the composition as described serves for in vivo cartilage repair . it basically consists of a naturally derived osteoinductive and / or chondroinductive mixture of factors or of a synthetic mimic of such a mixture combined with a nanosphere delivery system . a preferred mixture of factors is the combination of factors isolated from bone , known as bp and described by poser and benedict . the nanosphere delivery system consists of nanospheres defined as polymer particles of less than 1000 nm in diameter in which nanospheres the combination of factors is encapsulated . the nano - spheres are loaded with the mixture of factors in a weight ratio of 0 . 001 to 17 % , preferably of 1 to 4 % and have a release profile with an initial burst of 10 to 20 % of the total load over the first 24 hours and a long time release of at least 0 . 1 per day during at least seven following days . the nanospheres are composed of e . g . - lactic acid / glycolic acid )- copolymer . the loaded nanospheres are e . g . made by phase inversion . the composition is advantageously utilized as a device comprising any biodegradable matrix in which the nanospheres loaded with the factor combination is contained .