What are the internal fixation methods for treating osteochondral discontinuity? In order to restore stability to a bone discontinuity, a new form of internal fixation is the more common method. The surgeon may use a system of metal plates and screws for fixation around the bone (i.e. extramedullary fixation system) or a system of fixation with metal nails inserted in the bone marrow cavity (i.e. intramedullary fixation system, commonly used fixation devices called intramedullary nails). What are the key points for replacing the internal fixation system? If bone discontinuity occurs after the initial surgery, it is especially important to restore the stability of the fracture with a second surgery. The surgeon will use a stronger internal fixation, such as a thicker intramedullary nail or a longer plate. This increases the stability of the fracture and further stimulates and initiates the healing mechanism of the fracture. Often a combination of bone grafting is used to further promote fracture healing. Can external fixation be used to treat bone discontinuity? External fixation frames can also be used to treat bone discontinuities. Doctors can fix the fracture with a strong external fixation frame. This frame is attached to the bone by unthreaded steel pins (often called kerf pins) or semi-threaded nails. External fixation frames can be used to provide good stabilization not only for unstable osteogenic nonunions, but also for infected nonunions. Combinations of external fixation can also be used for the treatment of bone defects. What is a bone graft? Like other tissue and organ transplants, bone grafting is a procedure in which healthy bone tissue is obtained from another part of the body and transplanted to the site of a bone discontinuity or bone defect. Normally, healthy bone tissue is rich in cells that have the ability to “grow into bone” (i.e., cells with osteogenic potential and osteoblasts), which can initiate the bone healing process at the graft site. What are the common bone grafts? The following bone grafts are commonly used in clinical practice: autologous bone grafts (i.e., the patient’s own bone tissue), allogeneic bone grafts (i.e., someone else’s bone, usually from an organ donor), allogeneic bone grafts (i.e., animal bone, commonly bovine bone, sheep bone, shell bone), and bone graft substitutes (often referred to as artificial bone).