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​UPMC Surgeons Implanting Metal Cages into the Spine to Treat Chronic Low Back Pain

PITTSBURGH, May 26, 1999 — Surgeons at University of Pittsburgh Medical Center are implanting cylindrical metal cages into the spine to treat people who are disabled with chronic low back pain caused by degenerative disc disease. The implants are hollow, threaded cylinders made of titanium alloy that are implanted in the disc space between two or more vertebrae.

Back pain is the leading cause of workers’ compensation expense, the second-leading reason for physician office visits and the third-leading reason for surgical procedures. Disc degeneration affects some 12 million people in the United States, most between the ages of 20 and 60. More than 5 million Americans are disabled due to chronic back pain.

The process is called the BAK® interbody fusion system, manufactured by Sulzer Spine-Tech.

Between each of the 24 vertebrae of the human spine is a vertebral disc, comprised of cartilage-like material that separates the vertebrae and allows flexibility of movement. Injury, aging or repeated stress can produce degenerative disc disease—drying out or collapse of the disc—which can lead to excessive motion in the spine, inflammation of the nerves in and around the spine, nerve dysfunction and severe debilitating pain in the back, arms and legs.

"The discs act as spacers between the vertebrae," said William C. Welch, M.D., associate professor of surgery in the department of neurological surgery . "As they degenerate, the vertebrae move closer together and eventually cause pain. The titanium cylinders help to restore the degenerated disc space to or near its proper height, relieving pressure on the nerves."

During the minimally invasive surgery, portions of the disc and vertebral bones are removed to make room for the implants. In some cases, a small amount of bone may be taken from the patient’s hip and packed into the implant. This allows the bone to grow through and around the implant fusing the vertebral bodies and stopping the pain.

According to Dr. Welch, this type of surgery may offer several improvements over traditional techniques including: less patient trauma, reduced operating time, shorter hospitalizations and reduced costs.

"As little as five years ago, surgeons had few options for treating pain from chronic degenerative disc disease," said Dr. Welch. "This gives us a whole new venue for patients with this problem."

The most commonly performed surgery for chronic back pain is discectomy and vertebral fusion. In a discectomy, herniated disc material is removed through an incision in the back. Vertebral fusion is performed to eliminate spinal instability by fusing adjoining vertebra by implanting a bone graft into or around the disc space, which fuses the vertebra together over a period of several months.


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