Paediatric Femoral Neck Fractures

Paediatric femoral neck fractures are rare compared with adult hip fractures, but they are treated with a different level of urgency because the biology is different. The child has an open physis, a cartilage-rich proximal femur, a vulnerable femoral-head blood supply and many years of growth remaining. A well-aligned fracture can heal quickly; a poorly reduced or vascularly compromised fracture can leave the child with avascular necrosis, coxa vara, non-union, limb-length difference and early hip degeneration.

Most injuries follow high-energy trauma: road trauma, fall from height, sports collision or crush injury. A low-energy femoral neck fracture is not routine trauma until proven otherwise. It should trigger consideration of bone cyst, tumour-like lesion, metabolic bone disease, endocrine disease, infection, non-accidental injury in the right age group, or medication-related bone fragility.

The practical clinical sequence is:

• Identify the fracture and associated injuries.
• Classify with Delbet type and displacement.
• Decide whether the fracture is intracapsular and whether decompression is relevant.
• Restore an anatomical reduction.
• Stabilise the fracture without violating the joint.
• Protect weight bearing.
• Follow for union, femoral-head shape, neck-shaft angle and growth.

The proximal femur in a child is not a smaller adult hip. The proximal femoral physis contributes to growth, the greater trochanter has its own apophysis, and the femoral head relies heavily on vessels that run near the femoral neck.

The Delbet classification describes fracture location. It is useful because location correlates with femoral-head perfusion risk and fixation strategy. It should always be paired with displacement, reduction quality, child age and associated injuries.

History

A typical child presents after high-energy trauma with severe hip or groin pain and inability to bear weight. Some children describe thigh or knee pain, so a hip injury can be missed if the assessment stops at the knee.

Examination

Examine the child using trauma principles before focusing on the hip. A displaced femoral neck fracture is painful; repeated log rolling or forced positioning is unnecessary.

Initial imaging

Obtain an AP pelvis and a safe lateral view of the injured hip. In a painful fracture, do not force frog lateral positioning. A cross-table lateral or other safe lateral projection is preferable. The AP pelvis gives the contralateral hip for comparison and helps identify associated pelvic injury.

Image the whole femur when the mechanism is high energy, when thigh pain is present or when ipsilateral shaft fracture is possible. A femoral shaft fracture can distract attention from a proximal femoral injury, and the reverse is also true.

When CT helps

CT is useful when fracture anatomy is unclear, when reduction planning is difficult, when displacement is subtle, or when an associated pelvic or acetabular injury is suspected. CT should answer a management question; it should not delay urgent treatment of an obvious displaced fracture.

When MRI or laboratory work helps

MRI, blood tests and broader workup are considered when the mechanism is low energy, when there was preceding pain, when X-ray shows a lesion, or when infection or tumour is possible. MRI can also help later if avascular necrosis is suspected before radiographic collapse is obvious.

A child with a painful, non-weight-bearing hip after trauma is not always a femoral neck fracture. The differential matters because each alternative has a different urgency, imaging pathway and pitfall. The dangerous traps are the slipped capital femoral epiphysis (SCFE) mislabelled as a transphyseal fracture, and the low-energy "fracture" that is really a pathological lesion.

Much of this topic is taught as if it were settled. It is not. A consultant-level answer names where the evidence is genuinely conflicting and then states a defensible position.

There is no single randomised trial or dedicated international guideline for this rare injury; practice is built from cohort series, two meta-analyses and society fracture-management principles. The picture below is a global synthesis rather than any one country's protocol.

Global epidemiology

• Paediatric femoral neck fractures represent less than 1 percent of all paediatric fractures and roughly 1 percent of hip fractures across age groups.
• Bimodal mechanism: high-energy trauma (road traffic, falls from height) in most series, with a smaller pathological-fracture group.
• Delbet type II (transcervical) is the most common pattern; type I (transphyseal) is the rarest but carries the highest osteonecrosis risk.
• Pooled osteonecrosis rates by Delbet class are approximately 38, 28, 18 and 5 percent for types I to IV respectively (Moon and Mehlman), with contemporary cohorts reporting overall AVN around 23 to 29 percent.

Registry and high- versus limited-resource practice

• Unlike adult hip fractures, this injury is too rare for dedicated arthroplasty-style registries; evidence comes from single-centre cohorts and the pooled meta-analyses above. National paediatric trauma networks (rather than implant registries) are the practical data source.
• High-resource settings: rapid imaging, sub-specialist paediatric orthopaedic cover, image-intensifier-guided reduction and fixation, and structured multi-year AVN surveillance.
• Limited-resource settings: delayed presentation is common and a recognised cause of established non-union and coxa vara in toddlers; valgus osteotomy with minimal fixation is a described salvage where early anatomical fixation was not feasible.
• Regardless of setting, the modifiable lever is the same — achieve and hold an anatomical reduction and follow the head for years.

Paediatric femoral neck fracture is an emergency because the femoral head blood supply is vulnerable and complications are common. The treatment plan should be built around timing, displacement, Delbet type, reduction quality, fixation stability, capsular pressure and long-term surveillance for avascular necrosis.

Common pitfalls

• Treating the injury like an adult neck-of-femur fracture.
• Saying "hip fracture" without naming Delbet type.
• Forgetting to ask why a low-energy fracture happened.
• Accepting varus reduction.
• Avoiding open reduction when closed reduction is poor.
• Focusing on implant type but not reduction quality.
• Missing joint penetration on postoperative imaging.
• Stopping follow-up once the fracture unites.

Counselling points

Families need a clear explanation that this is rare and serious. The fracture can heal but still develop late femoral-head or growth problems. They should understand the need for repeat imaging, protected weight bearing, monitoring for pain or stiffness, and longer follow-up than many other childhood fractures.