The TOPS™ System is a lumbar facet joint replacement implant which stabilizes the spine without a rigid fusion. The TOPS is implanted at the diseased level (typically L4-L5, L3-L4, or L2-L3) following decompression surgery to alleviate pain stemming from spinal stenosis and degenerative spondylolisthesis. Spinal stenosis is a narrowing of the spinal canal, which causes a pinching of the spinal cord and nerve roots that extend from the spine to the legs. Degenerative spondylolisthesis refers to an abnormal slip of one spinal vertebra in relation to another that causes pain in the lower back and legs. The TOPS™ System is indicated for spinal stenosis and spondylolisthesis from L2 to L5.