Unilateral external fixation. Methods to increase and reduce frame stiffness.

Unilateral configurations with stiffness characteristics similar to those of the most rigid one- and two-plane bilateral constructs are easily built. Mechanically, most effective were two-plane unilateral frames with a short bone-rod distance. But single- and double-bar anterior unilateral frames had the best combination of clinical and mechanical features. To put gradual frame builddown on a rational basis, a sequence of stepwise frame reduction was developed. This sequence leads from the most rigid unilateral constructs to frames that allow almost complete force transmission across the fracture site while still providing adequate protection against the prevailing sagittal bending moments.