Cervical disc degeneration is a common cause of neck and arm pain that can greatly impact quality of life. The disc is a flexible material between the vertebrae that holds the bones together while still allowing for movement. Because of the demands put on the disc, it sometimes can 'herniate' or wear down causing pain. If treatments, such as rest, medications, physical therapy and activity modification are not successful, the standard surgical treatment is to remove the disc and then use a graft of bone and plate with screws to fuse the two vertebrae together.
According to Dr. Frank Phillips, orthopedic surgeon at Rush and primary investigator for the PCM Artificial Disc trial, spinal fusion is a highly successful operation for relieving symptoms, but there are potential drawbacks over time. The permanent fusion of bone eliminates natural movement between the vertebrae resulting in increased stress on the discs above and below the fusion. This additional pressure may cause excessive wear and tear on the adjacent discs, which may lead to more pain and the need for additional surgery.
"The goal is to find an implant that can simulate the natural function of the cervical disc and restore the physiologic motion of the cervical spine," said Phillips.
The PCM Artificial Cervical Disc combines the use of metal and plastic, the same materials that have been in use for 30 years in hip and knee replacements, to mimic the function of the disc. The implant has two halves: an upper metal (Cobalt Chrome alloy) endplate, and a lower metal endplate to which a plastic (polyethylene) spacer is attached. The endplates are designed to bond with the neighboring vertebrae. The interface between the two halves is like a ball and socket, allowing the upper half to slide and rotate forward and backward relative to the lower half.
The surgical approach to implant the PCM device is the same as that used for cervical discectomy and fusion. A small incision is made in the front of the neck and the damaged disc is removed along with any other tissue that is compressing the nerve. After shaping the edges of the vertebrae to ensure a proper fit, the PCM Artificial Disc is inserted. The surgery lasts approximately one to two hours and most patients leave the hospital the following day. A soft collar is optional for comfort and there are few activity restrictions recommended for the first six weeks.
If the cervical device is demonstrated to be safe and effective and is approved by the FDA, Philips believes it will be more widely used than the artificial lumbar disc, which has already received FDA approval for use in the lower lumbar spine. " "The anterior surgical approach to the cervical spine is more straight forward than the approach in the lumbar spine. Spine surgeons have used this approach routinely for many years. As a result, if it became necessary to replace or revise the cervical device, there would be considerably less risk compared to revising a lumbar disc," said Philips.
Developed in consultation with leading cervical spine surgeons from the United States, Europe, and Brazil, the PCM Artificial Disc was approved by the FDA for US clinical trials in December 2004. Up to twenty centers across the country will participate in the prospective, randomized, controlled study.
Patients in the study will be randomly selected in a 2 to 1 ratio to receive either the PCM Artificial Cervical Disc surgery or anterior cervical discectomy and fusion surgery. Qualified participants must be between the ages of 18 and 65; have been diagnosed with disc degeneration or disk herniation in the cervical spine and have arm or shoulder pain and weakness or other symptoms or nerve compression. In addition, they must have been treated by a physician for more than six weeks for pain and symptoms. Patients will be required to return for follow-up visits at Rush for at least two years.
Dr. Edward Goldberg and Dr. Howard An, both orthopedic surgeons, are be co-investigators along with Phillips. All of the physicians on staff at Rush University Medical Center and members of the private practice group Midwest Orthopaedics at Rush.
For more information on this clinical call 1-888-DOC-DISC (1-888-362-3472).