Lumbar Spine Surgery: Surgical Techniques to Treat Low Back and Leg Pain

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

The purpose of low back surgery is to reduce or relieve pain and restore lumbar spine stability. Two general surgical techniques help to achieve these goals:

• Decompression: removes of tissue pressing against a nerve structure. Decompression helps reduce radicular symptoms (leg pain, burning, numbness).
  
• Stabilization: limits motion between vertebrae. Stabilization helps reduce mechanical low back pain and symptoms.

Lumbar decompression procedures are generally performed from the posterior (back) and include the following techniques:

Foraminotomy: When disc material and/or bone spurs press against a nerve exiting the foramen (nerve passageway), a foraminotomy may be performed. Otomy is the medical term for making an opening. A foraminotomy makes the opening of the foramen larger and relieves nerve compression.

Laminotomy: To access disc material invading the spinal canal, a small opening is made in the lamina. A laminotomy is generally performed during a lumbar Minimal Access Spine Technology (MAST) procedure.

Laminectomy: Ectomy is the medical term for removal of. During a laminectomy, all or part of the lamina is removed. A laminectomy is performed to relieve spinal cord compression or to gain access to a disc from the back. Laminectomy is often used to treat lumbar stenosis, a narrowing of the spinal canal sometimes caused by arthritis.

Facetectomy: Involves a complete or partial removal of the facet joint. A facetectomy is performed to reduce nerve root compression or to gain access to disc space.

Discectomy: Surgical removal of all or part of a disc. Discectomy can be performed from the posterior (back) or front (anterior) through the abdominal cavity to reach the spine.

Understanding Spinal Stabilization
All the above procedures are decompression techniques. Foraminotomy and laminotomy usually do not disturb spinal stability. However, because laminectomy, facetectomy, and discectomy techniques remove something from the spine, the lumbar spine may need to be surgically stabilized. Spondylolisthesis (when one vertebra slips over the one below) often requires stabilization. The main stabilization techniques are:

Fusion: Bonds (fuses) bones together often using bone graft or a biological substance. Fusion stops motion between 2 or more vertebrae and provides long-term spinal stabilization. During a low back fusion, adjacent vertebral bodies, facet joints, and/or lamina may be fused together.

When fusion is performed from behind (posterior), the surgeon lays strips of bone graft from one vertebra to the one below. This is termed a posterior fusion. Sometimes, when the lamina has been removed, bone graft is placed from one transverse process to the one below. This is called a posterolateral fusion.

Surgeons have many bone graft choices including autograft, allograft, and biological substances such as recombinant human Bone Morphogenetic Protein-2 (rhBMP-2). The FDA approved rhBMP- 2 for use in lumbar spine fusion procedures where interbody cages are implanted from the front of the spine. The use of bone substitutes reduces problems associated when taking the patient's own bone for bone graft (autograft).

Instrumentation: Spine specific implants, called instrumentation, are regularly combined with fusion. Instrumentation includes such devices as wires, cables, plates, rods, screws, cages, and spacers. These devices hold the spine stable until the fusion heals solid.

Understanding Decompression and Fusion
Sometimes a spinal decompression and fusion are performed during the same surgery. However, these procedures require evaluation on a patient by patient basis. Below are common low back procedures that combine spinal decompression and stabilization with fusion and instrumentation.

Anterior Lumbar Interbody Fusion (ALIF): An ALIF is performed through the front of the spine, or around the abdominal cavity. A complete discectomy (removal of the disc) is performed. Then, cages filled with bone graft, or interbody spacers surrounded with bone graft, are implanted into the empty disc space. The devices and bone graft provide spinal stability. An anterior lumbar plate may be fixed at L5 - S1 for added stability.

Sometimes additional posterior instrumentation, such as screws connected to rods or a plate supplement an ALIF. This is called a 360 procedure because the spine is approached from the front and back.

Posterior Lumbar Interbody Fusion (PLIF): A PLIF is performed through the back of the spine. Decompression is performed by laminectomy and discectomy. The spine is stabilized using cages or interbody spacers and bone graft. Pedicle screws, connected to rods or plates, are fixed to the vertebral pedicles above and below the fusion site to supplement spinal stabilization.

Transforaminal Lumbar Interbody Fusion (TLIF): A TLIF is performed through the painful side of the body in which the patient has pain. A facetectomy allows access to a disc space from beneath the pedicle. Facetectomy and discectomy decompress the affected nerve and a single cage or interbody space and bone graft fuses the spine. Pedicle screws with rods or plates provide supplemental stabilization.

Extreme Lateral Lumbar Interbody Fusion (XLIF): XLIF is a minimal access procedure performed through the side of the body. After discectomy, a special cage is inserted into the interbody space to provide spinal stabilization. Pedicle screws may be used for added stabilization.

Lumbar Artificial Discs
Some surgeons implant lumbar artificial discs. Careful patient selection is important because an artificial disc is not an appropriate alternative to low back fusion in every case. An artificial disc allows motion to continue, whereas spinal fusion stops motion. This technology is new and only a few products are FDA-approved.

Conclusion
Patients can be encouraged that lumbar spine procedures are some of the most successful operations spine surgeons perform today. However, spine surgery to treat lumbar degeneration is performed only if all nonsurgical treatments fail. Patients who are well selected and have the appropriate surgical procedure generally recover rapidly and quickly return to activities of daily living.