Magnetic Kyphoplasty May Optimize Drug Delivery in Spinal Compression Fractures

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While conservative pain management, kyphoplasty, and bone strengthening agents are the mainstays of spinal compression fracture management, treatment in the future may involve improved prediction of which vertebral bodies are at risk using finite element modeling and targeted delivery drug delivery at the side of bone breakdown using magnetic kyphoplasty, according to Ankit I. Mehta, MD.1,2

Finite Element Modeling of the Spine

Dr. Mehta and colleague Farid M. L. Amirouche, PhD, both from the University of Illinois at Chicago, are investigating use of finite element modeling to predict which vertebral bodies are under the highest areas of stress and are more susceptible to developing osteoporotic compression fractures in the future. Finite element modeling uses 3D-imaging with computed tomography and accounts for bone mineral density as well as geometry and loading conditions when estimating bone strength.

In addition, finite element modeling may be used to study the effectiveness of vertebral augmentation and medications to prevent or treat spinal compression fractures (eg, bisphosphonates, calcitonin, teriparatide). “The effects of the different treatment options on vulnerable areas of the spine at heightened risk for compression, and the stress and strain forces at those locations can be quantitatively defined and compared with each other using finite element modeling, which might ultimately result in a consensus on the most appropriate approach to managing spinal compression fractures,” the researchers and their colleagues wrote in a 2017 review on the current and future treatment strategies for spinal compression fractures.1

Magnetic Kyphoplasty Shows Efficacy in Animal Model

Furthermore, Dr. Mehta and colleagues recently published a proof-of-concept study in PLOS ONE on magnetic kyphoplasty that in theory could be used for targeted drug delivery of bone strengthening agents for patients with osteoporosis or chemotherapy for patients with spinal fractures due to spinal malignancies.2 The researchers studied the degree of localization of systemically injected magnetic nanoparticles to upper thoracic vertebral bodies in a pig model that were subjected to kyphoplasty using polymethylmethacrylate with magnets or without (internal control).
Magnetic KyphoplastySchematic representation of experimental outline used to establish a porcine cement kyphoplasty model. A balloon is inserted into a porcine vertebra. Following inflation of the balloon, PMMA cement with or without magnets is injected into the vertebra. 24-hours after surgery, magnetic nanoparticles (MNPs) are injected systemically via the ear vein. (Image illustrated by Victoria Zakrzewski.). https://doi.org/10.1371/journal.pone.0201402.g001Microscopic images of the magnet-enhanced kyphoplasty showed heavy concentrations of magnetic nanoparticle clusters near the blood vessels, and diffuse magnetic nanoparticles throughout the tissue. In contrast, no magnetic nanoparticles were found in the internal control or a lumbar vertebra with no kyphoplasty (P<0.05 compared with the magnetic kyphoplasty vertebrae).

The researchers are currently conducting histology studies to study whether the magnetic nanoparticles have any toxicities. In the absence of toxicities, the researchers are planning to conduct a larger study of traumatic fractures in animal models to determine whether use of magnetic nanoparticles with targeted drug delivery of bone strengthening agents improves healing over systemic administration of these agents, Dr. Mehta told SpineUniverse.

“Spinal compression fractures are becoming a public health issue as the population ages, and we need to think of new creative modalities to help these patients,” said Dr. Mehta, who is Director of Spinal Oncology and Assistant Professor of Clinical Neurosurgery at the University of Illinois at Chicago.

Comments From the Field

Magnetic kyphoplasty “certainly has the potential to provide targeted drug therapy, and I am excited to see further development of this technology in the future,” commented Samuel Cho, MD, Chief of Spine Surgery at Mount Sinai West, Director of Spine Surgery Fellowship, and Associate Professor in the Department of Orthopaedic Surgery and Neurosurgery at the Icahn School of Medicine at Mount Sinai. “This is a proof-of-concept animal study that has demonstrated potential benefits of a new technology. There still needs to be a lot of work done to prove both safety and efficacy in humans.”

“I think current treatments consist of bisphosphonates, pain management, and vertebroplasty or kyphoplasty in select cases,” Dr. Cho told SpineUniverse. “Recently, recombinant parathyroid hormone therapy had some encouraging results. At its core, addressing osteoporosis will be the most direct way of treating, or preventing, compression fractures. However, new techniques such as magnetic kyphoplasty can provide more directed treatment once compression fracture has occurred.”

Disclosures
Dr. Cho and Dr. Mehta have no relevant disclosures.

Updated on: 03/15/19
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Ankit I. Mehta, MD
Assistant Professor, Clinical Neurosurgery
University of Illinois at Chicago
Samuel K. Cho, MD
Associate Professor
Department of Orthopaedic Surgery and Neurosurgery
Icahn School of Medicine at Mount Sinai
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