Abstract: A biodegradable implant for placement in nonunion bone fractures as a substitute for bone graft material is provided which is a flat plate or disk having a thickness of between about 1 mm and about 15% of the length of the bone, interconnected micropores, and canals substantially equivalent in size and spacing to naturally-occurring Haversian canals. The implant may additionally comprise additives such as growth factors, including bone morphogenic protein. In a preferred embodiment the implant is formed from a biodegradable polymer such as a polylactic acid-polyglycolic acid copolymer by a gel casting technique followed by solvent extraction to precipitate the implant as a microporous solid.