Orthopaedic Surgery - Hip Fracture in the Child

Basics

Pediatric hip fractures include fractures of the femoral neck, intertrochanteric region, and subtrochanteric proximal femur.

Femoral-neck fractures in children are rare but serious injuries because disruption of the blood supply to the femoral head can lead to osteonecrosis, nonunion, growth disturbance, coxa vara, and later degenerative arthritis.

Classification

The most commonly used system for pediatric femoral-neck fractures is the Delbet classification, as popularized by Colonna.

Delbet Type I

Type I is a transphyseal separation in which the femoral head separates from the neck through the proximal femoral physis.

It is the least common type and is generally seen in younger children.

A substantial proportion of these injuries are associated with dislocation of the femoral head from the acetabulum.

Delbet Type II

Type II is a transcervical fracture through the middle portion of the femoral neck.

This is the most common pediatric femoral-neck fracture pattern.

Delbet Type III

Type III is a cervicotrochanteric or basicervical fracture occurring near the base of the femoral neck.

It is the second most common pattern.

Delbet Type IV

Type IV is an intertrochanteric fracture, located between the greater and lesser trochanters.

This fracture generally carries a lower risk of osteonecrosis than the more proximal intracapsular types.

Importance of Initial Displacement

The degree of displacement at the time of injury is one of the most important predictors of femoral-head osteonecrosis.

More displaced fractures are more likely to disrupt the vulnerable vascular supply.

Anatomy and Blood Supply

The blood supply of the pediatric femoral head changes substantially during growth.

Early Childhood

At birth, vascular channels arising from the femoral circumflex system travel toward the femoral head through the proximal femoral neck.

The proximal femoral physis acts as a barrier to direct metaphyseal blood vessels entering the epiphysis.

After Approximately 4 Years of Age

By about 4 years of age, the medial femoral circumflex artery, particularly its retinacular branches, provides the dominant blood supply to the femoral head.

These vessels travel along the femoral neck and are vulnerable to injury during fracture or dislocation.

Ligamentum Teres

The artery within the ligamentum teres contributes only a relatively small portion of the total femoral-head blood supply and generally cannot compensate for major disruption of the retinacular vessels.

Surgical Relevance

Capsulotomy itself does not usually compromise the femoral-head circulation provided the important posterosuperior and posteroinferior retinacular vessels along the femoral neck are protected.

Fracture Stability

Approximately half of pediatric hip fractures are initially nondisplaced.

Once displacement occurs, the fracture is generally considered mechanically unstable.

Epidemiology

Pediatric hip fractures account for less than 1% of all fractures in children.

They are far less common than adult hip fractures because healthy pediatric bone is strong and usually requires substantial force to fracture.

Etiology

Approximately 75% of pediatric hip fractures are caused by major trauma.

Typical mechanisms include:

Motor vehicle collisions, pedestrian trauma, falls from significant height, and other high-energy injuries.

Pathologic Fractures

The remaining cases may occur through abnormal bone weakened by disorders such as:

Unicameral bone cyst, aneurysmal bone cyst, fibrous dysplasia, or other osseous lesions.

Nonaccidental Injury

In infants and young children, particularly when the history is inconsistent with the child’s developmental abilities, nonaccidental trauma must be considered.

Associated Conditions

Infants

A hip fracture in an infant should prompt careful assessment for possible nonaccidental injury unless there is a convincing high-energy mechanism.

Children

Because substantial force is usually necessary to fracture the pediatric femoral neck, other associated injuries should be actively sought.

Adolescents

In adolescents, proximal femoral physeal injury may resemble or overlap with slipped capital femoral epiphysis.

Atypical or pathologic slips should raise concern for underlying metabolic or endocrine disease, including:

Hypothyroidism and renal osteodystrophy.

Diagnosis

Signs and Symptoms

The usual presentation is sudden severe hip pain following trauma.

The child may be unable to stand, walk, or move the hip.

Swelling

Swelling may be visible in the:

Inguinal region, proximal thigh, or gluteal area.

