Question:medium
A child, left femur shaft fracture, managed by plating. What type of callus formation?
A child, left femur shaft fracture, managed by plating. What type of callus formation?
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Rigid (absolute-stability) fixation heals directly with minimal external callus; micromotion heals with bulky bridging callus.
Updated On: Jun 22, 2026
- Creeping substitution
- Primary callus
- Secondary callus
Show Solution
The Correct Option is B
Solution and Explanation
Tie the healing type to the stability of fixation.
Principle: The amount of strain at the fracture site decides how it heals. Rigid, gap-free fixation = low strain = direct (primary) healing with primary callus. Some movement = higher strain = indirect (secondary) healing with bulky bridging callus.
This case: A femoral shaft fracture fixed with a plate is compressed and held rigidly - absolute stability. Cutting cones of osteoclasts followed by osteoblasts cross the fracture line directly (contact/gap healing via Haversian remodelling), so only primary callus forms and there is little external callus on the x-ray.
Contrast: Had the fracture been treated in a cast or by intramedullary nailing (relative stability with micromotion), it would heal by secondary callus - the visible exuberant bridging callus.
Distractor check: Creeping substitution is a separate concept - live bone slowly replacing dead bone or a graft (seen in avascular necrosis and grafting), not the response to plating a fresh fracture.
Conclusion: Rigid plate fixation $\rightarrow$ primary callus (option B).
Principle: The amount of strain at the fracture site decides how it heals. Rigid, gap-free fixation = low strain = direct (primary) healing with primary callus. Some movement = higher strain = indirect (secondary) healing with bulky bridging callus.
This case: A femoral shaft fracture fixed with a plate is compressed and held rigidly - absolute stability. Cutting cones of osteoclasts followed by osteoblasts cross the fracture line directly (contact/gap healing via Haversian remodelling), so only primary callus forms and there is little external callus on the x-ray.
Contrast: Had the fracture been treated in a cast or by intramedullary nailing (relative stability with micromotion), it would heal by secondary callus - the visible exuberant bridging callus.
Distractor check: Creeping substitution is a separate concept - live bone slowly replacing dead bone or a graft (seen in avascular necrosis and grafting), not the response to plating a fresh fracture.
Conclusion: Rigid plate fixation $\rightarrow$ primary callus (option B).
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