This invention improves upon prior art total disc replacements (TDRs) by more closely replicating the kinematics of a natural disc. The preferred embodiments feature two or more fixed centers of rotation (CORs) and an optional variable COR (VCOR) as the artificial disk replacement (ADR) translates from a fixed posterior COR that lies posterior to the COR of the TDR to facilitate normal disc motion. The use of two or more CORs allows more flexion and more extension than permitted by the facet joints and the artificial facet (AF). AF joint-like components may also be incorporated into the design to restrict excessive translation, rotation, and/or lateral bending.

A retaining mechanism is disclosed, which comprises a plate including a first surface adapted to engage with an implant and a second opposing surface, the plate having mechanically-weakened areas, such that the plate is compressible from a first dimension to a second reduced dimension via the weakened areas, wherein the plate includes at least one ledge adapted to engage with a recess in the implant to prevent a fixation member inserted into the implant from backing out. A tool is also disclosed for compressing and inserting the retaining mechanism into engagement with the implant, as are respective methods of compression and insertion of the retaining mechanism into engagement with the implant.

An implant may include a first body member and a second body member, at least one bone contacting arched member, and a first external element extending from the first body member to the second body member, wherein the first external element has an undulating planar geometry in which the first external element undulates in a single plane.

The present disclosure describes an intervertebral implant having a laterovertically-expanding shell operable for a reversible expansion from a collapsed state into an expanded state, the laterovertically-expanding shell having one or more connectors, and a pair of lateral extension elements that function to laterally expand the footprint of the implant within an intervertebral disc space.

The present disclosure is directed to medical implants for better retention of biological bone graft material. The implants according to the present disclosure include an undulating crossbeam within a graft chamber to increase surface area and friction for retention of biological graft material above and below the crossbeam. In certain embodiments, implants can have smooth and curved sinusoidal peaks or sharp and planar sinusoidal peaks within the graft chamber.

An attachment device for cranioplasty may have a body defined from a sheet material and may include a first connection end having at least a first connection hole configured to cooperate with a fastener to anchor the attachment device to a bone flap or prosthesis covering at least part of the opening in the skull. A second connection end has at least a second connection hole configured to cooperate with a fastener to anchor the attachment device to a skull adjacent to an opening in the skull. A frame portion extends from the first connection end. A coil portion may be between the frame portion and the second connection end, the coil portion having struts configured for deforming in flexion, and webs between the struts configured for deforming in torsion. The frame portion is configured to be located over a periphery of the opening in the skull to block inward movement. The coil portion enables an out-of-plane deformation of the attachment device for the first connection end to move out of a neutral plane with the second connection end.

A joint implant to be mounted to a hard tissue of a patient comprises a body portion. The body portion having a tissue face configured to contact a prepared surface of the hard tissue of the patient, when the joint implant is mounted to the hard tissue of the patient. The tissue face of the body portion comprises an anchoring structure configured to anchor the joint implant on the hard tissue of the patient. The body portion is formed to fit the prepared surface of the hard tissue such that the joint implant is held in a predefined target position when mounted to the hard tissue