Joint prosthesis

Claim 2

An articulated prosthesis adapted to unite two elements such as bones comprising: a first arm comprising a stem portion at the end of which is loated a first rotary bearing component, a second arm comprising a second stem portion at one end of which is located a second rotary bearing component, and means for coupling said two bearing components such that they can rotate relative to each other about an axis.

Claim 3

A prosthesis as claimed in Claim 1 wherein the aforesaid first bearing component comprises two collars which are spaced apart from and axially aligned with each other and which together define a space bounded by two opposite and substan­tially parallel faces of the internal ends of said collars, and wherein said second bearing component comprises a part having planar outside surfaces capable of fitting into said space and which contains a cylindrical bore or a cylindrical depression on each side, so designed that when the second bearing component is fitted into the aforesaid space to form a hinge, the axis of rotation of said bore or said depressions coincides with the axis of rotation of the bores of said collars.

Claim 4

A prosthesis as claimed in Claim 2 wherein each depression is dish-shaped and provided with a bottom which forms a thrust surface.

Claim 5

A prosthesis as claimed in any one of the preceding claims wherein said coupling means comprises a cap consisting of three parts including a hub, a shaft section integral with said hub, and a retaining ring integral with said hub, said ring having an internal shoulder, there being a protruding lip around the exterior outside end of each collar integral with said collar, said shoulders and said lips being configured so that the shoulder on each retaining ring can be located on the lip of said collar when said shaft section is inserted in the bore of the collar and into one of said depressions.

Claim 6

A prosthesis as claimed in Claim 4 wherein the length of the said shaft section is such that the end of said shaft abuts against the bottom of said depression immediately before said shoulder reaches the protruding lip.

Claim 7

A prosthesis as claimed in any one of the preceding claims wherein at least one lubricating washer is positioned between said bearing components.

Claim 8

A prosthesis as claimed in any one of the preceding claims wherein each of said stem portions is of elongated shape.

Claim 9

A prosthesis as claimed in any one of the preceding claims which also comprises a sleeve adapted to be implanted in a bone cavity and having a cross-section corresponding to that of the stem portion and being adapted to receive said stem portion when said prosthesis is implanted.

Claim 10

A prosthesis as claimed in any one of the preceding claims wherein the stem portions have oval cross-sections.

Claim 11

A prosthesis as claimed in any one of the preceding claims wherein the stem portions and the coupling means comprise a metal and a plastic material, respectively.