Annular Ligament of the Radial Head Detail

ligamentum anulare radii detail

The annular ligament encircles the radial head and neck, attaching on both ends to the anterior and posterior margins of the radial notch of the ulna, forming a fibro-osseous ring that maintains the radial head within the proximal radioulnar joint.

Region: Upper Arm

Biomechanics

Function & Actions

Maintains the radial head within its articulation on the capitellum and within the radial notch of the ulna, allows forearm rotation by permitting radial head spinning within the ligamentous ring, and resists radial head distal migration.

Clinical Relevance

Clinical Notes

Annular ligament disruption accompanies radial head fractures and Monteggia fractures (radial head dislocation with ulnar fracture). In the paediatric pulled elbow (nursemaid's elbow), the annular ligament partially slips over the radial head — hyperpronation or supination manoeuvre repositions it. Annular ligament reconstruction using a triceps fascia strip is performed for chronic radial head instability.

Pathology

Common Injuries & Conditions

Nursemaid's Elbow — Annular Ligament Subluxation

Partial annular ligament slippage over the radial head from longitudinal traction on the extended arm in children under 5, reduced by hyperpronation or supination-flexion manoeuvre.

Annular Ligament Disruption in Monteggia Fracture

Annular ligament failure allowing anterior radial head dislocation in Monteggia fracture-dislocation, requiring anatomic ulnar fixation to allow indirect radial head reduction and annular ligament healing.