Resting Position

The limb is often held in a position of:

External rotation, flexion, and adduction, which may reduce capsular tension and pain.

Motion

With displaced fractures, active hip movement is usually impossible.

Passive movement is markedly painful and restricted, particularly:

Flexion, abduction, and internal rotation.

Crepitus

Pain and occasionally crepitus may be produced with hip motion.

Forceful examination should be avoided.

Infants

Infants may present with pseudoparalysis, refusing to move the involved extremity.

Limb Shortening

The affected leg may appear shortened by approximately 1–2 cm, particularly with a displaced fracture.

External rotation is common.

Physical Examination

Most children with a complete femoral-neck fracture are in substantial pain.

The examination should be gentle and should include assessment for associated injuries.

Incomplete or Nondisplaced Fracture

In patients without an obvious complete fracture, pain may be particularly evident with:

Internal rotation, abduction, and flexion of the hip.

Neurovascular Examination

Distal pulses, capillary refill, motor function, and sensation should be documented before and after reduction or operative treatment.

Imaging

Plain Radiographs

Initial imaging generally includes:

AP pelvis or AP hip and lateral views of the affected hip.

Radiographs may show superior and lateral displacement of the femoral shaft relative to the femoral head.

CT

CT may be helpful for:

Defining fracture comminution, assessing complex fracture geometry, evaluating associated acetabular injury, and determining the direction of femoral-head dislocation.

It is not necessary in every case.

Ultrasound

In newborns and very young infants, ultrasound may be useful because much of the proximal femur remains cartilaginous and therefore poorly visualized on radiographs.

Differential Diagnosis

Important alternatives include:

Slipped capital femoral epiphysis and developmental coxa vara.

Developmental Coxa Vara

Developmental coxa vara may demonstrate a characteristic vertical defect or cleft near the femoral neck and should not be mistaken for an acute fracture.

Treatment

General Principles

Treatment aims to obtain and maintain an anatomic or near-anatomic reduction with stable fixation while minimizing additional injury to the femoral-head blood supply.

Because displaced pediatric femoral-neck fractures are unstable and have a high complication rate, operative fixation is commonly required.

Reduction

Either closed or open reduction may be used.

Reduction should be:

Gentle, accurate, and performed without repeated forceful manipulation.

Residual translation or varus should be avoided because imperfect reduction substantially increases the risk of nonunion and deformity.

Fixation by Age

Implant choice depends on patient age and the size of the femoral neck.

Young Children

In children approximately 2–6 years old, fixation may use:

Smooth pins or small cannulated screws, typically around 4.0–4.5 mm when anatomy permits.

Older Children

In children approximately 7 years and older, larger cannulated screws, historically around 6.5–7.3 mm, may be used when appropriate.

Modern implant size should be individualized to the child’s anatomy.

Spica Casting

A hip spica cast is often added in younger children because the small femoral neck may limit the number or size of implants that can safely be inserted.

The cast provides additional protection against displacement.

Physeal Crossing

Type I

When fixation of a Type I transphyseal injury requires crossing the growth plate, smooth pins are generally preferred, often followed by a spica cast.

Types II–IV

For Types II–IV, implants should ideally avoid crossing the proximal femoral physis when stable fixation can still be achieved.

However, secure fixation takes priority over physeal preservation.

The proximal femoral physis contributes only about 3 mm of longitudinal growth per year, so inadequate fixation should not be accepted merely to avoid crossing it.

Associated Hip Dislocation

When femoral-head dislocation accompanies the fracture, only a gentle attempt at closed reduction should be made.

Repeated manipulations increase the risk of further vascular and physeal injury.

If reduction is unsuccessful, open reduction is indicated.

Surgical Approach

The open approach should generally correspond to the direction of dislocation:

Posterior approach for posterior dislocation and anterior approach for anterior dislocation.

Treatment by Delbet Type

Type I Without Dislocation

A gentle closed or open reduction is followed by fixation with a pin or screw as appropriate for age and anatomy.

Type I With Dislocation

This is one of the highest-risk pediatric hip injuries.

