Tibial Eminence Fracture - Pediatrics

summary
- A Tibial Eminence Fracture, also known as a tibial spine fracture, is an intra-articular fracture of the bony attachment of the ACL on the tibia that is most commonly seen in children from age 8 to 14 years during athletic activity.
- Diagnosis can be confirmed with radiographs of the knee. MRI studies can be helpful for determining associated ligamentous/meniscal damage.
- Treatment is closed reduction and casting or open reduction and fixation depending on the degree of displacement and success of closed reduction.

Epidemiology
- Incidence
  - 2-5% of knee injuries with effusion in the pediatric population
- Demographics
  - most common in ages 8-14

Etiology
- Pathophysiology
  - traumatic mechanism
    
    rapid deceleration or hyperextension/rotation of the knee, as in sports
    
    same mechanism that would cause ACL tear in adult
    
    fall from bike or motorcycle (typically resulting in hyperextension)
- Associated conditions
  - occur in 40% of eminence fractures
    
    meniscal injury
    
    collateral ligament injury
    
    capsular damage
    
    osteochondral fracture

Anatomy
- Osteology
  - tibial eminence
    
    non-articular portion of the tibia between the medial and lateral tibial plateau
    
    Consists of two spines: ACL attaches to medial spine
    
    ACL insertion is 9mm posterior to the intermeniscal ligament and adjacent to anterior horns of meniscus
    
    PCL does not attach to tibia spines
  - Pediatric specific
    
    Intercondylar eminence in incompletely ossified and is more prone to failure than ligamentous structures
    
    Failure occurs through deep cancellous bone
    
    Fracture usually confined to intercondylar eminence, but it may propagate to tibial plateau, medial is most common
- Ligaments
  - anterior cruciate ligament
    
    inserts 10-14 mm behind anterior border of tibia and extends to medial and lateral tibial eminence

Classification

Modified Meyers and McKeever Classification
Type I	Nondisplaced (<3mm)
Type II	Minimally displaced with intact posterior hinge
Type III	Completely displaced
Type III+	Type III fracture with rotation
Type IV	Completely displaced, rotated, comminuted

Presentation
- Symptoms
  - severe swelling and pain in the knee
  - inability to bear weight
- Physical exam
  - inspection
    
    immediate knee effusion due to hemarthrosis
    
    Knee usually in flexed position
  - ROM
    
    often limited secondary to pain
    
    once pain is controlled, lack of motion may indicate
    
    meniscal pathology
    
    displaced/entrapped fracture fragment
    
    positive anterior drawer

Imaging
- Radiographs
  - recommended views
    
    AP
    
    lateral
    
    most useful for determining fracture displacement
    
    intercondylar
    
    oblique
    
    helpful in determining the extent of tibial plateau involvement
- CT
  - useful for pre-operative planning
  - used when fracture displacement cannot be determined by plain radiographs
- MRI
  - better at determining associated ligamentous/meniscal damage than CT or radiographs
  - Majority of fractures show no additional internal derangement (meniscus injuries)
    
    15-37% of cases have associated intra-articular pathology

Treatment
- Nonoperative
  - closed reduction, aspiration of hemarthrosis, immobilization in full extension
    
    indications
    
    non-displaced type I and reducible type II fractures
    
    reduction technique
    
    see techniques below
    
    immobilization
    
    cast in extension for 3-4 weeks
    
    patients get extremely stiff with prolonged immobilization
    
    allows for gradual rehab program
- Operative
  - ORIF vs. all-arthroscopic fixation
    
    indications
    
    Type III or Type II fractures that cannot be reduced
    
    type II fractures may fail to reduce due to the entrapped medial meniscus, entrapped intermeniscal ligament, or the pull of the lateral meniscus attachment
    
    block to extension

Techniques
- Closed Reduction
  - aspiration
    
    when tense hemarthrosis is present, needle aspiration with the injection of lidocaine may help extend the knee
  - reduction
    
    extend the knee to full extension or hyperextension to observe for fragment reduction
  - immobilization
    
    cast is placed at 0 degrees of flexion
    
    cast in extension for 3-4 weeks
  - confirmation
    
    lateral radiograph to confirm reduction, and then serial radiographs to observe maintenance of reduction
    
    CT or MRI may be used when the adequacy of reduction is unclear
- Arthroscopic fixation
  - approach
    
    standard arthroscopic portals
  - technique
    
    reduction
    
    debride fracture
    
    disengage entrapped meniscus or intermeniscal ligament
    
    medial meniscus entrapment most common
    
    reduce fracture
    
    fracture fixation
    
    suture fixation
    
    Large avulsed fragments may be repaired directly
    
    Smaller avulsed fragments (usually in an older patient) may require sutures through the base of the ACL
    
    pros
    
    minimal damage to physis
    
    growth at level of physis will disrupt non-absorbable sutures to allow for continued growth
    
    cons
    
    technically demanding
    
    screw fixation
    
    pros
    
    less demanding than suture fixation
    
    possibly earlier mobilization
    
    cons
    
    requires larger osteochondral fragment
    
    hardware irritation
    
    not possible for small, comminuted fragments
    
    impingement from an improperly placed screw
    
    risk of iatrogenic comminution
    
    requires removal only if malpositioned
    
    physeal damage
  - post-operative care
    
    immobilize with cast in extension for 7-10 days and repeat radiographs to ensure no displacement
    
    This is variable, some surgeon allow immediate ROM
    
    early controlled range of motion
    
    length of limited weight bearing is controversial
- Open fixation
  - same principles as arthroscopic

Complications
- Loss of motion
  - very common, especially loss of extension
  - may be due to displaced fragment impinging on femoral notch
- Arthrofibrosis
  - more common with surgical reconstruction
- Growth arrest
  - from iatrogenic injury during surgery
- ACL laxity
  - incidence
    
    38-100%, more common in operatively treated knees
  - Lachman's laxity may be noted compared to contralateral limb
    
    functional instability is uncommon
  - Rate of ACL reconstruction following this injury is 15-25%

Prognosis
- Overall prognosis is good with 85% returning to prior level of sport