Paediatric Femur Fractures by Age

Treatment of a paediatric femoral shaft fracture is organised by age, but age is only the start. The final plan depends on age, weight, skeletal maturity, fracture pattern, length stability, soft tissues, associated injuries, mechanism, safeguarding concerns and the family's ability to manage immobilisation and follow-up. The wrong operation for the wrong age or fracture pattern creates malunion, malrotation, skin problems or avoidable reoperation.

How the child changes with age. Younger children heal quickly and remodel well, but the mechanism must be checked against what they can developmentally do. School-age children sit in the transition zone, where a spica may be burdensome and operative stabilisation is often attractive. Adolescents behave more like adults mechanically, yet many still have open physes, so the implant entry point and growth safety remain important.

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The biology explains why children can often be treated differently from adults, and it also explains the complications.

Healing and remodelling. Vascular bone and an active periosteum produce reliable callus. That is why younger children can often be treated with a harness or spica if alignment is acceptable.

Overgrowth. The femur can overgrow after a shaft fracture, especially in younger children. Some shortening may therefore be accepted, but the acceptance should be deliberate and followed.

Rotation. Rotational deformity remodels poorly, and malrotation is poorly seen on plain films. Rotation is therefore assessed clinically after reduction or fixation, not only on AP and lateral radiographs.

Length stability. Some patterns can shorten under load (they are listed under Classification). For these, flexible nails alone may be insufficient: the fracture is more likely to shorten and may need submuscular plating, external fixation or another stability strategy.

Implants. Flexible nails are load-sharing, submuscular plates provide relative stability, and rigid nails require safe entry points. The construct is matched to age, weight, fracture pattern and the open physes.

Soft tissues. Open fractures, severe swelling and polytrauma change priorities. Open-fracture care, external fixation or damage-control stabilisation may come before definitive fixation.

Pathological bone. Cysts, tumour, metabolic bone disease and osteogenesis imperfecta change healing and fixation. Treat the lesion and the bone-health diagnosis, not just the shaft fracture.

The practical classification sorts the fracture by its pattern and then by the context around the child. The age bands carry their treatment with them and are set out under Management.

Fracture pattern. Length stability is the major pattern distinction.

• Length stable: transverse and short oblique
• Length unstable, and prone to shortening: long oblique, spiral, comminuted and segmental
• Open: urgent antibiotics, debridement and stabilisation
• Pathological: a fracture through a lesion or abnormal bone, where the lesion is treated with the fracture

Context modifiers. Four features of the context can change the plan.

• Polytrauma may favour operative stabilisation
• Concern about non-accidental injury changes the pathway
• Obesity can make a spica or flexible nails less reliable
• Family and transport factors matter for safe discharge

History

The history places the fracture in the context of the whole child.

Mechanism. Establish whether it was a fall, a twisting injury, road trauma, sport, a high-energy crush or a low-energy event. High-energy trauma triggers whole-child assessment; a low-energy fracture raises questions of pathology or safeguarding.

Developmental fit. Ask whether the child walks and whether the mechanism matches their age and ability. A femur fracture in a non-walking child needs safeguarding and bone-fragility review, with the thresholds set out below.

Associated injuries. Ask about head, chest, abdominal, pelvic, hip, knee or other limb pain. A femur fracture can coexist with a femoral neck fracture, a floating knee, or a pelvic or visceral injury.

Bone health. Ask about previous fractures, bone pain, a known cyst, metabolic bone disease, malignancy or features of osteogenesis imperfecta. Pathological fractures need diagnosis-specific treatment.

Pre-hospital care. Traction, splinting, analgesia, time since injury and the transfer details define pain control, skin risk and urgency.

Family practicality. Ask about spica care, transport, toileting, skin checks, sleep, stairs and car seats. A spica is safe only if the family can manage the child at home.

Examination

Perform a paediatric trauma assessment before discussing implant choice.

The whole child. Airway, breathing, circulation, head, chest, abdomen, pelvis and the other limbs. A femur fracture may be one marker of major trauma.

Thigh and skin. Look for swelling, deformity, shortening, external rotation, an open wound, the bruising pattern and threatened skin. These change the urgency, the open-fracture pathway and the choice of fixation.

Neurovascular status. Record distal perfusion and sciatic, peroneal and tibial nerve function where testable. This documents a baseline and detects a vascular or nerve injury.

Associated joints. Examine the hip, knee, tibia and pelvis so that a femoral neck fracture, distal physeal injury, floating knee or pelvic injury is not missed.

Compartments. Children may not describe classic compartment symptoms. Watch pain behaviour, anxiety, increasing analgesia, swelling, and pain with passive stretch when it can be assessed.

Rotation. After reduction or fixation, compare foot progression, the thigh-foot profile and hip rotation with the other side.

The safeguarding assessment, with its actual thresholds

"Consider safeguarding" is an instruction everyone accepts and few can operationalise. Two thresholds make it actionable.

The trigger. The AAOS guideline sets a formal one: every child under 36 months with a femoral shaft fracture should be evaluated for child abuse. That means evaluated, rather than screened informally or merely considered. Three years is deliberately wider than the intuitive cut-off, because the point is to catch the child whose walking is delayed or whose history is plausible on first telling.

