A standard Hoffmann-Vidal quadrilateral fixation system for tibial
fractures was analyzed using different geometric and material variations of
the basic configuration. The fixation stiffness properties were quantitated
to provide objective comparison. The results have shown that the bone-pin
interface is the least-stiff link in the entire structure, particularly
under the anterior-posterior bending mode. Rigidity of the device can be
substantially improved by increasing the number of pins, using full
threaded pins with a larger diameter, decreasing side connecting-rod
distances, and increasing pin-separation distances in each pin group.
Symmetrical tightening of the compression screws by hand is sufficient to
produce compression of bone at the fracture site. The use of titanium pins
tends to reduce stiffness, but using a frame made of titanium can
significantly decrease the weight of the apparatus without decreasing its
stiffness.