Exploring Solutions for Damaged Tendons

Tendons are essential structures that link muscles to bones, enabling movement. When a tendon is hurt, even simple tasks can become difficult.

“Even if your muscles are strong, you won’t have proper function or stability if your tendons aren’t healthy,” says Dr. Nelly Andarawis-Puri, a biomedical engineer at Cornell University.

Tendon issues can occur due to inflammation— the body’s defense response— or as a result of tearing or gradual deterioration of the tendon. These problems, known as tendinopathies, often lead to symptoms like stiffness, pain, swelling, and muscle weakness.

Injuries may happen abruptly due to awkward motion, but most often they result from repeated use. Athletes are commonly affected, but anyone who performs repetitive tasks, such as typing or jumping exercises, may develop tendon pain or injuries.

If not properly healed, such tendon injuries may cause persistent problems. As we age, our bodies lose some of the ability to repair tendon tissue, making recovery more difficult.

Researchers are working to understand why tendons often don't heal completely and what treatments might improve recovery.

Interrupting the Damage Cycle

“Wear-and-tear injuries are the most frequent type of tendon damage,” Andarawis-Puri explains. “They might not cause pain at first but gradually build up until the tendon starts to break down.”

Acting quickly with treatment can help prevent further damage. Doctors may suggest rest, applying ice, and using pain medication to reduce discomfort.

These approaches don't directly repair the tendon. “But they can help you feel more comfortable and manage symptoms,” says Andarawis-Puri.

Physical therapy is another common strategy. But knowing how much activity is beneficial and how much might worsen the injury can be complex. “That’s difficult,” she says. “Each person is different.”

Her research team is focusing on tendon biology to better identify when exercise aids recovery. Tendons are primarily composed of tenocytes and collagen fibers arranged in spiral-like structures.

“These twisted fibers behave like springs, letting them stretch and bounce back,” says Dr. Adam Abraham, a chronic tendon injury specialist at the University of Michigan. This spring-like setup helps tendons manage physical stress.

“Tendons are a specialized, well-ordered tissue made mostly of collagen, which gives them strength,” says Dr. Jenna Galloway, a regenerative medicine researcher at Massachusetts General Hospital and Harvard Medical School. “Overuse can harm the collagen structure, and constant damage can change how the tendon functions.”

Andarawis-Puri explains that damaged collagen fibers appear bent under a microscope. Her studies in animals showed that exercising too early can worsen this bending. However, waiting two weeks before resuming movement can allow the structure to recover.

“We’ve found that timing exercise just right can help the tendon heal,” she states.

Her goal is to identify simple ways to tell when movement will support healing, rather than hinder it.

Restoring Long-Term Injuries

The precise structure of tendons is crucial for their performance.

“But tendons don’t change easily,” says Abraham. “They’re slow to react and recover, if they do at all.”

His team is studying how tendons change over time due to continual injuries. They’ve designed a method to grow mini tendon-like formations using cells taken from people's tendons.

“We’ve created a way to form tiny, hair-sized versions of tendons,” Abraham explains. “It might sound large-scale, but they’re quite small.”

Using this method, they expose the mini tendons to various conditions to observe their responses. By comparing samples from healthy people and those with tendon disease, they hope to find patterns.

“We can stress healthy models until they mimic the diseased ones,” Abraham says. “Cells from those with chronic injuries tend to stay in a permanently stressed state.”

He and his team are working to reverse this state. Using the 3D platform, they hope to test many conditions at once to find environments that promote healing.

They’re also experimenting with a gel that mimics a healthier tendon setting. When injected into damaged tissue, this gel may help rebuild the tendon’s structure.

Encouraging Regeneration

Some animals can completely regenerate their tendon tissue as adults. Zebrafish, for instance, can do this throughout their lives— something Galloway’s team is investigating.

Her research has demonstrated that in zebrafish, tenocytes are capable of reconnecting fully separated tendon tissue.

Humans and other mammals also have tenocytes, but in them, tendon injuries usually result in scarring that disrupts the collagen alignment.

“Mammals react differently to tendon tears,” Galloway observes.

“Zebrafish completely rebuild the tissue, whereas mammal cells form scars instead,” she adds.

Her team is studying these species differences and testing treatments in damaged mammalian tendons. Their hope is to improve healing responses in people, too.

Although much remains to be learned about tendon function and repair, taking care of your tendons and addressing injuries early remains key to preventing long-term issues.