Introduction: Type C pelvic ring disruptions are commonly associated with significant patient morbidity. It is the senior author’s (APP) experience that the sacro-iliac alar cartilage is commonly damaged at the time of initial trauma. If left untreated, this may give rise to post-traumatic arthrosis of the joint, with resultant pain. The natural history of type C disruptions is one of late pain. In this paper, we review our results of acute arthrodesis of the SI joint simultaneously with fixation of the posterior pelvis.

Methods: From 1987–2000, a consecutive series of 28 patients who underwent primary surgical fusion and internal fixation of the sacro-iliac joint underwent clinical and radiographic review. All patients were examined at latest follow-up (79.8 months) in regards to pain, range of motion, walking tolerance and the incidence of significant complications. Evaluation of the pelvic ring reduction and success of arthrodesis of the SI joint were made through radiographs of the pelvic ring. In addition patients completed the SF-36 as a measure of general health status and the Musculoskeletal Function Assessment (MFA) and WOMAC scores as a measure of functional outcome. Work status was also examined.

Results: The majority of these injuries were sustained in either motor vehicle crashes or high energy falls. There was a high incidence of associated injuries and co-morbidities. The male to female ratio was approximately 2:1 with a mean age of 27 years. At initial surgery, all patients were noted to have severe fragmentation and disruption of the alar cartilage. The majority of patients had sacro-iliac screw fixation for their posterior injury and an external fixator for anterior stabilization. At follow-up there was a low incidence of late posterior complex pain. All patients were independently mobile and there were minimal complications. Only 1 patient had to change jobs secondary to pelvic or low back pain. The functional outcome at long term follow-up was good with regards to the SF-36, MFA and WOMAC scores.

Conclusions: Type C pelvic ring injuries have a high incidence of disruption of the alar cartilage. Treatment of these injuries by primary fusion and internal fixation leads to good long-term results.