Expandable Shape-Memory Polymers for Suture Anchors

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DESCRIPTION (provided by applicant): This project will develop a shape-memory polymer suture anchor capable of dynamic expansion and is specifically designed for patients with poor bone mass density. Suture anchors are screw or wedge-like devices that fasten into the bone and are used to secure a detached tendon to the bone. After a 12-week period, the tendon should achieve natural biological fixation to be considered successfully repaired. Rotator cuff repair is the most common surgical procedure involving suture anchors and are performed over 75,000 times annually. A general challenge and constraint in repair is the large amount soft cancellous bone where the anchor must be placed, which makes the anchors more susceptible to migration, loosening/tunnel widening, and pullout. Furthermore, a growing number of patients over 60 years of age are receiving rotator cuff repairs and suffer from osteoporosis. Patients with poor bone mass density are highly at risk to device failure as bone density have been correlated to the fixation strength of suture anchors. The proposed shape-memory polymer suture anchor will be (i) designed to match its expansion forces to the bone's performance limits to optimize fixation strength and (ii) be able to dynamically adapt to tunnel widening to ensure stable fixation during the healing period. The broad impact of this work will introduce a new type of shape-memory biomaterial into the market as well as potentially revolutionize rotator cuff repair and reach into all procedures involving suture anchors. The SBIR Phase I is designed to not only provide feasibility to the shape-memory polymer suture anchor, but also to generate fundamental material information to move into Phase II. The two main aims of this Phase I are (i) link the polymer structure and device design to the radial recovery force, while proving biocompatibility and (ii) provide sufficient pullout data compared to current devices and illustrate the polymer can adapt to tunnel widening. The first aim will primarily consist of material synthesis, network and shape-memory characterization, and cytocompatibility testing. The second aim will make use of a porcine bone model to perform and compare monotonic and cyclic pullout testing of commercially available devices and shape-memory polymer prototypes. The primary research team will consist of a principal investigator from MedShape Solutions, Christopher Yakacki PhD, who has experience in synthesis and characterization of shape-memory polymers; a materials scientists from The Georgia Institute of Technology, Ken Gall PhD, who is a full professor specializing in shape-memory materials; and an orthopedic surgeon, Reed Bartz MD, who is an expert in arthroscopic shoulder repair. Project Narrative A growing percentage of the population is remaining physically active as they age. This project is relevant to this percentage of people that experience a debilitating injury such as a rotator cuff tear. This project will provide a means to restore function to their shoulders with less occurrence of surgical failure and increase their quality of life.