Startup uses sensors to find cause of knee pain

Apr 5, 2013

Tim Cortesi is a software engineer at a downtown Binghamton company called Sonostics. At the company's offices in Binghamton's startup incubator, he sticks four small patches attached to wires onto the muscles around his knee.

“So we’ve got four sensors, each sensor has one accelerometer in it,” says Cortesi.

Accelerometers like these measure the force exerted by each of the muscles. It's the same technology used by cars to know when to deploy airbags in a crash. When attached to a patient, the sensors pick up the work done by each muscle.

“Generally, we want to see those muscles working together equally so there’s not a difference, one is not pulling more than another,” says Cortesi.

In a properly functioning knee, the muscles involved in movement usually conform to certain ratios. For example, the muscles in front - the quadriceps - should exert about three times as much force as the muscles in back - the hamstring.

Data is collected as Cortesi goes through a simple set of motions and then charted on the company’s software.

“We’re able to see four lines going across the screen, four different colors, each line is corresponding to the individual muscles,” he says.

The therapy is called MyoWave and was developed at Binghamton University. The idea’s simple enough – to see whether there might be a less invasive way to treat a patient’s chronic knee pain, before looking at surgery.

“There might be some actual damage to my knee, but more than half the time, in fact 80 or more percent of the time, there’s a good possibility that I’ve got a muscle imbalance,” says Cortesi.

And if there’s an imbalance, patients are given an exercise routine designed to strengthen certain muscles.

In a recent study published in the New England Journal of Medicine, researchers found that physical therapy was as effective as surgery for one common type of injury to the cartilage that cushions the knee - a torn meniscus.

In another study, patients with osteoarthritis, which afflicts more than 20 million Americans, were either given knee surgery or a placebo. The results for those receiving surgery were no better than for those on the placebo.

“There may be a turn back to being more conservative in treatment and not rushing quickly to do surgery,” says Douglas Kerr, an orthopedic surgeon and team physician for Binghamton University’s athletic department.

Kerr says measuring muscle imbalance is a logical response to a painful knee.

“Because what I think happens is that pain causes dysfunction of the muscles and they lose strength,” Kerr says.

He says the muscle imbalance might not be causing the pain, but it’s important to address it during recovery.

Sonostics CEO Chuck Schwerin says the company is intended to be a first stop when a patient comes to a doctor with knee pain.

“So what we’re looking to do is put ourselves at the head of the line where we can rule out the most benign reason for joint pain, meaning muscle imbalance,” says Schwerin.

According to the Mayo Clinic, joint disorders are the second most common reason Americans visit the doctor; only skin disorders rank higher. And about one-third of Americans over fifty have a torn meniscus in their knee.

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The Innovation Trail is a collaboration between six upstate New York public media outlets. The initiative, funded by the Corporation for Public Broadcasting (CPB), helps the public gain a better understanding of the connection between technological breakthroughs and the revitalization of the upstate New York economy.