Review Question - QID 217879

The lateral ulnar collateral ligament (LUCL) is reliably torn in a posterolateral elbow dislocation, being the most common lateral elbow ligament which requires repair.

In cases of traumatic posterolateral elbow dislocation, the lateral elbow ligamentous structures are usually affected. Most commonly, the LUCL ruptures off of its humeral attachment and usually requires repair at the time of surgery. At the time of injury, the arm is usually positioned in supination and valgus in combination with an axial loading force. This causes the lateral ligament complex to fail first, followed by anterior capsule/coronoid injury and resultant posterolateral subluxation of the ulnohumeral joint and radial head. As such, fractures to the radial head and coronoid are also common in these injuries and may need to be addressed at the time of surgery.

O'Driscoll et al. explored posterolateral rotatory instability of the elbow. They discuss the elbow should be tested in supination and valgus with an axial compression force as it is brought from a flexed position to full extension. They postulated in this review that the LUCL was the pathologic ligamentous structure that led to rotatory subluxation of the ulnohumeral joint.

O'Driscoll et al. further described elbow instability, noting that based on cadaveric releases, there is a large spectrum of elbow instability. They further note that the order of disruption occurs from lateral to medial, and usually, the medial collateral ligament remains intact. As posterior dislocation occurs in the position of supination, the elbow experiences an external rotation moment and for this reason, the authors recommend the elbow be reduced in supination.

Figure A demonstrates a cadaveric specimen of the lateral elbow with the following structures marked: (1) LUCL, (2) radial collateral ligament, (3) accessory radial ligament, (4) annular ligament, (5) anconeus muscle.

Incorrect Answers:
Answer 2: The radial collateral ligament is part of the lateral collateral elbow complex, but the LUCL is the component most commonly directly injured in posterolateral elbow dislocation which would require repair.
Answer 3: The accessory radial collateral ligament does not commonly require repair after posterolateral elbow dislocation.
Answer 4: The annular ligament functions to stabilize the radial head in supination and pronation and does not typically require repair after posterolateral elbow dislocation.
Answer 5: The anconeus muscle does not require repair after posterolateral elbow dislocation.