Rotator cuff tears are among the most common tendon injuries, affecting millions annually, especially as people age. Over 40% of individuals over 65 suffer from these injuries, which generally occur at the tendon-to-bone insertion point. This makes surgical repair, which seeks to anatomically reattach the tendon, the primary treatment for restoring shoulder function. However, reattaching tendon to bone successfully poses substantial challenges, with high failure rates that increase with the patient's age and the severity of the tear. These rates can be as low as 20% in younger patients with minor tears and as high as 94% in elderly patients with massive tears.

Despite advancements in rotator cuff repair techniques over the past two decades, the basic method of using sutures to stitch two tissues together has not changed significantly. This method often fails due to "suture pull-through" or "cheesewiring," where the sutures tear through the tendons at high-stress points, causing gaps or ruptures at the repair site. Now, a team of engineers has developed a device inspired by python teeth as a supplement to existing rotator cuff suture repair that almost doubles repair strength. In a paper published recently by Science Advances, the researchers have described their biomimetic approach which mimics the design of python teeth to secure tendon reattachments to bone more effectively, while allowing the device to be customized to individual patients.

The innovation was achieved by a team at Columbia Engineering (New York, NY, USA) who extended their original idea of simply replicating python tooth shape to implementing advanced simulations, 3D printing, and ex vivo experiments on cadavers to refine the interaction between tooth shape and its mechanics. They crafted various tooth designs, optimizing individual teeth, arrays of teeth, and finally, a specific array suitable for rotator cuff applications. The resulting biomimetic device, built using biocompatible resin, features an array of teeth set on a curved base that grasps without cutting the tendon.

Each tooth is about 3mm high, approximately half the length of a standard staple, ensuring they do not pierce through the tendon. The device's base is 3D printed to conform precisely to the patient-specific curvature of the humeral head at the supraspinatus tendon attachment site, the most frequently injured rotator cuff tendon. The researchers are now focusing on developing a bioabsorbable version of this device that would degrade as the tendon naturally heals back to the bone, aiming to improve clinical outcomes further. They are also preparing for an upcoming pre-submission meeting with the FDA to discuss the potential market introduction of their innovative device.

“We decided to see if we could develop a device that mimics the shape of python teeth, that would effectively grasp soft tissues without tearing, and help reduce the risk of tendon re-tearing after rotator cuff repair,” said Iden Kurtaliaj, the study’s lead author. “We designed it specifically so that surgeons won’t need to abandon their current approach - they can simply add the device and increase the strength of their repair.”

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