What is the difference between displaced and non‑displaced fractures?

Difference Between Displaced and Non-Displaced Fractures

Displaced and non-displaced fractures differ fundamentally in the degree of bone fragment separation, measured by cross-sectional overlap on CT imaging: non-displaced fractures maintain >90% overlap of bone fragments, while displaced fractures have <50% overlap, with this distinction determining whether conservative management or surgical intervention is required. 1, 2

Radiographic Classification System

The Chest Wall Injury Society (CWIS) and American Society of Emergency Radiology established a standardized classification based on cross-sectional overlap visible on axial and multiplanar CT reformats 1:

• Non-displaced: >90% cross-sectional overlap of bone fragments 1, 2
• Offset: 50-90% cross-sectional overlap 1, 2
• Displaced: >0 to <50% cross-sectional overlap 1, 2
• Severely displaced: No cross-sectional overlap or overlapping bone fragments 1, 2

This "cross-sectional overlap" terminology accounts for both cortical and cancellous bone displacement and provides superior correlation with clinical outcomes compared to older measurement systems 1.

Clinical Implications of Displacement

Non-Displaced Fractures

Non-displaced fractures are inherently stable and heal reliably with conservative management alone, never requiring surgical intervention. 2, 3

• Blood loss is minimal due to intact periosteum and tamponade effect 1
• Pain is typically less severe than displaced fractures 1
• Risk of complications (nonunion, malunion, chronic pain) is substantially lower 2, 4
• Healing occurs predictably over 6-8 weeks with appropriate immobilization 3, 5

Displaced Fractures

Displaced fractures demonstrate fragment instability, increased complication risk, and frequently require surgical stabilization to prevent long-term morbidity. 1, 2

• Blood loss is significantly greater, potentially exceeding one liter in long bones due to disrupted periosteum and cancellous bone bleeding 1
• Pain is considerably more severe due to greater soft tissue disruption 1
• Risk of avascular necrosis increases (particularly in intracapsular hip fractures) 1
• Nonunion and malunion rates are substantially elevated without surgical intervention 1, 4
• Long-term morbidity includes chronic pain, deformity, respiratory compromise (rib fractures), and reduced quality of life persisting up to 2 years 2

Management Algorithm Based on Displacement

For Non-Displaced Fractures

Conservative management is the standard of care and includes: 2, 3

1. Multimodal analgesia: Acetaminophen 1000mg every 6 hours scheduled as first-line, NSAIDs for breakthrough pain as second-line, opioids at lowest effective dose for shortest duration as third-line 2, 3
2. Respiratory support (rib fractures): Deep breathing exercises, incentive spirometry, early mobilization 3, 5
3. Immobilization: Cast or splint for appropriate duration based on fracture location 1, 3
4. Close follow-up: Clinical reassessment within 1-2 weeks to detect late displacement 3, 5, 6

For Displaced Fractures

Surgical stabilization should be considered when: 1, 2

• Flail chest is present (rib fractures) 2, 3
• ≥3 ipsilateral severely displaced fractures with mechanical ventilation 2
• ≥25% hemithorax volume loss 1
• Displaced intracapsular hip fractures (to prevent avascular necrosis) 1
• Severely displaced fractures with no cross-sectional overlap 2, 3

The highest quality recent evidence demonstrates that surgical stabilization in non-ventilated patients with ≥3 displaced fractures reduces pleural space complications, pain scores, respiratory disability, and improves quality of life 1, 2.

Critical Pitfalls to Avoid

Initially non-displaced fractures can subsequently displace in 9.8% of cases within the first 5 days, making early radiographic follow-up (4-6 days post-injury) mandatory to detect unstable fractures before significant displacement occurs. 6

• Under-treatment of pain in non-displaced fractures leads to immobilization, shallow breathing, atelectasis, and pneumonia 3
• Assuming all non-displaced fractures remain stable without follow-up imaging risks missing secondary displacement requiring surgical intervention 6, 7
• Excessive reliance on opioids causes respiratory depression, particularly in elderly patients with rib fractures 3
• Failing to implement early respiratory physiotherapy results in preventable pulmonary complications 3

Anatomic Considerations

The degree of displacement—not anatomic location alone—determines treatment strategy. 3

For example, in rib fractures, ribs 4-6 in the anterolateral location are frequently plated when surgery is indicated, but plating is recommended only when fractures are significantly displaced (not for minimally displaced or non-displaced fractures) 3. Similarly, displaced intracapsular hip fractures require arthroplasty due to disrupted capsular blood supply, while undisplaced fractures can be treated with internal fixation 1.