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. Its disruption produces posterolateral rotatory instability (PLRI) — the elbow supinates and the radial head subluxes posterolaterally under varus-supination stress. LUCL reconstruction using a palmaris or gracilis graft through bone tunnels restores PLRI. The lateral pivot shift test demonstrates PLRI under anaesthesia.

Region: Upper Arm

Anatomical Data

Origin, Insertion & Supply

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

Clinical Relevance

Clinical Notes

LUCL insufficiency produces the snapping, locking elbow that goes out with the arm extended and loaded in the supinated position. Arthroscopic lateral pivot shift test, the chair-rising test, and the floor push-up test all provoke PLRI. 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.