How a camera that sees like a shrimp could save baseball pitchers months of recovery time

Could a shrimp hold the secret to keeping Cardinals pitchers healthy? With the help of Washington University researchers, the answer might be yes.

A group of professors, led by Spencer Lake, professor of mechanical engineering and materials science at Washington U., have been awarded a $388,541 grant from the National Science Foundation to develop a new imaging technique. Inspired by the eyes of the mantis shrimp, this technique could help treat and prevent a common elbow injury among baseball pitchers, which requires season-ending surgery.

One of the most devastating yet common injuries for baseball pitchers is a torn elbow ligament known as the UCL (ulnar collateral ligament).

“The overhand throwing motion is one of the fastest recorded human motions at almost 7,000 degrees per second,” said Dr. Jeffrey Dugas, orthopedic surgeon and sports medicine specialist at the Andrews Sports Medicine and Orthopaedic Center in Birmingham, Ala. “To say that it puts a fair amount of stress on the arm would be an understatement.”

The treatment for UCL tears is Tommy John surgery, a reconstruction procedure first performed in 1974 on the eponymous Los Angeles Dodgers pitcher. In this surgery, the elbow ligament is reconstructed using a ligament from elsewhere in the body, typically the wrist or knee, and reattached to the bone.

The number of Tommy John surgeries performed has skyrocketed in the past two decades. In the 2017 MLB season, 26 percent of active pitchers had undergone the surgery, according to Joe Roegele of the Hardball Times, a baseball writer who has been tracking Tommy John statistics.

Twenty-four Cardinals have had Tommy John surgery since its invention, the second-highest in Major League Baseball — behind only the Atlanta Braves, at 26. This includes four pitchers in the past three seasons: Lance Lynn in 2015, Zach Duke in 2016, and Alex Reyes and Trevor Rosenthal in 2017.

Not only is the surgery expensive — easily exceeding $15,000, not including extensive physical therapy — but a team also loses the services of a valuable player.

Dr. Matthew Smith, professor of orthopedic surgery at Washington University School of Medicine and a collaborator on the new study, said that while Tommy John surgery has a high success rate, there is substantial room for improvement in the recovery time, which is typically 12-18 months.

UCL tears aren’t just a problem at the professional level. “Since the mid- to late ’90s there’s been a big increase, and it’s gotten younger,” Dugas said. “Now we see it in high school kids all the time, and even junior high school kids.”

Both Dugas and Smith cited the rise of year-round baseball and single-sport specialization of youth players as likely factors in the rise of these injuries in adolescents.

Pitch style and speed can also factor into the likelihood of injuring the UCL.

“We know that throwing a curveball or a change-up, they place different stresses on the arm,” Dugas said.


Detecting change

The newly funded research plans to look at this ligament in more detail than was previously possible to see how it reacts to different stresses and accumulates damage over time. Using ligaments from human cadavers, researchers will repeatedly stress the ligament in ways that simulate different pitches.

“We can pull it and stretch it and hold it or whatever and see how it changes in real time,” Lake said.

The new technique will use familiar materials — a white LED light and a video camera — to see small details in ligaments as they move. To see these details, the technique borrows a trick from an unexpected place: the eyes of the mantis shrimp.

“They’re these crazy sea critters that, among other things, can sense differences in polarized light,” Lake said. Polarized light is “still just light,” said Lake, “but you can think of it as taking disorganized light and organizing it in a particular way.” That organization is called polarization. Polarized sunglasses take advantage of this to let in light that is organized a certain way and block out light that is organized in other ways.

In the new technique, polarized light is shone on the ligament. That light bounces off the collagen fibers, which make up the ligament and is recorded by the camera. Depending on what the ligament looks like at that time, the organized light will bounce off of it in a certain way and become slightly disorganized. As you move and change the ligament, the light bounces off in slightly different ways.

To see these subtle changes in how the light is reflected, small filters are placed over each pixel of the camera. Developed by Victor Gruev, a professor in electrical and computer engineering at the University of Illinois Urbana-Champaign, these filters work like the eyes of the mantis shrimp, detecting tiny changes in how the light is polarized. These small changes can be translated back to exact positions of the ligament, on a pixel-by-pixel level.

“Ligaments are very well organized tissues. You have these fibers that comprise these tissues that are all kind of aligned in the same direction, like a really strong net,” said Mark Buckley, professor of biomedical engineering at the University of Rochester, “but when they become damaged, you lose some of this alignment. … Polarized light is a really good way of looking at how aligned these fibers are.”

“Traditionally, all we could do is look at how the tissue could stretch, but now we can look at how it reorganizes,” Smith said. “We can look at what happens on the microstructural level instead of what happens macroscopically.”

Polarized light imaging could have distinct advantages over current methods of imaging ligaments and other tissues, such as ultrasound and MRI, according to Buckley. “Ultrasound you aren’t generally able to see fine structural features,” he said, and while MRI gives a more detailed look, it is both expensive and slow.

Lake, Smith and Gruev believe the detailed, small-scale information gained from these studies will have wide-ranging implications for UCL injuries, from prevention to surgery to rehabilitation.

For example, a modification to the typical Tommy John procedure known as an internal brace has emerged in the last five years. The newly reconstructed ligament is further supported by a tape that is dipped in bovine collagen. This tape helps to mimic the stiffness of the original ligament while the donor ligament stiffens throughout the healing process. Recovery from internal brace Tommy John surgeries has been as short as six months for some players. Smith said that information from polarized light imaging could help develop tapes which better emulate the healthy ligament.

Moreover, the polarized light imaging technique could be used to examine many other soft tissue injuries. As a part of this same study, the researchers will examine damage to rotator cuff tendons over time.

“Rotator cuff tears affect a large chunk of the population, particularly the elderly,” Lake said.

“We always try to translate basic science findings into clinical practice,” Smith said. “Our goal is to move the care of patients forward in a better direction.”

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