Rami Comminution Is Associated With Displacement of Minimally Displaced Lateral Compression Type 1 Injuries on Lateral Stress Radiographs.

OBJECTIVES

To determine whether displacement on lateral stress radiographs (LSRs) in patients with minimally displaced lateral compression type 1 pelvic ring injuries is associated with any demographic and/or injury characteristics.

DESIGN

Retrospective comparative cohort.

SETTING

Urban level 1 trauma center.

PATIENTS/

PARTICIPANTS

Ninety-three consecutive patients with minimally displaced lateral compression type 1 injuries.

INTERVENTION: Displacement of pelvic ring injury on LSR (≥10 mm vs. <10 mm).

MAIN OUTCOME MEASUREMENTS: Demographic and injury characteristics (mechanism of injury, Nakatani rami classification, rami comminution, Denis zone, complete/incomplete sacral fracture, sacral comminution).

RESULTS

65.6% of patients (n = 61) had ≥10 mm of displacement on LSR. On univariate analysis, displacement was associated with increased age [median difference 11: confidence interval (CI), 2-23], female sex [proportional difference (PD): 25.1%, CI, 3.9%-44.4%], Nakatani classification (type I PD: 27.9%, type II PD: -19.5%), and rami comminution (PD: 55.6%, CI, 35.4%-71.3%). On multivariate analysis, displacement was only associated with rami comminution (odds ratio: 16.48, CI, 4.67-58.17). Displacement was not associated with energy of injury mechanism, sacral fracture Denis zone, complete sacral fracture, sacral comminution, or bilateral rami fractures.

CONCLUSIONS

Although rami comminution was the only variable found to be independently associated with displacement ≥10 mm on LSR, no single variable perfectly predicted displacement. Future studies are needed to determine whether displacement on stress radiographs should change the management of these injuries.

LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.