Femoral Shaft Fractures - Pediatric - Pediatrics

Introduction

Overview
- pediatric femoral shaft fractures are one of the most common pediatric orthopedic fractures and are the most common reason for pediatric hospitalization due to orthopedic injury
  - treatment may be casting or operative depending on the fracture pattern and age of patient
  - any femur fracture in a child not yet walking should raise concern for non-accidental trauma
Epidemiology
- incidence
  - 1.6-2% of all pediatric fractures
  - bimodal distribution
    - increased rate in toddlers age 2-4 years and adolescents
  - most common reason for pediatric hospitalization due to orthopaedic injury
- demographics
  - males more commonly affected 2.6:1
Pathophysiology
- mechanism of injury
  - fall is the most common cause < 10 years old
  - motor vehicle accident is the most common cause > 10 years old
- correlated with age due to the increased thickness of the cortical shaft during skeletal growth and maturity
Associated conditions
- high suspicion for child abuse required
  - abuse must be considered if the child is < 3 years and especially if present in a patient before walking age
  - femur fractures are one of the most common fractures associated with child abuse
- medical conditions and comorbidities
  - osteogenesis imperfecta
  - osteopenia secondary to neuromuscular disorders
  - benign or malignant bone tumors
Prognosis
- high rate of fracture union if appropriate treatment is selected based on patient age and fracture pattern
- timing of surgical intervention
  - early surgical intervention (< 24-48 hours) of femur fractures in the setting of a closed head injury leads to decreased length of hospital stay and is not associated with an increase in pulmonary complications

Anatomy

Osteology
- anterior bow to femur
- isthmus is the narrowest portion of the femur
Muscles
- iliopsoas creates a flexion and external rotation force on the proximal fragment
- adductors create a shortening and varus force on the distal fragment
Biomechanics
- femoral shaft cortical diameter and cortical thickness increase with age

Classification

Descriptive classification
- characteristics of the fracture
  - transverse
  - comminuted
  - spiral
  - others
- location of the fracture
  - proximal, middle, or distal third
- integrity of the soft-tissue envelope
  - open vs. closed fracture
Stability
- stable fractures
  - typically transverse or short oblique
- unstable fractures
  - long spiral (fracture length > 2x bone diameter at that level)
  - comminuted

Presentation

Symptoms
- thigh pain
- inability to walk
- report of deformity or instability
Physical exam
- gross deformity
- shortening
- swelling of the thigh

Imaging

Radiographs
- AP and lateral of the femur
  - allow for complete evaluation of the fracture location, configuration, and amount of displacement
- ipsilateral AP and lateral of knee and hip
  - to rule out associated injuries

Treatment

Nonoperative
- Pavlik harness
  - indications
    - children < 6 months old
    - any fracture pattern
- spica casting
  - indications
    - children 0-5 years old
    - relatively contraindicated with polytrauma, open fractures and shortening > 2-3 cm
- traction + delayed spica casting
  - indications
    - younger patients with significant shortening
    - rarely utilized
Operative
- flexible intramedullary nails
  - indications
    - most length stable fracture patterns in children 5-11 years old weighing < 49kg (100 lbs)
- submuscular bridge plate fixation
  - indications
    - unstable fractures in children > 5 years old and > 49kg (100lbs)
    - very proximal or very distal fractures
    - severe comminution
- antegrade rigid intramedullary nail fixation
  - indications
    - in patients > 11 years old or approaching skeletal maturity
    - unstable fractures
    - fractures in patients weighing > 49kg (100 lbs)
- external fixation
  - indications
    - damage control orthopedics in a polytrauma patient
    - open fractures
    - associated vascular injuries requiring revascularization
    - segmental or significantly comminuted fractures

Treatment Table by Age
< 6 months	• any fracture pattern	• Pavlik harness • early spica casting
6 months - 5 years	• stable fracture pattern	• early spica casting
6 months - 5 years	• unstable fracture pattern • polytrauma, multiple/open fx	• traction with delayed spica casting • external fixator
5-11 years	• length unstable fx (comminuted or spiral) • very proximal or distal fx • any weight	• ORIF with submuscular bridge plating • external fixation
> 11 years	• patient weighs > 49kg (100 lbs)	• antegrade rigid intramedullary nail fixation
> 11 years	• proximal or distal fx • severe comminution	• ORIF with submuscular bridge plating

