This invention revolves around medical devices, especially the non-metal ball-headed hip joint prosthesis, including acetabular cup, non-metal femoral head and femoral stem prostheses. In this invention, the acetabular cup is combined with the lining as a metal cup, and the traditional metal or ceramic ball head is replaced by non-metal femoral head prosthesis with metal inner core.

A prosthetic implant is disclosed comprising: a first component comprising a first inner surface and a first outer surface, a second component comprising a second outer surface adapted to contact and engage with the first inner surface, the second component further comprising a second inner surface, a third component comprising a third outer surface adapted to contact and engage with the second inner surface, the third component further comprising a third inner surface, and a fourth component comprising a fourth outer surface adapted to contact and engage with the third inner surface; wherein the second component is rotatable relative to the first component about a first axis, the third component is rotatable relative to the second component about a second axis perpendicular to the first axis, and the fourth component is rotatable relative to the third component about a third axis perpendicular to the first axis and second axis; the first inner surface and the second outer surface are each formed with a first partial cylindrical shape, the first inner surface and the second outer surface each comprise a flat surface normal to the first axis and are engageable with one another such that the second component is rotatable relative to the first component about the first axis only, the second inner surface and the third outer surface are each formed with a second partial cylindrical shape, the second inner surface and the third outer surface each comprise a flat surface normal to the second axis and are engageable with one another such that the third component is rotatable relative to the second component about the second axis only, and the third inner surface and the fourth outer surface are each formed with a third partial cylindrical shape, the third inner surface and the fourth outer surface each comprise a flat surface normal to the third axis and are engageable with one another such that the fourth component is rotatable relative to the third component about the third axis only.

The present invention disclosed resolves the main problems of bone-sparing hip resurfacing surgery by using only an acetabular component in which the femoral head articulates, being only shaved to a spherical shape and cleared of osteophytes that could impinge on the acetabulum and so restrict the range of motion. The inner surface of the resurfacing cup is aspherical in shape creating an annular contact with the femoral head. The inner, articulating surface of the cup (10) is ADLC or pyrolytic carbon coated to reduce friction and wear of the femoral head. The surgical approach is well developed with surgery time significantly reduced by avoiding the use of the femoral resurfacing component. The cup is preferably of the double¬shell type for cementless fixation, but it can also be made as a single shell for cementless or cemented fixation. Should a revision surgery due to wear of the femoral head become necessary, the cup can be retained and combined with a dual mobility femoral component.

This invention corresponds to a prosthesis for total or hip resurfacing replacement, which comprises a prosthetic femoral head made of highly cross-linked polyethylene, with a diameter ranging from 38 mm to 64 mm, to articulate with a cup or acetabular component made of metal. When the invention applies to total hip replacement, the polyethylene head includes a metal core, which contains inside the female counterpart (14) to mate with the male counterpart (13) of a Morse taper, located at the upper end of the femoral component. The use of this type of head for total hip replacement, articulated with an ultra-polished acetabular cup, reduces the risk of dislocation, transmits less angular and torque forces to the Morse taper than large metal heads, and avoids the problems related to the metal-metal bearing or with the use of large metal heads with thin polyethylene. When the invention relates to hip resurfacing replacement, the highly cross-linked polyethylene femoral head has a lower polyethylene extension or stem with or without internal metal reinforcement (151) or a metal stem integrated into a metal-back (152). Using these types of heads for hip resurfacing replacement heads eliminates the problems associated with metal-on-metal resurfacing replacements.

