The Pathoanatomy of Lateral Ligamentous Disruption in Complex Elbow Instability

Author(s): McKee MD, Schemitsch EH, Sala MJ and O’Driscoll SW

Source: Journal Shoulder Elbow Surg 12: 391-6, 2003.

Summary:

It is now clear that the lateral ligament complex is the primary stabilizer of the elbow to both varus loads and ulnuhumeral rotational stability.  With loss of the lateral extensor and collateral ligament origins, the elbow manifests posterolateral rotatory instability, which may be the mechanism of elbow dislocation and responsible for recurrent instability.  The authors sought to determine the pattern of lateral soft-tissue failure in 62 cases of dislocation and/or fracture-dislocation of the elbow.  Mean age was 43 years, with 42 men and 19 women compromising the cohort.  Associated fractures included the coronoid (39), radial head (36), proximal ulna (14) and distal humerus (6).  Disruption of the lateral soft-tissue complex was seen in all elbows.  Six patterns were identified:  proximal avulsion (32), bony avulsion from the epicondyle (5), midsubstance rupture (18), ulnar failure of the ligament (4) and combined patterns (3).  66% of cases had ligament failure and concomitant rupture of the common extensor origin.  The authors stress the importance of lateral soft-tissue repair in the surgically treated unstable dislocation and fracture dislocation of the elbow.  Of note, the medial collateral ligament was found disrupted in over half of cases.

Dislocation of the elbow most commonly occurs by a rotatory mechanism in which the proximal forearm (ulna and radius) supinates away from the humerus (posterolateral rotatory mechanism).  As such, lateral ligament and extensor tendon disruption is common.  While the vast majority of simple elbow dislocations without fracture can be treated non-operatively, surgery is indicated when the dislocation occurs with an associated significant periarticular fracture.  In this setting, the elbow loses its bony and soft-tissue support.  At surgery, once the bone and joint surfaces are addressed, special care must be taken to repair the lateral (and occasionally medial) soft-tissue origins.  As documented in this study and those previously, the ligament and forearm extensor and flexor-pronator tendons most common fail at their humeral origin.  Greater soft-tissue injury is associated with greater potential for instability.

 

Related Links
Journal Shoulder Elbow Surg