Posterior Elbow Capsule Ligament

capsula articularis cubiti posterior

The posterior elbow capsule is a thin, relatively lax fibrous structure covering the olecranon fossa and the posterior aspects of the radiohumeral and ulnohumeral joints. It attaches proximally around the margins of the olecranon fossa and distally to the olecranon and annular ligament, and it blends with the overlying triceps. The posterior fat pad lies between the capsule and the floor of the olecranon fossa.

Anatomical Data

Attachments

Origin	Posterior distal humerus above the olecranon fossa and around the capitulum and trochlea
Insertion	Margins of the olecranon and the annular ligament

Biomechanics

Function & Actions

Provides posterior containment of the elbow joint. It is slack in extension and becomes taut in flexion, so it helps limit terminal flexion.

Clinical Relevance

Clinical Notes

Contracture of the posterior capsule in post-traumatic elbow stiffness limits flexion, and posterior capsular release is part of surgery to regain flexion. The posterior capsule tears in elbow dislocation. On a lateral radiograph after trauma, a visible posterior fat pad indicates a joint effusion (haemarthrosis) and suggests an occult fracture, most often of the radial head in adults or supracondylar in children. Heterotopic ossification in the posterior capsule is a common cause of elbow stiffness after distal humeral fractures.

Pathology

Common Injuries & Conditions

Posterior Elbow Capsule Contracture

Fibrotic thickening of the posterior elbow capsule after trauma or prolonged immobilisation limiting elbow flexion, treated by stretching or surgical posterior capsular release.

Posterior Fat Pad Sign

Displacement of the posterior fat pad by joint effusion on lateral radiograph, indicating an occult intra-articular fracture after elbow trauma.

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