Allografts, which are taken from human bone (e.g. cadavers), and xenografts, which are taken from animal bone (usually cows), have been used in orthopedic surgery for many years. However, it can never be 100% sure that these materials are free from infectious contaminants and they can cause an immune response. Most of these materials used today are demineralized, which means they have gone through a special cleaning process. Although demineralization should remove most of the dangerous substances, it will not remove prions, which are believed to cause diseases such as vCJD ("mad cow disease").

Other disadvantages of allografts and xenografts are that the resorbtion proceeds in an unpredictable way, encapsulations are possible, and material residue may interfere with bone remodeling. Therefore many surgeons now use autografts or synthetic materials.