Posterior iliac crescent fracture-dislocation: is it only rotationally unstable?

Posterior iliac crescent fracture-dislocation is generally considered rotationally unstable and vertically stable. The current study (1) investigated whether vertical instability may occur in posterior iliac crescent fracture-dislocation and (2) analyzed the clinical features of vertically unstable iliac crescent fracture-dislocation as well as treatment strategies. Patients with pelvic fracture who were treated in the authors' department from June 2009 to June 2012 were retrospectively reviewed. This study analyzed the clinical features, including incidence, hemodynamic state, associated injuries, injury severity score, and treatment methods for vertically unstable iliac crescent fracture-dislocation. Four patients had vertically unstable fracture-dislocation, accounting for 12.9% of all iliac crescent fracture-dislocations. All 4 patients were hemodynamically unstable on admission and had complications of associated injuries with a higher injury severity score. In 3 of the 4 patients, iliac crescent fracture-dislocations were reduced via the posterior approach at the initial stage and these patients underwent fixation with a plate. The remaining patient was initially given transcondylar traction because of severe complications and underwent open reduction and internal fixation (ORIF) via a posterior approach at a later stage. The outcomes of all 4 patients were rated as good or excellent by the Kobbe rating system at the last follow-up. Vertical instability may occur in iliac crescent fracture-dislocation. The authors propose ORIF of the fracture-dislocation via a posterior approach. When initial surgery is not possible because of severe associated organ injuries, the authors propose transcondylar traction to allow reduction of the sacroiliac joint and ORIF at a later stage.