Definition of Non-Displaced Rib Fracture
A non-displaced rib fracture is defined as having greater than 90% cross-sectional overlap of the fractured bone ends on CT imaging. 1, 2
Radiographic Classification System
The Chest Wall Injury Society (CWIS) and American Society of Emergency Radiology (ASER) established a standardized classification system based on cross-sectional overlap visible on axial and multiplanar CT reformats 1:
- Non-displaced fractures: >90% cross-sectional overlap 1, 2, 3
- Offset fractures: 50-90% cross-sectional overlap 1, 2
- Displaced fractures: >0 to <50% cross-sectional overlap 1, 2
- Severely displaced fractures: No cross-sectional overlap or overlapping ribs 1, 2
Clinical Significance of the Definition
The term "cross-sectional overlap" provides superior correlation with the degree of displacement by accounting for both cortical and cancellous bone on CT imaging, making it easier to understand and more clinically useful than older classification systems 1.
This definition is critical because surgical stabilization is never indicated for isolated non-displaced fractures, regardless of the number present 2, 3. The >90% overlap threshold represents maintained structural integrity with adequate soft-tissue support 4.
Special Considerations in COPD/Asthma Patients
Patients with chronic respiratory disease require heightened vigilance and lower thresholds for intervention, even with non-displaced fractures. 2
- Pain control must be more aggressive in these patients to prevent respiratory splinting and subsequent complications 2
- Regional anesthesia should be considered earlier in the treatment algorithm 2, 3
- The threshold for considering surgical stabilization should be lower if respiratory function deteriorates despite optimal medical management, though this applies primarily to displaced fractures 2
Diagnostic Accuracy Considerations
CT imaging is far superior to plain chest radiography for detecting and classifying rib fractures 5:
- Plain chest radiographs miss rib fractures more than 50% of the time 5
- Initial radiology reports are often incomplete or inaccurate regarding fracture number and location, with 43% of reports incorrectly identifying fractures and 72% of those differing by more than one fracture 5
- Systematic re-reading of CT scans using the standardized classification system is essential for accurate diagnosis and treatment planning 1, 5
Progressive Displacement Risk
Non-displaced fractures can become more displaced over time, which is a critical pitfall to recognize 6: