Part II: The mechanics of fracture fixation

Abstract

A wide variety of options are available for fixation of fractures. Mechanical stability is generally not necessary for fracture healing, but is important for maintaining alignment to prevent malunion. The degree of angulation, rotation and shortening which can be tolerated and still be compatible with good function is dependent upon the particular type of fracture, its location and the expected performance of the patient. In general, the stiffer the fixation is, the less the fracture site will move, the less callus will form and the less is the stress on the healing tissues. The less stiff (or more compliant) the fixation, the more abundant the peripheral callus and the more stress on the tissues as they form to optimize tissue alignment, strength and stiffness. External fixation provides the best control of structural stiffness of fixation and provides the option of changing the stiffness during the treatment. Of the internal fixation methods, intramedullary fixation devices are the least biologically invasive option and least mechanically destructive. Plate fixation provides the most stable, rigid fixation but the greatest alteration of the natural healing processes. Functional cost or fracture brace management provides the least stable, most compliant fixation and the least interference with the natural healing processes. Each has its place in the armamentarium of the orthopaedic trauma surgeon.