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Posterior Elbow Recess

recessus posterior cubiti

The posterior elbow recess is an extension of the common elbow synovial cavity into the olecranon fossa, accommodating the olecranon tip in full extension. It communicates freely with the anterior recess and the lateral compartment through the common synovial space. Joint effusions preferentially collect in the posterior recess, displacing the posterior fat pad.

Region: Upper Arm

Clinical Relevance

Clinical Notes

The posterior fat pad sign on lateral elbow X-ray represents displacement of the posterior fat pad by an effusion in the posterior recess. In adults with acute elbow injury, a visible posterior fat pad indicates a haemarthrosis and an occult fracture until proven otherwise. The posterior recess is accessed during elbow arthroscopy via the posterolateral and straight posterior portals. Removal of loose bodies from the posterior recess and olecranon fossa is one of the most common elbow arthroscopy procedures.

Pathology

Common Injuries & Conditions

Posterior Fat Pad Sign

Displacement of the posterior fat pad by haemarthrosis filling the posterior elbow recess, visible on lateral X-ray as a sail-shaped lucency posterior to the humerus, indicating an occult fracture requiring further imaging.

Posterior Elbow Impingement

Osteophyte formation and loose bodies in the posterior recess producing a block to full extension and posterior elbow pain in extension, treated by arthroscopic debridement of the olecranon fossa.