Skeletal Deformity After Anterior External Fixation of the Pelvis

OBJECTIVE:To study the deformity of acutely injured unstable pelves before and after emergent application of an anterior external fixator. DESIGN:Retrospective. SETTING:Large pelvic fracture referral practice. PATIENTS:Eleven of 151 patients referred to our institution after emergent application of an external fixator by the referring orthopaedist before transfer who were hemodynamically unstable and had a mechanically unstable pelvic injury with pre-external fixator radiographs and post-external fixator radiographs adequate to determine pelvic deformity. MAIN OUTCOME MEASUREMENTS:We reviewed all available radiographs both before and after placement of the external fixator (the anterior-posterior, inlet, outlet, and computed tomography), determining whether the external fixator improved or worsened the deformity. RESULTS:Although many deformities existed, we found that application of an anterior frame consistently worsened this deformity. Seven of the 11 patients (64%) had worsening of the posterior cephalad translation or posterior diastasis despite apparent improvement anteriorly on the anterior-posterior radiograph. “External fixator deformity,” defined as increased flexion and/or internal rotation of the hemipelvis, also occurred in 8 of 11 patients (73%). After placement of the external fixator, all patients displayed greater than 1 cm of either posterior cephalad translation or posterior diastasis (average 3.4 cm, range 1.3-4.6 cm). CONCLUSIONS:Due to the forces placed on the pelvis during application of an anterior external fixator by the surgeon, an external fixator deformity may occur (flexed and internally rotated hemipelvis). Furthermore, most patients had an increase in posterior cephalad translation or posterior diastasis with placement of an external fixator. The surgeon should be aware of the potential of increasing the pelvic deformity when applying an emergent anterior external fixator.