Artificial hip joint and method of implanting in a patient

Claim 2

An artificial hip joint comprising a cup adapted to be inserted into the pelvis and a ball having means adapted to be secured to the femur, said cup having an axis of rotation and an inner substantially spherical surface which defines a socket symmetrical about said axis and an outer surface of revolution formed symmetrically about said axis, said cup outer surface define means for guiding shiftable movement of said cup about its axis of rotation when inserted within said pelvis, said ball including a substantially spherical surface having a radius which is less than the radius of said cup inner surface, said ball fitting within said socket and contacting said cup inner surface at locations spaced from the axis of rotation of said cup in all positions of said ball during normal fore and aft walking movement of said femur, whereby said movement of the femur causes rolling movement of said ball relative to said cup and correlative shiftable movement of said cup about its axis of rotation.

Claim 3

The hip joint of claim 1 wherein said cup includes an annular outturned lip defining a circular ball-receiving opening into said socket, said lip being symmetrical about said axis of rotation of said cup.

Claim 4

The hip joint of claim 2 wherein said cup outer surface defines a stem projecting in the opposite direction of said cup opening and along said axis.

Claim 5

The hip joint of claim 3 wherein said stem is tapered.

Claim 6

The hip joint of claim 3 wherein said stem is separated from said cup lip by an annular shouldEr defined by said cup outer surface, said shoulder and lip defining load bearing surfaces for contacting said pelvis.

Claim 7

The hip joint of claim 1 wherein said cup inner surface is interrupted by an indentation formed at the axis of rotation of said cup.

Claim 8

An artificial hip joint comprising an artificial acetabular component and an artificial femoral component, said acetabular component constituting a cup having an axis of rotation and an inner substantially spherical surface defining a socket symmetrical about said axis and an outer surface of revolution formed symmetrically about said axis, said outer surface including means for guiding shiftable movement of said cup about its axis of rotation when inserted into the acetabulum of a patient''s pelvis, said femoral component including a stem adapted for insertion into the shaft of the femur after removal of the femoral head therefrom, said stem carrying a ball, said ball having a substantially spherical surface the radius of which is less than the radius of the inner surface of said acetabular component, said ball fitting within said socket and contacting the inner surface of said acetabular component at locations spaced from the axis of rotation of said cup in all positions of said ball during normal fore and aft walking movement of said femur whereby said movement of the femur will cause shiftable movement of said cup about its axis of rotation and rolling movement of said ball relative to said cup when said cup and ball are implanted within the acetabulum and femur of said patient.

Claim 9

An artificial hip joint comprising an artificial acetabular component and an artificial femoral component, said acetabular component constituting a cup having an axis of rotation and an inner substantially spherical surface defining a socket symmetrical about said axis and an outer surface of revolution formed symmetrically about said axis, said outer surface including means for guiding shiftable movement of said cup about its axis of rotation when inserted into the acetabulum of a patient''s pelvis, said femoral component including a stem adapted for insertion into the shaft of the femur after removal of the femoral head therefrom, said stem carrying a ball, said ball having a substantially spherical surface the radius of which is less than the radius of the inner surface of said acetabular component, said ball fitting within said socket and contacting the inner surface of said acetabular component at locations spaced from the axis of rotation of said cup in all positions of said ball during normal fore and aft walking movement of said femur whereby said movement of the femur will cause shiftable movement of said cup about its axis of rotation and rolling movement of said ball relative to said cup when said cup and ball are implanted within the acetabulum and femur of said patient.

Claim 10

The hip joint of claim 7 and an outturned annular lip defined by said cup outer surface, said lip defining a circular ball-receiving opening into said socket.

Claim 11

The hip joint of claim 8 wherein said cup outer surface defines a stem which projects in the opposite direction of said cup opening and along said axis.

Claim 12

The hip joint of claim 9 wherein said cup stem is tapered.

Claim 13

The hip joint of claim 9 wherein said cup stem is separated from said lip by an annular shoulder constituting a part of said cup outer surface, said shoulder and lip defining load bearing surfaces adapted to contact the pelvis of said patient.

