In the procedure, a small incision is made on each side of the affected vertebra. Through a hollow tube called a canula, surgeons insert a small instrument with an inflatable balloon at the tip. Once it is placed inside the vertebra, the balloon is filled with air to increase the space inside the collapsed bone. After the fracture is reduced and normal anatomy restored, the team injects a cement-like substance that helps the vertebra stay permanently reformed.
Kyphoplasty is a major improvement over an older procedure called vetebroplasty in which cement is injected into the bone, with no attempt to correct the collapse, according to Sigurd Berven, MD, UCSF assistant professor of orthopedic surgery, co-director of the UCSF Osteoporosis Comprehensive Care Clinic and lead investigator of the study.
"Post operatively, these patients typically experience pain relief and measurable improvement of spine function. Most are able to return to normal activities within one or two weeks," he said.
Mary Williams, 62, is one such patient. She knew she had osteoporosis and had been consulting her physician to prevent further bone density loss. One day, while exercising, she experienced sudden, sharp pain, which she thought was a pulled muscle. After several days, a visit to her doctor confirmed the fracture of a vertebra in her mid back. Over the course of the next few months, the pain persisted and Mary found that she was limited in her ability to walk long distances and to sit for long periods. This meant she could no longer attend the ballet or night classes. Mary also felt progressive social isolation and despair. Since the procedure, she has resumed many of her normal activities. Eight million women and two million men in the United States have osteoporosis. Eighteen million more are at risk, especially as the population ages. After age 65, about 30 percent of women have osteoporosis.
Once vertebral bones lose mineral density, they may fracture and collapse, becoming wedge-shaped instead of rectangular. These vertebral compression fractures are the most common fractures associated with osteoporosis, outnumbering hip and wrist fractures combined. In the U.S., nearly 700,000 patients a year sustain vertebral compression fractures, and up to thirty percent of these patients may have pain and limited function.
"These fractures are often brought on by everyday activities or after a minor trauma like falling," said Berven. "Once the bone has collapsed, patients often have severe limitations, including pain and a stooped posture called Dowager's hump."
The procedure is part of the integrated care offered at UCSF Vertebral Compression Fracture Comprehensive Care Clinic. A collaborative effort between the UCSF departments of orthopedic surgery and rheumatology, the clinic offers expertise in the surgical as well as ongoing medical management of osteoporosis, including prevention.
Nancy Lane, MD, UCSF associate professor in the San Francisco General Hospital Medical Center (SFGHMC) division of rheumatology and co-director of the UCSF clinic is a nationally recognized expert in the medical management of osteoporosis. She is currently directing a clinical trial using recombinant parathyroid hormone related peptide for treatment of osteoporosis. Initial evidence suggests that this protein may be effective in actually increasing bone mineral density and in stimulating new bone formation.
Additional investigators on the kyphoplasty study include: Bobby Tay, MD, UCSF assistant professor of orthopedic surgery; Vedat Deviren, MD, UCSF assistant professor of orthopedic surgery, and Serena Hu, MD, UCSF associate professor of orthopedic surgery.
For more information about the kyphoplasty study, sponsored by Kyphon Inc., contact the UCSF Spine Center at (415) 353-2808 or the UCSF Vertebral Compression Fracture Comprehensive Care Clinic at (415) 353-2218.
Kyphon, Inc., based in Sunnyvale, CA, develops medical devices using their proprietary balloon technology for orthopedic applications.
Visuals: Patients undergoing the procedure, x-rays and other diagnostic tools that show dramatic improvements in spine shape and function, clinic visits with patients who have had the procedure. Kyphon, Inc. has developed sophisticated animation of the procedure.