ABSTRACT
Whether or not external fixation should be applied to the femur, and on what grounds, will depend upon a variety of factors. It is rarely considered to be the treatment of first choice. External fixation can, however, be indicated in certain circumstances. Looking for optimal rigidity in such cases we tested and compared the stability of 14 different femoral external fixators in an experimental model. It was found that the weight of the different frames varied from 400 to 2000 g. The comparative stability also varied widely. Movements of between 1 mm and 4 cm and rotations varying from almost 0 degrees to 16 degrees were measured at the (experimental) fracture site, based upon the geometry of an adult patient. In view of this finding primary bone-healing would not be expected to occur, since it demands more stability than external femoral fixation can offer. A relatively simple two-dimensional (unilateral) frame can be as rigid as a three-dimensional one, in response to all but transverse loading.
