Healing the knee: a new frontier in meniscus tear repairs

A new project from South Dakota State University's Jerome J. Lohr College of Engineering is developing a bioadhesive that has the potential to significantly improve meniscus tear repair outcomes while also speeding up the healing process. 

Before the start of the 2024 National Football League season, the Minnesota Vikings’ 10th overall pick and projected starting quarterback J.J. McCarthy went down with a knee injury. Testing revealed that McCarthy had suffered a meniscus tear and would miss the entire season following surgery.

McCarthy's story is not unique. Meniscus tears are a common knee injury — especially in contact sports like football — and affect over 1 million people annually. The severity of the injury depends on the tear, which can range from full to partial. Repairing a meniscus often requires surgery — as it did in the case of McCarthy. But according to South Dakota State University assistant professor Solaiman Tarafder, surgery isn't always the answer.

"Although surgery is often necessary, it doesn't always fully resolve the issue, potentially leading to the tear worsening, persistent pain and, eventually, osteoarthritis," Tarafder explained.

Tarafder, a faculty member in SDSU's Department of Mechanical Engineering, is using his expertise in biomaterials and tissue engineering to come up with a unique solution for meniscus tear repairs that could potentially improve outcomes while also speeding up the healing process for injured players like McCarthy.

Through a two-year, $200,000 National Science Foundation-backed project, Tarafder will continue an ongoing research project that seeks to develop a hydrogel bioadhesive that is biodegradable and harnesses the properties of hydrophilic polydopamine, a substance that resembles the structure of adhesive proteins secreted by marine mussels.

Bioadhesives are made from either natural or synthetic polymers, and stick to biological components like cells, tissues and organs through physical or chemical interactions. In the biomedical fields, one of the uses of bioadhesives is for tissue repair and regeneration — which is exactly why Tarafder is utilizing them for meniscus tear repair. He is developing a bioadhesive to achieve strong tissue adhesion by drawing inspiration from nature. Tarafder's approach includes the use of hydrophilic polydopamine, which he developed, along with other natural polymers like collagen, hyaluronic acid and fibrin.

Polydopamine — a polymer that is similar in nature to marine mussel adhesive proteins — has also shown great potential in the biomedical field due to its adhesion ability, biodegradability and biocompatibility. Hydrophilic polydopamine shares these same traits, but unlike traditional polydopamine, hydrophilic polydopamine is water soluble, making it a better substance for Tarafder's bioadhesive.

"We chose hydrophilic polydopamine for its remarkable adhesive properties, inspired by nature's own solutions. Its ability to bond strongly in wet environments makes it ideal for tissue repair, where maintaining adhesion in the presence of body fluids is critical," Tarafder said.

The meniscus is two wedge-shaped — almost rubbery — pieces of fibrocartilage that act as shock absorbers between the femur and the tibia. The meniscus plays a key role in knee stability. Without a healthy, intact meniscus, it is difficult to make quick, lateral movements or "cuts." To assess a meniscus tear, magnetic resonance imaging (MRI) scans are often required.

For this project, Tarafder will assess the biomechanical properties of hydrophilic polydopamine fueled hydrogel bioadhesives in the lab setting. He will then test the regeneration properties of the developed hydrophilic polydopamine-fueled hydrogel bioadhesive that will work by filling in the meniscus tear via injection.

"By combining the adhesive properties of hydrophilic polydopamine with the body's natural healing mechanisms, we hope to stimulate essential cellular responses such as stem cell recruitment, proliferation and differentiation," Tarafder said. "This approach has the potential to significantly enhance mechanical integration and stability, speeding up the healing process and providing a more effective solution for meniscus injuries."

The successful completion of this project also has the potential to significantly advance the field of meniscus repair by providing a more effective treatment option. This research could also extend to the repair of other musculoskeletal connective tissues such as cartilage, tendon and bone, Tarafder added.

Tarafder's project is titled "ERI: Meniscus Tear Healing with Hydrophilic Polydopamine Fueled Hydrogel Bioadhesive" and is being funded under the National Science Foundation’s Disability and Rehabilitation Engineering program.