Decompression usually isn't suitable during pregnancy, or with hardware such as pedicle screws and rods, a lumbar fusion less than six months old, severe osteoporosis or unstable spondylolisthesis, a recent lumbar compression fracture or pars defect, metastatic, pelvic or abdominal cancer, an aortic aneurysm, a disc space infection, severe peripheral neuropathy, or paralysis.