Historical series report osteonecrosis rates approaching 100% in some displaced Type I injuries with dislocation and a very high incidence of later degenerative arthritis.

Reduction

A gentle attempt at closed reduction may use:

Longitudinal traction, abduction, and internal rotation.

If this fails, open reduction and fixation are required.

Type II

Type II transcervical fractures are the most common pediatric femoral-neck fractures.

Most are displaced.

Osteonecrosis Risk

Historical osteonecrosis rates are approximately 50%, with displaced fractures carrying substantially greater risk than nondisplaced injuries.

Treatment

Both displaced and nondisplaced Type II fractures are generally treated with:

Reduction and internal fixation using screws or pins.

Type III

Type III fractures are the second most common pattern.

Historical osteonecrosis rates are approximately 25%.

Displaced Type III

Treatment consists of:

Gentle closed reduction or open reduction followed by internal fixation.

Nondisplaced Type III

Prophylactic screw fixation is commonly recommended because late displacement can occur.

In selected children younger than approximately 8 years, an abduction spica cast may occasionally be considered, but close monitoring is essential because of the risk of:

Late displacement and coxa vara.

Type IV

Intertrochanteric fractures are generally treated with stable fixation appropriate to the child’s size and fracture pattern.

A pediatric hip compression screw or similar fixed-angle device may be used.

Surgical Technique

Imaging

A radiolucent or fracture table with fluoroscopic image intensification is typically used.

Reduction Maneuver

Common reduction principles include:

Longitudinal traction and correction of external rotation, usually with internal rotation.

Acceptable Reduction

No significant translation across the width of the femoral neck should be accepted.

Residual displacement predisposes to progressive varus and nonunion.

Surgical Approaches

For intracapsular reduction of Type II and III fractures, exposure may be obtained through a proximal extension of the tensor fascia lata–gluteal interval or another suitable approach.

Type I and very proximal Type II injuries may require an anterior iliofemoral approach.

Instrumentation

Types I–III

Fixation often uses 2–3 cannulated screws or smooth pins, sized appropriately for the child’s age and anatomy.

Type IV

A pediatric hip compression screw with side plate or other fixed-angle construct may be used.

Age-Specific Management

Ages 7–12 Years

Pediatric hip screw fixation may be combined with a hip spica cast for approximately 8–12 weeks, depending on stability.

Age 13 Years and Older

Older adolescents may often be treated similarly to adults.

A hip screw and side plate or other adult-type fixation may cross the physis if required for stability.

Postoperative casting is usually unnecessary when fixation is secure.

Timing of Surgery

Operative management should generally be performed urgently, usually within 24 hours.

Type I With Dislocation

A Type I injury accompanied by hip dislocation requires immediate treatment because of the extreme risk to femoral-head vascularity.

Osteonecrosis and Timing

Although early reduction is strongly favored, studies have not demonstrated a perfectly consistent relationship between exact operative timing and osteonecrosis.

Initial vascular injury and fracture displacement appear to be major determinants.

Implant Removal

There is no universally mandatory time for implant removal.

When removal is planned, it is commonly performed after solid healing, often within approximately 12–18 months.

Potential reasons include prevention of bony overgrowth around the implant or later stress concentration and refracture.

Neonatal Epiphysiolysis

Neonatal proximal femoral epiphyseal separation is a special injury pattern.

Acute Recognition

If diagnosed before callus forms, gentle skin traction may be used to restore alignment.

Delayed Recognition

If callus is already visible, simple immobilization and observation are usually preferred.

Open reduction is generally avoided because neonatal hips have substantial remodeling potential if the physis remains viable.

Follow-Up

Close monitoring is necessary for growth disturbance and osteonecrosis, although the incidence of osteonecrosis in this particular neonatal pattern may be relatively low.

Follow-Up

The long-term outcome is largely determined by the degree of injury to the femoral-head blood supply.

These patients require prolonged follow-up because major complications may not become apparent for months or years.

Prognosis

The prognosis depends on:

Delbet type, initial displacement, patient age, quality of reduction, vascular injury, development of osteonecrosis, and occurrence of growth arrest.

