Kyphoplasty is a new technique developed for treating spinal fractures due to osteoporosis. Kyphoplasty also appears to offer benefits for patients with multiple myeloma. It offers an additional benefit over vertebroplasty in that it helps restore the height of the compressed vertebra. The medical devices used in the procedure were developed by Kyphon Inc. and have been marketed in the United States since 1998 for use in the treatment of spinal fractures and certain other fractures.
What it is
Like vertebroplasty, kyphoplasty is a minimally invasive procedure that is performed using local or general anesthesia. The physician makes a small incision on each side of the fractured vertebrae using x-ray guidance and creates a path into the bone using special instruments. He or she then inserts two tiny tubes, each containing a small inflatable KyphX® balloon, into the compressed vertebra (see figure). The balloons are inflated with a radiopaque dye for visualization, attempting to restore the vertebra to its original height. The balloons are removed and the cavities created by the balloons are then filled with bone cement. The bone cement usually hardens within 15 minutes. This stabilizes the bone and preserves the re-established height, relieving pain and restoring spinal alignment that may help prevent future fractures. On average, it takes about 30 to 45 minutes to treat each fracture.
Potential side effects
As with vertebroplasty, the risks associated with kyphoplasty are minimal in trained hands. Although infrequent and usually clinically insignificant, cement leakage may occur. In rare cases, cement that has leaked outside the bone can put pressure on the spinal cord or a spinal nerve. In some of these cases, surgery may be required to relieve the pressure. Patients may be monitored by x-ray or computed tomography (CT) for up to an hour following the procedure in order to detect any cement leakage. Other complications that have been reported in the literature include a single case of transient fever and a blood clot in the space surrounding the spinal cord. (Garfin et al. Spine. 2001;26(14):1511-1515.)
It is thought that cement leakage may be less likely to occur during kyphoplasty than vertebroplasty because compared to vertebroplasty, the injections during kyphoplasty are performed under relatively low pressures into the preformed cavity in the bone. For this reason, a more viscous cement mixture (which may be less likely to leak) can also be used. It is thought that the change in bone density that occurs with the introduction of cement into a vertebra may put pressure on adjacent vertebrae and increase the risk of future fractures. For this reason, patients are often monitored for new fractures following the procedure.
Use in Myeloma
Data from 55 kyphoplasty procedures performed on 18 myeloma patients at the Cleveland Clinic show that that the procedure was well tolerated and resulted in rapid clinical improvement in pain and function. In addition, patients recovered about a third of the vertebral height they lost as a result of the compression fractures. No major complications were seen and asymptomatic cement leakage occurred in 2 (4%) of the procedures. (Dudeney et al. J Clin Oncol. 2002;20(9):2382-7.)
As noted above, a study evaluating the use of vertebroplasty and kyphoplasty for painful vertebral fractures in cancer patients showed that both procedures provided significant pain relief in 84% of patients. (Fourney et al. J Neurosurg. 2003;98(1 suppl):21-30.) Relief was immediate in most patients and appeared durable over time. A total of 97 vertebrae were treated in 56 patients at M.D. Anderson Cancer Center (TX), including 21 patients with myeloma. Asymptomatic cement leakage was seen in 0 of 32 kyphoplasty procedures and 6 of 65 vertebroplasty procedures. The authors attribute the low rates of cement leakage in this study to the use of cement that hardens rapidly and injection of smaller volumes of cement. There were no early or delayed complications related to the procedures and no patient was worse after treatment. Patients receiving kyphoplasty recovered an average of 42% of the vertebral height lost due to the fracture.
Although both kyphoplasty and vertebroplasty are effective treatments for spinal fractures, some clinicians prefer kyphoplasty to vertebroplasty due to the reduced incidence of cement leakage, the injection of cement under lower pressure (which may reduce the risk of further fracture of the vertebrae), and the restoration in vertebral height achieved.
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