SUMMARY

• Capitellum Fractures are traumatic intra-articular elbow injuries involving the distal humerus at the capitellum.

• Diagnosis is made using plain radiographs of the elbow.

• Treatment may be nonoperative for nondisplaced fractures but any displacement generally requires anatomic open reduction and internal fixation.

EPIDEMIOLOGY

• Incidence

  • 1% of elbow fractures

  • 6% of all distal humerus fractures

ETIOLOGY

• Pathophysiology

  • mechanism of injury

    • typically, low-energy fall on outstretched hand

    • direct, axial compression with the elbow in a semi-flexed position creates shear forces

  • pathoanatomy

    • radiocapitellar joint is an important static stabilizer of the elbow

    • capitellar fracture can cause potential block to motion and instability due to loss of the radiocapitellar articulation

• Associated conditions

  • concomitant injuries to radial head and/or LUCL can occur up to 60% of the time

ANATOMY

• Radiocapitellar articulation

  • essential to longitudinal and valgus stability of the elbow

    • can also lead to coronal plane instability with capitellar excision if medial structures are not intact

  • integral relationship with the posterolateral ligamentous complex of the elbow (i.e. LUCL)

CLASSIFICATION

• Bryan and Morrey Classification (with McKee modification)
  Type I	Large osseous piece of the capitellum involved Can involve trochlea
  Type II	Kocher-Lorenz fracture Shear fracture of articular cartilage Articular cartilage separation with very little subchondral bone attached
  Type III	Broberg-Morrey fracture Severely comminuted Multifragmentary
  Type IV	McKee modification Coronal shear fracture that includes the capitellum and trochlea

PRESENTATION

• History

  • fall on outstretched arm (typically fall from standing)

  • typically, elbow is in semi-flexed elbow position

• Symptoms

  • elbow pain, deformity

  • swelling

  • wrist pain may also occur

• Physical exam

  • inspection and palpation

    • ecchymosis, swelling

    • diffuse tenderness

  • range of motion & instability

    • may have mechanical block to flexion/extension and/or rotation

  • neurovascular exam

IMAGING

• Radiographs

  • recommended

    • AP and lateral of the elbow

      • best demonstrated on lateral radiograph 

        • "double arc" sign created from subchondral bone of capitellum and lateral part of trochlea 

           

• CT

  • delineates fracture anatomy and classification 

TREATMENT

• Nonoperative

  • posterior splint immobilization for < 3 weeks

    • indications

      • nondisplaced Type I fractures (<2 mm displacement)

      • nondisplaced Type II fractures (<2 mm displacement)

• Operative

  • open reduction and internal fixation

    • indications

      • displaced Type I fractures (>2 mm displacement) 

         

      • Type IV fractures

    • technique

      • ORIF with lateral column approach 

         

        • indications

          • isolated capitellar fractures

          • type IV fractures that can have trochlear involvement

      • ORIF with posterior approach with or without olecranon osteotomy

        • indications

          • capitellar fractures with associated fractures/injuries to distal humuers/olecranon and/or medial side of the elbow

  • arthroscopic-assisted ORIF

    • indications

      • isolated type I fractures with good bone stock

  • fragment excision

    • indications

      • displaced Type II fractures (>2 mm displacement)

      • displaced Type III fractures (>2 mm displacement)

  • total elbow arthroplasty

    • indications

      • unreconstructable capitellar fractures in elderly patients with associated medial column instability 

         

TECHNIQUE

• ORIF with lateral column approach

  • approach

    • lateral approach recommended for isolated Type I and Type IV fx 

        

    • supine positioning 

    • lateral skin incision centered over the lateral epicondyle extending to 2cm distal to the radial head 

  • technique

    • headless screw fixation 

    • minifragment screw using posterior to anterior fixation

      • counter sink screw using anterior to posterior fixation 

    • mini-fragment or capitellar plates can be used to capture fractures with proximal extension 

    • avoid disruption of the blood supply that comes from the posterolateral aspect of the elbow

    • do not destabilize LUCL

• ORIF with posterior approach with or without olecranon osteotomy

  • approach

    • indicated when more extensive articular work is needed 

    • can also be used when concomitant medial sided injuries and/or distal humeral fractures require more fixation

    • lateral decubitus positioning

    • long-posterior based incision along the elbow

      • radial and ulnar based flaps allow access to both medial and lateral sides of elbow

  • technique

    • fracture-pattern specific

      • independent headless compression/cannulated screws for capitellar component

      • supplemental fixation for concomitant pathology

        • parallel or orthoogonal distal humerus plates

        • radial head arthroplasty/ORIF

      • LUCL/UCL repair via bone tunnels or suture anchors

• Arthroscopic-assisted ORIF

  • approach

    • definitive indications not fully known

    • experienced arthroscopists, indicated for isolated capitellar fractures

    • supine or lateral positioning (dependent on desire for anterior or posterior access) 

    • 70 degree scope can be helpful in gaining access

    • can be combined with limited open technique for fracture manipulation

  • technique

    • standard portals (anteromedial, anterolateral, posterolateral)

    • proximal anterolateral portal established under fluoroscopic guidance to place trocar to allow for reduction of fracture fragment 

      • extend elbow and push fragment with trocar for reduction

      • flex radial head past 90 to lock reduction

    • anteromedial and posterolateral portals allow for fracture debridement

    • freer elevator can help maintain reduction while cannulated/headless compression screws are placed under fluoroscopic guidance (typically posterior to anterior in direction) 

COMPLICATIONS

• Elbow contracture/stiffness (most common) 

   

• Nonunion (1-11% with ORIF)

• Ulnar nerve injury

• Heterotopic ossification (4% with ORIF)

• AVN of capitellum

• Nonunion of olecranon osteotomy

• Instability

• Post-traumatic arthritis

• Cubital valgus

• Tardy ulnar nerve palsy

• Infection

PROGNOSIS

• Most patients will gain functional range of motion but have residual stiffness

• Surgical treatment results are generally favorable

  • reoperation rates as high as 48% (mostly due to stiffness)