Interventional Update: Vertebral Augmentation — Comparing Kyphoplasty and Kiva Procedures
By Beth W. Orenstein
Vol. 15 No. 10 P. 14
Patients with vertebral cracks, fractures, or collapses who don’t respond to conservative treatments such as bracing, bed rest, physical therapy, and pain management have a new surgical option: the Kiva VCF Treatment System. The system, which was developed by Benvenue Medical, is similar to balloon kyphoplasty in that it is a vertebral augmentation procedure that treats the broken vertebra by creating an internal cast to restore the compressed vertebra to its normal size.
Three comparative studies have found that the Kiva system meets or exceeds the performance of balloon kyphoplasty. Kiva VCF Treatment System received 510(k) clearance from the FDA for the reduction and treatment of spinal fractures in January 2014.
Vertebral compression fractures are often caused by osteoporosis. Each year, some 700,000 vertebral compression fractures occur in the United States, and the pain can be disabling. The number is only expected to grow as the population ages.
Medicare and private insurance carriers view the two procedures as the same, “but when it comes to the procedures, there are significant differences,” says Sean Tutton, MD, FSIR, a professor of radiology and surgery at the Medical College of Wisconsin in Milwaukee. Tutton says that in most cases, balloon kyphoplasty requires two small incisions approximately 1 cm in length on either side of the vertebral body that needs repair. “Some operators, myself included, can do the balloon kyphoplasty on just one side, but that’s not always the case,” he says. “That’s not how it’s designed to be used.”
Working through the incisions, the physician performing the procedure inserts cannulas or tubes into the two pedicles, bone projections from the back of the vertebral body, one on each side. The pedicles arch over the nerves of the spinal cord.
Once the balloons are in place, they are inflated in an attempt to restore the height of the fractured vertebra. When the balloons are deflated, it leaves a void or cavity that is filled with bone cement.
“You inject cement to fill the space you created until you get to the endpoint you’re looking for,” says Tutton, who has experience with both procedures.
The Kiva system uses a flexible implant made of a medical polymer to restore height to the vertebral body and hold the cement. Inserting the implant requires an incision about 1 cm in length, about the same size as with balloon kyphoplasty. The physician uses the incision to insert an introducer into the vertebral body.
“The introducer allows the operator to deploy a preshaped Nitinol guidewire coil for precise placement of the implant,” says Wayne J. Olan, MD, director of interventional and endovascular neurosurgery at George Washington University Medical Center in Washington, D.C.
The implant slides over the coil and follows its path down into the vertebral body. “Once you are finished placing the implant, you retract the coil and remove the delivery device,” Tutton says.
Next, a cement needle is inserted into the back of the implant that was placed in the vertebra. “That allows you to inject the cement. The cement goes through little slots on the inside of the implant,” he explains. The physician customizes the amount of the Kiva implant delivered during the procedure to restore the vertebra to its original height.
Tutton says one advantage to the Kiva design is that the cement—which has the potential to leak and to be too hard, often leading to new fractures down the road—is contained. He also notes that the implant provides structural support whereas in balloon kyphoplasty, only the cement supports the vertebra.
“You are using less than half the cement you normally would have so you minimize the risk of cement leakage,” Olan adds.
Olan says another benefit of the implant is that its material is more similar to real bone than cement. “You don’t have a rock of cement inside the vertebral body,” he says. “With the implant, the vertebra is not as stiff, which is another way to minimize the risk of subsequent fractures.” A comparison study from Germany published in Pain Physician in 2013 found that the Kiva system produces fewer new fractures than kyphoplasty.
Done under local or general anesthesia, the two procedures require relatively the same amount of time: one hour or less. However, Tutton says he saves time because the Kiva system requires only going through one pedicle.
“You’re [also] potentially cutting down on the invasiveness of the procedure as compared to when you have to go through both pedicles,” he says. If the physician can perform the procedure in a shorter amount of time, it could mean less radiation for the patient. “You don’t need to look and see what you are doing [with fluoroscopy] for as long a time,” Tutton adds.
— Beth W. Orenstein is a freelance medical writer based in Northampton, Pennsylvania, and a regular contributor to Radiology Today.