The L4 and L5 are the two lowest vertebrae of the lumbar spine.
These vertebrae are very strong cylindrical bones, and they form the roof (L4) and floor (L5) of the cushion (disc) that sits between them. This is called a vertebral motion segment: 2 vertebrae with a disc in between.
Given that these strong vertebrae form the lower part of the lumbar spine, why do they most commonly cause pain?
Here are 5 points you need to know about this type of pain – number 5 is not commonly known.
1.The L4 – L5 spinal motion segment is prone to degeneration over time.
The bottom segments of the spine bear the weight of the upper body, communicate motion to the hips, and allow a wide range of motion in the back to allow bending and twisting.
The weight load and mobility of this area makes the L4-L5 motion segment susceptible to developing pain from injury and/or degenerative changes from repetitive stresses over time.
2. A problem at the L4 – L5 motion segment is a common cause of sciatica.
This spinal motion segment includes a a pair of nerve roots that exit through a boney opening in the back of the spine. Compression or inflammation of this nerve is commonly caused by boney growth into the nerve passage that causes it to narrow, a slipped disc that can inflame the nerve root and/or compress it, or when L4 slips forward on L5 (spondylolisthesis). The narrowing and inflammation that these common problems cause can result in sciatica (pain down the leg or legs). Symptoms may radiate down the leg causing pain, numbness, and/or weakness, foot drop, and more severe problems can cause difficulty walking.
3. L4-L5 issues can lead to hip pain and stiffness.
Common conditions -- such as a lumbar herniated disc, degenerated disc, spinal stenosis, or spondylolisthesis - can cause problems with the spinal nerve at this level that extends to the hips. If you have hip pain, it may actually be coming from your back. It is important to make sure your doctor determines if your pain is coming from your back or your hip, or both. Only then can an appropriate course of treatment be determined.
4. Buttock pain is a hallmark symptom of a problem at the L4-L5 lumbar motion segment.
Pain that radiates into the buttock often points to a problem at the L4-L5 level. The buttock pain may be sharp, burning, or a deep ache. It is usually felt on one side but may occur on both sides. Frequently the pain radiates past the buttock down into the leg.
5. The nerve inside the L4-L5 vertebral endplates may cause low back pain.
The nerve just inside each vertebral endplate is called the basivertebral nerve. When this nerve is diagnosed as the source of pain it is called vertebrogenic pain, meaning that the vertebra at that spinal level is the source of the pain (“genic”). It typically causes chronic low back pain and does not radiate into the leg.
The L4-L5 spinal motion segment is also subject to many additional causes of pain, including osteoarthritis, synovial cysts and other boney growths.
There is a lot more to know about this spinal motion segment – read All about the L4-L5 motion segment and also Treatments for L4-L5.
