Constrained acetabular liner

Patent metadata

Field	Value
Publication number	US-12303394-B2
Application number	US-202217867828-A
Country	US
Kind code	B2
Filing date	Jul 19, 2022
Priority date	Jun 20, 2019
Publication date	May 20, 2025
Grant date	May 20, 2025

First claim

We claim:

1. A method of performing a total hip replacement in a human patient comprising the steps of:
providing an acetabular cup comprising a liner having an inner surface, the inner surface comprising:
a hemispherical surface having a radius of curvature, being disposed about a central axis, and intersecting a hemispherical plane perpendicular to the central axis, the intersection of the hemispherical surface and the plane defining a circle having a circle radius equal to the radius of curvature;
a retaining region continuous with the hemispherical surface, having the radius of curvature, connected with the hemispherical surface at the plane along a first arc of the circle on the plane, and extending a first distance out of the plane;
an insertion region on the hemispherical plane and connected with the hemispherical surface along a second arc of the circle on the plane and comprising an increased radius portion, wherein the hemispherical surface does not extend past hemispherical plane in insertion region, wherein a radial distance from the central axis to the insertion region is greater than the circle radius, and wherein a maximum opening distance from an edge of the retaining region to an edge of the insertion region is less than twice the circle radius;

preparing an acetabulum of the patient to receive the acetabular cup;
affixing the acetabular cup to the prepared acetabulum;
providing a femoral prosthesis comprising a femoral neck, a femoral stem connected with the femoral neck and adapted to be implanted into a femur of the patient, and femoral ball, wherein the femoral ball comprises:
a spherical ball surface with a ball radius equal to the radius of curvature of the hemispherical surface,
a ball center at a geometric center of the spherical ball surface, and
a planar surface, wherein the femoral neck is connected with the ball perpendicular to the planar surface, wherein the planar surface is located an offset distance from the ball center less than the ball radius, and wherein the offset distance and the ball radius define a ball height equal to the sum of the ball radius and the offset distance;

affixing the femoral stem to a femur of the patient;
positioning the femoral prosthesis with the femoral ball spherical ball surface in contact with the retaining region at an insertion angle and with an edge of the planar surface in contact with the increased radius portion; and
pressing the femoral ball into the liner.

2. The method of claim 1 , wherein the acetabular cup comprises an anchor adapted to be affixed with an acetabulum of the patient and wherein the anchor comprises an inner surface with substantially the same shape as an outer surface of the liner, and wherein the step of affixing the acetabular cup comprises:
affixing the anchor to the prepared acetabulum; and
affixing the liner to the anchor.

3. The method of claim 1 , wherein the maximum opening distance and the ball height form an interference fit between the ball and the liner.

4. The method of claim 3 , wherein the step of pressing the femoral ball into the liner further comprising generating a tactile snap-fit when the ball is fully seated in the liner.

5. The method of claim 2 , wherein the liner comprises one or more protrusions extending from the outer surface of the liner and arranged radially along a circumference of the outer surface, wherein the anchor comprises one or more slots arranged to engage the protrusions.

6. The method of claim 5 , wherein one or more protrusions are positioned to mutually engage at a plurality of angularly distinct orientations with the one or more notches, the method comprising, prior to the step of affixing the liner to the anchor, selecting a one of the distinct orientations and engaging the protrusions and notches in the selected orientation.

7. The method of claim 2 , comprising the step of providing one or more grooves on the outer surface of the liner.

8. The method of claim 7 , wherein the step of affixing the liner to the anchor comprises applying an adhesive, wherein the adhesive at least partially fills the grooves.

9. The method of claim 1 , wherein the liner comprises one or more of a polymer, a ceramic, a metal, and a metal alloy.

10. The method of claim 2 , wherein the anchor comprises one or more of a polymer, a ceramic, a metal, and a metal alloy.

11. A total hip replacement comprising:
a femoral portion comprising,
a femoral stem adapted to be implanted into a prepared femur bone of an organism;
a femoral ball; and
a femoral neck, the femoral neck adapted to connect the femoral ball with the femoral stem,
wherein the femoral ball comprises a spherical ball surface with a ball radius, a ball center at a geometric center of the spherical ball surface, and a planar surface, wherein the femoral neck is adapted to connect with the ball perpendicular to the planar surface, and wherein the planar surface is located an offset distance from the ball center point less than the ball radius, and wherein the offset distance and the ball radius define a ball height equal to the sum of the ball radius and the offset distance; and

an acetabular cup liner with an inner surface, the inner surface comprising:
a hemispherical surface having a cup radius of curvature, being disposed about a cup central axis, and intersecting a hemispherical plane perpendicular to the cup central axis, the intersection of the hemispherical surface and the hemispherical plane defining a circle having a circle radius equal to the cup radius of curvature;
a retaining region continuous with the hemispherical surface, having the same cup radius of curvature, extending along a first arc of the circle on the hemispherical plane, and extending a first distance out of the hemispherical plane; and
an insertion region continuous with the hemispherical surface connected with the hemispherical surface along a second arc of the circle on the hemispherical plane and comprising an increased radius portion, wherein the hemispherical surface does not extend past hemispherical plane in insertion region, wherein a radial distance from the cup central axis to the insertion region is greater than the circle radius,
wherein a cup opening distance is defined by a maximum opening distance between an edge of the retaining region and an edge of the insertion region, wherein the cup opening distance is substantially the same as the ball height, wherein the cup opening distance is less than twice the ball radius and wherein the ball height and cup opening distance are selected to provide an interference fit between the liner and ball.

12. The total hip replacement according to claim 11 , wherein an engagement between the ball and the liner generates a tactile snap fit when the ball is fully engaged in the liner.

13. An acetabular prosthesis comprising a liner and an anchor, wherein the liner comprises an inner surface and an outer surface, the inner surface comprising:
a hemispherical surface having a radius of curvature, being disposed about a central axis, and intersecting a hemispherical plane perpendicular to the central axis, the intersection of the hemispherical surface and the plane defining a circle having a circle radius equal to the radius of curvature and wherein the radius of curvature defines a liner center;
a retaining region continuous with the hemispherical surface, having the radius of curvature, connected with the hemispherical surface at the plane along a first arc of the circle on the plane, and extending a first distance out of the plane;
an insertion region on the hemispherical plane and connected with the hemispherical surface along a second

Assignees

• Feinstein Institutes For Medical Research

Inventors

• Asnis Stanley
• Goldstein Todd

Classifications

• A61F2/3609

  Femoral heads or necks; Connections of endoprosthetic heads or necks to endoprosthetic femoral shafts (A61F2/3601 takes precedence) · CPC title

• A61F2002/349

  Shell having a wavy or undulated peripheral rim · CPC title

• A61F2002/3654

  Connections of heads directly to shafts · CPC title

• A61F2/4609

  of acetabular cups · CPC title

• A61F2002/365

  Connections of heads to necks · CPC title