Olecranon Fossa Space

fossa olecrani — spatium

The olecranon fossa is the posterior recess on the distal humerus that accommodates the olecranon process during full elbow extension. This triangular fossa between the medial and lateral columns of the distal humerus forms the posterior compartment of the elbow joint. The posterior fat pad within it is elevated by joint effusion. In some individuals, a supratrochlear foramen perforates the entire distal humerus, creating a continuous fossa.

Region: Forearm

Clinical Relevance

Clinical Notes

The olecranon fossa is the site of posterior elbow impingement from multiple pathologies: osteophyte formation at the olecranon tip impinging on the fossa floor in valgus extension overload (pitcher's elbow); loose body formation in the fossa from osteochondritis dissecans; and scarring of the posterior fat pad after elbow fracture producing extension block. Arthroscopic debridement of posterior osteophytes and loose body removal is performed through the posterior elbow portals targeting the olecranon fossa. The proximal posterior portal enters the fossa directly for visualisation.

Pathology

Common Injuries & Conditions

Posterior Elbow Impingement in Throwing Athletes

Repetitive valgus extension loading during the follow-through phase of throwing compresses the posteromedial olecranon against the fossa, producing osteophyte formation at the olecranon tip that impinges on the fossa floor causing posterior elbow pain at maximum extension; arthroscopic osteophyte removal from the olecranon fossa relieves impingement and allows return to throwing.