Internal fixation for the transforaminal sacral fracture.

The mechanical stability of alternate forms of internal fixation of the transforaminal sacral fracture were compared. A transforaminal sacral fracture was made in each of 6 fresh-frozen cadaveric pelvic specimens. Implants compared for fixation included: a single and 2 fully threaded iliosacral screws inserted through the posterior ilium and anchored into the first sacral vertebral body both with and without the addition of a posterior tension band plate; and 2 transiliac bars inserted through the posterior tubercles. The femora of each specimen were potted and fixed to the table of a materials tester. The pelvis was restrained only from flexing and extending, and a compressive load was applied through the lumbar spine, representing a standing loading condition. Flexion of the sacrum and displacement at the fracture site were measured during loading. Although creation of the injury increased motion considerably, there was no measurable increase in stability provided by any of the implants or combination of implants in this model when an anatomic reduction was obtained.