[Dynamization of fracture fixation : Timing and methods]

Abstract

The dynamization of fracture fixation is a frequently used method to improve the fracture healing process; however, the term dynamization is used for different methods of altering the fixation of fractures during the bone healing process. The dynamization of intramedullary nail fixation by removing the interlocking screws is the most frequently applied method. This method can cause a telescopic movement between the nail and tubular bone that closes gaps in bony continuity and potentially compresses the fracture fragments. Experimental and clinical studies showed that this dynamization can accelerate the bone healing process. In particular dynamization may improve the outcome for fractures with residual fracture gaps following reduction but which allows support of the fragments. An alternative dynamization method involves decreasing the stiffness of the fracture fixation during the healing process. This method is used mainly with external fixation. In this procedure, stabilizing elements of the fixator are removed at some time during the treatment leading to greater flexibility of the fixation. Good results are reported for this method when the dynamization is performed in the late phase of the fracture healing process. If sufficient callus formation has taken place, callus bridging and maturation can be achieved. For reverse dynamization, which starts with a flexible fixation and is later stabilized, no significant advantages could be shown. The aim of fracture treatment should be stable fixation from the beginning. If the fracture fixation is unstable, it should be stabilized as soon as possible.

Keywords: Biomechanics; External fixators; Fracture healing; Intramedullary nailing; Tibial fractures.