Improving Care and Operational Readiness with Additively Manufactured Microfibrous Implants for Ligament and Tendon Regeneration

Background: This research will advance the development of a revolutionary additive biomanufacturing approach to rapidly producing medical material for USAF end users and dual-use civilian medicine. Multiaxial robotic filament winding machines have produced many US Air Force products, such as rocket fairings and nose cones, helicopter blades, and other common materials (e.g., carbon fiber bike frames). Filament winding produces tight-tolerance parts with superior mechanical properties beyond conventional tissue engineering fiber production methods (i.e., electrospinning, etc.). Yet filament winding is a technology that has not yet been adapted to biomedical applications. Our group has succeeded in producing and manipulating 5-150 micron fibers that can be additively manufactured using a custom 4-axis filament winding, called Three Dimensional Microfilament Fabrication, or 3DMF, to produce medical implants that are particularly well-suited to musculoskeletal tissue repair and regeneration.   We have engineered a novel additive manufacturing platform (3DMF) to produce highly aligned polymeric implants to share the load of the repair and promote biological integration using advanced polymers based on nanocellulose for remarkable biocompatibility, stability, and strength, far exceeding other biomaterials, such as collagen and polylactides, both of which are weak and highly immunogenic in comparison. Our 3DMF manufacturing is revolutionary for medical device production and produces implants to significantly improve the standard of care while adding minimal time, complexity, and cost to the case, yet targeting dramatically improved outcomes by our biomechanical and biomaterial mechanisms.  Military Relevance Anterior cruciate ligament (ACL) tears are common in the USAF from field injuries, off-duty sporting, weightlifting, and other recreational activities, accounting for nearly 15% of all debilitating injuries. Occurring in over 3,000 warfighters annually, ACL tears are extremely debilitating, expensive to treat, and have a long recovery time. More than half of service members with ACL injury have their activity limited or are unable to return to duty following ACL surgery.  Persistent pain and stiffness of the knee with a 20% failure of the ACL within 2 years are reported in patients.