New research confirms role for balloon kyphoplasty in restoring height to fractured vertebrae

Spine

Vertebral compression fractures are a painful and debilitating condition. When untreated, they can lead to a downward spiral of health problems.

To address these concerns, many physicians recommend repairing these fractures via minimally invasive vertebral augmentation procedures, such as bilateral balloon kyphoplasty (BKP) or titanium implantable vertebral augmentation devices (TIVADs).

Until recently, no definitive research quantified the degree of height restoration possible using BKP, BKP with Medtronic's Kyphon Assist™ directional cannula and TIVAD solutions like Stryker's SpineJack™*.

Becker's Spine Review recently spoke with three experts on vertebral compression fractures about a new cadaver study4, funded in part by Medtronic, that compared the height restoration and post-surgery anterior height loss under stress loads that can be expected using these different techniques:

  • Thomas Andreshak, MD, orthopedic surgeon and coauthor of the 2022 Height Restoration Study
  • Allan Brook, MD, interventional radiologist and coauthor of the 2022 Height Restoration Study
  • Eric Grovender, PhD, senior clinical research program manager, Medtronic

Height restoration is a foundational principle of vertebral compression fracture management

If untreated, one vertebral compression fracture can lead to others. "When a vertebral body collapses and it's left wedged or angled, that causes a condition called kyphosis, which increases the forces on the adjacent vertebrae," Dr. Andreshak said. "It's kind of like the Leaning Tower of Pisa gravity and osteoporosis increase the risk of additional fractures in the future."

The effect of multiple fractures over time can compound, resulting in height loss, pain and a lower quality of life due to kyphosis. "If you look at patients sagittally, compression fractures add up and people become more and more kyphotic or bent forward," Dr. Brook explained. "Kyphosis makes it hard for people to function. They can't see in front of them as they walk, so they often trip and fall, resulting in more severe fractures."

In addition, kyphosis can compress the lungs, leading to shortness of breath and reduced pulmonary function. When kyphosis occurs lower in the lumbar spine, it can compress the abdomen, resulting in loss of appetite, weight loss and more bone loss. "It becomes a vicious cycle of not moving due to pain, which leads to bone loss, which then increases the risk for more fractures," Dr. Brook said.

As a result, when vertebral compression fractures occur, physicians are reluctant to leave vertebrae deformed or in an abnormal position. "We want to restore the height of the vertebrae back to their normal position and alignment as much as possible. The goal is to restore a patient's ability to function and reduce their risk of future fractures," Dr. Andreshak said. Returning fractured and compressed bones to their initial shape and size helps patients engage in daily activities again with less pain.

New research sheds light on the effectiveness of different treatments for vertebral compression fractures

In recent years, various techniques have been developed to treat vertebral compression fractures such as balloon kyphoplasty (BKP) and TIVADs. The research findings on the efficacy of these different tools haven't always been clear.

Balloon kyphoplasty is a minimally invasive surgical procedure for the treatment of spinal fractures due to osteoporosis, cancer or non-cancerous tumors.

Although the complication rate for BKP is low, as with most surgical procedures serious adverse events, some of which can be fatal, can occur including heart attack, cardiac arrest (heart stops beating), stroke and embolism (blood, fat or cement that migrates to the lungs or heart). Other risks include infection; leakage of bone cement into the muscle and tissue surrounding the spinal cord and nerve injury that can, in rare instances, cause paralysis; leakage of bone cement into the blood vessels resulting in damage to the blood vessels, lungs and/or heart.

In 2019, Stryker published a clinical study aimed at supporting a noninferiority finding for its SpineJack™* TIVAD device. As an additional endpoint, the study purported to demonstrate superiorityofTIVAD over BKP.Thisstudy had limitations, however.

"The primary objective of the SAKOS clinical study was to compare pain, disability and adverse events through the 12-month period following a vertebral augmentation procedure with either a SpineJack™* or a Medtronic Kyphon™ balloon kyphoplasty device," Dr. Grovender said. "However, there are critiques of the study design out there in the literature. A major shortcoming is that SAKOS compared the performance of the SpineJack™* device with the old Kyphon™ technology; that is, a previous generation of balloons that doesn't achieve the same inflation pressures. One would reasonably expect that those older products may not deliverthe same degree of height restoration as the current generation of Medtronic products that have higher pressure specifications."