Surgical Techniques

Pavlik harness
- technique
  - avoids the need for sedation or anesthesia
- complications
  - can compress femoral nerve if excessive hip flexion is used in presence of a swollen thigh
    - identified by decreased quadriceps function
Immediate spica casting
- technique
  - applied with reduction under sedation or with general anesthesia
  - single-leg spica or one-and-one-half spica (to control rotation)
    - distal femoral buckle fracture may be treated with long leg cast alone (not spica)
  - hips flexed 60-90° and approximately 30° of abduction
  - external rotation is typically needed to correct a rotational deformity
  - molded into recurvatum and valgus as the muscular forces will pull fracture into procurvatum and varus
  - molds along the distal femoral condyles and buttocks help to maintain reduction
  - acceptable limits are based on age
    - the goal of reduction should include obtaining < 10° of coronal plane and < 20° of sagittal plane deformity with no more than 2cm of shortening or 10° of rotational malalignment
  - a special car seat is sometimes needed for transport (often can use a regular car seat if single-leg spica is used)
- complications
  - compartment syndrome
    - decreased with applying smooth contours around popliteal fossa, limiting knee flexion to < 90° and avoiding excessive traction
    - Decreased by avoiding applying short leg cast first followed by traction on poplitea fossa
    - monitored for by observing the child's neurovascular exam and level of comfort
- outcomes
  - healing times vary from 4-8 weeks based on age
Traction + delayed spica casting
- technique
  - placed in distal femur proximal to distal femoral physis
    - proximal tibial traction can cause recurvatum due to damage to the tibial tubercle apophysis
  - used for 2-3 weeks to allow early callus formation
  - spica casting then applied until fracture healing
- more complications than immediate spica casting
Flexible intramedullary nails
- approach
  - all distal approach
    - 2cm incision medially and laterally at level of distal physis
    - spread with hemostat to starting point 2cm proximal to physis
  - distal and proximal approach
    - 2cm incision laterally at level of distal physis and 2cm incision proximally at greater troch apophysis
- instrumentation
  - nail size determined by multiplying the width of the isthmus of femoral canal by 0.4
  - the goal is 80% canal fill
- complications
  - the most common complication is pain at insertion site near the knee
    - in up to 40% of patients
    - recommended that < 25mm of nail protrusion and minimal bend of the nail outside the femur are present
  - increased rate of complications in patients 11 years or up or > 50 kg
  - malunion
    - increased rates with comminuted, shortened, or very proximal/distal fractures
- outcomes
  - generally good outcomes
  - time to union is typically 10-12 weeks
  - removal of the nail can be performed at 1 year
Submuscular bridge plate fixation
- approach
  - laterally based incision and plating with minimal disruption of soft tissue envelope
  - small proximal and distal incisions and plate is placed between periosteum and vastus lateralis on the lateral side of the femur
- fracture is provisionally reduced with closed or percutaneous techniques
- instrumentation
  - typically use 12-16 hole 4.5mm narrow LC-DC plate with 3 screws proximal and 3 screws distal to the fracture
  - plate may need to be bent to accommodate the natural bend of the femur
  - contoured femur plates are also an option
- complications
  - hardware removal
  - refracture following hardware removal
- outcomes
  - favorable time to union, weight bearing, hardware irritation, and limp outcomes
Antegrade rigid intramedullary nail fixation
- approach
  - trochanteric entry nail
  - lateral entry nail
    - avoid piriformis entry due to risk of injury to vascularity to femoral head
- soft tissue
  - lateral incision proximal to the greater trochanter
  - sharp or electrocautery through fascia lata to obtain starting point at the tip of the greater trochanter
- closed versus open reduction of the fracture
- instrumentation
  - with fracture reduced follow steps to insert intramedullary nail with caution to not cross distal physis
- complications
  - osteonecrosis risk is 1-2% with piriformis start in a patient with open proximal physes
  - the exact risk of osteonecrosis with greater trochanter and lateral entry nails is unknown
  - secondary deformities of the proximal femur can occur after greater trochanteric insertions
    - narrowing of the femoral neck
    - premature fusion of greater trochanter apophysis
    - coxa valga
    - hip subluxation
- outcomes
  - decreased risk of angular malunion
  - favorable outcomes in adolescents
External fixation
- technique
  - applied laterally
    - avoid disruption and scarring of quadriceps
  - 10-16 weeks of fixation is typically needed for solid union weight-bearing
  - weight-bearing as tolerated can be considered with stiff constructs
- complications
  - more complications than internal fixation
  - pin tract infections are frequent
    - as high as 50% of fixator related complications
    - treated with oral antibiotics and pin site care
  - higher rates of delayed union, nonunion and malunion
  - increased risk of refracture (1.5-21%) after removal of fixator especially with varus malunion

Complications

Leg-length discrepancy
- overgrowth
  - the most common complication in younger patients
  - 0.7 - 2 cm is common in patients <10 years
  - typically occurs within 2 years of injury
- shortening
  - is acceptable if less than 2 - 3 cm because of anticipated overgrowth in young patients
  - can be symptomatic if greater than 2 - 3 cm
    - temporary traction or fixation used to prevent persistent shortening
Osteonecrosis (ON) of the femoral head
- reported with both piriformis and greater trochanter entry nails
- femoral nailing through the piriformis fossa is contraindicated in adolescents with open physes because of the risk of osteonecrosis of femoral head
- main supply to femoral head is deep branch of the medial femoral circumflex artery
  - branches into superior retinacular vessels that supply the femoral head
  - vulnerable as it lies near the piriformis fossa
Nonunion and malunion
- higher risk with load bearing devices
  - external fixator or submuscular plates
- can occur after flexible intramedullary nailing in patients
  - aged over 11 years old
  - who weigh >49 kg (>108 lb)
- the typical deformity is varus + flexion of the distal fragment
- remodeling is greatest in the sagittal plane
- rotational malalignment does not remodel
- nearly 50% of fractures treated with flexible nails have 15 degrees of malalignment
Refracture
- most common after external fixator removal with varus alignment