Tibial Eminence Fracture

Introduction

A fracture of the bony attachment of the ACL on the tibia
Epidemiology
- rare injuries
- most common in ages 8-14
Mechanism
- traumatic
  - rapid deceleration or hyperextension of the knee
  - same mechanism that would cause ACL tear in adult
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
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

Imaging

Radiographs
- recommended views
  - standard knee radiographs
CT
- useful for pre-operative planning
MRI
- better at determining associated ligamentous/meniscal damage than CT or radiographs

Treatment

Nonoperative
- closed reduction, aspiration of hemarthrosis, immobilization in full extension
  - indications
    - non-displaced type I and reducible type II fractures
  - reduction maneuver = extend the knee to full extension to observe for fragment reduction
Operative
- ORIF vs. all-arthroscopic fixation
  - indications
    - Type III or Type II fractures that cannot be reduced
    - block to extension

Sugical Techniques

Arthroscopic fixation
- approach
  - standard arthroscopic portals
- technique
  - debride fracture
  - disengage entrapped meniscus or intermeniscal ligament
    - medial meniscus entrapment most common
  - reduce fracture
  - fracture fixation
    - suture fixation
      - pros
        
        avoids physis
      - cons
        
        technically demanding
    - screw fixation
      - pros
        
        less demanding than suture fixation
        
        possibly earlier mobilization
      - cons
        
        hardware irritation
        
        impingement from improperly placed screw
        
        physeal damage
- post-operative care
  - early range of motion
  - length of limited weight bearing is controversial
Open fixation
- same principles as arthroscopic

Complications

Los of motion
- very common, especially loss of extension
Arthrofibrosis
- more common with surgical reconstruction
Growth arrest
ACL laxity
- incidence
  - 10% of knees managed surgically
  - 20% of knees managed non-operatively
- often not clinically significant