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function. The sonopathologic features of MSUS-detected synovial-tendon damage
range from loss of the normal fi brillar echotexture, irregularity of the tendon margin,
hypoechoic areas within the tendon, and discontinuity of the tendon [ 24 ]. In the
clinical setting, MSUS assessment of synovial-tendon damage may be used to iden-
tify and follow tendons that are prone to rupture. To date the available grading sys-
tem proposed by OMERACT has been tested in one expert multiobserver study
[ 17 ]. They defi ned synovial-tendon damage on GS as internal and/or peripheral
focal tendon defect (i.e., absence of fi bers) in the region enclosed by the tendon
sheath, seen in two perpendicular planes. The grade of damage assessed in both
longitudinal and transverse planes compasses three semiquantitative scores: grade
0 = normal, grade 1 = partial tendon rupture, and grade 2 = complete tendon rupture.
The most reliable tendons were the extensor carpialis ularis and tibialis posterior—
probably because both tendons are thick straight-running and do not split.
As far as the articular cartilage, MSUS is able to depict several hyaline cartilage
abnormalities; however, its clinical use in RA is hampered because there are no
longitudinal studies aimed to identify cartilage damage progression. In fact, only
few MSUS studies in RA have included descriptions of cartilage abnormalities [ 25 ,
26 ]. Recently, it has been demonstrated that MSUS measures of metacarpal carti-
lage is closely related to anatomical cartilage thickness in anatomic specimens and
that both radiographic joint space widening and joint space narrowing represents
cartilage thickness in patients with RA [ 27 ]. These authors suggested that MSUS
metacarpal cartilage thickness measurement could be used when radiographs are
not available or when joint malalignment exists. The qualitative MSUS cartilage-
changes include loss of sharpness of the superfi cial margin, focal or diffuse cartilage
thinning, and loss of sharpness of the deep margin that represents subchondral bone
involvement secondary to cartilage attached infl amed synovial tissue in RA [ 25 ,
28 ]. A study was carried out to assess the reproducibility of the proposed cartilage
scoring system. Results depicted a moderate to good interobserver reproducibility
of a semiquantitative scoring system based on the qualitative morphological carti-
lage damage in RA [ 29 ].
The Synovio-Entheseal Complex and Synovitis
The “ synovio-entheseal complex ” represents the close anatomical integration
between the enthesis and synovium. According to this scenario, the enthesis fi bro-
cartilages that are located next to synovium (in joint, bursae, or tendons) rely on the
synovium for lubrication, oxygenation, and removal of microdebris. Being fi bro-
cartilagenous, the enthesis insertion is avascular. Therefore, derangements in the
enthesis are expected to trigger an infl ammatory response in the adjacent vascular
synovium [ 30 ].
In spondyloarthropathies (SpA), enthesitis has been considered the pathologic
hallmark and have been reported early in the disease course before irreversible
lesions develop. In contrast to both clinical and radiographic assessments of enthesi-
J. Uson and Y. El Miedany