A spinal anchor assembly for securing a spinal fixation element has an anchor element adapted for attachment to bone. The anchor element has an opening for receiving a spinal fixation element and side walls on opposed sides of the opening with a plurality of inferior surfaces defined on the side walls. A twist-lock closure closes the opening and captures the spinal fixation element. A locking element can be provided on the closure element and the anchor element. The locking element can be configured so that when the closure element is rotated from the open position to the closed position, the locking element engages to deter the closure element from twisting back to the open position.

An apparatus and method is provided for interbody fusion including distracting, in a given direction, and supporting opposing vertebral bodies. A plurality of wafers are consecutively inserted between the vertebral bodies to create a column of wafers. The column of wafers is oriented between the vertebral bodies so as to expand in the given direction as the wafers are consecutively added to the column.

A prosthesis for the replacement of multiple diseased or traumatized spinal facets comprises a portion that replaces at least a bony portion of the facets to be replaced and where the prosthesis attaches to the vertebra in a manner that does not require attachment to, or abutment against, the lamina. Multiple configurations of the prosthesis provide for replacement of the two inferior facets, the two superior facets, a superior and inferior facet, or all four facets. A method of installing the prosthesis is provided that is comprised of the steps of resecting at least a portion of the facets that carry the diseased or traumatized spinal facets and attaching the prosthesis in a manner that does not require attachment or abutment against the lamina.

An apparatus and method is provided for interbody fusion including distracting, in a given direction, and supporting opposing vertebral bodies. A plurality of wafers are consecutively inserted between the vertebral bodies to create a column of wafers. The column of wafers is oriented between the vertebral bodies so as to expand in the given direction as the wafers are consecutively added to the column.

An apparatus and method is provided for interbody fusion including distracting, in a given direction, and supporting opposing vertebral bodies. A plurality of wafers are consecutively inserted between the vertebral bodies to create a column of wafers. The column of wafers is oriented between the vertebral bodies so as to expand in the given direction as the wafers are consecutively added to the column.

A prosthesis for the replacement of multiple diseased or traumatized spinal facets comprises a portion that replaces at least a bony portion of the facets to be replaced and where the prosthesis attaches to the vertebra in a manner that does not require attachment to, or abutment against, the lamina. Multiple configurations of the prosthesis provide for replacement of the two inferior facets, the two superior facets, a superior and inferior facet, or all four facets. A method of installing the prosthesis is provided that is comprised of the steps of resecting at least a portion of the facets that carry the diseased or traumatized spinal facets and attaching the prosthesis in a manner that does not require attachment or abutment against the lamina.

An apparatus and method is provided for interbody fusion including distracting, in a given direction, and supporting opposing vertebral bodies. A plurality of wafers are consecutively inserted between the vertebral bodies to create a column of wafers. The column of wafers is oriented between the vertebral bodies so as to expand in the given direction as the wafers are consecutively added to the column.

A prosthesis replaces all or a portion of a natural facet joint on a vertebral body. The prosthesis has a prosthesis body accommodating fixation to the vertebral body at or near a pedicle and without support by a lamina. The prosthesis body has a fastening element installed within the vertebral body at or near a pedicle. The prosthesis further has an artificial facet joint structure carried by the prosthesis body at a location spaced from the fastening element. The artificial facet joint structure is adapted and configured to replace all or a portion of a natural facet joint.

A prosthesis for the replacement of multiple diseased or traumatized spinal facets comprises a portion that replaces at least a bony portion of the facets to be replaced and where the prosthesis attaches to the vertebra in a manner that does not require attachment to, or abutment against, the lamina. Multiple configurations of the prosthesis provide for replacement of the two inferior facets, the two superior facets, a superior and inferior facet, or all four facets. A method of installing the prosthesis is provided that is comprised of the steps of resecting at least a portion of the facets that carry the diseased or traumatized spinal facets and attaching the prosthesis in a manner that does not require attachment or abutment against the lamina.

A prosthesis replaces all or a portion of a natural facet joint on a vertebral body. The prosthesis has a prosthesis body accommodating fixation to the vertebral body at or near a pedicle and without support by a lamina. The prosthesis body has a fastening element installed within the vertebral body at or near a pedicle. The prosthesis further has an artificial facet joint structure carried by the prosthesis body at a location spaced from the fastening element. The artificial facet joint structure is adapted and configured to replace all or a portion of a natural facet joint.