Processed bone. Bag of frozen ground-up donated bone in a bone bank. This form of bone is used to replace diseased bone, often being used to fill in spaces around a joint replacement or during other bone surgery. Bone is a commonly transplanted tissue, second only to blood. Bone tissue is donated both after death and from patients undergoing joint replacement surgery and other bone operations. The donor and bone are carefully screened for disease to ensure the bone is healthy. Other bone grafts include whole bones and parts of bones, often used to reconstruct injured patients or replace cancerous bone. Photographed in the Rizzoli Institute, Bologna, Italy.