ALIF: ANTERIOR LUMBAR INTERBODY FUSION SURGERY

OVERVIEW

ALIF (Anterior Lumbar Interbody Fusion) is a procedure that treats spinal injuries and diseases by approaching the spine from the front of the body to remove the damaged disc or bone. This procedure can be performed as traditional, open surgery, or with minimally invasive techniques. The benefit of accessing the spine from the front instead of the back is that back muscles and nerves are not disturbed.

ANATOMY

The spine consists of 33 individual bones (known as vertebrae) that interlock. The vertebrae are categorized into five regions:

• Cervical
• Thoracic
• Lumbar
• Sacrum
• Coccyx

The primary function of the vertebrae in the lumbar region of the spine is to bear the weight of the body. To support that weight, lumbar vertebrae are larger compared to the other vertebrae.

Intervertebral discs sit between the vertebrae. They are the shock absorbers for the spine. They are flat, round, and about half an inch thick. They are made of two components — the nucleus pulposus and the annulus fibrosus. The nucleus has a jelly-like consistency and can be found in the center of the disc. The “jelly” allows the disc to be flexible and strong. The annulus is the flexible outer ring of the disc and consists of several layers. When moving or standing, weight is put on the nucleus, causing it to expand while the annulus holds it in place. Together, the nucleus and annulus allow for movement to take place while simultaneously maintaining the strength of the spine. Many nerve endings surround the annulus, and as a result, an injured annulus can cause pain.

DESCRIPTION

Anterior Lumbar Interbody Fusion (ALIF) is a spine surgery that approaches the spine from the front of the body to remove disc or bone material from between two adjacent lumbar vertebrae. The procedure may be performed either as an open surgery or using minimally invasive techniques.

In contrast to a posterior approach to low back surgery, when your surgeon uses an anterior approach, they can access your spine without moving the nerves or muscles. Organs and blood vessels must be moved to the side with an anterior approach.

There are several reasons why someone would need to undergo an ALIF, such as:

• One or more broken vertebrae
• Spondylolisthesis (slippage of one vertebra over another)
• Protruding or degenerated discs (the cushiony cartilage between the vertebrae)
• Instability of the spine (abnormal or excessive motion between two or more vertebrae)
• People with low back or leg pain due to degenerative disc disease

For the most part, any spinal instability that has not responded to non-surgical treatments are potential candidates for this procedure. But ALIF as a stand-alone technique is usually not recommended for people whose bones have become very soft due to osteoporosis, or in patients with instability or arthritis.

There are many factors your physician will consider in determining if this procedure is right for you. These include your age, health, lifestyle, and anticipated level of activity following the surgery.

SURGICAL PROCEDURE

During the procedure, an incision is made in the abdomen, and the organs and major blood vessels are moved, allowing your surgeon to have a clear view and easy access to the front of the spine. Once your surgeon can access the spine, the degenerated disc is removed from the affected disc space, followed by the insertion of either bone graft or a suitable substitute into the disc space between the vertebrae.

The graft material acts as a binding medium and helps maintain standard disc height. As the body heals, the vertebral bone and bone graft eventually grow together and stabilize the spine. Instrumentation, such as rods, screws, plates, cages, hooks, and wire, also may be used to create an “internal cast” to support the vertebral structure during the healing process.

Once the procedure is finished, all the organs and blood vessels are returned to their original positions, and the incision is closed.

Surgeons typically perform an ALIF as a traditional, open procedure as described above. But another option is to access the spine using minimally invasive (endoscopic) technologies. They allow surgeons to reach the affected vertebrae through small incisions and intramuscular tunnels created to accommodate special guidance, illumination, and surgical tools.

NEXT STEPS

Contact your Florida Orthopaedic Institute physician to learn more about ALIF: Anterior Lumbar Interbody Fusion.