Gradient bioresorption calcium phosphate fibers will be chemically incorporated into poly-l-lactic acid (PLLA) matrix to produce load-bearing and bioresorbable composites. These composites will be evaluated thoroughly in vitro under loading conditions. Innovative composite design and fabrication techniques are introduced to effectively address deficiencies in current resorbable fixation devices. Factors controlling the composite integrity and strength retention will be studied and optimized. These composites will sustain sufficient mechanical strength for up to 6 months before they predictably and gradually lose their strength. Complete bioresorption of the composites in the body can be tailored to within 2 to 3 years. Biocompatibility assessments will be conducted in vitro and then in vivo. Composite intramedullary rods will be prepared and evaluated in a dog femoral fracture model using equivalent stainless steel devices as controls. Comprehensive efficacy determination, including other load-bearing fracture fixations and skeletal repairs, will be continued in Phase III. At the conclusion of this Phase II program, (1) XL Sci-Tech will have an integrated pilot facility capable of producing selected composite fixation devices for clinical trials; and (2) the efficacy of load-bearing long bone fracture fixation using bioresorbable composite intramedullary rods with cross-locking pins will be established.
Gradient calcium phosphate fiber/polymer composites are ideal for bioresorbable orthopedic devices, which can replace the currently used metal devices and overcome major inherent problems/risks and costs associated with metal devices and their removal. These composites may also be useful for maxillofacial surgery and dental applications.
