Surgical implants are configured for placement posteriorly to a
spinal canal between vertebral bodies to distract the spine and enlarge the
spinal canal. In the preferred embodiments the device permits spinal flexion while limiting spinal extension, thereby providing an
effective treatment for treating
spinal stenosis without the need for laminectomy. The invention may be used in the cervical, thoracic, or
lumbar spine. Numerous embodiments are disclosed, including elongated, length-adjustable components coupled to adjacent vertebral bodies using pedicle screws. The preferred embodiments, however, teach a device configured for placement between adjacent vertebral bodies and adapted to fuse to the lamina,
facet,
spinous process or other posterior elements of a single
vertebra. Various mechanisms, including shape,
porosity, tethers, and bone-
growth promoting substances may be used to enhance fusion. The tether may be a wire, cable, suture, or other single or multi-filament member. Preferably, the device forms a pseudo-joint in conjunction with the non-fused
vertebra. Alternatively, the device could be fused to the
caudal vertebra or both the cranial and caudal vertebrae.