There are several ways to treat older adults who suffer pain, loss of height, and disability from osteoporotic vertebral compression fractures. For some patients, pain relief and quality of life can be improved with conservative care. This may include physical therapy, rest, pain relieving medications, and sometimes a brace or cast.
But for those individuals who have persistent pain (which is usually severe), a surgical procedure called balloon kyphoplasty (BK) may be recommended. The surgeon inserts a thin needle into the fractured vertebra (spinal bone) with a deflated balloon on the end. The balloon is placed inside the vertebra and inflated to restore the height of the bone. Then the balloon is removed and a liquid cement is injected into the space left by the balloon inflation. When the cement hardens, the expanded vertebral body retains its shape, restoring height of the bone and relieving pain.
But there have been problems with cement leakage. The cement can ooze out through the fracture lines or enter into the blood vessels. The result can be direct injury to the nerves and/or blood vessels, causing paralysis or blood clots. Rigidity of the bone from the cement can also lead to new fractures.
These problems with balloon kyphoplasty have sent researchers back to the drawing board for new ideas. Scientists have experimented with finding better cements. Surgeons have tried using less cement. Companies making surgical instruments have designed better needles.
And now, a new device called KIVA has been invented to restore vertebral height. Both balloon kyphoplasty (BK) and KIVA are considered augmentation devices. They both restore bone height in different ways. Whereas BK is an inflated balloon that can leave a space that is filled with cement, KIVA is a system of coils placed inside the bone using much less cement. The coils can be stacked on top of each other to re-elevate the ends of the vertebral bone. This type of system creates a uniform cylinder shape so that when the cement is injected into the bone, there is even distribution from front to middle to back.
In this study, results using the KIVA implant are compared with results using the balloon kyphoplasty. The surgeons used a variety of different ways to measure results. X-rays and CT scans were used to view vertebral height and look for wedging of the vertebral bones.
If the entire vertebral body is not restored (front, middle, and back), the front of the bone remains collapsed. An X-ray taken from the side will show the fractured vertebra looks like a pie-shaped wedge. Unless the full vertebral body is restored, any wedging causes spinal deformity and kyphosis (spine curved forward). The extra compression on the bone can lead to pressure on the spinal cord, spinal nerves, and/or lead to new fractures.
Other ways they measured and compared results included amount of cement leakage, complications from cement leakage, pain levels, and patients’ perception of quality of life. Kyphotic spinal angle and cement leakage were measured digitally using a special e-film software. The software made it possible to measure even one-degree of difference in spinal alignment.
Patients were followed for just slightly more than one year (13 to 15 months). Results showed that patients in both groups did get significant pain relief and improved physical function. Both treatment approaches restored vertebral height. But only the KIVA implant was able to prevent kyphosis in the spine. The number of new fractures was about the same between the two groups.
But the big difference was that cement leakage was much less with the KIVA. And cement leakage with the KIVA was always outside the spinal canal with less risk of neurologic damage. In fact, there were two cases of intracanal (inside the spinal canal) leakage with balloon kyphoplasty (BK) (and none with the KIVA implant). Those two BK patients had to have emergency surgery to avoid being paralyzed for life.
The authors conclude by restating there is a need to improve on balloon kyphoplasty. Cement leakage is a problem. Sometimes the balloon deflates too much before the cement is injected into the space. Loss of vertebral height (especially when there is wedging) can lead to spinal deformity, more pain, and another fracture.
The new KIVA implant may help overcome some of these problems. There were better results with the KIVA over balloon kyphoplasty in two areas: less kyphosis and less cement leakage. The KIVA device doesn’t push and crush the bone like the balloon does. And there is very low pressure with the KIVA to form an evenly round cement column inside the bone.
More studies are needed to see if the better results with KIVA over balloon kyphoplasty (BK) stand up to the test of time. This study was short-term at best (follow-up slightly more than one year). Following patients longer and assessing back pain, quality of life, and new fractures are the next steps before KIVA devices can be recommended over other treatment approaches.