The lateral ulnar collateral ligament (LUCL) runs from the lateral epicondyle of the humerus to the supinator crest of the ulna, blending with the annular ligament and the radial collateral ligament to form the lateral collateral ligament complex. The LUCL is the primary restraint to posterolateral rotatory instability (PLRI) of the elbow, preventing the radial head and ulna from rotating posterolaterally away from the humerus.
Prevents posterolateral rotatory instability of the elbow by tethering the ulna and radial head to the lateral humeral condyle, resisting axial loading in supination and valgus extension.
LUCL insufficiency is the cause of posterolateral rotatory instability (PLRI), presenting with lateral elbow pain, clicking, and apprehension during extension and supination (the lateral pivot shift test). LUCL injury occurs from elbow dislocation, lateral release procedures in tennis elbow surgery, and recurrent elbow instability. Reconstruction uses a palmaris longus or gracilis graft looped from the lateral epicondyle to the supinator crest. LUCL assessment is critical before any lateral elbow release to avoid creating iatrogenic PLRI.
LUCL disruption from elbow dislocation or iatrogenic over-release of lateral soft tissues produces the positive lateral pivot shift test with the elbow snapping posterolaterally in supination-extension; reconstruction with tendon graft from lateral epicondyle to supinator crest restores lateral collateral stability.
