The United States' Food and Drug Administration (FDA) has approved the Charité Artificial Disc (DePuy Spine, Inc.) for degenerative disc disease and low back pain in the lower lumbar spine. This is a potentially exciting opportunity/option for patients with low back pain related to degenerative disc disease. The FDA notes that "this device is indicated for spinal arthroplasty in skeletally mature patients with degenerative disc disease (DDD) at one level from L4 to S1. DDD is defined as discogenic back pain with degeneration of the disc confirmed by patients' history and radiographic studies."

Charité Artificial Disc
Photo Courtesy of DePuy Spine, Inc.

Treatment Indications
Fusions in the lumbar spine are performed for a number of indications. These include back pain from degenerative disc disease, infections, tumors, instability, fractures, pseudoarthrosis, failed previous surgery, spondylolisthesis, scoliosis, etc. The artificial disc is useful for only a limited number of these indications and causes of low back pain. The Charité Artificial Disc, and other artificial discs when approved, should not be considered as a panacea treatment for low back pain. It is not like a total hip or knee.

Clinical Results
The clinical results from the FDA trials and European reports are very encouraging. At 1-2 years the clinical outcome is 70%-80% successful. This is not significantly different than patients who had spine fusions for degenerative disc disease. However, the operation is shorter; there is no need to go thorough an anterior and posterior (front and back) fusion (approach) to stabilize the spine; there is not a need to follow the patient radiographically for a long time to determine if the fusion is stable; and patients return to their normal daily activities much quicker than those undergoing fusions.

Limiting Factors
One limiting factor in surgically treating low back pain is our inability to precisely diagnose the cause. If it is felt to be the disc, and the pain does not respond to normal non-operative treatments, surgical fusion may be considered. The results, however, are only 70% -80% effective in selected patients. This is the same for artificial discs. This operation does not open opportunities for patients who are not already being considered for fusion surgery, it just changes the nature of the procedure, and perhaps, short-mid term outcomes. Another factor that may be important is that with fusion accelerated degeneration of adjacent levels occurs. Hopefully, because the Charité Artificial Disc allows motion, the break down at adjacent levels will be less or significantly delayed.

Closing Words
Complications do occur with any surgery. If it is necessary to remove the disc anteriorly, the salvage procedure is a fusion. This may include even more levels. Repeat surgery after artificial disc replacement is technically very difficult.