Bi-axial prosthetic joint
OwnerC. Thomas Waitsinventor
Life of this patent
Estimating the term…
Abstract
Bi-axial implants for the replacement of human joints which require multi-axis rotation and translation as well as for the replacement of anatomical ball and socket joints. A first member has a fixation element such as a stem for affixation to a first bone and a convex head, which head is received in a cavity in a second member having a concave surface which member is designed for attachment to a second bone. Located between the convex and concave surfaces is a ring bearing which forms a circular line of contact with the convex head and a circular line of contact with the concave surface. When a load is applied and transferred between the first and second members, the position of the ring bearing shifts to an alignment substantially transverse to the direction in which the load is being applied.
Claims20
A bi-axial prosthetic joint comprising
- a first member having means for fixation to a first bone and having a convex head,
- a second member which is shaped for attachment to a second bone and which includes a generally smooth concave surface portion of a size sufficient to receive said head, and
- a ring bearing which has a central opening and is shaped and proportioned to generally form a first ring of contact with said convex head of said first member and a second ring of contact with said concave surface of said second member, said ring bearing having sufficient rigidity such that some clearance will always be maintained under normal physiological load between facing surface portions of said first member head and said ring bearing adjacent said first ring of contact and between facing surface portions of said ring bearing and said second member concave surface adjacent said second ring of contact, and said ring bearing being free to shift and slide along said concave surface of said second member and along said convex head.
A composite bi-axial prosthetic joint which comprises a first member having a pair of generally spherical convex heads which are located a predetermined distance from each other, both being affixed to a common base means that is designed for attachment to a first bone,
- a second member which is attachable to a second bone and which includes a pair of adjacent concave surfaces shaped and proportioned to receive said pair of heads, and
- a pair of separate ring bearings, each having a central opening, respectively positioned between one of said heads and one said concave surface of said second member, each of said ring bearings generally having a first ring of contact with said respective convex head and a second ring of contact with said respective concave surface of said second member and being free to separately shift relative to both said respective convex head and said concave surface, and each said ring bearing having sufficient rigidity such that some clearance will always be maintained under normal physiological load between facing surface portions of said first member head and said ring bearing adjacent said first ring of contact and between facing surface portions of said ring bearing and said second member concave surface adjacent said second ring of contact.
A bi-axial prosthetic joint comprising
- a first member having means for fixation to a first bone and having a convex head,
- a second member which is shaped for attachment to a second bone and which includes a generally smooth concave surface portion of a size sufficient to receive said head, and
- a ring bearing which is generally teardrop-shaped in cross-section having a wide section and a narrow section, said ring bearing being free to shift relative to said concave surface and to said convex head and being proportioned and shaped so that, under essentially no load, said wide section forms one ring of contact with one member of (a) said first member head and (b) said second member concave surface and is out of contact with the other member thereof, and said narrow section forms another ring of contact with said other member of (a) and (b) and is out of contact with said one member of (a) and (b), whereby clearance exists between said first and second members and said ring bearing except for said two rings of contact.
Dependencies are inferred from the claim text.