Which fracture is slowest to heal and often develops non-union?

Intracapsular Femoral Neck Fractures Are Slowest to Heal and Most Prone to Non-Union

The intracapsular femoral neck fracture (option A) is the slowest to heal and most frequently develops non-union among the listed fracture types. 1, 2

Why Intracapsular Femoral Neck Fractures Have Poor Healing Potential

• Intracapsular femoral neck fractures have high rates of non-union, occurring in up to 43% of patients, particularly with displaced fractures 2
• These fractures are considered high-risk due to their tendency for delayed union, non-union, displacement, and avascular necrosis 1
• The intracapsular location disrupts the blood supply to the femoral head, significantly impairing the healing process 3
• Lateral "tension-type" femoral neck fractures are inherently unstable and prone to displacement, often requiring percutaneous screw fixation 1

Comparison with Other Fracture Types

• While scaphoid fractures (option B) can have healing complications due to tenuous blood supply, they don't have the same non-union rates as femoral neck fractures 4
• Lower third of tibia fractures (option C) are considered high-risk for stress fractures but have better healing potential than intracapsular femoral neck fractures 1
• Proximal humerus fractures (option D) generally have adequate blood supply and better healing potential 4
• Distal femur fractures (option E) have better vascularity and healing potential compared to intracapsular femoral neck fractures 4

Risk Factors for Non-Union in Intracapsular Femoral Neck Fractures

• Displacement of the fracture increases non-union risk (odds ratio 2.93) 3
• Poor reduction quality significantly increases non-union risk (odds ratio 18.92) 3
• Patient age over 40 years is associated with higher failure rates 5
• Comorbidities including alcohol excess, renal disease, and respiratory disease increase failure risk 5
• Delayed fixation (>24 hours) correlates with higher rates of complications 6, 5

Diagnostic Approach for Suspected Non-Union

• Initial radiographs should be obtained, though they have limited sensitivity (30-70%) 1
• MRI without contrast is the preferred second-line study after negative radiographs due to its excellent sensitivity in detecting stress abnormalities and bone marrow changes 1
• CT without contrast can provide detailed structural information about bone architecture and is useful for surgical planning 4
• Bone scintigraphy with SPECT can be used but is less specific than MRI and often requires supplemental imaging 1

Treatment Considerations

• Prompt anatomic reduction and stable fixation can reduce non-union incidence 2
• The quality of reduction is the most important factor affecting outcome 7
• Treatment of established non-union depends on patient age, femoral head vascularity and sphericity, neck-shaft alignment, and potential limb length discrepancy 2
• Options for treating non-union include refixation, osteotomy, bone grafting, or prosthetic replacement 2