Knotless Soft Tissue Augments for Improving Arthroscopic Rotator Cuff Repair Biomechanics

Knotless Soft Tissue Augments for Improving Arthroscopic Rotator Cuff Repair BiomechanicsLoad sharing and reinforcing soft tissue with knotless suture augments present a disruptive and innovative technology to managing the surgical care of rotator cuff injuries and prospectively other injuries where suture pull-through can have catastrophic effects. This phase I SBIR proposal endeavors to develop a new field of study and redefine clinical practice via innovative soft tissue augment (STA) implants to improve suture load distribution and tissue healing in rotator cuff repair (RCR) and related surgeries. The significance of this project is medical engineering of strong, reinforcing, resorbable polymeric implants that will allow for studying joint repair stability, understanding the causes/mechanisms of RCR failure, and ultimately preventing these failures via a commercial product. Central to the NIAMS mission, tendon re-tear following surgical RCR occurs in as high as 20-45% or more of primary repairs. This failure rate is an unacceptable fact, given that 800,000 RCR procedures are performed annually in the U.S. alone. In addition, rotator cuff injuries do not heal well on their own, cause limited mobility, persistent pain, and impact return to activity.Current RCR surgical strategies involve extensive use of sutures passed arthroscopically to provide tissue approximation. Unfortunately, suture-only repair commonly fails and instead leads to mechanically weak scar tissue formation, prone to subsequent failure, pain, and disability. The tendon-to-suture interface is believed to be the most common RCR failure mode. It is hypothesized that RCR failure occurs via gap formation at the enthesis, primarily due to elongation or suture cut-through at the suture-tendon interface. STAs we are engineering will distribute and share the mechanical load and prevent suture-to-tendon failure as an innovative approach to significantly improve RCR. Hypothesis: If Soft Tissue Augments (STAs) improve tissue repair biomechanics by reinforcing standard suture-based rotator cuff repair, then type 2 retears will be significantly reduced.Aim 1: To determine and optimize soft tissue augment biomechanical properties. Approach: 3D printed tendon augments implants will be produced from PDO and UHMWPE from the two STA designs (round and tab shaped) for surgeon assessment and simulated use. The tendon suture augments will be tested in cadavers for validating arthroscopic delivery. In addition, STAs surgically placed on the repaired tendons will be tested for biomechanical performance in pull-to-failure and cyclic testing relative to repair with only sutures (the standard of care).Aim 2: To determine soft tissue augment stability and biocompatibility. Approach: STA will also be assessed for biocompatibility per ISO 10993-6. The STA implant stability will also be assessed per ASTM 1635-16 standard testing to determine the resorption rate of the soft tissue augments.