A spinal distraction implant alleviates pain associated with spinal stenosis, and facet arthropathy by expanding the volume in the spine canal and/or neural foramen. The implant provides a spinal extension stop while allowing freedom of spinal flexion. The implant consists of:An apparatus for implantation between spinous processes, comprising:a spacer body；a first retention member (248, 252) movably coupled to the spacer body so as to be movable between a retracted position and a deployed position；a second retention member (250, 254) movably coupled to the spacer body so as to be movable between a retracted position and a deployed position； andwherein when the first retention member and the second retention member are in the retracted position, the spacer body may be inserted between adjacent spinous processes and when the first retention member and the second retention member are in the deployed position the spacer body is inhibited from laterally moving with respect to the adjacent spinous processes.
