Two minimally invasive procedures — vertebroplasty and kyphoplasty — involve the injection of a medical cement to stabilize compressed vertebrae. Introduced in the United States in the 1990s, they've become increasingly available for the treatment of fracture pain that doesn't respond to more conservative therapy. According to Dr. John Pan, a radiologist at Boston's Brigham and Women's Hospital, bracing and analgesics are usually tried first "to see if the fracture heals on its own. If it doesn't and the person continues to have pain — usually after four to six weeks — that's when the procedure is considered."
There are very few controlled studies comparing the long-term effectiveness and safety of vertebroplasty and kyphoplasty — with each other or with conservative treatment. It's not clear whether either procedure improves spine stability or prevents fractures in the long run. But the main reason for these procedures is pain, and as many as 85% to 90% of people who undergo them experience immediate relief. A review of 21 studies involving 1,309 patients, published in 2007 in the journal Pain Physician, found that both techniques reduced pain by more than 50%.
No one knows exactly how these procedures do that. One theory is that the pain is largely an inflammatory response to the uneven distribution of mechanical forces caused by bone fragmentation. The cement is thought to help by restabilizing the vertebra, which reduces inflammation and thus pain. It's also possible that the cement destroys pain-conducting nerve endings in the vertebra.
Before either procedure, MRI is usually performed to determine if the patient is likely to benefit. A good candidate is one whose MRI shows the presence of bone edema, or fluid, which is associated with recent fracture. If bone edema is absent, that implies the fracture has healed and is not what's causing the pain. An MRI can also help ascertain whether a disk, the spinal cord, or other soft tissue is involved.
Both kyphoplasty and vertebroplasty are performed percutaneously (that is, through the skin), often as day surgery and under conscious sedation. If the fractures are numerous or severe, or the patient is older and in poor health — or cannot tolerate lying on his or her stomach — general anesthesia may be used. Sometimes an overnight hospital stay is necessary. Here's what's involved:
Vertebroplasty. Guided by computed tomography (CT) or fluoroscopy (real-time x-rays), a specially trained radiologist, neurologist, or orthopedic surgeon inserts a hollow needle through a small incision in the skin into the compressed portion of the vertebra. When the needle is in place, she or he injects a surgical cement (methyl methacrylate), which has the consistency of toothpaste. It's mixed with an agent that allows the physician to see its flow into the vertebra. The cement hardens within about 15 minutes. The patient is monitored for two to three hours in the recovery room before going home.
Kyphoplasty. In this procedure, which is also image-guided and performed through tiny incisions in the back, inflatable balloons are inserted through tubes in both sides of the fractured vertebra (see illustration). The balloons are inflated, creating a cavity and restoring vertebral height. They are then deflated and withdrawn and the cavity is filled with cement. The procedure takes 30 to 60 minutes for each fracture and sometimes involves an overnight hospital stay.
What is kyphoplasty?
Kyphoplasty is a two-step process. First, a tubelike device with a balloon at the end is inserted into each side of the collapsed vertebra (A). The balloons are then inflated, creating a cavity and restoring vertebral height. The balloon is withdrawn and cement is injected, filling the cavity (B).
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