Fixation of pelvic fractures and dislocations. An experimental study on the loading of pelvic fractures and sacro-iliac dislocations after external compression fixation.

A trapezoid external compression fixation frame, assembled with the Hoffman instruments, was used for stabilizing experimental injuries to the pelvic skeleton of ten cadaver specimens. The resistance to loading in a position corresponding to upright standing was tested in 17 experiments and related to the calculated load in vivo. The results indicated that ipsilateral injuries, either presenting as dislocations of the sacro-iliac joint and symphysis or as unilateral fractures of the sacrum or ilium in combination with fractures of the pubic rami could be stabilized by the external compression frame well enough to permit weight-bearing in the upright standing position. Bilateral injuries to the pelvic skeleton, vertical or oblique, could not, however, be stabilized enough to resist more than a fraction of the normal load in the upright standing position.