Claim 14

An artificial hip joint comprising an artificial acetabular component and an artificial femoral component, said acetabular component constituting a cup having an axis of rotation and an inner substantially spherical surface defining a socket symmetrical about said axis and an outer surface of circular shape on all planes normal to said axis and concentric with said axis, said outer cup surface including means for guiding rotation of said cup about said axis when positioned in the acetabulum of a patient''s pelvis with said axis at an angle to the normal direction of weight transfer from the pelvis to the femur when a patient stands erect, said femoral component including a stem adapted for insertion into the shaft of the femur after removal of the femoral head therefrom, said stem carrying a ball, said ball having a substantially spherical surface whose radius is slightly less than the radius of the inner surface of said acetabular component, said ball fitting within said socket and contacting a limited area of the inner surface of said acetabular component at a location spaced from the axis of rotation of said cup in all positions of said ball during normal fore and aft walking movement of said femur, whereby walking movement of the femur causes rotative movement of said cup about its axis and rolling movement of said ball relative to said cup.

Claim 15

An artificial hip joint comprising an artificial acetabular component and an artificial femoral component, said acetabular component constituting a cup having an axis of rotation and an inner substantially spherical surface defining a socket symmetrical about said axis and an outer surface of circular shape on all planes normal to said axis and concentric with said axis, said outer cup surface including means for guiding rotation of said cup about said axis when positioned in the acetabulum of a patient''s pelvis with said axis at an angle to the normal direction of weight transfer from the pelvis to the femur when a patient stands erect, said femoral component including a stem adapted for insertion into the shaft of the femur after removal of the femoral head therefrom, said stem carrying a ball, said ball having a substantially spherical surface whose radius is slightly less than the radius of the inner surface of said acetabular component, said ball fitting within said socket and contacting a limited area of the inner surface of said acetabular component at a location spaced from the axis of rotation of said cup in all positions of said ball during normal fore and aft walking movement of said femur, whereby walking movement of the femur causes rotative movement of said cup about its axis and rolling movement of said ball relative to said cup.

Claim 16

The hip joint of claim 12 wherein said cup includes an outwardly projecting annular flange defining a lip at the mouth of said cup.

Claim 17

The hip joint of claim 13 wherein said cup outer surface defines a stem which projects coaxially of said cup opposite said mouth.

Claim 18

The hip joint of claim 14 wherein said cup stem is tapered.

Claim 19

The hip joint of claim 14 wherein said cup stem is separated from said flange by an annular shoulder constItuting a part of said cup outer surface, said shoulder and flange defining load bearing surfaces adapted to contact the pelvis of said patient.

Claim 20

A hip prosthesis comprising interfitting acetabular and femoral components; said acetabular component having a spherical socket and an external configuration including a guide portion for maintaining said acetabular component in predetermined orientation in an acetabular recess of a pelvis during use; said acetabular component having an axis relative to which and on all planes normal to which all internal and all external surfaces are circular and concentric to facilitate rotation in said recess; said femoral component including an elongated stem, a spherical head and a reduced diameter neck portion between said stem and head; said stem anchoring said femoral component in a femur during use; said head and neck having an axis relative to which and on all planes normal to which all surfaces of said head are circular and concentric; said head having a radius slightly less than the radius of said acetabular socket whereby weight transfer contact between said parts occurs only at a limited area of each; said components being designed for installation in an orientation in which said axes are disposed at an angle in all normal usage in standing and walking whereby said limited area of weight transfer contact in said socket occurs spaced from the axis of said acetabular component.

Claim 21

A hip prosthesis comprising interfitting acetabular and femoral components; said acetabular component having a spherical socket and an external configuration including a guide portion for maintaining said acetabular component in predetermined orientation in an acetabular recess of a pelvis during use; said acetabular component having an axis relative to which and on all planes normal to which all internal and all external surfaces are circular and concentric to facilitate rotation in said recess; said femoral component including an elongated stem, a spherical head and a reduced diameter neck portion between said stem and head; said stem anchoring said femoral component in a femur during use; said head and neck having an axis relative to which and on all planes normal to which all surfaces of said head are circular and concentric; said head having a radius slightly less than the radius of said acetabular socket whereby weight transfer contact between said parts occurs only at a limited area of each; said components being designed for installation in an orientation in which said axes are disposed at an angle in all normal usage in standing and walking whereby said limited area of weight transfer contact in said socket occurs spaced from the axis of said acetabular component.

Claim 22

The hip prosthesis of claim 17 wherein said head is offset an approximate 25* angle from the longitudinal axis of said elongated stem.

Claim 25

The method of claim 19 wherein steps e, f and g precede steps b, c and d.