Courtesy: Kaye Wilkins MD
Lynn Staheli MD
www.global-help.org
Pediatric Fractures – Basic Principles
1. Why Pediatric Fractures Are Unique
A child is not a miniature adult.
Pediatric fractures differ because children have:
- Increased osteogenic potential
- Faster healing
- Greater remodeling capacity
These unique biological characteristics influence:
- Fracture patterns
- Healing behavior
- Treatment principles
2. Basic Bone Concepts
A. Types of Bone
1. Tissue Bone
Characteristics:
- Rigid structure
- Osteocytes embedded within matrix
- Osteocytes cannot divide
- Cannot grow independently
2. Organ Bone
Examples:
- Femur
- Tibia
- Radius
Functions:
- Structural support
- Hematopoiesis
- Mineral storage
Unlike tissue bone, organ bone can grow because it contains specialized growth structures.
3. Bone Growth
A. Growth in Length – Endochondral Ossification
Growth in length occurs at the physis (growth plate).
Zones of the Physis
| Zone | Function |
|---|---|
| Resting zone | Germinal cell reserve |
| Proliferative zone | Chondrocyte multiplication |
| Hypertrophic zone | Weakest zone, common fracture site |
| Calcification zone | Matrix calcification |
| Ossification zone | Bone formation |
Important Concept
Cartilage is replaced by bone rather than directly converted into bone.
B. Calcification vs Ossification
| Feature | Calcification | Ossification |
|---|---|---|
| Nature | Passive | Active |
| Tissue | Dead tissue | Living tissue |
| Typical setting | Often pathological | Physiological |
| Example | Dystrophic calcification | Bone formation |
C. Growth in Width – Intramembranous Ossification
Occurs primarily at the periosteum.
Mechanism:
- Bone apposition externally
- Bone resorption internally
4. Importance of Blood Supply
Epiphyseal Blood Supply
- Supplies growth cells
- Critical for physeal growth
Damage may cause:
- Growth arrest
- Angular deformity
- Limb length discrepancy
Metaphyseal Blood Supply
- Responsible for cartilage resorption
- Damage leads to failure of cartilage removal
5. Bone Remodeling
Remodeling Process
- Initial formation of weak “quantity” bone
- Progressive remodeling into strong lamellar “quality” bone
Remodeling Potential
Best remodeling occurs near active physes.
Remodeling Capacity Order
Physis > Metaphysis > Diaphysis
6. Failure Patterns in Pediatric Bone
A. Physeal Injuries
The physis is the weakest area in pediatric bone.
Children often sustain physeal injury instead of ligament rupture.
Example
Valgus stress at knee:
| Adult | Child |
|---|---|
| Ligament tear | Physeal injury |
B. Metaphyseal Injuries
Pediatric metaphyseal bone is soft and fails under compression.
Common Types
Torus fracture
- Compression injury
- Stable fracture pattern
Greenstick fracture
- One cortex breaks
- Opposite cortex bends
Complete Fracture
- Both cortices disrupted
C. Diaphyseal Injuries
Types of Deformation
| Type | Description |
|---|---|
| Elastic deformation | Reversible |
| Plastic deformation | Permanent bend without fracture line |
| Partial failure | Greenstick fracture |
| Complete fracture | Full cortical disruption |
D. Apophyseal Injuries
Apophyses are muscle attachment sites.
Injury Pattern
| Child | Adult |
|---|---|
| Avulsion fracture | Tendon or muscle tear |
7. Healing of Pediatric Fractures
Phases of Healing
1. Inflammatory Phase
- Hematoma formation
- Inflammatory response
2. Reparative Phase
- Callus formation
- Formation of immature woven bone
3. Remodeling Phase
- Conversion to mature lamellar bone
8. Special Features of Pediatric Healing
A. No Callus in Physeal Fractures
Physeal injuries heal through growth mechanisms rather than callus formation.
B. Growth Stimulation After Fracture
Fracture increases blood supply and may stimulate growth.
Example
Femoral shaft fractures may produce approximately 1 cm of overgrowth.
C. Harris Growth Arrest Lines
Harris growth arrest lines
Features:
- Dense transverse metaphyseal lines
- Represent temporary growth arrest
- Migration away from physis indicates continued growth
9. Remodeling Principles
Best Remodeling Occurs
- Near joints
- In the plane of joint motion
- In younger children
Poor Remodeling Occurs In
- Rotational deformities
- Diaphyseal deformities
Important Rule
Approximately:
- 75% of remodeling occurs at the physis
- 25% occurs in metaphysis and diaphysis
10. Clinical Pearls
- Greater deformity may be accepted in children compared with adults
- Avoid physeal injury whenever possible
- Rotational deformity must be corrected because remodeling is poor
- Remodeling is better:
- In younger patients
- Closer to joints
- In the plane of movement
11. Key Take-Home Message
Children possess remarkable healing and remodeling capacity, but remodeling is not unlimited.
Successful pediatric fracture management requires understanding:
- Growth physiology
- Remodeling potential
- Acceptable deformity limits
- Risk of physeal injury
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