Internal fixation of malar fractures: an experimental biophysical study

Open reduction and internal fixation of displaced zygoma fractures are necessary to avoid immediate and delayed facial disfigurement. Interosseous wires, Kirschner wires, and more recently, rigid metallic miniplates have been recommended for fixation of these and other midfacial fractures. However, the precise physical stability of the zygoma with respect to wire versus miniplate fixation methods and with respect to the number and location of miniplates applied is not known. Noncomminuted zygoma fractures were simulated by saw osteotomy in eight fresh human cadaver heads (16 zygoma "fractures"). Each zygoma was sequentially fixated with three miniplates, two miniplates, one miniplate, and three interosseous wires across the orbital rim and arch "fractures". Static and oscillating loads simulating maximal physiologic masticatory stresses were applied to the fixated zygoma along the lines of action of the masseter muscle by means of a tensometer. The stability and adequacy of each pattern of fixation were recorded. Double-miniplate fixation across the orbital rim of simulated noncomminuted zygoma "fractures" is sufficient to withstand static and oscillating loading similar to physiologic masticatory forces. Neither single-miniplate fixation nor triple-wire fixation are sufficient to stabilize the zygoma against similar forces.