Medtronic thought it was important to provide the healthcare provider community with data showing how its current­ generation devices performed with respectto height restoration. The research team also wanted to explore the potential impact of using a directional cannula to place the BKP balloons into a better position. To achieve these goals, Medtronicfunded in part a lab study using functional spine units from human cadavers. The results from the Height Restoration Study were published online in June 2022. Print publication is expected laterthis year.

The Height Restoration Study compared three bilateral procedures with respect to height restoration and sustainability post-operatively: BKP, BKP with Kyphon Assist™ directional cannula, and TIVAD.

Five osteoporotic female human cadaver thoracolumbar spines were dissected into 30 two-functional spine units, and then vertebral wedge compression fractures were created by reducing the anterior height of the vertebrae by 25 percent. Post-fracture, surgery was performed on the two-functional spine units using the three different bilateral procedures.

Post-surgery, cyclic loading was performed on each two­ functional spine unit using loads that were representative of walking (600 newtons), standing up or sitting down (850 newtons), and lifting a 5-to-10-kilogram weight from the floor (1250 newtons).

The study found all three treatments (BKP, BKP w/ Kyphon Assist™, and TIVAD) can restore height similarly after a vertebral compression fracture. With all treatments, at least 94 percent height restoration was attained. Furthermore, after the highest level of cyclic loading, less anterior height loss (around 10 percent) was observed in the BKP w/ Kyphon Assist™ group compared to TIVAD.

"Speaking to this cadaver study specifically, there is scientific value," Dr. Grovender of Medtronic said. "It shows in real human tissue that Medtronic's latest-generation balloon for kyphoplasty appears to achieve a height restoration that is at least equivalent to the Stryker SpineJack™* device. Under high-loading use conditions, it might even perform better. That was the take­ home message from this cadaver study."

The study authors have been presenting these results at international and national conferences. "The best and brightest physicians are all impressed that we got 94 percent of vertebral bodies back to significant height restoration," Dr. Brook said. "The data shows that by treating patients earlier, you get better results. If we treat a patient with a spinal fracture, the mortality data suggests that they have a much better chance of living over the next one to five years. We need family physicians to realize this."

Innovations in vertebral augmentation devices mean surgeons can treat patients sooner and procedures take less time

Newtechnologiesforvertebral augmentation enable physicians to achieve their clinical goals in a shorter period of time. "When you have a device like Kyphon Assist™ directional cannula with a stronger balloon, it's more likely to do its job," Dr. Brook said. "Weaker balloons may not be able to elevate the endplates the way you want, or they may burst. In addition, directional tools work more consistently. The Kyphon Assist™ device's design allows surgeons to target certain areas in bones that need extra augmentation or are hard to get to."

Medtronic's Kyphon VuE™ visually enhanced bone cement has also been a game changer when it comes to vertebral augmentation. After removing the kyphoplasty balloon, surgeons inject cement into the vertebral body to restore its height and shape. Historically, it's been difficult to know whether enough cement has been applied.

"If we don't fill all the cracks and crevices appropriately with cement, the fracture could collapse," Dr. Andreshak said. "We thought one reason for height loss over time after vertebral augmentation was that we weren't putting enough cement in to stabilize the fracture. Kyphon VuE™ is a tracer cement with different sized particles of barium that we can see on an X-ray. This enables us to watch the flow. That means we can get a better fill by making sure the cement goes to areas where we want it13. In addition, we can minimize leakage rates which could lead to complications14. This product allows us to take our skills up another notch and to be more perfect in what we do."

Conclusion

As the patient population ages, vertebral compression fractures will become more common. Between 30% and 50% of people over 50 have at least one of these fractures15. Innovative approaches to vertebral augmentation are an effective way to address this issue.

"If we can help patients maintain mobility later in life, they will have a better quality of life and maintain their function," Dr. Andreshak said. "That's very important. Rather than being complacent and satisfied with the products and procedures we've always used for vertebral augmentation, let's continue to improve them and make them even better."

Dr. Grovender concurred. "Medtronic continues to fund clinical res_e rch to_br_ing i novati:e roducts to market or he_lp establish or inform their safety and effectiveness in post-market settings for the benefit of the healthcare community and ultimately for our patients."

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