Where the risk concentrates. The recognised risk factors for abuse are:

• Age under 12 months
• Non-ambulatory status
• Delayed presentation
• A history inconsistent with the injury or with the child's developmental ability
• Other injuries

A femoral shaft fracture in a child who has never walked is the single strongest of these: the force required has no innocent mechanism available to a child who cannot yet generate it. A spiral femur fracture is not automatically abuse, but the mechanism must fit.

Scale. In a two-year audit of one UK city's emergency department, fractures of any kind occurred in the order of 53 per 10,000 children under two years. This is not a rare scenario an orthopaedic trainee will avoid.

The documentation failure you control. In the same audit the interval between injury and presentation was unrecorded in 34% of cases, though it is central to the abuse assessment and free to capture. Record when the injury happened, who was present, when the child was last seen to move the leg normally, and who brought them in. A note that omits the timeline weakens every later assessment, including your own.

Radiographs. AP and lateral views of the femur, always including the hip and knee, define the level, pattern, shortening and any associated joint injury. In high-energy trauma, look specifically for a distal femoral physeal injury and a femoral neck injury.

Trauma imaging. After high-energy injury, imaging as indicated by the paediatric trauma team finds head, chest, abdominal, pelvic or other limb injuries.

Pathological concern. Full-length radiographs and lesion-specific MRI or laboratory tests identify a cyst, tumour or bone fragility.

Rotation. The clinical profile comes first. CT is used only when necessary, to quantify malrotation when clinical assessment is unreliable.

After treatment. Post-treatment radiographs confirm length, angulation and implant position. Serial films then check union, maintenance of alignment and complications.

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Treatment is a ladder. Start with analgesia, temporary splintage or traction, skin and neurovascular care, and whole-child assessment. Then choose definitive treatment by age, size, pattern and context.

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The spica. The hip spica is the workhorse non-operative treatment for femoral shaft fractures in infants and young children. It encases the trunk and the affected leg or legs to hold length and alignment. The practical questions from the history are confirmed before discharge, and the family is taught skin care, hygiene, transport and return precautions; discharging a child in a cast the family cannot safely manage is the failure.

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Choosing the construct. Match the fixation to length stability, weight and comminution; the common failure is flexible nails in a fracture that predictably shortens. A rigid trochanteric-entry nail is used only when maturity and anatomy are appropriate. External fixation is for an open fracture, severe soft-tissue injury or damage control.

Checking rotation. Check rotation clinically after reduction or fixation. The common failure is accepting AP and lateral alignment while missing malrotation.

Acceptable deformity by age

Remodelling potential falls with age, so the tolerated deformity narrows as the child gets older. Acceptable angulation depends on its plane as well as the age, and acceptable apposition also changes with age. Younger children also overgrow, so bayonet shortening of up to ~1.5–2 cm is deliberately accepted in the under-10s. Rotation has no place in the table: it remodels poorly at every age, is not accepted, and must be corrected.

Early

• Compartment syndrome
• Skin breakdown or cast problems
• Loss of reduction or shortening
• Open-fracture infection
• Associated injuries missed in polytrauma

Late

• Malrotation
• Limb length discrepancy from overgrowth or shortening
• Knee stiffness after flexible nailing or immobilisation
• Refracture after early implant removal
• AVN risk with inappropriate rigid nail entry

Follow-up

What a good result means. Outcome is more than radiographic union. A good result includes acceptable length, rotation and angulation, hip and knee motion, skin integrity, family functioning, a safe return to activity, and no missed safeguarding or polytrauma issue. Stopping follow-up at union is the failure.

What each review checks.

• Skin, pain, and cast or wound problems, early
• Alignment and shortening, until callus is reliable
• Knee and hip motion, after immobilisation or fixation
• Limb length and rotation, measured clinically
• Implant removal, planned only when indicated and timed safely

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Paediatric femoral shaft fractures are common worldwide, but implants, resources and pathways differ. The principles below let you defend a plan in any examination system.

Global epidemiology

• Femoral shaft fractures account for roughly 1.5 to 2% of all paediatric fractures, with a bimodal age distribution: a peak in toddlers (often low-energy or non-accidental) and a second peak in adolescents (high-energy).
• There is a consistent male predominance and a strong association of the youngest fractures with non-accidental injury (see Clarke et al, Injury 2012).
• In a non-ambulant infant, abuse rather than implant choice is the dominant clinical question.

Side-by-side guidance

Registry and outcome notes

• Paediatric femoral shaft fractures are not tracked in arthroplasty registries (NJR, AJRR, AOANJRR), so evidence comes from institutional series and meta-analyses rather than implant-survival registries.
• The most robust comparative evidence is from systematic reviews of flexible nailing versus submuscular plating (Hu et al 2023; Liu et al 2024), which show comparable union and complication trade-offs rather than a single superior implant.

High-resource versus limited-resource practice

The age-based framework hides several genuinely contested decisions. These are the points examiners use to separate a safe trainee from a thinking one.

Common pitfalls

• Choosing treatment from age alone.
• Missing non-accidental injury.
• Ignoring femoral neck or knee associated injury.
• Using flexible nails for an unstable comminuted fracture without plan for shortening.
• Not checking rotation.
• Discharging a spica family without practical education.