Orthopedic implants to repair fractures to the radius and ulna. Note the visible break in the ulna. (right forearm)
Internal fixation is an operation in orthopedics that involves the surgical implementation of implants for the purpose of repairing a bone, a concept that dates to the mid-19th century and was made applicable for routine treatment in the mid-20th century. An internal fixator may be made of stainless steel or titanium.
Open Reduction Internal Fixation (ORIF) 
Open Reduction Internal Fixation (ORIF) involves the implementation of implants to guide the healing process of a bone, as well as the open reduction, or setting, of the bone itself. Open reduction refers to open surgery to set bones, as is necessary for some fractures. Internal fixation refers to fixation of screws and/or plates, intramedullary bone nails (femur, tibia, humerus) to enable or facilitate healing. Rigid fixation prevents micro-motion across lines of fracture to enable healing and prevent infection, which happens when implants such as plates (e.g. dynamic compression plate) are used. Open Reduction Internal Fixation techniques are often used in cases involving serious fractures such as comminuted or displaced fractures or in cases where the bone would otherwise not heal correctly with casting or splinting alone.
Risks and complications can include bacterial colonization of the bone, infection, stiffness and loss of range of motion, non-union, mal-union, damage to the muscles, nerve damage and palsy, arthritis, tendonitis, chronic pain associated with plates, screws, and pins, compartment syndrome, deformity, audible popping and snapping, and possible future surgeries to remove the hardware.
Closed Reduction Internal Fixation 
Closed Reduction Internal Fixation (CRIF) is reduction without any open surgery, followed by internal fixation. It appears to be an acceptable alternative in unstable displaced lateral condylar fractures of the humerus in children, but if fracture displacement after closed reduction exceeds 2 mm, open reduction and internal fixation is recommended.
See also 
- Arbeitsgemeinschaft für Osteosynthesefragen
- CNT Network Bio-stress Sensors
- External fixation
- List of orthopedic implants
- T. Schlich (2002) Surgery, Science and Industry. A Revolution in Fracture Care, 1950s-1990s (Houndsmills, Basingstoke: Palgrave)
- General Principles of Internal Fixation. URL: http://emedicine.medscape.com/article/1269987-overview Accessed 9 January 2010
- MedicineNet.com URL: http://www.medterms.com/script/main/art.asp?articlekey=13714 Accessed 9 January 2010
- The Original Interlocking Nail System Accessed 10 February 2011
- Song, K. S.; Kang, C. H.; Min, B. W.; Bae, K. C.; Cho, C. H.; Lee, J. H. (2008). "Closed Reduction and Internal Fixation of Displaced Unstable Lateral Condylar Fractures of the Humerus in Children". The Journal of Bone and Joint Surgery 90 (12): 2673–2681. doi:10.2106/JBJS.G.01227. PMID 19047713.