Tibial Eminence Fracture - Pediatrics

Introduction

Overview
- 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
  - treatment is closed reduction and casting or open reduction and fixation depending on the degree of displacement and whether it can be reduced
Epidemiology
- incidence
  - 2-5% of knee injuries with effusion in the pediatric population
- demographics
  - most common in ages 8-14
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
Prognosis
- overall prognosis is good with 85% returning to prior level of sport

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%