Biomechanics of Plate Osteosynthesis

The operative treatment of bone fractures using plates and screws is a standard successful technique. However, problems are encountered as a result of the associated additional trauma and disturbance of the bone blood supply, which increase the risk of delayed union and infection, as well as a result of poor fixation in osteoporotic bone. The locking plate (locked internal fixator) technique is an approach to optimize internal fixation. It aims a flexible elastic fixation to imitate spontaneous healing including induction of callus formation. The technology supports what is called today "minimally invasive plate osteosynthesis" (MIPO), which gives priority to biology over mechanics. In addition, locking plate technology has gained wide acceptance to ensure better anchorage in osteopenic bone. This has been circumstantiated by numerous biomechanical and clinical studies. This paper describes the important biomechanical principles to be taken into account when using either conventional or locking plates.