Lateral Ulnar Collateral Ligament (LUCL)

ligamentum collaterale ulnare laterale cubiti

The LUCL is the critical lateral elbow stabiliser, running from the lateral epicondyle to the supinator crest of the ulna and blending with the radial collateral and annular ligaments as part of the lateral collateral ligament complex. Its disruption produces posterolateral rotatory instability (PLRI): the forearm supinates away from the humerus and the radial head subluxes posterolaterally under valgus, supination and axial load. LUCL reconstruction using a palmaris or gracilis graft through bone tunnels restores stability. The lateral pivot shift test demonstrates PLRI, most clearly under anaesthesia.

Anatomical Data

Attachments

Origin	Lateral epicondyle (isometric point)
Insertion	Supinator crest of the ulna

Biomechanics

Function & Actions

Actions	Primary restraint against posterolateral rotatory instability of the elbow maintains the ulnohumeral articulation during varus and rotational loads

Acts as the primary restraint to posterolateral rotatory instability of the elbow and resists varus stress.

Clinical Relevance

Clinical Notes

LUCL insufficiency produces lateral elbow clicking, snapping or giving way with the arm extended and supinated under load, as when pushing up from a chair. The lateral pivot shift test, the chair-rising test, and the floor push-up test all provoke PLRI. Causes include elbow dislocation and iatrogenic injury from over-release of the lateral soft tissues during tennis elbow surgery or radial head procedures, so the LUCL must be protected in lateral elbow approaches. LUCL reconstruction is performed for recurrent symptomatic PLRI unresponsive to conservative management.

Pathology

Common Injuries & Conditions

Posterolateral Rotatory Instability

LUCL disruption from elbow dislocation producing snapping elbow with varus-supination loading managed with LUCL reconstruction.

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