Complications

Complications occur in as many as approximately 60% of pediatric femoral-neck fractures in some historical series.

The unique and changing blood supply of the developing proximal femur is responsible for many of these problems.

Osteonecrosis

Osteonecrosis is the most common and most devastating complication.

It may involve:

The epiphysis alone, both epiphysis and metaphysis, or the metaphysis with relative sparing of the femoral head.

Incidence

Historical series report osteonecrosis in approximately 42% of pediatric femoral-neck fractures overall, usually becoming apparent within about 9–12 months.

Approximate rates by Delbet type have been reported as:

Type I: nearly 100%

Type II: approximately 52%

Type III: approximately 27%

Type IV: approximately 14%

Rates vary among modern series.

Risk Factors for Osteonecrosis

Factors associated with greater risk include:

Initial fracture displacement, Delbet Types I and II, associated dislocation, and age greater than approximately 10 years.

Ratliff Classification of Osteonecrosis

Ratliff Type I

There is total involvement and collapse of the femoral head.

This carries the worst prognosis and historically represents the most common pattern.

It reflects widespread injury to the lateral epiphyseal blood supply.

Ratliff Type II

Only part of the epiphysis is involved, with limited or minimal collapse.

This may reflect more localized vascular injury, often affecting the anterolateral femoral head.

Ratliff Type III

There is increased sclerosis of the femoral neck from the fracture line to the physis, while the femoral head itself is relatively spared.

This pattern is associated with metaphyseal vascular injury.

Treatment of Osteonecrosis

The goals are to preserve:

Hip motion, femoral-head containment, and joint congruity.

Selected patients may benefit from corrective osteotomy that rotates a less-deformed portion of the femoral head into the weight-bearing zone.

Nonunion

Nonunion occurs in approximately 5–8% of pediatric femoral-neck fractures.

Risk Factors

Closed treatment of displaced Types II and III has historically been associated with higher rates of:

Nonunion, late displacement, and coxa vara.

Stable internal fixation after accurate reduction lowers the risk by preventing varus collapse.

Coxa Vara

Coxa vara may develop because of:

Malunion or growth arrest of the proximal femoral physis.

Remodeling

If the femoral neck-shaft angle is less than approximately 110°, spontaneous remodeling is unlikely to provide adequate correction.

Treatment

In the absence of severe osteonecrosis, a subtrochanteric valgus osteotomy with internal fixation, sometimes combined with bone grafting, can provide good long-term correction.

Premature Physeal Closure

Premature closure of the proximal femoral physis may occur even when implants do not cross the growth plate.

It is often related to the original injury or associated osteonecrosis.

Limb-Length Discrepancy

The proximal femoral physis contributes approximately 3 mm of longitudinal growth per year, representing about 15% of total lower-extremity length growth.

Isolated closure may therefore cause only modest shortening, but combined osteonecrosis and growth disturbance can result in a more substantial limb-length discrepancy.

Growth Monitoring

Children with premature physeal closure should be followed with serial assessment of limb length.

Long-standing monitoring may include:

Standing limb-length imaging or scanograms and bone-age assessment using hand and wrist radiographs.

Contralateral Epiphysiodesis

If a clinically significant projected limb-length inequality develops, contralateral epiphysiodesis may be considered at the appropriate time.

Trochanteric Overgrowth

Growth disturbance can occasionally produce symptomatic relative overgrowth of the greater trochanter.

In selected children older than approximately 8 years, trochanteric advancement or transfer may be considered if abductor mechanics are substantially impaired.

Patient Monitoring

Children with proximal femoral fractures require long-term surveillance for:

Osteonecrosis, nonunion, coxa vara, physeal arrest, limb-length discrepancy, trochanteric overgrowth, deformity, loss of hip motion, and secondary degenerative arthritis.

Follow-up should include serial physical examination and radiographs, particularly throughout the first year, when osteonecrosis often first becomes evident, and subsequently through skeletal growth when significant physeal injury has occurred.