The elbow anterior recess is the anterior extension of the common elbow synovial cavity between the distal humerus and the anterior capsule, occupying the coronoid and radial fossae. In full extension it is expanded; in flexion the coronoid process and radial head fill these fossae and compress the recess. Synovial fluid displaced anteriorly by elbow flexion gives the anterior recess its characteristic crescent shape on ultrasound.
The elbow anterior recess is the primary site for elbow joint aspiration using the lateral soft spot approach (between radial head and olecranon) or the anterior approach. On lateral radiograph, the anterior fat pad displaced anteriorly from the coronoid fossa by effusion produces the sail sign, indicating intra-articular pathology. The fat pad sign is crucial in detecting occult radial head and coronoid fractures in children. In elbow arthritis, loose bodies, and synovial chondromatosis, the anterior recess is the predominant site of pathological synovial proliferation.
Intra-articular elbow effusion from fracture, synovitis, or haemarthrosis displaces the anterior fat pad from the coronoid and radial fossae, producing the triangular sail sign on lateral radiograph that indicates intra-articular pathology even when no fracture line is visible, prompting CT or MRI for occult fracture assessment.
Osteochondral loose bodies from primary elbow OCD, osteochondrosis, or chondromatosis preferentially accumulate in the anterior elbow recess, producing locking, catching, and terminal extension deficit that localises the loose body and guides the anterior arthroscopic portal for retrieval.
