To analyze the clinical and radiological results of the different fixation methods according to the type and displacement of unstable pelvic ring injuries.

Twenty-three patients with unstable pelvic ring injuries from January 2005 to December 2009 were classified according to the AO/OTA classification system. When patients had been diagnosed with unstable pelvic ring injuries with partial instability, they were treated by anterior fixation with a plate and posterior percutaneous iliosacral screw fixation. When patients had been diagnosed with unstable pelvic ring injuries with complete instability, they were treated by open reduction and anterior to posterior fixation with a plate through the ilioinguinal approach. The radiological results were evaluated using Matta and Saucedo's method, and the clinical results were evaluated using Rommens and Hessmann's method.

The outcomes from the radiological evaluation were that the displacement of the posterior pelvic ring were improved by about 6.65 mm in unstable pelvic ring injuries with partial instability. The displacement of the posterior pelvic ring were improved by about 7.8 mm in unstable pelvic ring injuries with complete instability. The clinical results were excellent in 13 cases and good in 6 cases on latest follow-up.

Good results can be achieved by selecting the treatment method according to the type of unstable pelvic ring injurie and displacement.