Benvenue Medical, Inc., a company developing minimally invasive solutions for spine repair, has met the pre-determined stopping rules for enrollment completion in the KAST (Kiva System as a Vertebral Augmentation Treatment – A Safety and Effectiveness Trial) clinical trial. The KAST study is a randomized controlled trial comparing Kiva to balloon kyphoplasty; the trial enrolled 300 patients at 21 centers in the U.S., Canada, Belgium, France and Germany. The study is being conducted to support a subsequent 510(k) filing for market clearance from the FDA.
Benvenue Medical Progresses in KAST Study

“The KAST study enrolled ahead of schedule, and we believe the positive response we received is due to our investigators’ enthusiasm for a new treatment option for painful and debilitating osteoporotic vertebral fractures moving away from traditional vertebroplasty or balloon-based vertebral augmentation, ” said Sean M. Tutton, M.D., FSIR, Co-Principal Investigator in the KAST Study and Professor of Radiology and Surgery at the Medical College of Wisconsin in Milwaukee, in the July 31, 2012 news release.
“We appreciate the efforts of the investigators and research coordinators, as well as the spine community’s enthusiasm to evaluate the potential benefits of the Kiva System. The results will be important to guiding treatment recommendations for VCFs [vertebral compression fractures], ” said Steven R. Garfin, M.D., Co-Principal Investigator of the KAST Study and Professor and Chairman of the Department of Orthopaedic Surgery at the University of California, San Diego Medical Center.
Success will require non-inferiority on the primary endpoint, which is a composite of pain, function, and safety at one year of follow-up on patients treated on study. The study is designed to evaluate superiority on key secondary endpoints including PMMA (polymethyl-methacrylate) cement volume, extravasation rate, and height restoration as well as other endpoints. The Kiva VCF Treatment System features a proprietary flexible implant made from PEEK-OPTIMA, and is designed to function as a mechanical support structure and a reservoir to contain and direct the flow of bone cement.
The implant is delivered percutaneously in a continuous loop fashion into the vertebral body with an all-in-one disposable device through a small diameter, single incision. The amount of the Kiva Implant can be determined by the surgeon in the OR; the implant is delivered over a removable guidewire, and is designed to provide structural support to the vertebral body and to directionally control and contain bone cement.

Discussion
This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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