Causes / typical injury mechanism: Lateral ulnar collateral ligament (LUCL) injury is typically caused by dislocation of the elbow joint, but it can also occur after iatrogenic injury or chronic stress. Insufficient healing of the lateral elbow ligaments after the acute injury can result in posterolateral rotary instability (PLRI) at the radiocapitellar and ulnohumeral joints.

Refer to elbow dislocation for emergent management of the acute injury.

Classic history and presentation:

• The patient reports a history of one or more elbow dislocations, which may have reduced spontaneously or required closed reduction.
• The primary complaint is pain at the posterolateral elbow.
• The patient may have mechanical symptoms such as catching, clicking, or locking.
• The symptoms are worse when pushing up from the arms of a chair.

Prevalence:

• There are no clear studies on the prevalence of this injury. Ulnar ligamentous injuries, in general, have increased substantially in the past 20 years.
• Less than 10% of patients will have persistent instability of the elbow after nonoperative treatment of an elbow dislocation.

Pathophysiology: The LUCL is typically disrupted from a fall onto an outstretched hand that dislocates the elbow: axial compression, supination, and valgus forces. The spectrum of elbow instability also includes bony malalignment and medial ligamentous insufficiency.

Grade / classification system: LUCL injuries are classified based on the segment of the ligament that is disrupted: proximal, middle, or distal, with or without an attached bone fragment.