Python-inspired device doubles rotator cuff repair strength

New York, NY — June 24, 2024 — Most people, when they think of pythons, visualize the enormous snake contracting and swallowing its victims whole. But did you know that pythons first latch on to their prey with their sharp, backward-curved teeth? Medical researchers have long known that these teeth are perfect for gripping soft tissue rather than cutting it, but no one has yet managed to put this concept into surgical practice. Over the years, imitating these teeth for surgical purposes has been a frequent topic of discussion in the laboratory of Dr. Stavros Thomopoulos, professor of orthopedics and biomedical engineering at Columbia University.

Biomimicry is key to new study

A leading researcher focused on the development and regeneration of the tendon-bone attachment, Thomopoulos has a particular interest in the advancement of tendon-bone repair, which is necessary for rotator cuff repair and ligament reconstruction anterior cruciate. In a paper published today by Science Advances, his team reports developing a python tooth-inspired device to complement current rotator cuff suture repair, and found that it nearly doubled repair strength.

“As we age, more than half of us will experience a rotator cuff tear that results in shoulder pain and decreased mobility,” said Thomopoulos, who holds joint appointments at Columbia Engineering and Columbia’s Vagelos College of Physicians and Surgeons as the Robert E. Carroll and Jane Chace Carroll Professor of Biomechanics (Orthopedic Surgery and Biomedical Engineering). “The best medical intervention is rotator cuff surgery, but a remarkably high percentage of these repairs will fail within months. Our biomimetic approach, inspired by the design of python teeth, allows for more secure reattachment of tendons to bone. The device not only increases the strength of the repair, but can also be customized to the patient. We are very excited about the potential of our device to improve the care of rotator cuff injuries.”

Rotator cuff injuries

Among the most common tendon injuries, rotator cuff tears affect more than 17 million people in the United States each year. The incidence of injuries increases with age: more than 40% of the population over the age of 65 suffers a rotator cuff tear.

Because rotator cuff tears typically occur at the point where the tendon attaches to the bone, rotator cuff repair aims to anatomically restore the tendon attachment. Surgical repair is the primary treatment for restoring shoulder function, with more than 600,000 procedures performed annually in the United States at a cost of $3 billion.

However, successful reattachment of the tendon to the bone remains a significant clinical challenge. High failure rates occur after surgery, increasing with patient age and tear severity. These rates range from 20% in younger patients with minor tears to 94% in older patients with massive tears. The most common failure of rotator cuff repairs is tearing of the sutures within the tendon at the two or four grip points where forces are concentrated.

Although advances have been made in rotator cuff repair techniques over the past 20 years, the fundamental approach of sewing two tissues together has remained largely unchanged, still relying on sutures transferring tension to the high stress grip points. After tendon-to-bone reattachment surgery, sutures can tear tendons at these points of high stress, a phenomenon known as “suture pulling” or “cheesewiring,” leading to gapping or rupture at the tendon. repair site.

“We decided to see if we could develop a device mimicking the shape of a python’s teeth, which would effectively grip soft tissue without tearing and help reduce the risk of tendon tears after rotator cuff repair.” , said Iden Kurtaliaj, head of the study. lead author and former doctoral student in biomedical engineering in Thomopoulos’ lab.

The device

The team’s original idea was to copy the shape of python teeth, but they went much further, using simulations, 3D printing and ex vivo experiments on cadavers to explore the relationship between tooth shape and the mechanics of gripping and cutting. Kurtaliaj manufactured a range of tooth models, optimized individual teeth, tooth rows and finally a rotator cuff specific tooth row. The end result was a biomimetic device, made of a biocompatible resin – a set of teeth on a curved base – capable of gripping, not cutting, the tendon. The teeth are relatively small – 3mm tall for a human rotator cuff, or about half the length of a standard staple – so they do not pass through the tendon. The base can be customized via 3D printing to match the patient-specific curvature of the humeral head at the supraspinatus tendon attachment site (the most commonly torn rotator cuff tendon).

“We designed it specifically so that surgeons don’t have to abandon their current approach: they can simply add the device and increase the strength of their repair,” Kurtaliaj noted.

The team

Kurtaliaj led the research as a doctoral student under the mentorship of Drs. Stavros Thomopoulos and Guy Genin, the Harold and Kathleen Faught Professor of Mechanical Engineering at Washington University in St. Louis, with input for implementation clinic of Dr. William Levine, Chairman of the Department of Orthopedic Surgery at Columbia University College of Physicians and Surgeons.

“Through our laboratory’s close collaboration with orthopedic surgeons, we were fortunate to have input from Dr. Levine, as well as other surgeons at Columbia, throughout the process of developing the design of the device,” Thomopoulos said.

Next steps

Researchers are currently working to develop a bioresorbable version of the device that would degrade as the rotator cuff grows back to the bone, further improving its clinical applicability. They are also preparing for a pre-submission meeting with the FDA to help transition their device to market.

About the study

–The study is titled “Python Tooth-Inspired Fixation Device for Improved Rotator Cuff Repair.”

–The authors are: Iden Kurtaliaj1,2,3, Ethan D. Hoppe4,5, Yuxuan Huang4,6, David Ju4,5, Jacob A. Sandler4,5, Donghwan Yoon4,5, Lester J. Smith7, Silvio Torres Betancur1, Linda Effiong1,8, Thomas Gardner1, Liana Tedesco1, Sohil Desai1, Victor Birman9, William N. Levine1, Guy M. Genin4,5,6*, Stavros Thomopoulos1,2*

1Department of Orthopaedic Surgery, Columbia University

2Department of Biomedical Engineering, Columbia University

3Department of Neurosurgery, Icahn School of Medicine at Mount Sinai

4NSF Science and Technology Center for Mechanobiological Engineering, Washington University in St. Louis

5Department of Mechanical Engineering and Materials Science, Washington University in St. Louis

6Department of Biomedical Engineering, Washington University in St. Louis

7Department of Radiology and Imaging Sciences, Indiana University School of Medicine

8Koru Medical Systems, Mahwah, New Jersey

9Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology

–This work was supported by the National Institutes of Health (R01 AR077793 and R21 AR076008) and the NSF (CMMI 1548571).

–Competing interests: Multiple authors have filed two patent applications related to the subject matter of this article: Genin G, Hoppe E, Yoon DH, Thomopoulos S, Kurtaliaj I, Tedesco L, Kovacevic D, Birman V, Smith L, Galatz L, Levine W, inventors. Soft tissue-hard tissue interface fixation device. US Patent Application US 17/766,503. February 15, 2024; and Genin G, Hoppe E, Yoon DH, Thomopoulos S, Kurtaliaj I, Tedesco L, Kovacevic D, Birman V, Smith L, Galatz L, Levine W, inventors. Soft tissue-hard tissue interface fixation device. US Patent Application US 17/932,232. April 13, 2023. All authors declare no other competing interests.