Narrowing in the lumbar spine, or lumbar stenosis, causes compression of the nerves going into the legs. Typical symptoms include pain and often weakness in the legs worsened with prolonged standing or walking. Sometimes back or hip pain can occur as well. Oftentimes, the legs feel better with rest or when the back is flexed (bent forward), and patients will typically say they prefer to lean forward (i.e. on the grocery cart).

As with cervical stenosis, some people are born with a narrow spinal canal (congenital stenosis). Degenerative changes that accumulate over time can occupy the space in the spinal canal that usually is occupied by the nerves. Thickened ligament and enlarged joints can encroach on the spinal canal, as can disc bulges. In many cases, there's an element of both congenital stenosis (preexisting narrowing) and degenerative changes.

Conservative measures such as epidural steroid injections and physical therapy may improve symptoms, often temporarily. These modalities can provide symptomatic relief, but they do not directly treat the pathology. Definitive treatment involves surgical decompression. By removing the thickened ligament and bone, the spinal canal is "unroofed," making more room for the nerves within it.