, which A) has a total length L, ranging from 200 to 500 mm, B) a first curved section of length Gi < L and with the radius of curvature Ri and C) between the proximal end part and the first curved section, a second curved section of length G2 £ Gi and with a radius of curvature R2 < Ri, and D) the tangents at the two end points of one of a central section, including the two curved sections, enclose an angle gamma between 9° and 12°.

2. The intramedullary nail of claim 1, wherein the length G3 of the proximal end part ranges from 1/6 L to 1/3 L.

3. The intramedullary nail of claims 1 or 2, wherein the tangents U,13 and ti j23 the two end points of the first curved section enclose an angle alpha ranging from 7° to 10° and preferably from 8° to 9°.

4. The intramedullary nail of claims 1 or 2, wherein the tangents t4i-i3 and ti,23 the two end points of the first curved section enclose an angle alpha ranging from 8° to 9°.

5. The intramedullary nail of one of the claims 1 to 4, wherein the tangents t4,i3 and ti3,2 at the two end points of the second curved section enclose an angle beta ranging from 1° to 3.

6. The intramedullary nail of one of the claims 1 to 5, wherein the proximal end part axially adjoins the second curved section and is constructed as a straight section of length G3< L. 6 INTELLECTUAL PROPERTY OFFICE OF N.Z. t h JAN 2009 RECEIVED 555699

7. The intramedullary nail of one of the claims 1 to 6, wherein the first curved section of length Gi has a radius of curvature ranging from 300 to 1300 mm.

8. The intramedullary nail of one of the claims 1 to 7, that the ratio L/Ri ranges from 0,2 to 0,8.

9. The intramedullary nail of one of the claims 1 to 8, wherein the distal end part is constructed as a straight section with the length "I" < L.

10. The intramedullary nail of claim 9, wherein the length "I" ranges from 0,20 L to 0,55 L.

11. The intramedullary nail of claim 8, wherein the length "I" ranges from 0,25 L to 0,50 L.

12. The intramedullary nail of one of the claims 1 to 11, wherein it has a longitudinal borehole, which is coaxial with the central axis.

13. The intramedullary nail of one of the claims 1 to 12, wherein, in the region of the proximal end part, there is at least one locking hole extending transversely to the central axis.

14. The intramedullary nail of one of the claims 1 to 13, wherein, in the region of the distal end part, there is at least one locking hole extending transversely to the central axis.

15. The intramedullary nail of one of the claims 1 to 14, wherein, in the region of the distal end part, there are at least two locking holes extending transversely to the central axis. INTELLECTUAL PROPERTY OFFICE OF N.2. 1 4 JAN 2009 R F n F l \/ P n 555699

16. The intramedullary nail of claim 15, wherein the two locking holes, extending transversely to the central axis, enclose and angle of 45° to 90° with one another.

17. The intramedullary nail of one of the claims 1 to 16, wherein the distal end part has three locking holes, the distance between the central locking hole and the other two locking holes being different.

18. The intramedullary nail of one of the claims 1 to 17, wherein the length Gi of the first curved section ranges from 0,2 to 0,4 L.

19. The intramedullary nail of one of the claims 1 to 18, wherein the radius of curvature R2 of the second curved section ranges from 10 to 50 mm.

20. The intramedullary nail of claim 1, substantially as herein described with reference to any one of Figures 1 to 3. INTELLECTUAL PROPERTY OFFICE OF N.Z. I k JAN 2009