Breakthrough rotator cuff treatment rebuilds and protects shoulder muscle from reinjury

[Apr. 17, 2023: JJ Shavit, The Brighter Side of News]

Advances in surgery have made better rotator cuff repairs possible. But surgery failure rates can be high. (CREDIT: Adobe Images)

Rotator cuff tears are a common injury in adults. Advances in surgery have made rotator cuff repairs more effective, but failure rates are still high. However, a team of researchers from UConn School of Medicine led by Dr. Cato Laurencin discovered a new technique that could help repair the damaged shoulders of millions of people around the world.

Laurencin, a surgeon, engineer and scientist, along with graduate student Nikoo Shemshaki and other researchers at the UConn Connecticut Convergence Institute, reported in the Proceedings of the National Academy of Sciences (PNAS) that a graphene/polymer matrix embedded in the shoulder muscle can prevent re-injury. The technique uses advanced materials to encourage muscle growth in the rotator cuff muscles, tackling the real problem: muscle degeneration and fat accumulation.

“Most repairs focus on the tendon,” Laurencin explains, “and how to reattach it to the bone most effectively. But the real problem is that the muscle degenerates and accumulates fat. With a tear, the muscle shrinks and the body grows in that area instead.When the tendon and muscle are finally surgically reattached to the shoulder bone, the weakened muscle can no longer withstand the normal stresses and the area can be injured again.

To combat this problem, the UConn team developed a polymer mesh infused with graphene nanoplatelets. When they used it to repair the shoulders of rats that had chronic rotator cuff tears with muscle wasting, the muscle grew back. When they tried to grow muscle on the mesh in a Petri dish in the lab, they found that the material seemed to encourage the growth of myotubes, the precursors to muscle, and discourage the formation of fat.

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“This really is a potential breakthrough treatment for rotator cuff tears. It tackles the real problem: muscle degeneration and fat accumulation,” explains Laurencin.

Researchers are now focused on studying the matrix in a large animal and are eager to develop the technology in humans. If successful, it could be a game-changer for millions of people with rotator cuff injuries.

Rotator cuff tears are a common injury that can cause significant pain and disability, affecting millions of people worldwide. The rotator cuff is a group of four muscles and tendons that surround the shoulder joint, helping to hold the arm bone in place. When one or more of these tendons tear, it can lead to pain, weakness, and limited mobility.

A rotator cuff tear occurs when the tendons – fibrous connective tissues that connect muscles to bones in the shoulder area are stretched further from the arm bone i. humerus, in turn causing muscle tension, pain and discomfort. This happens because the shoulder is essentially a ball and socket joint which forces the muscles, bones and tendons to stay within the range of motion. There are two types of rotator cuff tears: partial and complete. In a partial tear, the tendon is torn only to a certain extent and a fragment of tissue still remains attached to the arm bone. A complete tear occurs when the tendon completely detaches from the humerus. (CREDIT: Creative Commons)

Traditionally, rotator cuff tears have been treated with surgery, but success rates have been variable. Surgeons aim to reattach the torn tendon to the bone, but this can be difficult when the muscle has degenerated and accumulated fat.

Dr. Laurencin and his team’s new approach to treating rotator cuff tears could revolutionize the field. By focusing on muscle regeneration, rather than just reattaching the tendon, they hope to fix the underlying problem and prevent further injury.

The researchers developed a polymer mesh infused with graphene nanoplatelets, a light and strong material with excellent electrical and thermal conductivity. They then implanted the mesh into the shoulder muscle of rats suffering from chronic rotator cuff tears and muscle atrophy. Over time, they observed that the muscle grew back and the rats regained mobility and strength in their shoulders.

Dr. Cato T. Laurencin of UConn School of Medicine

The researchers also tested the material in a Petri dish, where they found that it promoted the growth of myotubes, the precursors to muscle, and discouraged fat formation.

Although these results are promising, the researchers recognize that more work needs to be done. They plan to test the matrix on larger animals before moving on to human trials.

Shoulder injuries are a common problem, with rotator cuff tears being a leading cause of shoulder pain and disability. According to the American Academy of Orthopedic Surgeons, more than 2 million people in the United States seek medical treatment for rotator cuff tears each year. These injuries can occur suddenly, from a fall or other trauma, or develop gradually over time due to overuse or age-related wear and tear.

Traditional treatments for rotator cuff tears include physical therapy, medications, and surgery. Surgery is often needed to repair the torn tendon and reattach it to the bone. However, surgery is not always successful, and many patients experience new tears or ongoing shoulder pain and weakness.

The new technique developed by Dr. Laurencin and his team represents a significant advance in the field of treatment of shoulder injuries. By targeting the underlying problem of muscle degeneration and fat accumulation, researchers hope to improve the success rate of rotator cuff repairs and reduce the risk of re-injury.

The matrix developed by the UConn researchers is composed of a polymer mesh infused with graphene nanoplatelets, a strong and lightweight material that has a range of potential medical applications. The matrix is ​​designed to be implanted into damaged muscle tissue, where it can provide support and promote muscle growth.

To test the matrix, the researchers conducted experiments on rats with chronic rotator cuff tears and muscle atrophy. They implanted the matrix into the shoulder muscles of rats and watched how the tissue reacted over time. They found that the matrix was able to promote muscle growth and discourage fat accumulation, leading to improved muscle function and a reduced risk of re-injury.

Encouraged by these results, the researchers plan to continue their work by testing the matrix in larger animal models, such as pigs, before moving on to human trials. They hope to refine the technique and optimize the matrix design to achieve even better results.

The potential benefits of the new technique are significant. However, there are still many challenges to overcome before the matrix can be widely adopted as a treatment for rotator cuff tears. In addition to the need for further testing and refinement, there are also concerns about the matrix’s safety and long-term effects. Some experts have raised questions about the potential of graphene nanoplatelets to cause inflammation or other adverse effects in the body.

Despite these challenges, Dr. Laurencin and his team are optimistic about the potential of their new technique. They believe that by addressing the underlying problem of muscle degeneration and fat accumulation, they can significantly improve the results of rotator cuff repairs and help patients recover more quickly and completely from their wounds.

Symptoms of Rotator Cuff Injury

Pain associated with a rotator cuff injury can:

  • Being described as a dull ache deep in the shoulder

  • disturb sleep

  • Make it difficult to comb your hair or reach behind your back

  • Be accompanied by arm weakness

  • Some rotator cuff injuries do not cause pain.

causes

Rotator cuff injuries are most often caused by progressive wear and tear of tendon tissue over time. Repetitive overhead activities or prolonged periods of heavy lifting can irritate or damage the tendon. The rotator cuff can also be injured in a single incident during falls or accidents.

Risk factors

The following factors can increase the risk of rotator cuff injury:

  • Age. The risk of rotator cuff injury increases with age. Rotator cuff tears are more common in people over the age of 60.

  • A few trades. Jobs that require repetitive overhead arm movements, such as carpentry or house painting, can damage the rotator cuff over time.

  • Certain sports. Certain types of rotator cuff injuries are more common in people who play sports like baseball, tennis, and weightlifting.

  • Family history. There may be a genetic component involved in rotator cuff injuries, as they seem to occur more frequently in certain families.

Complications

Left untreated, rotator cuff problems can lead to permanent loss of motion or weakness in the shoulder joint.

This work was funded by NIH National Institute of Arthritis and Musculoskeletal and Skin Diseases Grant No. DP1AR068147 and National Science Foundation Emerging Frontiers in Research and Innovation Grant No. 1332329.

For more scientific news, see our New discoveries section on The bright side of the news.

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