Biomaterial approval opens citrate route to medical implants

A medical device made from a biomaterial reported in the Elsevier journal Biomaterials [Qui, H. et al., Biomater. (2006) 27, 5845–5854; DOI: 10.1016/j.biomaterials.2006.07.042] has been granted clearance from the US Food and Drug Administration. The material can be used in orthopedic implants employed to allow soft tissue grafts to be attached to bone and was developed by Guillermo Ameer of Northwestern University in Evanston, Illinois, USA, and his colleagues.

This is the first thermoset biodegradable synthetic polymer to be approved for implantable medical devices and its unique chemical and mechanical properties will make it useful for a wide range of applications in this area. The material, known as Citregen, helps with the healing process by mimicking the body’s intrinsic biochemical and structural support network. Fundamentally, the material protects soft tissue grafts during insertion and optimizes graft fixation to bone.

The material is based on elastomeric polymers based on citrate, specifically poly(diol citrate). The materials are soft and can recover from deformation readily. Citrate can be released from the material and has natural antimicrobial and anti-inflammatory. In this context, however, it is the crucial role of citrate in bone regeneration where it regulates cellular metabolic processes and the formation of mineral structures.

“Citregen is an unprecedented and innovative bioresorbable biomaterial technology developed to support the body’s normal healing process and promote tissue regeneration,” Ameer explains. “When used to fabricate devices for the reconstruction of tissues, such as ligaments, blood vessels, bladder and bone, results have been impressive and beyond our expectations.”

The material has been used to fabricate a screw system that will be produced and marketed by Acuitive Technologies. The system can be used to attach soft tissue grafts to bone. The osteoconductive material is gradually absorbed by the body after surgery, leaving behind a biocompatible ceramic structure that is then metabolized by the body so that bulk degradation and chronic inflammation do not occur as might be seen with earlier biodegradable polymers employed in this way, such as poly-lactides. Ameer has worked on these semi-synthetic biomaterials for almost two decades and is pleased to see the output of his pioneering research now approved for medical applications. The Citrelock Interference Screw System will become available through Acuitive’s orthopedic distribution partner in early 2021.