Paediatric Distal Radius, Buckle and Physeal Wrist Fractures

Paediatric distal radius injuries are among the most common fractures in childhood, usually after a fall on an outstretched hand. They range from a stable compression injury to a displaced fracture involving both cortices or the distal radial physis. The clinical skill is matching the amount of treatment to the true stability of the injury.

A buckle fracture is a compression bulge in the cortex. It is stable because there is no complete cortical disruption. It should not be treated like a displaced fracture. Conversely, a complete metaphyseal fracture or displaced physeal injury should not be softened into the word "buckle" just because the child is young.

Remodelling potential is excellent near the distal radial physis, especially in younger children and sagittal-plane deformity. It is less reliable in adolescents, coronal deformity, rotational deformity, unstable complete fractures and injuries close to skeletal maturity. Distal ulna physeal injury deserves special attention because growth disturbance can create ulnar variance and distal radioulnar joint problems.

The goals are simple: identify the pattern, protect the skin and nerves, avoid unnecessary follow-up for stable buckle fractures, reduce unacceptable deformity gently, use a well-moulded non-tight cast when needed, and give families clear cast and swelling return advice.

Most paediatric distal radius fractures occur after axial load through an extended wrist. The injury pattern depends on bone elasticity, cortical failure, periosteal hinge integrity and whether the force exits through the metaphysis or the physis.

Remodelling depends on age, plane of deformity and proximity to the distal radial physis. Younger children have more growth remaining. Sagittal-plane deformity remodels more predictably than coronal deformity, and rotation does not remodel reliably. Shortening or bayonet apposition may be acceptable in selected young children, but it should not be used as a blanket rule for adolescents near skeletal maturity.

Median nerve symptoms can occur from swelling, deformity or a tight cast. Distal ulna physeal injury carries growth-disturbance risk and should not be forgotten when the radius fracture dominates the X-ray.

History

The history should separate a stable low-energy wrist injury from a displaced fracture, associated injury or safeguarding concern.

Examination

Inspection separates a comfortable stable injury from a deformed unstable fracture. Do not force wrist movement when the diagnosis is clinically obvious.

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• Look at both cortices before calling a buckle fracture.
• Assess dorsal or volar tilt, translation, shortening and associated ulna fracture.
• Do not miss distal ulna physeal injury.
• In adolescents, consider carpal injury if pain is not explained by distal radius findings.
• Repeat imaging depends on stability, age, reduction and local fracture protocol.

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The first management decision is whether the injury is truly stable. A true buckle fracture can be managed simply because it is a stable compression injury. A displaced complete or physeal fracture needs alignment assessment, reduction decision, cast quality and follow-up.

Cast Quality and Redisplacement (Cast Index)

After reduction of a displaced fracture, the quality of the cast mould is the surgeon-controlled factor that most predicts redisplacement. A good cast is three-point moulded and elliptical (flattened) rather than round in cross-section.

• Cast index = the internal sagittal (lateral) cast width ÷ internal coronal (AP) cast width measured at the fracture level. A well-moulded cast is elliptical with a cast index around 0.7; a cast index > 0.8 (a round, poorly-moulded cast) is strongly associated with loss of reduction.
• Related described measures include the three-point index, gap index, padding index and Canterbury index — all quantify moulding/contact and predict redisplacement.
• Practical implication: if the post-reduction cast index is > 0.8 or the mould is poor, anticipate redisplacement — re-mould (e.g. wedge) or review early, and have a low threshold for fixation in the older child.

Early

• Median nerve symptoms.
• Cast tightness, swelling or pressure injury.
• Loss of reduction.
• Compartment syndrome, rare but serious.
• Missed associated elbow or carpal injury.

Managing acute median-nerve dysfunction / acute carpal tunnel syndrome: a displaced distal radius fracture can injure the median nerve by stretch, contusion or compression. The first step is prompt fracture reduction, which relieves most stretch/compression neurapraxia — then re-examine the nerve. Distinguish two situations: (1) a neurapraxia that is stable or improving after reduction → observe with serial examination; (2) a deficit that is progressive, or persists/worsens after an adequate reduction (acute carpal tunnel syndrome) → this is a surgical emergency requiring urgent carpal tunnel release/decompression. Also avoid over-flexed ("Cotton-Loder") casting, which raises carpal tunnel pressure and can precipitate median neuropathy.

Late

• Malunion with residual deformity.
• Distal radial or ulnar physeal arrest.
• Wrist stiffness from over-immobilisation.
• Refracture after early return to sport.
• Cosmetic deformity or functional limitation if alignment unacceptable.

Paediatric distal radius injuries should be separated into stable buckle fractures, greenstick or complete metaphyseal fractures, and physeal injuries. These are different problems. A buckle fracture is a stability and comfort problem; a displaced physeal injury is a reduction, growth and follow-up problem.

The practical error is over-treating stable buckle fractures while under-recognising physeal injuries. True torus fractures should not need repeated X-rays, prolonged casting or fracture-clinic congestion when diagnosis is secure and the family has clear return advice. Conversely, a displaced physeal injury needs reduction quality, neurovascular status, cast mould, re-displacement risk and later growth assessment considered.

Return to sport depends on pain-free wrist motion, tenderness resolution and injury pattern. A buckle fracture returns earlier than a displaced physeal fracture or complete metaphyseal fracture.

Common pitfalls

Paediatric distal radius fractures are a worldwide problem and the single most common skeletal injury requiring intervention in children. Practice varies more by health-system resource and local protocol than by true biological difference, so the global picture matters for any exam answer.

Global epidemiology

• Distal forearm fractures account for roughly a quarter to a third of all childhood fractures, with peak incidence around the pubertal growth spurt.
• Boys are affected more often than girls overall, mirroring activity exposure; in the FORCE cohort 61 percent were boys.
• Rising incidence has been linked to increased sport participation, higher body mass index and reduced bone mineral density in some populations.
• Distal ulnar physeal injuries show growth disturbance in around one in five cases, and intra-articular (Salter-Harris III/IV) distal radius fractures in around two in five.

Side-by-side guidance

Registry and trial evidence

• Paediatric fracture care is driven by trial evidence rather than implant registries (registries dominate adult arthroplasty, not childhood fractures).
• The FORCE equivalence RCT (965 children, 23 UK hospitals) is the landmark dataset supporting bandage-and-discharge for torus fractures.
• Cohort data from North American children's hospitals define the growth-arrest risk that justifies physeal surveillance.

High- versus limited-resource practice

• In well-resourced systems the debate is about doing less: removable splints, no routine repeat films and reduced clinic visits for buckle fractures.
• In limited-resource settings the priorities are accurate triage to avoid missing displaced or physeal fractures, safe casting where image-guided fixation is unavailable, and clear caregiver safety-netting because follow-up may be difficult.
• Across all settings the universal non-negotiables are neurovascular assessment, recognition of the physis and a well-moulded, non-tight cast when immobilisation is used.

Several questions in paediatric distal radius care remain genuinely unresolved, and examiners reward candidates who can state both sides rather than quote a single number.