This invention relates to the technological sector dedicated to the manufacture of hip prostheses.
As is known, these prostheses comprise a shank bearing the joint prosthesis proper which is inserted into the patient's femur.
This operation, using existing hip prostheses, is carried out by coaxially inserting the shank into the diaphysis of the femur after the entire head and neck of the same have been amputated.
The inventor of this invention is of the opinion that this type of surgery is in many cases more destructive than is necessary, sacrificing the diaphysis bone and in particular the metaphysis part thereof, restricting or thus rendering more complex the possibility of subsequent limb prosthesis surgery.
In order to overcome these disadvantages the inventor has conceived of a hip prosthesis with the shank formed in such a way that it can be inserted transversely into the neck of the femur after resection of the epiphysis alone has been performed.
The shank of the hip prosthesis according to the invention is in fact designed in such a way that it can be inserted into the proximal part of the femur, causing it to pass through the cervical and large trochanter area, that is particularly within the cervical-trochanter area, without having to insert it coaxially into the diaphysis.
In order to achieve this objective the inventor has conceived a hip prosthesis which comprises a shank whose longitudinal axis follows a curved path substantially similar to the profile of the top part of the femur in the said cervical-trochanter area.
As will be better seen below, the aforesaid longitudinal axis may comprise a curved section substantially reproducing the form of the said external profile of the cervical-trochanter area, or at least two consecutive straight segments not in line which approximately match the said shape substantially, with an upwards facing concavity.
In both cases the longitudinal axis of the aforesaid shaft is, when inserted in the femur, approximately parallel to the profile of the cervical-trochanter area already described.
The subject matter of this invention therefore comprises a hip prosthesis as described in appended Claim 1.
A more detailed description of two preferred embodiments of the hip prosthesis according to the invention will now be provided with reference to the appended drawings, in which:
Considering first
Using a hip prosthesis 1 according to the invention it is therefore possible to achieve a reliable implant in the femur 3 of the patient without it being necessary to act destructively removing the metadiaphysis tissue, and this offers the advantages already illustrated above.
The only difference lies in the fact that in prosthesis 11 in question shank 12 is shaped in such a way that its longitudinal axis Q-Q comprises two consecutive straight segments C, D which are not in line with each other.
Again in this case this longitudinal axis can be arranged in such a way that it runs approximately parallel to the abovementioned profile P, with the same results and the same advantages.
Of course, if it is desired to make the path of the aforesaid longitudinal axis even more similar to the profile P of the head of the femur a prosthesis provided with a shaft according to the invention in which the said longitudinal axis comprises a piece formed of a number of consecutive unaligned segments greater than 2 may be constructed. (This situation is not shown in the drawings).
In
The inventor also provides the possibility of forming a recess 5 in the concave part of shank 12, which in this case comprises surface 12a in the top position, extending approximately the entire length of the shank in order to improve the reliability of the connection between the prosthesis and the bony tissue of the femur in a known way.
Number | Date | Country | Kind |
---|---|---|---|
01310/04 | Aug 2004 | CH | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/IB05/01835 | 6/8/2005 | WO | 2/5/2007 |