Fractures of the articular surface of the distal humerus

Includes fracture of the capitellum or trochlea

Capitellum

Background

• Also called Kocher fracture
• Rare fractures
• Often difficult to diagnose if fracture fragment is small

Classification

• Type 1 (Hahn-Steinthal)
  • Fracture of the capitellum in the coronal plane
  • Involves large part of the osseous portion of the capitellum and may contain part of the trochlea
• Type 2 (Kocher-Lorenz)
  • Involves articular cartilage (anterior) with little bone attached
• Type 3
  • Comminuted fracture
    

Capitellum Fracture classification

Mechanism of Injury

• Transmission of forces through the radial head
  • Fall onto the hand with elbow in some degree of flexion
  • Fall onto the point of the elbow while it is flexed

Clinical Examination

• Pain, tenderness and swelling over the lateral aspect of the elbow
• Bony block to the range of movement
  • Associated with anteriorly displaced fragments (Type 1)
  • Not with posteriorly displaced fragments
• Limited range of movement
• Crepitus on movement

Associated injury

• Radial head fracture
• Posterior dislocation of the elbow
• Medial collateral ligament damage (tenderness and swelling over the medial aspect of the elbow with possible valgus instability)

Investigations

• AP and lateral x-rays of the elbow are needed
• Best visualised on a lateral view