Intervertebral disk prosthesis notably for cervical vertebrae
View Patent ↗A prosthesis comprises having two portions independent of each other, a first portion and a second portion, at least one of which includes an articular surface, said first portion and said second portion each comprising a circular seat delimited by an arched wall. An element of the prosthesis is an O-ring in an elastically deformable material, and one of said seats is dimensioned to receive a radially outer portion of this ring while the other seat is dimensioned to receive a radially inner portion of this ring.
1. An intervertebral disk prosthesis notably for cervical vertebrae, comprising:
two flattened elements, each of the two flattened elements having a main surface extending in a first plane;
a first flattened element of the two flattened elements forms a first circular seat extending in a plane parallel to said first plane, delineated by a first, radially inward oriented, concave wall, the first concave wall being arched-shaped when viewed in a second plane perpendicular to said first plane;
a second flattened element of the two flattened elements forms a second circular seat extending in the plane parallel to said first plane, delineated by a second, radially outward oriented, concave wall, the second concave wall being arched-shaped when viewed in said second plane;
an O-ring element comprising an elastically deformable and compressible material, the O-ring element capable of being elastically deformed and compressed radially and axially; and
a diameter of said first circular seat being such that said first circular seat receives a radially outer portion of the O-ring element and a diameter of said second circular seat being such that said second circular seat receives a radially inner portion of the O-ring element.
2. The intervertebral disk prosthesis according to claim 1 , wherein
the intervertebral disk prosthesis includes two plate-like elements anchored on vertebral plates of respective adjacent vertebrae, each plate-like element forming an articular surface;
one of said two flattened elements is a first intermediate element including an articular surface adapted to cooperate with the articular surface of a first plate-like element of the two plate-like elements; and
the other of said two flattened elements is a second intermediate element including an articular surface adapted to cooperate with the articular surface of a second plate-like element of the two plate-like elements.
3. The intervertebral disk prosthesis according to claim 2 , wherein
one plate-like element of the two plate-like elements is configured to be connected to an overlying vertebra and the articular surface of the one plate-like element is spherical and concave and the articular surface of the first intermediate element is spherical and convex, and
the other plate-like element of the two plate-like elements is configured to be connected to the underlying vertebra and the articular surface of the other plate-like element includes a cylindrical and concave articular surface, a generatrix of the cylindrical and concave articular surface being directed after implantation in an anteroposterior direction relative to the vertebra, and the articular surface of the second intermediate element is cylindrical and convex.
4. The intervertebral disk prosthesis according to claim 3 , wherein said cylindrical and concave articular surface of the plate-like element has a dimension in the anteroposterior direction larger than a dimension in the anteroposterior direction of said cylindrical and convex conjugate articular surface of the second intermediate element, so that the second intermediate element is mobile in the anteroposterior direction relative to the other flattened element configured to be connected to the underlying vertebra.
5. The intervertebral disk prosthesis according to claim 3 , wherein
said cylindrical and concave articular surface of the plate-like element and said cylindrical and convex conjugate articular surface of the second intermediate element are congruent,
said spherical articular surfaces are congruent, and
the different articular surfaces have identical radii of curvature, respectively.
6. The intervertebral disk prosthesis according to claim 3 , wherein
said cylindrical and concave articular surface of the plate-like element and said cylindrical and convex conjugate articular surface of the second intermediate element are are congruent,
said spherical articular surfaces are congruent, and
a radius of curvature of said cylindrical and concave articular surface of the plate-like element and a radius of said cylindrical and convex conjugate articular surface of the second intermediate element are is different from a radius of curvature of said spherical articular surfaces.
7. The intervertebral disk prosthesis according to claim 3 , wherein
a radius of (i) the spherical articular surfaces of the one plate-like element configured to be connected to the overlying vertebra and of (ii) the first intermediate element is such that a center of rotation is located after implantation below the vertebral plate of the underlying vertebra, and
a radius of (i) the cylindrical articular surfaces of the other plate-like element configured to be connected to the underlying vertebra and of (ii) the second intermediate element is such that a center of rotation is located, after implantation, above the vertebral plate of the overlying vertebra.
8. The intervertebral disk prosthesis according to claim 1 , wherein
one of said two flattened elements is a first plate-like element anchored on a vertebral plate of a first vertebra,
the intervertebral disk prosthesis includes a second plate-like element anchored on the vertebral plate of a second vertebra adjacent the said first vertebra and having an articular surface, and
the other flattened element of the two flattened elements is an intermediate element including an articular surface adapted to cooperate with the articular surface of said second plate-like element.
9. The intervertebral disk prosthesis according to claim 8 , wherein
said first plate-like element is configured to be connected to an overlying vertebra,
said second plate-like element is configured to be connected to an underlying vertebra and includes a spherical and convex articular surface, and
said articular surface of said intermediate element is a spherical and concave articular surface.
10. The intervertebral disk prosthesis according to claim 8 , wherein
said first plate-like element is configured to be connected to an underlying vertebra,
said second plate-like element is configured to be connected to an overlying vertebra and includes a spherical and concave articular surface, and
said articular surface of said intermediate element is a spherical and convex articular surface.
11. The prosthesis according to claim 1 , wherein
each of said concave walls extends, when viewed in said second plane, over an arc greater than 90 degrees, so that the O-ring element is elastically deformed and compressed when inserted into the respective circular seat delimited by the concave wall, the concave wall retains the O-ring.
12. The prosthesis according to claim 1 , wherein said O-ring comprises a center and a radially inner circular edge and a radially outer circular edge, said radially inner circular edge being closer to said center than said radially outer circular edge.