THE UNSTABLE ILIAC FRACTURE - A BIOMECHANICAL EVALUATION OF INTERNAL-FIXATION

Neither plating nor lag screw fixation of a displaced iliac wing fract ure as part of nit unstable pelvic ring disruption has been studied bi omechanically. The pur-pose of this study was to compare the stability of various combinations of fixation, specifically contrasting lag scr ews placed between the tables of the ilium with plating in different l ocations across the fracture line. Various combinations of these fixat ion implants were evaluated for an unstable iliac fracture. A longitud inal iliac fracture was created in each of six I?emi-pelvic specimens prior to testing. Compressive force, lip to 500 N or to the magnitude necessary to displace the fracture 2 mm, was applied to the fracture l ine through the hemi-pelvis far each of the plate al rd lag screw comb inations rested. There was no statistical difference between any of th e implants or combinations tested. A single 3.5-mm reconstruction (cep halad) plate placed along the cephalad internal aspect of the iliac cr est provided the least stability allowing 2 mm of displacement with a mean load of 80 N. The two combinations of fixation that required the greatest lends for 2 mm of displacement were a single 3.5-mm lag (ceph alnd) screw inserted into the iliac crest between the tables of the il ium coupled with either a 3.5-mm reconstruction (brim) plate placed al ong the internal aspect of the inferior iliac fossa at the pelvic brim (239 N) or a 4.5-mm lag (brim) screw between the inner and outer tabl es at the inferior aspect of the fracture just above the greater sciat ic notch (225 N). (C) 1997 Elsevier Science Ltd.