Review Question - QID 216791

Following elbow dislocations, injury to the LCL and anteromedial facet of the coronoid result in posteromedial rotatory instability of the elbow.

Posterior rotatory instability of the elbow occurs following injuries to both the anteromedial facet of the coronoid and the LCL. The anteromedial facet, specifically, is the critical weight-bearing portion of the ulnohumeral joint. Damage to this structure causes posteromedial subluxation that often results in severe progressive arthritis. In the setting of posteromedial rotatory instability, the anteromedial facet of the coronoid should be fixed, with one of several techniques (suture, plate, retrograde screws, etc.).

Sanchez-Sotelo et al reviewed medial oblique compression fracture of the coronoid process of the ulna. They reported that this injury is much more complex than previously appreciated. They concluded that injury to this specific portion of the coronoid facet may lead to joint subluxation or dislocation.

Pollock et al reviewed the effects of anteromedial facet fractures of the coronoid and lateral collateral ligament injury on elbow stability and kinematics. They reported that the size of the anteromedial coronoid fracture fragment affects elbow kinematics, particularly in varus stress. The size of an anteromedial coronoid fracture and the presence of concomitant ligament injuries may be important determinants of the need for open reduction and internal fixation.

Bryce et al reviewed the anatomy and biomechanics of the elbow. They reported that the anterior bundle of the medial collateral ligament (AMCL) is the most discrete portion of this ligamentous complex and inserts onto the anteromedial facet of the coronoid. They concluded that the AMCL is able to provide significant stability against valgus force, making it one of the primary static constraints of the elbow.

Illustration A demonstrates the anteromedial facet of the coronoid.

Incorrect Answers:
Answer 2: Coronoid tip fractures are associated with posterolateral, not posteromedial rotatory instability.
Answer 3: The radial head is commonly injured during "terrible triad" injuries which may result in posterolateral rotatory instability. This is commonly associated with a fracture to the coronoid tip.
Answer 4: While the AMCL may attach to the anteromedial facet of the coronoid, it is not typically injured when a fracture of the anteromedial facet occurs.
Answer 5: The annular ligament circumscribes the radial head and is not associated with rotatory instability of the elbow.