Biomechanics and clinical application principles of locking plates

Th e introduction some 10 years ago of the combination of biological bridge plating with indirect reduction techniques was considered by some to be an important and welcome evolution, but by others (2,5,6) as a revolution against rigid AO principles. It had become evident that in the cortex directly underneath a plate, and to a lesser extent in the vicinity of an intramedullary nail, considerable structural changes occur. Th ese changes were first attributed to so-called stress protection by a metallic implant much more rigid than bone. Further research (1,3) gave rise to the theory that disturbed blood flow within the cortical bone was responsible for the intense remodeling processes that could be observed underneath every plate that was pressed against bone by screws (figure 1). Reducing the area of contact between plate and bone, as achieved by the LC-DCP design, significantly reduced the vascular changes caused by pressure