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.

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.

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 the distal 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.

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.

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 implant for use in spinal surgery comprises a resilient element having an inflatable cavity. It is formed of a biologically compatible material and is arranged for placement between end plates of adjacent vertebra. The implant may also include a wound disc replacement element. A method of performing spinal surgery on a patient comprises securely mounting a patient onto a patient support table; imaging a spinal region of the patient; building up a three-dimensional image file of the spinal region of the patient; storing the image file; and utilizing the image file for planning and carrying out computer controlled spinal surgery on the patient utilizing the implant. A computer-controlled surgical implant system comprises a steerable endosurgical implanting assembly operative to install the implant at a desired location in a patient; and a computerized controlled, which operates the steerable endosurgical implanting assembly.

A method of performing a computer-assisted surgical procedure on the spine of a patient comprising the steps of: planning, on a computer, a surgical procedure based on at least one of two- and three-dimensional images of the patient's spine; affixing a robotic assembly over an operative region of the patient; determining, with a computer in communication with the robotic assembly, a desired trajectory of a surgical tool along at least one of an access path and an implant path towards the surgical target site; and placing at least a portion of the surgical tool through the aperture along said desired trajectory along at least one of said access path and said implant path towards the surgical target site.

An implant for use in spinal surgery comprises a resilient element having an inflatable cavity. It is formed of a biologically compatible material and is arranged for placement between end plates of adjacent vertebra. The implant may also include a wound disc replacement element. A method of performing spinal surgery on a patient comprises securely mounting a patient onto a patient support table; imaging a spinal region of the patient; building up a three-dimensional image file of the spinal region of the patient; storing the image file; and utilizing the image file for planning and carrying out computer controlled spinal surgery on the patient utilizing the implant. A computer-controlled surgical implant system comprises a steerable endosurgical implanting assembly operative to install the implant at a desired location in a patient; and a computerized controlled, which operates the steerable endosurgical implanting assembly.

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.