A spinal implant includes a first member that is curved along an axis between opposite ends. The first member defines a bore and a first thread. A second member is positioned in the bore and is curved between opposite ends. The second member includes a second thread engaged with the first thread. The second thread includes a series of gear teeth. A third member is positioned in the bore and is curved between opposite ends and includes opposite ends. A driver includes a gear configured to engage the gear teeth such that rotation of the driver relative to the first member and the second member rotates the second member relative to the first member to translate the second member relative to the first member along the axis. Systems and methods are disclosed.

A system and method for sharing and absorbing energy between body parts. In one particular aspect, the system facilitates absorbing energy between members forming a joint such as between articulating bones.

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.

An ankle prosthesis is provided that includes a tibial stem with a retractable member configured to be controllably movable between a retracted position and an extended position so that in the extended position the retractable member engages the surface of the bone that defines an intramedullary canal so as to enhance anchoring of the tibial stem within the tibia.

Improved hip arthroplasty trial devices and hip arthroplasty trial systems are described. A hip arthroplasty trial device has a head member having a central axis and defining an inner chamber, a head member opening providing access to the inner chamber, and a cavity extending inward from the outer surface of the head member. A rotatable member is disposed in the inner chamber and along an axis between the central axis and one side of the head member. The cavity extends along an axis between the central axis and another, opposite side of the head member. A spacer is disposed within the head member opening and is moveable between a spacer first position and a spacer second position. Rotational movement of the rotatable member moves the spacer from the spacer first position to the spacer second position.

An implant including first and second end plates, each of which defines at least one anterior ramped surface and at least one posterior ramped surface. A posterior actuator is positioned between the first and second end plates and has guiding ramp surfaces which correspond with the posterior ramped surfaces. An anterior actuator is positioned between the first and second end plates and guiding ramp surfaces which correspond with the anterior ramped surfaces. An actuator assembly extends between the posterior actuator and the anterior actuator and is configured to selectively move the posterior actuator and the anterior actuator simultaneously, move posterior actuator independently of the anterior actuator, or move the anterior actuator independently of the posterior actuator.

A spinal jack adapted for installation between first and second vertebral processes, including a central body supporting first and second inter-expandable jack halves between retracted and expanded positions. Each of the jack halves further includes gripping portions adapted for engaging the vertebral processes. A geared mechanism provides for expanding or retracting the jack halves in order to establish a corrected adjusted orientation between the processes.

An expandable intervertebral total disc replacement implant, including an inferior component, including a first core including a first outer surface and a first inner surface, and a first arm telescopingly engaged with the first core, a superior component, including a second core including a second outer surface and a second inner surface, and a second arm telescopingly engaged with the second core, and an expansion mechanism connected to the first core, the second core, and at least one of the first arm and the second arm.

A spinal joint distraction system for treating a facet joint including articular surfaces having a contour is disclosed and may include a delivery device including a generally tubular structure adapted to engage a facet joint, an implant adapted to be delivered through the delivery device and into the facet joint, the implant comprising two members arranged in opposed position, and an implant distractor comprising a generally elongate member adapted to advance between the two members of the implant causing separation of the members and distraction of the facet joint, wherein the implant is adapted to conform to the shape of the implant distractor and/or the articular surfaces of the facet upon being delivered to the facet joint. Several embodiments of a system, several embodiments of an implant, and several methods are disclosed including a method for interbody fusion.

A system and methods for assembling an expandable vertebral implant for engagement between vertebrae. The implant may expand and/or collapse between a variety of lengths. The implant may include an inner core, an outer core, and/or a middle core such that the inner and outer cores may be moveable relative to each other along an axis. The middle core may include one or more gear teeth. The implant may include one or more locking mechanisms. The implant may include one or more endplates. One endplate may be fixed and/or polyaxial. A tool may be used to vary the length of the implant.