Online Exclusive: Growing Bone: Low-Intensity Vibrations Could be the Key
After 25 years of development, Marodyne prepares to enter the market with a musculoskeletal health device.
Clint Rubin, Ph.D.
“Use it or lose it,” says Clinton T. Rubin, Ph.D., State University of New York distinguished professor and chair of the department of biomedical engineering. He is referring to Wolff’s law—a concept well known in the orthopedic surgical world—that posits that bone in a healthy person will adapt to loads under which it is placed. If the pressure on a bone increases, it will adapt and even grow over time to bear that weight.
A helpful way to understand it, said Rubin, is to think about the consequences of removing the loading on bone. Astronauts lose bone mass at a rate of 2 percent per month (normal rates range from 2 percent per year to a decade depending on a person’s health) due to microgravity in space. Another way to understand it is to observe those who put an extraordinary amount of load on their bone on a regular basis. The Journal of Bone & Joint Surgery
published a landmark study in 1977, “Humeral Hypertrophy in Response to Exercise,” that demonstrated that professional tennis player have 35 percent more bone in their playing arm than their non-playing arm.
Wolff’s law was posited by 19th century German surgeon Julius Wolff, and is used in orthopedic reconstructive and reparative practice every day. Osteopenia (bone mineral density [BMD] that is lower than normal peak BMD but not low enough to be classified as osteoporosis) can become a problem underneath fracture plates, or bone resorption around knee or hip implants.
“The problem becomes: What is it about mechanical loading that stimulates bone? Is it some sort of magic formula? Is higher [stress] more important than lower?” asked Rubin. Rubin has been working for years—“too many to count”—on a technology that can deliver juts the right amount of pressure to bone so that it will grow back to the ideal size for a patient. He is lead researcher and chief scientific officer at Marodyne Medical LLC, a Lakeland, Fla.-based company that has spent 25 years developing a vibration technology with Rubin at the helm for musculoskeletal health and regeneration. This year will finally see the fruit of that labor released to global markets in the form of LivMD. LIV stands for low-intensity vibration, which is the key to this new technology aimed at building bone and musculoskeletal health.
“What we’ve found is that high-magnitude loading can be good for bone,” explained Rubin. “But the problem is if you’re frail, infirm or elderly, it’s kind of risky to tell them to go out and play [tennis] against Venus Williams to build up their bone—they might actually break their bone. So over the course of trying to figure out what is the minimal input we can put in the system, we found that we can lower the load-lower the challenge to the skeleton if we increase the frequency—in this case, the frequency being cycles per second.”
LivMD is a completely non-invasive device. Patients stand on it, like a scale, and the device sends vibrations up through the body at a rate of 30 cycles per second. In terms of thickness of vibration, this is only 100 microns, or the width of two human hairs. Rubin compared this frequency to walking, which would add up to just one cycle per second. The device transmits signals directly up the weight-bearing skeleton, and is a “smart” or a targeted approach, said Rubin. Smaller bones respond more actively to the vibrations, so as bone is added on, the response diminishes.
Rubin recalled the Bone Phone of the 1980s, which was a device worn on a person’s clavicle. Sound from the device would transmit through the skeleton and was clearly audible.
“It turns out that the skeleton is a great transmitter and amplifier of mechanical signals,” Rubin said. “Like when you’re standing on the sidewalk and a truck goes by, you can feel the jostle and you can almost hear it through your feet. So even though the vibration that the LivMD device is actually delivering is very small, because of the viscoelastic nature of the material [in this case, bone], once you’re above five cycles per second, the material becomes very stiff.”
Marodyne’s strategy is to submit the LivMD to the U.S. Food and Drug Administration (FDA) as a Class I exercise device, and make no claims to bone healing. This will make the path to market easier. Once the device clears that hurdle, the company aims to request indications for treatment of specific conditions.
In the future, the company hopes to gain a comprehensive range of indications for conditions including osteoporosis, sarcopenia (muscle loss that comes with aging), muscle wasting and cerebral palsy. The technology has already gone through several clinical trials that demonstrated the device was anabolic to children with cerebral palsy, osteoporotic women between the ages of 16 and 20, and patients on bed rest who experience loss of balance. “When you think of risk of fracture in an osteoporotic population, it’s not just bone quantity and quality, it’s also the figurative three legs of a stool: Bone, muscle and balance,” explained Rubin. “The drugs that are FDA-approved for osteoporosis—which are great—really target only the bone. The Marodyne device, in clinical trials, demonstrated that it’s anabolic to bone and to muscle, and helps with postural stability. We think we’re addressing the risk of fracture from a number of different directions simultaneously.”
And the applications don’t end at orthopedics: “Don’t get me started,” enthused Rubin. This completely non-invasive technology stimulates mesenchymal stem cells (MSCs) in the bone marrow to turn into bone and muscle. MSCs, which are key to the musculoskeletal discipline, can differentiate into a variety of different cell types. Since there are a finite number of progenitor cells in the bone marrow, and LIV is dictating that they become bone and muscle, they are not becoming fat. Marodyne has conducted animal and cell studies that show that LIV keeps the body thinner, which suggests a future in weight control applications as well.
“It would be great if one day we got an FDA indication for osteoporosis or augmentation of fracture healing and these other things that depend on Wolff’s Law,” said Rubin. “But if we’re really actually driving stem cells to become higher order connective tissues and not become fat … that’s where we think, ultimately years down the road, the technology will lead into: A non-drug, non-invasive means of controlling obesity and [comorbid conditions such as] diabetes.”
After a quarter century of research and development, Rubin’s enthusiasm for low intensity vibration technology is understandable. An academic, he joked about the notion of his ilk sequestering themselves in the ivory tower with their small corner of research. But it pays off. Later this year, Marodyne will release LivMD in 29 countries as well as the European Union, the United Kingdom and the United States. The U.S. release is set for April. The company has partnered with the Laser Spine Institute based in Tampa, Fla., to make the device accessible to a wide patient population immediately upon release.