Methods for processing tissues to render them suitable for implantation, e.g. in an orthopedic site. Tissues are rendered substantially acellular and substantially nonimmunogenic by exposure to processes that result in cell lysis, increasing permeability of the extracellular matrix, degrading the debris from lysis, and removing the debris. Methods of forming tissue implants, kits for processing tissue implants, and methods of using tissue implants are also disclosed.