Background Internal fixation has become the preferred treatment for type-C pelvic ring injuries, but controversies persist regarding surgical approach and surgical technique.Patients We evaluated 101 consecutive patients with type C1-C3 pelvic ring injuries who had been treated with standardized reduction and internal fixation techniques.Results Our findings suggest a correlation between excellent reduction followed by sufficient fixation of the pelvic ring and functional outcome. Unsatisfactory reduction (displacement > 5 mm), failure of fixation, loss of reduction and a permanent lumbosacral plexus injury were the commonest reasons for an unsatisfactory functional result. All 40 patients with an associated lumbosacral plexus injury showed at least some evidence of neurological recovery. 14 underwent complete neurologic recovery. 8 had only sensory deficits and the remaining 18 also had motor deficits at the final followup. Complications were rare, but some of them were severe: loss of reduction in 8%, malunion in 10%, deep wound infection in 2%, and a lesion of the L5 nerve root in 1%.Interpretation Our results suggest that special attention should be paid to preoperative planning, reduction of the fracture, decompression of the nerve roots, and fixation of the most severe sacral fractures. Our results seem to favor internal fixation of displaced (> 10 mm) and unstable rami fractures and symphyseal disruptions in conjunction with posterior fixation, to achieve better stability of the whole pelvic ring.