Terrible Triad Injury of Elbow - Trauma

Introduction

A traumatic injury pattern of the elbow characterized by
- elbow dislocation (often associated with posterolateral dislocation or LCL injury )
- radial head or neck fracture
- coronoid fracture
Pathophysiology
- mechanism
  - fall on extended arm that results in a combination of
    - valgus, axial, and posterolateral rotatory forces
      - produces posterolateral dislocation
- pathoanatomy
  - structures of elbow fail from lateral to medial
    - LCL disrupted first
    - anterior capsule injured next
    - possible MCL disruption
Prognosis
- historically poor outcomes secondary to
  - persistent instability
  - stiffness
  - arthrosis

Anatomy

Radial head
- a primary restraint to posterolateral rotatory instability (PLRI)
- secondary valgus stabilizer
- forearm in neutral rotation, lateral portion of articular margin devoid of cartilage
  - roughly between radial styloid and listers tubercle
Coronoid process
- provides an anterior and varus buttress to ulnohumeral joint
- resists posterior subluxation beyond 30 deg of flexion
- fracture fragment typically has some anterior capsule attached
  - useful in repair
Medial collateral ligament
- three components
  - anterior bundle
    - most important to stability, restraint to valgus and posteromedial rotatory instability
      - inserts on sublime tubercle (anteromedial facet of coronoid)
      - specifically inserts 18.4mm dorsal to tip of coronoid process
  - posterior bundle
  - transverse ligament
Lateral collateral ligament
- inserts on supinator crest distal to lesser sigmoid notch
- the primary restraint to posterolateral rotatory instability
- four components
  - lateral ulnar collateral ligament (most important for stability)
  - radial collateral ligament
  - annular ligament
  - accessory collateral ligament
- when injured is usually avulsed off of the lateral epicondyle

Presentation

Symptoms
- patients complain of pain, clicking and locking with elbow in extension
Physical exam
- possible varus / valgus instability patterns
- distal radial ulnar joint must be evaluated for possible Essex-Lopresti injury

Imaging

Radiographs
- evaluate for concentricity of ulnohumeral and radiocapitellar joints
- line drawn through center of radial neck should intersect the center of the capitellum regardless of radiographic projection
- evaluate lateral radiograph for coronoid fracture
- need prereduction and postredcution films
- consider PA and lateral films of wrist and forearm when indicated
CT
- often utilized for better evaluation of coronoid fracture
- 3D imaging for determining fracture line propagation

Treatment

Nonoperative
- immobilize in 90 deg of flexion for 7-10 days
  - indications (rare)
    - ulnohumeral and radiocapitellar joints must be concentrically reduced
    - radial head fx must not meet surgical indications
    - coronoid fx must be small
    - elbow should be sufficiently stable to allow early ROM
  - technique
    - one week of immobilization followed by progressive ROM
    - active motion initiated with resting splint at 90 degrees, avoiding terminal extension
    - static progressive extension splinting at night after 4-6 weeks
    - strengthening protocol after 6 weeks
Operative
- ORIF versus radial head arthroplasty, LCL reconstruction, coronoid ORIF, possible MCL reconstruction
  - indications
    - terrible triad elbow injury that includes an unstable radial head fracture, a type III coronoid fracture, and an associated elbow dislocation
    - coronoid fractures involving less than 10% of the coronoid do not confer elbow stability in cadaveric studies and therefore do not require repair
      - should instability persist after addressing the radial head and the LCL complex in the presence of a small coronoid fracture, the next best step is MCL reconstruction

Techniques

ORIF vs replacement of radial head, coronoid ORIF, LCL reconstruction, and possible MCL reconstruction
- approach
  - posterior skin incision advantageous
    - allows access to both medial and lateral aspect of elbow
    - lower risk of injury to cutaneous nerves
    - more cosmetic
- technique
  - radial head ORIF vs. arthroplasty
    - radial head ORIF indicated if non comminuted fractures that involve < 40% articular surface
      - 1.5, 2.0, or 2.4mm countersunk screws
      - plate if necessary; 2.0 plates cause minimal loss of motion even when placed on radial neck
      - plate position should be posterolateral
        
        safe zone: 90-110 arc from radial styloid to Lister's tubercle with arm in neutral rotation
    - radial head arthroplasty indicated for comminuted radial head fxs
      - implant should articulate 2mm distal to the tip of the coronoid process
      - radial head resection without replacement is NOT indicated in presence of Essex-Lopresti lesion or in ligamentously injured elbows
      - if <25% head damaged or fragments not reconstructable and nonarticulating, can excise fractured portion if elbow stable (rarely indicated)
  - coronoid ORIF
    - can be fixed through radial head defect laterally
    - sutures, suture anchors, screws, or rarely plate fixation.
      - suture passed through 2 drill holes
      - posterior to anterior lag screws if fragment large
      - basal coronoid fxs (rare) fixed with anteromedial or medial plate on proximal ulna
  - LCL repair
    - usually avulsed from origin on lateral epicondyle
    - reattach with suture anchors or transosseous sutures
      - must be reattached at center of capitellar curvature on lateral epicondyle
    - if MCL is intact, LCL is repaired with forearm in pronation
    - if MCL injured, LCL is repaired with forearm in supination to avoid medial gapping due to overtightening
    - repairs are performed with elbow at 90 degrees of flexion
  - MCL repair
    - indicated if instability on exam after LCL and fracture fixation, especially with extension beyond 30 degrees
- postoperative
  - elbow fixators - hinged or static
    - consider when instability is noted after complete bone and soft tissue repair
  - immobilization
    - immobilize elbow in flexion with forearm pronation to provide stability against posterior subluxation
    - if both MCL and LCL were repaired, splint in flexion and neutral rotation

Complications

Instability
- more common following type I or II coronoid fractures
Failure of internal fixation
- most common following repair of radial neck fractures
  - poor vascularity leading to osteonecrosis and nonunion
Post-traumatic stiffness
- very common complication
- initiate early ROM to prevent
Heterotopic ossification
- consider prophylaxis in pts with head injury or in setting of revision surgery
Post-traumatic arthritis
- due to chondral damage at time of injury and/or residual instability