Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1988-04-08
1990-03-27
Apley, Richard J.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
623 18, A61F 236, A61F 230, A61F 504
Patent
active
049117220
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a femoral prosthesis to be implanted in the upper end of the femur when the femoral head needs to be replaced because more particularly of traumatism or arthrosis. It also relates to the method of implementing same.
BACKGROUND OF THE INVENTION
In general, each femoral prosthesis includes a more or less long shank which is embedded in the femoral stump. The part which emerges therefrom is slanted with respect to the shank or stem by about 120.degree. and serves as a base for a sphere which is intended to replace the femoral head.
Thousands of operations of this kind are carried out each year, which operation gives back a normal life to patients. For that, a greaty variety, as to shape and design, of prostheses exist, but these prostheses have certain drawbacks.
At the beginning, a standard shank was used which was locked in the femoral diaphysis with cement, but cement loses its mechanical properties in the long run, and almost all the feomral prostheses of this type finish by becoming loose with the years.
The ideal is then to do without cement and to lock the prosthesis right away by any means.
Some attempts have been made by implanting adjusted prostheses covered with microscopic roughnesses, force fitted, filling the femur to a maximum and which are rehabited by the bone in the months following the operation.
This technique has in fact two drawbacks, the first being the large number of prostheses in stock required so as to have the size which is exactly adapted to the femur of the patient, and the second being the risk of bursting the upper part of the femur due to the force fitting of these prostheses.
Compromises have been found such as the self locking prosthesis of the "Muller" type which is universally known.
Its shape is especially designed, but despite everything it uses a thin layer of cement.
OBJECT OF THE INVENTION
The object of the present invention is to overcome the above drawbacks and provides a prosthesis the shank of which includes a slit in which is fitted a mechanism capable, once the prosthesis is freely positioned in the medullar cavity, of moving away one of the pieces forming the shank, until the prosthesis is locked against the corticals.
SUMMARY OF THE INVENTION
The invention relates more precisely to a mechanical self locking femoral prosthesis including a Morse taper (3) and a shank (5) forming with the Morse taper (3) an angle corresponding to the cervico-diaphysial angle (.alpha.), characterized in that it includes two parts (7) and (7') as well as a slit (f) of width (l) formed in the shank (5) over the whole of its length, in which slit is fitted a mechanism capable of providing controlled lateral movement of one of the parts (u) called mobile with respect to the other part (7') called fixed, as a function of the dimensions of the medullar cavity concerned.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood from the following explanations and the accompanying Figures in which:
FIG. 1 is a view of the prosthesis in the initial state of introduction in the femoral stump;
FIG. 2 is a section of this prosthesis on the line II--II in FIG. 1;
FIG. 3 is a broken section on the line III--III in FIG. 2, the prosthesis being in the initial state of introduction in the femural stump; and
FIG. 4 is also a broken section on the line IV--IV in FIG. 21 in a configuration corresponding to a prosthesis widened by the internal mechanism of the invention.
For the sake of clarity, the same elements bear the same references in all the Figures.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT
A prosthesis 1, of the invention, shown in FIG. 1 in an external view, uses the same cervico-diaphysial angle, the same external profile 2, and the same Morse taper 3 receiving an adapted head as are to be found in a Muller's prosthesis. The lateral upper faces of the prosthesis have scores 4 so as to provide better holding of the prosthesis in the femural stump, and the general surface condition is a porous or
REFERENCES:
patent: 2381050 (1945-08-01), Hardinge
patent: 2490364 (1949-12-01), Livingston
patent: 2685877 (1954-08-01), Dobelle
patent: 3846846 (1974-11-01), Fischer
patent: 4530115 (1985-07-01), Muller et al.
patent: 4681590 (1987-07-01), Tansey
patent: 4704128 (1987-11-01), Frey
patent: 4728333 (1988-03-01), Masse et al.
Apley Richard J.
Crespy Gilles
Crosby D. F.
Kerberenes Rene
Office Medico Chirurgical International S.A. (O.M.C.I.)
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