What is the best imaging modality for diagnosing sternal fractures?

Imaging for Sternal Fracture

Primary Recommendation

CT chest without IV contrast is the imaging modality of choice for diagnosing sternal fractures, utilizing sagittal and 3-D reconstructions for accurate detection. 1, 2, 3

Imaging Modalities in Order of Preference

CT Chest (Preferred)

• CT chest without IV contrast accurately detects sternal fractures through evaluation of sagittal and 3-D reconstructions and should be the primary imaging modality. 1, 2, 3
• CT demonstrates superior sensitivity compared to conventional radiography, detecting fractures that may be missed on plain films. 4
• In trauma populations undergoing chest CT, sternal fractures are identified in approximately 2.4% of patients with blunt chest trauma. 4
• CT is particularly valuable for characterizing fracture displacement, identifying associated injuries (hemothorax, hemopericardium, cardiac contusion), and detecting complications. 1, 5

Chest Radiography (Limited Role)

• Anteroposterior and lateral chest radiographs are commonly used as first-line imaging in trauma centers, particularly for hemodynamically unstable patients, but have significant limitations. 1
• Conventional radiography has a misdiagnosis rate of approximately 5.5% for sternal fractures and frequently misses occult injuries. 6
• Chest radiography can identify indirect findings suggesting sternal injury (displaced rib fractures, hemothorax, widened mediastinum) but has limited ability to directly visualize sternal fractures. 1
• Lateral radiography remains useful for demonstrating the degree of fracture displacement when present. 7

Ultrasound (Emerging but Not Standard)

• Ultrasound demonstrates better sensitivity than lateral radiography for detecting sternal fractures, with a misdiagnosis rate of approximately 6.3%. 7, 6
• US can identify fractures missed by conventional radiography in 8.7% of cases. 7
• However, US may underestimate the degree of fracture displacement compared to radiography. 7
• There is insufficient evidence to recommend US as a primary imaging modality, though it may serve as a complementary tool when CT is unavailable. 1, 7

Critical Clinical Correlation

Mandatory Cardiac Evaluation

• All patients with sternal fractures require immediate baseline ECG and cardiac troponin levels, regardless of imaging findings. 2, 3
• Approximately 6% of patients with sternal fractures develop arrhythmias or myocardial contusion, but this occurs primarily when ECG changes or rising troponin levels are present. 1
• Patients with normal ECG and normal cardiac troponins can be safely discharged without prolonged observation or echocardiography. 2, 3
• Echocardiography is not recommended for isolated sternal fractures when ECG and troponins are normal. 1, 2

Associated Injuries

• Sternal fractures are complicated by other injuries in 98.8% of cases, with only 1.2% being truly isolated. 6
• Common associated injuries include extremity fractures, brain injury, lung contusion, intraabdominal injuries, and spinal fractures (13% of cases). 6, 5
• Displaced fractures of the corpus sterni are associated with higher rates of thoracic and cardiac injuries. 5
• Fractures or disruptions of the manubriosternal synchondrosis show increased concurrence with spinal fractures. 5

Practical Algorithm

1. Obtain CT chest without IV contrast with sagittal and 3-D reconstructions for definitive diagnosis 1, 2, 3
2. Simultaneously obtain ECG and cardiac troponin levels at presentation 2, 3
3. If ECG abnormal or troponins rising: monitor for arrhythmias and perform echocardiography 1, 2
4. If ECG and troponins normal and no other injuries: safe for discharge 2, 3
5. Evaluate for associated injuries based on CT findings, particularly spinal fractures in manubriosternal injuries 5

Common Pitfalls

• Do not rely on chest radiography alone, as it misses a significant proportion of sternal fractures and associated injuries. 1, 6
• Do not skip cardiac evaluation even in seemingly benign isolated sternal fractures, as myocardial contusion can occur without obvious displacement. 1, 2
• Do not routinely admit all patients with sternal fractures for observation; admission should be based on cardiac markers, associated injuries, and hemodynamic stability. 4, 8
• In patients with displaced fractures, maintain high suspicion for concomitant thoracic and cardiac injuries requiring further evaluation. 5