This invention corresponds to a prosthesis for total or hip resurfacing replacement, which comprises a prosthetic femoral head made of highly cross-linked polyethylene, with a diameter ranging from 38 mm to 64 mm, to articulate with a cup or acetabular component made of metal. When the invention applies to total hip replacement, the polyethylene head includes a metal core, which contains inside the female counterpart (14) to mate with the male counterpart (13) of a Morse taper, located at the upper end of the femoral component. The use of this type of head for total hip replacement, articulated with an ultra-polished acetabular cup, reduces the risk of dislocation, transmits less angular and torque forces to the Morse taper than large metal heads, and avoids the problems related to the metal-metal bearing or with the use of large metal heads with thin polyethylene. When the invention relates to hip resurfacing replacement, the highly cross-linked polyethylene femoral head has a lower polyethylene extension or stem with or without internal metal reinforcement (151) or a metal stem integrated into a metal-back (152). Using these types of heads for hip resurfacing replacement heads eliminates the problems associated with metal-on-metal resurfacing replacements.

The invention reduces wear in total joint articulations by modifications of the shape of either component of the kinematic pair, so as to result in an annular surface contact between the two components. Fluid trapped between the two components within the inner contour of the annular contact area is pressurized under load due to elastic deformation of the components and exuded out through inter-articular gap over the surface of contact, aiding in lubrication and reducing the wear. Reduced to practice for a total hip joint with UHMWPE-metal pair, the wear rate tested in a hip joint simulator up to five million cycles was reduced by factor seven to fifteen compared to conventionally shaped components.

A prosthetic implant is disclosed comprising: a first component comprising a first inner surface and a first outer surface, a second component comprising a second outer surface adapted to contact and engage with the first inner surface, the second component further comprising a second inner surface, a third component comprising a third outer surface adapted to contact and engage with the second inner surface, the third component further comprising a third inner surface, and a fourth component comprising a fourth outer surface adapted to contact and engage with the third inner surface; wherein the second component is rotatable relative to the first component about a first axis, the third component is rotatable relative to the second component about a second axis perpendicular to the first axis, and the fourth component is rotatable relative to the third component about a third axis perpendicular to the first axis and second axis; the first inner surface and the second outer surface are each formed with a first partial cylindrical shape, the first inner surface and the second outer surface each comprise a flat surface normal to the first axis and are engageable with one another such that the second component is rotatable relative to the first component about the first axis only, the second inner surface and the third outer surface are each formed with a second partial cylindrical shape, the second inner surface and the third outer surface each comprise a flat surface normal to the second axis and are engageable with one another such that the third component is rotatable relative to the second component about the second axis only, and the third inner surface and the fourth outer surface are each formed with a third partial cylindrical shape, the third inner surface and the fourth outer surface each comprise a flat surface normal to the third axis and are engageable with one another such that the fourth component is rotatable relative to the third component about the third axis only.

The present invention relates to an artificial hip joint replacement system. The system includes an acetabulum portion having a cup suitable to be received by a subject's acetabular bone. The cup includes a rigid portion and an elastic portion attached to the rigid portion. Also included in the system is a ball received within the cup and in contact with the elastic portion and a femoral stem attached to the ball. The elastic portion is positioned to cause expansion and allow contraction of a space between the ball and the rigid portion of the cup so they are further apart from one another during periods of low mechanical loads.

An acetabular shell system. The shell system includes an acetabular shell having a convex outer portion and a concave inner portion. The shell system also includes a polymer sleeve having an outer portion sized and shaped to engage at least a portion of the concave inner portion of the acetabular shell.

Bone-sparing hip resurfacing surgery using only an acetabular component in which the femoral head articulates, being only shaved to a spherical shape and cleared of osteophytes that could impinge on the acetabulum and so restrict the range of motion. The inner surface of the resurfacing cup is aspherical in shape creating an annular contact with the femoral head. The inner, articulating surface of the cup is ADLC or pyrolytic carbon coated to reduce friction and wear of the femoral head. The surgical approach significantly reduces surgery time by avoiding the use of the femoral resurfacing component. The cup is preferably of the double-shell type for cementless fixation, but it can also be made as a single shell for cementless or cemented fixation. Should a revision surgery due to wear of the femoral head become necessary, the cup can be retained and combined with a dual mobility femoral component.