Understanding Lumbar Artificial Disc Technology

Article written by Nilesh M Patel, MD, Yaw Boachie-Adjei, BS, Louis G Jenis, MD

Background
Low back pain (LBP) is a significant cause of disability in the US and worldwide. There are a number of theories about the cause of low back pain with the leading etiology related to the degeneration of the intervertebral disc. The discs are located in between each of the vertebrae and provide “shock absorption”, flexibility and strength of the spine.

Pathology
As individuals age, the intervertebral discs degenerate and lose their mechanical properties. The discs collapse leading to narrowing of the spinal canal, with pressure on the nerves. Superficial nerves supplying sensation to the discs may become irritated as discs degenerate and cause back pain. The syndrome of painful disc collapse is referred to as degenerative disc disease (DDD).

Treatment
Most patients with DDD are successfully treated non-operatively with physical therapy and exercise. Surgery is an option for patients who experience pain not improved by all means of conservative therapy. Lumbar fusion has traditionally been the surgical treatment of choice for LBP due to DDD and has been shown to diminish pain and decrease disability in well-selected patients.

A potential long-term consequence of spinal fusion may be accelerated degeneration of neighboring joints. The fusion of one segment means there is one less joint to share in the distribution of movement and loads.This additional burden on neighboring discs may accelerate their own degeneration.

Artificial Discs
A recent advancement in the treatment of DDD is through the use of artificial discs. This technology has been available in Europe for over a decade, and recently gained Food and Drug Administration (FDA) approval for use in the United States in October 2004. There are a number of different disc designs and each is unique in its own way but all maintain a similar goal; to reproduce the size and function of a normal intervertebral disc.

Artificial discs allow motion to continue after the degenerated disc is removed by your surgeon. This is because the prosthesis is designed to imitate normal movement between adjacent vertebrae. The artificial disc may enlarge the space available for the nerves, relieve the pressure on the joints in the back of the spine (facet joints), and maintain the natural curvature of the back. In addition, following an artificial disc implantation, the patient is encouraged to move their trunk. Early motion may translate into earlier rehabilitation and recovery.

There are a number of different discs on the market. Some of them are made of metal, while others are metal and plastic. Materials used include medical grade plastic (polyethylene), and a medical grade cobalt chromium alloy. These materials are used in many other medical implants such as hip and knee replacements.

The surgery may take 3-6 hours and is performed through an incision in the abdomen. Most patients are standing and walking by the first day after surgery. The main risks of the procedure are to the large veins and arteries from/tothe legs that need to be dissected away from the front of the disk. Additionally men are at risk for fertility issues after this procedure.

Who is a candidate for Disc Replacement?

  • Mostly back pain thought to be caused from the intervertebral disc
  • No significant facet joint disease or bony compression on nerves
  • Not excessively overweight
  • No prior major surgery in the lumbar spine
  • No deformity (Scoliosis)

Your surgeon may have a few tests performed prior to surgery to see if you are a candidate for the procedure. These may include an MRI, discography, CT scan and X-rays. If you are told you need a spinal fusion, you may want to ask your surgeon if you are a candidate for lumbar disc replacement.