What is Spinal Fusion?

Spinal fusion of the lower back, or Lumbar interbody fusion, is a surgical procedure where the spinal vertebrae in the lumbar area (lower back) are fused in order to stabilize them. This surgery becomes necessary as the disc between vertebrae degenerate and spread, causing the disc to lose height. This degeneration may be due to herniated disc or genetics and age. The vertebrae may lower and shift, impinging on nerves and causing pain in the lower extremities. Spinal fusion is a form of treatment used to restore the height of the disc and treat back or leg pain due to degenerative disc disease.

Indications

Lumbar interbody fusion is performed when the intervertebral disc is degenerated, resulting in instability of the spine. As the disc loses height due to degeneration, the vertebrae may shift and cause nerve pain by touching the nerve or by inflammation of the capsules surrounding parts of the vertebrae. When back pain becomes severe and not manageable by conservative measures, surgery is needed to remove the damaged disc, restore the original height of the disc with a spacer such as the aprevo patient-specific spinal implant.

Types of Lumbar Interbody Fusion

Broadly classified, there are 2 main types of LIF – Anterior and posterior. This classification is based on the approach that is adopted to access the spine. The anterior approach is performed by accessing the spine through the abdomen, while the posterior approach is performed through the back. Your surgeon will discuss their recommended approach with you.

How is LIF performed?

Prior to the procedure, consent is obtained, and the patient is administered a general anesthetic agent. Depending on the approach, the skin over the abdomen or back is cleaned with antiseptic solution. The patient is placed either on their back (for anterior approach) or on their front (for posterior approach).

In the anterior approach, once the skin is incised, the muscles and blood vessels that are present are moved in order to get access to the spine. The degenerated disc is removed, and the space is replaced with temporary ‘spacers’ that help to align the vertebra in the required position. This helps relieve any pressure on the nerves and can reduce pain. These temporary spaces are then replaced by small cages (called interbody cages) that contain bone graft. These cages are then screwed into place. Sometimes, rods may be needed to further stabilize the spine.

In conventional surgery, the surgeon orders multiple spacers of varying size and angles to restore the height of the disc and attempt to restore the spine’s alignment based on your x-ray and MRI films. The aprevo system utilizes your films and delivers a customized 3d implant that is personalized specifically for you. The aprevo system helps to restore your natural alignment and disc height using your own body as the template to create the implant.

The posterior approach is exactly the same, except for the way to spine is approached.

Once the procedure is complete, the patient is observed for a short period of time and then discharged home.

Recovery

Recovery can take a few weeks to months. The bone graft within the cage grows over time, and will cause fusion of the vertebra. This stabilizes the spine permanently.

Benefits of LIF

The benefits are more with the anterior approach than with the posterior approach. The anterior approach does not damage any nerves that lie near the spine. The bone graft that is inserted is compressed, and studies show that compressed bone grafts tend to fuse the vertebra better.

Risks

As with any surgery there are risks with anesthesia, blood loss, and procedural errors. Talk to your doctor and ask about general risks for spine surgery, as well as any specific risks you may encounter due to your genetics and general health.