Paediatric Fractures and Salter-Harris Classification
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Direct answer
Paediatric fractures differ from adult fractures because the physis, or growth plate, is often the weakest point, and the Salter-Harris classification grades physeal fractures into five types. Greenstick and buckle fractures occur because children's bone is more porous and the periosteum is thick, so the bone bends or buckles rather than breaking completely. Type V is a crush injury of the physis and carries the highest risk of growth arrest.
What you must remember
- Salter-Harris I: a separation through the physis with no bony fragment, often with a normal radiograph.
- Salter-Harris II: the commonest type, with the fracture through the physis and a triangular metaphyseal fragment, the Thurston Holland fragment.
- Salter-Harris III: an intra-articular fracture through the epiphysis and physis, which needs anatomical reduction.
- Salter-Harris IV: a fracture through the epiphysis, physis and metaphysis, also intra-articular and at risk of bridging.
- Salter-Harris V: a crush injury of the physis, with the highest risk of growth arrest.
- Greenstick fracture: an incomplete fracture in which the bone bends and one cortex breaks while the other stays intact.
- Buckle or torus fracture: a compression injury with bulging of the cortex, usually managed with a splint.
Reading a physeal fracture by its path
Physeal fractures are described by the path the fracture takes through the growth plate, because that path determines both treatment and growth outcome. The table links each type to its fracture path and to the usual risk of growth disturbance, which also shapes what the family is counselled about.
| Type | Fracture path | Growth arrest risk |
|---|---|---|
| I | Through the physis only | Low |
| II | Through the physis, exiting through the metaphysis | Low |
| III | Through the epiphysis and physis, intra-articular | Moderate |
| IV | Through the epiphysis, physis and metaphysis | Moderate to high |
| V | Crush injury of the physis | Highest |
Types I and II are usually treated by closed reduction and casting, while types III and IV need accurate joint reduction to protect the articular surface. Any physeal injury needs follow-up for deformity and leg length. Follow-up matters most for types IV and V, where a bony bridge across the physis can cause angular deformity or a short limb.
Where the exam tries to catch you
Questions on this topic usually test the type with the greatest growth risk and the injuries that look normal on radiograph.
- Trap: dismissing a tender physis because the radiograph is normal Correct: Salter-Harris I fractures are often radiographically occult, so the child is immobilised and reassessed, with MRI or ultrasound when needed.
- Trap: calling type II injuries high-risk for growth arrest Correct: type II carries a low risk, whereas types IV and V threaten growth.
- Trap: attributing a spiral fracture in a non-walking infant to a fall during play Correct: this pattern raises concern for non-accidental injury and needs a safeguarding review.
- Trap: treating a greenstick fracture with open surgery Correct: greenstick fractures are usually managed by closed reduction and casting.
Frequently asked questions
What is the Salter-Harris classification?
The Salter-Harris classification grades fractures involving the physis, or growth plate, into five types from I to V. It is based on the fracture path through the physis, epiphysis and metaphysis, and it helps predict the treatment needed and the risk of growth disturbance.
Which Salter-Harris type carries the highest risk of growth arrest?
Salter-Harris type V carries the highest risk of growth arrest because it is a crush injury that damages the germinal cells of the physis. Types III and IV carry a moderate risk when the fracture crosses the growth plate, and anatomical reduction is required.
What is a greenstick fracture in a child?
A greenstick fracture in a child is an incomplete fracture in which the bone bends and one cortex breaks while the opposite cortex remains intact. It occurs because the child's bone is more porous and flexible, and it is usually treated with reduction and casting.
Why are buckle fractures common in children?
Buckle fractures are common in children because the metaphysis of young bone compresses and bulges without a visible break in the cortex. They usually heal well with a splint or cast for a few weeks, since the thick periosteum and porous bone absorb the force.