An artificial bone fragment in the form of a multi-layer membrane for bone formation, in particular a distraction membrane suitable for callus distraction is provided. In addition, the use of the artificial bone fragment for bone regeneration, in particular by callus distraction, and methods for bone regeneration, in particular callus distractions are provided. The distraction membrane includes at least a first, a second and a third layer. The first layer includes collagen. The second layer is rigid and the third layer includes a mineral material. A mating surface is formed by the first layer and a contact surface is formed by the third layer.
