September 13, 2006

(SACRAMENTO, Calif.) — For two years, a headache was Deborah Ingman's constant companion. It was with her when she awoke in the morning, as a dull pain. It would worsen until, by the end of the day, the pain was severe and caused swelling on the right side of her head. Her headache was accompanied by numbness in her right arm, with the tingling extending into her pinky and ring fingers. At times, the pain was so intense that Ingman had to retreat to her bedroom, lie down and try to ensconce herself in silence.

“My doctor kept telling me it was stress, gave me antidepressants and told me I needed to 'destress' myself,” Ingman said.

When she switched to a new primary care doctor, Ingman was insistent about finding a resolution for her headaches. Because Ingman also had herniated discs in her lower back, which caused sciatic pain, her new doctor decided that Ingman needed to see a back specialist, and referred her to Kee Kim, an associate professor of neurological surgery at UC Davis Medical Center and co-director of the UC Davis Health System Spine Program.

Based on Ingman's symptoms, Kim suspected that the source of her headaches and arm numbness was in her neck. An MRI confirmed two crumbling discs there, a sign of degenerative disc disease, which consists of a breakdown of the normal structural design of the cervical spine.

Kim is part of a group of neurosurgeons and orthopaedic surgeons in the spine program taking part in a nationwide study investigating the use of an artificial cervical disc to treat people with degenerative disc disease. Ingman accepted Kim's invitation to enroll in the study and, in late May, Kim replaced her damaged discs with the artificial models.

Today, Ingman said, “I'm back to normal. I don't have the headaches, my head is no longer swollen and the numbness in my arm is gone.” In fact, Kim's staff had to dissuade Ingman from doing too much too soon. Two weeks after her surgery, Ingman had resumed doing strenuous household chores, including mowing the lawn and scrubbing the kitchen floor on her hands and knees.

The artificial disc under investigation is a replacement implanted in place of damaged adjacent discs. Degenerative disc disease refers to a breakdown of the normal structural design of the cervical spine, which is located in the neck. Normally, the neck is flexible, but when the degeneration occurs, patients may experience pain and stiffness that can limit daily activities. If the condition progresses, it can pinch the nerves and the spinal cord, leading to arm pain, numbness, weakness and even paralysis.

The study will involve about 600 patients at up to 20 hospitals around the United States who are having surgery to relieve degenerative disc disease at either one or two adjacent disc levels. Two-thirds of the study participants will receive the artificial disc, while the remaining one third will receive the current standard of care, an operation called anterior cervical discectomy and fusion. In this procedure, the damaged discs are removed and replaced with bone-graft material, and the adjacent vertebrae are fused together. This treatment changes the mechanics of the spine and may cause stiffness in the neck.

After Ingman's diagnosis, Kim warned that if it was left untreated, she was at risk for paralysis. Initially “leery” of enrolling in the artificial disc study, Ingman agreed to participate after hearing about the other treatment option available, spinal fusion surgery. She rejected that procedure to avoid the loss of flexibility associated with it.

“I'm a very active person,” Ingman said. “I like to do yardwork.” Since her surgery, Ingman has not only resumed doing domestic chores, she has gone hiking with her husband, one of their longtime, favorite pastimes.

The artificial disc being used in the study is intended to provide an additional therapeutic option to maintain motion, segment position and spacing while preserving flexibility in the affected vertebral level. The purpose of the study is to compare the safety and effectiveness of the artificial disc to the fusion surgery.

The potential advantages of artificial discs include a faster recovery time, decreased pain in the neck and/or arm, and reduced symptoms. The artificial disc to be used in the study, called the Mobi-C®, is manufactured by LDR Spine. There is no guarantee that using the Mobi-C prosthesis will produce these benefits. The Mobi-C cervical disc prosthesis is an investigational device and is limited by federal law. The prosthesis is only available as part of a clinical study approved by the Food and Drug Administration for investigational use.

The Mobi-C consists of three parts: two metal plates that feature teeth that fit into the bone and a plastic insert that is placed between the plates. The plastic insert is flat on the bottom and round on the top. The top plate has a round socket, which allows it to move along the top of the plastic insert.

The surgeons of the UC Davis Health System Spine Program have extensive familiarity with artificial disc technology. In 2003, they participated in a clinical trial using an earlier-generation artificial disc.