Lumbar Spine Surgery and Low Back Degenerative Disorders

Part 1: Lumbar anatomy
Part 2: Lumbar degenerative conditions
Part 3: Lumbar surgery options

The lumbar discs are tough structures. Nevertheless, wear and tear from normal life can cause discs to break down and lead to low back osteoarthritis. In the spine, osteoarthritis is called spondylosis. It is essentially the same degenerative process that leads to arthritis of the hip and knee joints. The degenerative process can lead to significant changes in the lumbar spine anatomy. These changes can cause low back pain or leg symptoms because of:

• Internal disruption of the intervertebral disc
  
• Abnormal motion of the vertebrae
  
• Compression of the cauda equina and/or nerves

The degenerative process in the lumbar spine includes distinct characteristics. Some or all characteristics may be present.

Degenerative Processes Affecting the Lumbar Spine

Characteristic: Desiccation (Disc Dehydration)
The first stage of degeneration occurs when the nucleus pulposus begins to lose water. This early stage is not painful and is called desiccation, which essentially means dehydration. Eventually, the affected disc loses height and hydrostatic pressure (balance) because of water loss.

Characteristic: Discogenic Pain
Fibers in the annulus fibrous may tear and rupture causing the onset of sudden, but persistent low back pain. Some doctors call this discogenic pain because pain originates from within the disc. Discogenic pain is also referred to as mechanical axial back pain because pain occurs when the patient is active.

Characteristic: Abnormal Motion
Abnormal motion occurs between vertebral bodies when a disc no longer functions as an effective shock absorber. Too much motion can make discogenic pain worse. Too much motion can also cause facet joint pain as cartilage-coated joint surfaces wear down.

Characteristic: Bulging Disc or Ruptured Disc
Remnants of an annulus fibrosus may bulge backward into the spinal canal and cause cauda equina or nerve compression. Compression of nerve structures can cause leg pain, numbness, and tingling. This is called lumbar radiculopathy. Sometimes, a disc completely ruptures and the nucleus pulposus comes into direct contact with nerve structures.

Characteristic: Bone Spurs
Bone spurs, called osteophytes, can begin to develop anywhere on the vertebrae. Osteophytes can protrude into the spinal canal and foramina (nerve passageways) causing cauda equina or nerve root compression.