Prosthesis and methods for subtotal dome arthroplasty of the hip joint

A subtotal prosthesis for reducing pain and enhancing function of a patient's hip joint which has been damaged by trauma or degenerative disease, comprising:

• a femoral prosthetic component adapted to replace at least a portion of the weight-bearing dome area of a patient's femoral head which has been damaged, and substantially less than all of the patient's femoral head articular surface, said femoral component including:
• a superior articular surface having a convex shape and forming less than a hemispheroid, the articular surface having a curvature approximating the curvature of the removed portion of the patient's femoral head;
• and
• femoral fixation means positioned on the inferior side of the femoral prosthetic component for fixing the femoral prosthetic component to the patient's femoral head which remains after the removal of substantially less than all of the femoral head including the portion of the weight-bearing dome area of the patient's femoral head such that the femoral head articular surface and the femoral component superior articular surface form a substantially continuous articular surface and the remainder of the patient's femoral head articular surface and femur is left intact;
• and
• an acetabulum component, said acetabulum component adapted to replace substantially less than all of the patient's acetabulum including at least a portion of the weight-bearing dome area of the patient's acetabulum opposing the position of the femoral component when affixed upon the femoral head when the hip joint is in a weight-bearing posture position, the acetabulum component including:
• an inferior articular surface having a concave shape and forming less than a hemispheroid, the curvature of the inferior articular surface substantially complementing the curvature of the superior articular surface so as to be congruent therewith;
• and
• backing plate means positioned on the superior side of the acetabulum component, the backing plate means including means for fixing the acetabulum component into a recess formed in the patient's acetabulum such that the inferior articular surface and the articular surface of the patient's acetabulum form a substantially continuous articular surface;
• and
• the inferior and the superior articular surfaces comprising materials forming a low friction interface such that the prosthesis is capable of supporting the weight of the patient and effecting a subtotal hip arthroplasty.

A subtotal prosthesis for repairing a patient's damaged hip joint comprising:

• a femoral component adapted to replace only a first portion of the patient's femoral head, said first portion of the patient's femoral head corresponding approximately to the dome area of the femoral head, said femoral component including:
• a superior articular surface being generally shaped as less than a convex hemispheroid, the superior articular surface having a curvature approximating the curvature of the first portion of the patient's femoral head and generally replacing the damaged articular surface of the patient's femoral head;
• and
• an inferior fixation surface, said inferior fixation surface including means for fixing the femoral component on the femoral head in place of the removed first portion while leaving the remaining bone of the femur substantially intact;
• and
• an acetabulum component being adapted to replace only a first portion of the patient's acetabulum, said first portion of the acetabulum corresponding to the first portion of the patient's femoral head, said acetabulum component including:
• an inferior articular surface being generally shaped so as to congruently correspond to the curvature of the superior articular surface, the inferior articular surface having a first dimension which is less than a second dimension, the inferior articular surface and the superior articular surface comprising materials which when in contact in the hip joint form a low friction interface;
• and
• means for fixing the acetabulum component within a recess formed in the patient's acetabulum such that the inferior articular surface and the patient's acetabulum articular cartilage form an approximately continuous articular surface and such that the superior and inferior articular surfaces bear a substantial amount of the patient's weight when the hip is in a weight-bearing posture such that the femoral and acetabulum components effect a subtotal hip dome arthroplastry.

A method of repairing a patient's damaged hip joint, comprising the steps of:

• providing a femoral arthroplasty component comprising a superior articulating surface, said superior articulating surface shaped as a convex hemispheroidal section;
• removing at least a portion of the weight-bearing dome area of the femoral head and substantially less than all of the patient's femoral head;
• fixing the femoral arthroplasty component on the remaining portion of the femoral head such that the superior articulating surface and the articular surface of the femoral head form a substantially continuous articular surface;
• providing an acetabulum arthroplasty component comprising an inferior articulating surface, said inferior articulating surface having a curvature approximately congruent tot he curvature of the inferior articulating surface;
• removing substantially less than all of the patient's acetabulum to form a recess in the acetabulum articular surface, the acetabulum surface which is removed being that which substantially interfaces with the portion of the femoral head which was removed when the hip joint is in a weight-bearing posture position;
• and
• fixing the acetabulum component in the recess formed in the patient's acetabulum in order that the inferior articulating surface and the acetabulum articular surface form a substantially continuous articular surface and such that when the hip joint is in a weight-bearing posture the femoral arthroplasty component and the acetabulum arthroplasty component bear a substantial portion of the patient's weight so as to effect a subtotal hip arthroplasty.

A method of reducing pain and enhancing function of a patient's hip joint in which the articular cartilage has been damaged or diseased, the method comprising the steps of:

• removing at least a portion of the weight-bearing dome area of the patient's femoral head and substantially less than all of the patient's femoral head;
• providing a femoral arthroplasty component comprising a superior articulating surface, the superior articulating surface being generally shaped as less than a convex hemispheroid so as to approximate the shape of the femoral head articular surface;
• fixing the femoral arthroplasty component in the location where the portion of the femoral head was removed such that the superior articular surface simulates the articular surface of the patient's femoral head;
• forming a recess in the patient's acetabulum in a location opposite from the position of the femoral component when the hip is in a weight-bearing posture position;
• providing an acetabulum arthroplasty component comprising an inferior articular surface, said inferior articular surface having a curvature congruent with the curvature of the superior articular surface and said inferior articular surface comprising a material which provides for a low friction interface to be formed when the superior and inferior articular surfaces are in contact with each other in the human body;
• and
• fixing the acetabulum component in the recess formed in the patient's acetabulum such that the inferior articular surface forms a substantially continuous articular surface with the articular surface of the patient's acetabulum and such that the interface between the femoral and acetabulum components bears a substantial portion of the force on the hip joint when the hip joint is in a weight-bearing posture, such that the implanted femoral and acetabulum components effect a subtotal hip dome arthroplasty.

A subtotal prosthesis for repairing a patient's hip joint which has been damaged due to trauma or disease, comprising:

• a femoral prosthetic component adapted to replace at least a portion of the weight-bearing dome area of the patient's femoral head which has been damaged, and substantially less than all of the patient's femoral head, said femoral component including:
• a superior articular surface having a convex shape and forming less than a hemispheroid, the articular surface having a curvature approximating the curvature of the removed portion of the patient's femoral head;
• and
• femoral fixation means positioned on the inferior side of the femoral prosthetic component for fixing the femoral prosthetic component to the patient's femoral head which remains after the removal of substantially less than all of the femoral head such that the remainder of the patient's femoral head articular surface and femur is left intact;
• and
• an acetabulum component, said acetabulum component adapted to replace substantially less than all of the patient's acetabulum including at lest a portion of the weight-bearing dome area of the patient's acetabulum opposing the position of the femoral component when affixed upon the femoral head when the hip joint is in a weight-bearing posture position, the acetabulum component including:
• an inferior articular surface having a concave shape and forming less than a hemispheroid, the curvature of the inferior articular surface substantially complementing the curvature of the superior articular surface so as to be substantially congruent therewith, the perimeter of the inferior articular surface being of a generally circular shape;
• and
• backing plate means positioned on the superior side of the acetabulum prosthetic component, the backing plate means including means for fixing the patient's acetabulum such that the inferior articular surface and the patient's acetabulum form a substantially continuous articular surface;
• the inferior and the superior articular surfaces comprising materials forming a low friction interface such that the prosthesis is capable of supporting the weight of the patient and effecting a subtotal hip arthroplasty.