[Technical aspects and value of arthrosonography in rheumatologic diagnosis. 4: Ultrasound of the elbow].

Musculoskeletal ultrasonography is an important imaging technique in the diagnosis of rheumatic diseases especially for early manifestation. It allows sensitive detection of small joint fluid collections as well as differentiation of soft tissue lesions and bone lesions. The following standard scans are suggested for sonographic evaluation of the elbow: 1) anterior humeroradial longitudinal scan, 2) anterior humeroulnar longitudinal scan to detect effusions, synovial proliferation, loose joint bodies, bone lesions (osteoarthritis/arthritis), 3) anterior transverse scan over the trochlea to evaluate these structures in an additional dimension, 4) posterior longitudinal scan and 5) posterior transverse scan of the olecranon fossa with flexed/extended elbow to evaluate the same objectives as the above mentioned scans and additionally to detect olecranon bursitis, and optional 6) distal dorsal longitudinal scan to differentiate soft tissue lesions such as rheumatoid nodules or gout tophi, 7) anterior transverse scan over the radius head to evaluate lesions of the radius head, tendopathy, calcinosis, 8) lateral humeroradial longitudinal scan to evaluate epicondylitis, 9) medial humeroulnar longitudinal scan to evaluate calcinosis, epicondylitis, signs of compression of the ulnar nerve. A linear transducer with a frequency of about 5-7.5 MHz is recommendable. The anterior distance between trochlea and the capitulum of the humerus between the bone and the joint-capsule of the elbow is > or = 2 mm in probable and > or = 3 mm in definite synovitis or effusions. Synovitis or effusions are probable if the difference between the right and left elbow is 1 mm, and they are definite if the difference is > or = 2 mm.