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Radial head fractures

Radial head fractures are relatively common injuries, especially in adults, although they can be occult on radiographs. 

Epidemiology

Although fractures of the radial head are seen in all age groups, they usually occur in adults (85% between 20-60 years of age) and more frequently in women (M : F 1 : 2) 2

Mechanism

Radial head fractures usually occur as a result of indirect trauma, with most resulting from a fall on an abducted arm with minimal or moderate flexion of the elbow joint (0-80 degrees) 2. This results in valgus pronation stress with the radial head forcibly pushed against the capitellum of the humerus 1-2. In practice the history is often of a fall on an outstretched arm 5.  A direct blow to the elbow can cause a radial head fracture, but is uncommon. 

While the majority radial head fractures are isolated, a number of other injuries may also be seen 2

  • fracture of the coronoid process of the ulna
  • medial collateral ligament tear
  • interosseous membrane injury
  • triangular fibrocartilage complex injury at the wrist (Essex-Lopresti fracture-dislocation)

Radiographic features

The Mason classification can be used to further classify radial head fractures, although  in practice, most radiologists merely describe the injury. 

Plain radiograph

The elbow is typically radiographed in AP and lateral projections, although an oblique view is very frequently also obtained to better visualise the radial head (see elbow radiography).

Radial head fractures can be subtle and easily missed on plain films.  It is important to assess the film for a a joint effusion and where one exists, to take extra care in assessment of the radial head.  Even when a fracture cannot be identified, the presence of a joint effusion in adults should be treated as a non-displaced radial head fracture.

Elbow effusions are best seen on lateral projection where fluid in the join capsule elevates the peri-capsular fat. A minimally elevated anterior fat pad may be seen on normal elbow radiographs. However, posteriorly, the peri-capsular fat is usually hidden in the olecranon grove and fossa and its presence is indicative of fluid in the joint seen as a sail sign

Reporting checklist

In addition to reporting the presence of a radial fracture a number of specific features should be sought +/- commented upon. 

  • fracture 
    • location
    • involvement of the articular surface
    • articular step-off / gap
    • comminution
    • impaction, displacement and impaction
  • associated injuries
    • evaluate rest of elbow for 
      • coronoid process fractures
      • capitellum osteochondral injuries
      • elbow dislocations
      • olecranon fracture
      • ligamentous injury (widening of joint space due to medial collateral tear)
  • evaluate wrist
CT

CT is increasingly being obtained in joints with intra-articular involvement, as it is far superior in assessing articular contour and presence of intra-articular fragments. 

Treatment and prognosis

Treatment depends on the degree of displacement and involvement of the articular surface (as well as associated injuries). In general type I (see Mason classification) injuries can be treated conservatively whereas type II injuries require open reduction and internal fixation (ORIF) 4,5. Type III injuries often require early complete excision of the radial head 2

Radial head replacement is also an option, to help stabilise the elbow joint and prevent proximal migration of the radius 2

Generally patients can expect good a good outcome although secondary osteoarthritic change is certainly encountered in patients with intra-articular fractures. 


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