Hitchhiker plants inspire improved techniques for reattaching tendon to bone

For most people, getting burrs stuck on your clothes during a hike is nothing more than a nuisance, something to pick off and throw out when you get home. But for researchers at the Center for Engineering MechanoBiology, or CEMB, the hooks on these little hitchhikers are inspiring new suturing schemes for surgical reattachment of tendon to bone.

The research was supported in part by the U.S. National Science Foundation and published in Proceedings of the Royal Society A.

Tendon-to-bone reattachment is required in many surgical procedures, perhaps most commonly in repairing torn rotator cuff tendons in the shoulder, a condition that affects more than 30% of the population over 60 years of age. Current suturing methods fail to distribute stress evenly, leading to failure rates as high as 94% due to ineffective attachment and tearing of the sutures.

A team of researchers led by Guy Genin, CEMB co-director at Washington University in St. Louis, has developed a new approach to suturing based on the mechanics and spacing of a hitchhiker plant's attachment system. The strategies show promise for balancing forces across sutures, reducing the stress on healing tendons and potentially doubling repair strength over current suturing schemes.

"We're thinking about critical issues in medical practice and working to bring people together from across disciplines to work on big problems," Genin said. "When the late Barbara Pickard, a pioneer of mechanobiology who helped found the CEMB, got burrs on her socks during a walk through the desert, she didn't discard them; she latched onto the idea that nature could provide novel solutions in unexpected places."

Decades after Pickard's walk, she shared her experience with burrs — similar to the hitchhiker plants that inspired hook-and-loop fastener technology — with Genin and Ethan Hoppe, lead author of the new study.

The team found collaborator Matt Guilliams, a plant systematist at the Santa Barbara Botanic Garden, who sent fruits that helped the modeling of how burrs hold onto soft materials. The mathematical model the team developed pointed to a unique scheme that balances forces.

Pre-clinical testing of the new suturing method is already underway in the laboratory of co-author Stavros Thomopoulos at Columbia University. "Current experiments in the lab are evaluating how suture spacing inspired by hitchhiker plants affects rotator cuff repair strength," Thomopoulos said.

Genin and Thomopoulos anticipate that these improved techniques may be in surgical practice within the next two years.