Synovial Pannus

Fig. 8.68a,b. Synovitis of the elbow joint posterior joint recess, a Longitudinal 12-5 MHz US image over the posterior olecranon recess with b T2w SE MR imaging correlation in a patient with rheumatoid arthritis presenting with painful elbow and loss of extension. US shows a bulk of hypoechoic synovial pannus fiUing the recess (arrows). Deep to the triceps muscle (tm), the posterior fat pad (asterisks) is elevated by the pannus. Note the prominence of the tip of the olecranon (O) and the humeral trochlea (TR) bulging within the recess... 

Fig. 10.41 a,b. Hypertrophic tenosynovitis of the extensor carpi ulnaris in a patient with rheumatoid arthritis, a Short-axis and b long-axis 12-5 MHz US images of the extensor carpi ulnaris tendon (ecu) reveal hypoechoic synovial pannus (arrowheads) which causes abnormal distention of the synovial sheath. The extensor carpi ulnaris is displaced anteriorly because of loosening of the retinaculum. Note the pannus filling the distal radioulnar joint cavity (arrow)... 

Similar to other joints in the body, differentiation between effusion and synovial pannus maynotbe easy at wrist due to their similar hypoechoic echotexture. As a general rule, the pannus appears more echogenic and pressure applied on it with the probe causes only a partial collapse of the recess, whereas free fluid is easily squeezed away from the field-of-view of the US image. Owing to the superficial position of the wrist joints, color and power Doppler systems can be helpful for this purpose by revealing blood flow inside the synovial membrane. One should be aware that the hyperemia is dependent on the degree of inflammation and that a less active fibrous pannus may appear completely free of color flow signals. 

Fig.l0.70a,b. Bone erosions. a,b Transverse 12-5 MHz US images over the ulnar head in two patients with longstanding rheumatoid arthritis reveal bone erosions (arrows) as small regular defects of the cortical outline. Note the synovial pannus (arrowheads) located inside and around them... 

Fig. 10.72a,b. Caput ulnae syndrome in rheumatoid arthritis, a Longitudinal and b transverse 12-5 MHz US images over the extensor carpi ulnaris tendon (straight arrows) reveal synovial pannus inside the distal radio-ulnar joint (asterisk) and the extensor carpi ulnaris tendon sheath (arrowheads). The tendon is dislocated (curved arrow) out of its ulnar groove due to the tear of the retinaculum. See Fig. 10.20b for comparison with normal findings... 

Fig. 11.57a-c. Rheumatoid arthritis, a Longitudinal and transverse (see insert) 12-5 MHz US images over the dorsal aspect of the metacarpophalangeal joint of the index finger reveal bony erosions (arrows) over the surface of the metacarpal head (Met) associated with distension of the dorsal recess of the joint by synovial pannus (asterisks), b Contralateral normal finger. Comparing a and b observe the different appearance of erosions compared with the normal focal notch (arrowhead) located on the dorsal aspect of the metacarpal. PP, proximal phalanx, c Radiographic correlation confirms erosions (arrow) at the level of the metacarpal head... 

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