Spinous process spacer

A spinal implant for maintaining a desired spatial relationship between adjacent vertebrae of a spine, the spinal implant comprising:

• a body having a collapsed state during implantation of the spinal implant into a spinal implantation site between adjacent vertebrae, and an expanded state at the spinal implantation site between the adjacent vertebrae, the collapsed state defining a generally annular profile, and the expanded state defining a first area for receiving a first bony portion of a first vertebra of the adjacent vertebrae and a second area for receiving a second bony portion of a second vertebra of the adjacent vertebra, wherein the body comprises a plurality of stacked plates, each plate comprising a center section, a rectangular bore in the center section, and a plurality of flanges extending from the center section;
• and
• an expansion assembly releasably connected to the body and configured to expand the body from the collapsed state to the expanded state, the expansion assembly comprising:
• a rod slidably extending through the rectangular bore in the center section of each plate, the rod having a first end, a second end, and a plurality of planar sides defining a rectangular cross-section;
• a first plate retention component axially slidably connected to the second end of the rod and abutting the center section of a plate of the plurality of stacked plates that is at a second end of the plurality of stacked plates, the first plate retention component having a ring and a plurality of spaced-apart spokes extending from the ring, wherein the first plate retention component is retained relative to the rod by the plurality of spokes in direct frictional engagement with the plurality of planar sides of the rod;
• whereby pulling the rod through the second plate retention component when the body is in the collapsed state expands the body toward the expanded state.

A spinous process spacer for maintaining a desired spatial relationship between adjacent vertebrae of a spine, the spinal implant comprising:

• a plurality of adjoining plates, each one of the plurality of adjoining plates having a center section, a rectangular bore in the center section, and a plurality of flanges pivotally connected to the center section, the plurality of adjoining plates defining a collapsed state during implantation of the spinal implant into a spinal implantation site between adjacent vertebrae and an expanded state at the spinal implantation site between the adjacent vertebrae, the collapsed state defining a generally annular profile and the expanded state defining a first area for receiving a spinous process of a first vertebra of the adjacent vertebrae and a second area for receiving a spinous process of a second vertebra of the adjacent vertebra;
• an expansion assembly connected to the plurality of adjoining plates and configured to expand the plurality of adjoining plated from the collapsed state to the expanded state, the expansion assembly comprising:
• a rod slidably extending through the rectangular bore in the center section of each plate, the rod having a first end, a second end, a longitudinal axis, and a plurality of planar sides parallel to the longitudinal axis and defining a rectangular cross-section;
• a first plate retention component at a first end of the rod and abutting the center section of a plate of the plurality of stacked plates that is at a first end of the plurality of stacked plates, the first plate retention component comprises a cup shaped body that receives the rod;
• and
• a second plate retention component slidably connected to a second end of the rod and abutting the center section of a plate of the plurality of stacked plates that is at a second end of the plurality of stacked plates, the second plate retention component having a ring and a plurality of inwardly projecting spokes extending from the ring and spaced apart from adjacent spokes, wherein the first plate retention component is retained relative to the rod by the plurality of spokes in frictional engagement with the plurality of planar sides of the rod;
• whereby pulling the rod through the second plate retention component when the body is in the collapsed state expands the body toward the expanded state;
• wherein each flange of each plate has a ridge on a first side and a channel on a second side, whereby the ridge of the flange of a plate engages the channel of the flange of an adjoining plate.