Isolated radial head dislocation, a rare and easily missed injury in the presence of major distracting injuries: a case report
© Rethnam et al; licensee BioMed Central Ltd. 2007
Received: 18 April 2007
Accepted: 29 June 2007
Published: 29 June 2007
High velocity accidents can lead to major injuries – long bone fractures, abdominal trauma, pelvic fractures and chest injuries. These injuries can act as distracting factors during the initial assessment of a polytrauma patient and innocuous but significant smaller injuries can be missed. We present a rare case of isolated anterolateral radial head dislocation in a polytrauma patient.
Isolated dislocation of the radial head in adults is rare. If neglected, these can cause restriction of forearm supination and pronation, secondary degenerative arthritis of the elbow and distal radioulnar joints. This important injury can easily be missed in the presence of major distracting injuries.
A 44-year old man presented to us with a high velocity motorbike accident after a head-on collision with a truck. On arrival to the A&E, he was alert and conscious but was hypotensive and tachycardic. He complained of pain in the groin and both knees. There was no significant past history. Examination revealed extensive bruising of the pelvic region, scrotal swelling and bilateral knee effusions. Initial radiographs showed an open book type pelvic fracture but no other bony injuries were identified. Stress views of the knees in theatre revealed ligamentous laxity bilaterally. The pelvis was stabilised with an external fixator after initial resuscitation and splints applied to both knees.
Isolated dislocation of the radial head without concomitant ulnar fracture or humeroulnar subluxation in adults is a rare injury. Most cases appear to be in children. Only 20 cases have been reported in adults in the last 30 years. Most were treated conservatively with no recurrence.  Anterior dislocation of the radial head is even rarer with only 4 cases reported in the literature.  The mechanism leading to an isolated radial dislocation has been variously described. Although most authors describe an indirect mechanism, Takami et al described a direct trauma to a semiflexed elbow leading to an anterior dislocation of the radial head.  The postulated mechanism of injury have been described as pronation of an extended elbow  or traction injury to the right elbow and crush injury to the forearm  although Bonatus et al speculated that the injury occurred in a position of hyperextension and supination.  Typical clinical presentation is a maintenance of flexion and extension of the elbow following the injury but loss of supination and pronation.  Reduction was achieved by a pronation maneuver.  Most authors propose immobilization of the elbow in flexion and supination in a plaster cast  while Bonatus et al  & Negi et al  immobilised their cases in flexion & pronation. The period of immobilisation varied from 10 days.  to 4 weeks.  Most acute cases can be reduced closed and the functional outcome seems to be good post reduction. If missed or neglected, an open reduction has to be done with either an annular ligament reconstruction  or a radial head excision deemed as the procedure of choice .
We speculate the mechanism in our patient to be a hyperextension of the elbow with forearm in midprone position leading to an anterolateral dislocation of the radial head. The reduction was achieved in supination and immobilisation of the elbow in flexion and supination gave a favourable final outcome.
In the presence of major distracting injuries like long bone fractures, pelvic fractures, chest and abdominal injuries, an isolated radial head dislocation can be easily missed as pain is masked by the presence of major distracting injuries and flexion and extension of the elbow is normal. If supination and pronation of the forearm is not assessed, this injury can be missed resulting in degenerative arthritis of the elbow and the distal radioulnar joints.
This case report has been prepared to stress the importance of a thorough secondary survey in patients with polytrauma after high impact motor vehicle accidents. A proper secondary survey in patients with major distracting injuries can prevent important injuries being missed.
Written consent was obtained from the patient for publication of study. Funding was neither sought nor obtained.
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