The Role of the Computed Tomographic Scan in the Diagnosis of Acetabular Fracture in the Immature Pelvis.

OBJECTIVES

We present a series of skeletally immature patients sustaining acetabular fractures. We hypothesized that if the secondary ossification centers of the acetabulum are not completely ossified, fractures often will not be identified on plain radiography. Our objective was to determine the efficacy of diagnostic plain radiography in these patients.

DESIGN

Retrospective case series.

SETTING

Urban, level-I trauma center.

PATIENTS/PARTICIPANTS: Skeletally immature patients with acetabular fractures following blunt force trauma.

INTERVENTION

We obtained a dedicated axial computed tomographic (CT) scan of the pelvis with sequential sections of 2.5-mm thickness.

MAIN OUTCOME MEASURES

The accuracy of plain radiography as compared with CT in diagnosing acetabular fractures in skeletally immature patients.

RESULTS

Fourteen patients with 16 fractures of the acetabulum were identified by CT scan; however, 69% (11 of 16) were not visible on plain radiography. Radiographs were less likely to identify acetabular fractures compared with pelvic ring fractures [31% (5/16) vs. 92% (11/12); odds ratio, 0.04; 95% confidence interval, 0.01-0.37; P = 0.001]. Patients younger than 12 years were less likely to have acetabular fractures identified on plain radiography [9% (1/11) vs. 80% (4/5); odds ratio, 0.03; 95% confidence interval 0.01-0.59; P = 0.013]. The mean age of patients whose acetabular fractures were not identified on plain radiography was less than those whose fractures were identified on plain radiography (7.6 ± 2.9 vs. 12.8 ± 1.6; P = 0.004). Acetabular fractures visible on plain radiography were more likely to require operative stabilization [60% (3/5) vs. 0% (0/11); P = 0.004].

CONCLUSIONS

In skeletally immature patients with suspected injury to the pelvis, particularly in patients younger than 12 years, diagnostic evaluation using plain radiographs alone may lead to missed injuries. If an acetabular fracture is identified, patients should be followed closely both clinically and radiographically to ensure early identification of any developing posttraumatic deformity.

LEVEL OF EVIDENCE

Level IV; Diagnostic-Investigating a diagnostic test.