Abstract:
A medical device for implantation in a hip joint of a patient, the medical device comprising a prosthetic caput femur (819) comprising: a spherical portion adapted to be received in an acetabulum or a prosthetic acetabulum (65) fixated to the pelvic bone (9) of the patient. The medical device further comprises a releasing member (820) adapted to restrain the spherical portion in the acetabulum or the prosthetic acetabulum. The releasing member is further adapted to release the spherical portion from the acetabulum or the prosthetic acetabulum, when a strain, exceeding a predetermined threshold, is exerted on the hip joint, thereby releasing the prosthetic caput femur from the acetabulum or prosthetic acetabulum.
Abstract:
A hip joint prosthesis adapted to be implanted in a hip joint of a human patient. The hip joint prosthesis has a length axis extending in a proximal-distal direction when implanted. The hip joint prosthesis comprises a first proximal area and a second distal area, and wherein said first proximal area comprises a first metallic material having a first elasticity and wherein said second distal area comprises a second metallic material having a second elasticity. The first and second metallic materials are connected through net attractive forces, and the first and second metallic materials have different elasticity, such that the difference in elasticity affects the elasticity of the hip joint prosthesis along the length axis thereof.
Abstract:
A prosthetic joint has a central axis and includes: (a) a first member of rigid material and including a body having a cantilevered perimeter flange extending therefrom, the flange defining a wear-resistant, concave first contact surface having a protruding rim and a recessed central portion; and (b) a second member of rigid material with a wear-resistant, convex second contact surface. The first and second contact surfaces bear directly against each other so as to transfer axial and lateral loads from one of the members to the other, while allowing pivoting motion between the two members. The flange is shaped and sized so as to deform elastically and permit the first contact surface to conform in an irregular shape to the second contact surface when the joint is placed under a predetermined load.
Abstract:
The invention relates to an orthopedic stabilizing device for placement in an interosseous space defined by adjacent bony surfaces, comprising: a deformable monolithic body having a distal end and a proximal end, an upper bone contact structure and a lower bone contact structure, a locator arm adjacent the proximal end, a locator arm adjacent the distal end, a center section having a distal end and a proximal end extending between said upper bone contact structure and said lower bone contact structure, each locator arm being joined to said upper bone contact structure, said lower bone contact structure and said center portion at the respective distal and proximal ends by a deformation joint thereat, a first partial column on said upper bone contact structure projecting toward said center section, a second partial column on said lower bone contact structure projecting toward said center section, said center section including a third partial column projecting toward said upper bone contact structure and a fourth partial column projecting toward said lower bone contact structure, said body being expandable along a height axis between a first smaller height to a second larger expanded height, said center section being movable in a direction transverse to said expanded height, said partial columns not being engaged with each other at said first height and operative to form upon expansion a load-bearing column along the height axis by the direct engagement of said first partial column with said third partial column and the second partial column with said fourth partial column, said load-bearing column spanning the distance between said upper bone contact structure and said lower bone contact structure.
Abstract:
A medical device for treating hip joint osteoarthritis in a human patient by providing at least one artificial hip joint surface is provided. The hip joint having a ball shaped caput femur as the proximal part of the femoral bone with a convex hip joint surface towards the centre of the hip joint and a bowl shaped etabulum as part of the pelvic bone with a concave hip joint surface towards the centre of the hip joint. The medical device comprises the artificial hip joint surface comprising at least one of; an artificial caput femur or an artificial caput femur surface comprising, a convex form towards the centre of the hip joint, and an artificial acetabulum or an artificial acetabulum surface comprising, a concave form towards the centre of the hip joint. The artificial convex caput femur or the artificial convex caput femur surface is adapted to be fixated to the pelvic bone of the human patient and the artificial concave acetabulum or artificial concave acetabulum surface is adapted to be fixated to the femoral bone of the human patient.
Abstract:
A method for forming an implant for a bone comprises the step (20) of generating a first general shape for the implant having a length extending along a long axis of the bone. A step (40) determines an area moment of inertia of a cross section of the implant. Step (40) also determines an area moment of inertia for a cross section of bone coplanar to the cross section of the implant. A percent stress shielding is calculated (50) from the area moments of inertia of the implant and the bone. A step (60) compares the calculated percent stress shielding to a preset threshold. Iteratively, additional general shapes are generated (80) for the implant by locally adjusting the cross section of the implant until the calculated percent stress shielding meets the preset threshold.