An improved mechanism for expanding or lifting a device in accordance with various embodiments of the present invention is a coaxial screw gear sleeve mechanism. In various embodiments, coaxial screw gear sleeve mechanisms includes a post with a threaded exterior surface and a corresponding sleeve configured to surround the post, the corresponding sleeve having a threaded interior surface configured to interface with the threaded exterior surface of the post and a geared exterior surface. A drive mechanism can be configured to interface with the geared exterior surface of the sleeve, causing a device utilizing such a mechanism to expand or lift between a collapsed configuration and an expanded configuration.

The present invention provides a prosthetic wrist implant comprising: a radial implant component having an elongated radial stem extending proximally adapted for attachment to radius, a carpal implant component having a distal surface adapted for attachment to one or more carpal bones, and a interposed component between the radial implant component and the carpal implant component that is flexible and allows for changes in orientation between the radial component and the carpal components relative to each other component.

A facet joint replacement system includes a facet joint replacement device including an enclosing body and an articulating body. The enclosing body includes an interior surface defining an inner cavity of the enclosing body. The interior surface includes a first articulating surface and a projection extending inwardly relative to a surrounding area of the interior surface. The articulating body is positioned within the inner cavity of the enclosing body and is configured to move within the enclosing body. The articulating body includes a second articulating surface and a recess extending inwardly relative to a surrounding area of the articulating body and aligned with the projection of the interior surface of the enclosing body so as to allow movement of the projection along the recess of the enclosing body while constraining rotational motion of the articulating body within the enclosing body.

An orthopedic prosthesis includes a head which internally accommodates the major motion of a patient, e.g., during walking, thereby reducing wear against a cup or liner. A neck may be utilized which rotates within the distal member about an axis aligned with the major motion of the patient. The orthopedic prosthesis may also include a sacrificial anode, a seal made of natural fibers, and utilize lubricant made of honey.

A facet joint replacement device includes an enclosing element including an enclosing body and an inferior attachment member. The enclosing body includes an inner cavity defined by an interior surface of the enclosing body, wherein a portion of the interior surface of the enclosing body forms a superior articulating surface. The facet joint replacement device also includes an inferior articulating element including an articulating body and a superior attachment member. The inferior articulating body is positioned within the inner cavity of the enclosing body of the enclosing element and is configured to move within the inner cavity of the enclosing body of the enclosing element. The inferior articulating body includes an inferior articulating surface. The movement of the articulating body of the inferior articulating element is constrained in at least one direction within the inner cavity of the enclosing body of the enclosing element.

An orthopedic prosthesis includes a proximal member which internally accommodates the major motion of a patient, e.g., during walking, thereby reducing wear against a cup or liner. A distal member may be utilized which rotates within a proximal member about an axis aligned with the major motion of the patient. The orthopedic prosthesis may also include a head and neck, the neck being rotatably mounted within the head, the head being rotatably mounted within the acetabulum region of a patient.

A facet joint replacement device includes an enclosing element including an enclosing body and an inferior attachment member. The enclosing body includes an inner cavity defined by an interior surface of the enclosing body, wherein a portion of the interior surface of the enclosing body forms a superior articulating surface. The facet joint replacement device also includes an inferior articulating element including an articulating body and a superior attachment member. The inferior articulating body is positioned within the inner cavity of the enclosing body of the enclosing element and is configured to move within the inner cavity of the enclosing body of the enclosing element. The inferior articulating body includes an inferior articulating surface. The movement of the articulating body of the inferior articulating element is constrained in at least one direction within the inner cavity of the enclosing body of the enclosing element.

Medical devices in accordance with various embodiments of the present invention employ one or more coaxial screw gear sleeve mechanisms. In various embodiments, coaxial screw gear sleeve mechanisms include a post with a threaded exterior surface and a corresponding sleeve configured to surround the post, the corresponding sleeve having a threaded interior surface configured to interface with the threaded exterior surface of the post and a geared exterior surface. A drive mechanism can be configured to interface with the geared exterior surface of the sleeve, causing the device to expand.

Medical devices in accordance with various embodiments of the present invention employ one or more coaxial screw gear sleeve mechanisms. In various embodiments, coaxial screw gear sleeve mechanisms include a post with a threaded exterior surface and a corresponding sleeve configured to surround the post, the corresponding sleeve having a threaded interior surface configured to interface with the threaded exterior surface of the post and a geared exterior surface. A drive mechanism can be configured to interface with the geared exterior surface of the sleeve, causing the device to expand.

A system including a prosthesis assembly for a constrained knee including a tibial baseplate, a mobile bearing, and a fixed bearing. The tibial baseplate can include a distal surface and a proximal surface that can be configured to receive a hinge post. The mobile bearing can be configured to couple with the tibial baseplate and to rotate about at least a first axis approximated by a centerline of the hinge post. The rotation about at least the first axis can be limited by at least the first engagement feature. The fixed bearing can be configured to be coupled to the tibial baseplate. The fixed bearing can be restrained from rotating about the first axis by at least the first engagement feature of the tibial baseplate. The tibial baseplate can be configured to be assembled with either the mobile bearing or the fixed bearing.