Diagnostic ultrasound ( PDFDrive )

888 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
FIG. 24.16 Focal Full-Thickness Tear of Supraspinatus Tendon.
In this long-axis image of the supraspinatus tendon, there is a focal
full-thickness tear, and the gap between the tendon retracted end and
the greater tuberosity is illed with echogenic debris (arrow) and luid.
FIG. 24.17 Full-Thickness Supraspinatus Tear With Associated
Cartilage Interface Sign. A hyperechoic line (arrowheads) is seen along
the surface of the normal hypoechoic cartilage (arrow), along the superior
aspect of the humeral head (*).
Partial-thickness tears are characterized by a focal area of
hypoechogenicity or mixed echogenicity involving one side of
the tendon, but not extending through the entire thickness. 58
here are several subtypes of partial-thickness tears of the rotator
cuf (Figs. 24.18 and 24.19). Bursal-sided partial-thickness tears
(Fig. 24.19A and B) occur supericially, just deep to the subacromial
subdeltoid bursa. Articular-sided tears (see Fig. 24.19C
and D) occur at the undersurface of the tendon in contiguity
with the joint space. Intrasubstance tears (Fig. 24.19E) can occur
either within the substance of the tendon footprint at the enthesis
or longitudinally within the tendon ibers. hese tendons may
not be identiied at arthroscopy because they do not communicate
with either the bursal or the articular surfaces of the tendon.
A speciic partial-thickness tear type is the “rim-rent” tear
(see Fig. 24.19F), occurring at the articular side of the supraspinatus
tendon, extending into the tendon footprint on the greater
tuberosity. 67,68 his type of tear is most commonly seen in athletes
who engage in overhead-throwing activities.
Partial-thickness tears vary from small, 1- to 2-mm tears to
those involving more than 50% of tendon thickness. Although
tears of 50% or greater have typically been referred for repair,
patients with tears involving as little as 25% of the tendon may
beneit from arthroscopic debridement. 69,70 Surgical decisions,
however, are made in the context of the individual patient
performance status, limitation by the injury, comorbidities, and
patient preference. Partial tears occur most commonly along the
articular side of the tendon in younger patients. 70 Care must be
taken to adequately assess the anterior leading edge ibers of the
supraspinatus tendon, where these tears can oten occur. 71 Bursalsided
partial-thickness tears may manifest as lattening of the
bursal contour of the tendon of varying severity. 29 his may lead
to an hourglass-like diameter shit between areas of normal and
attenuated tendon. 28
An associated sign frequently observed in the setting of both
partial- and full-thickness rotator cuf tears is the inding of
cortical irregularity of the greater tuberosity, a inding with a
75% positive predictive value for the presence of an associated
rotator cuf tear. 72 his is more severe in full-thickness tears and
represents bony remodeling with irregularity, pitting, and
erosion. 73 A second sign that can be seen in both partial articularsided
and full-thickness tears is the “cartilage interface” sign,
mentioned earlier.
In analysis of partial- and full-thickness tears, it is important
to quantify the extent of the tear in both its long and short axis
(tear length and width); for example, in the case of a supraspinatus
tendon tear, a measurement of the medial to lateral tear length
should be made in long axis, and a measurement of the anterior
to posterior tear width should be made on short-axis imaging.
Postsurgical Rotator Cuff
Ater surgical rotator cuf repair, the appearance of the rotator
cuf and surrounding sot tissues is abnormal, as can be expected,
with loss of normal sot tissue planes and abnormal echotexture
of the rotator cuf tendon. Because of loss of normal interface
with the overlying subacromial bursa, dynamic assessment may
aid in identiication and visualization of the supraspinatus
tendon. 74 Bony irregularity at the site of anchor placement is
expected, and echogenic suture material within the tendon may
contribute to the heterogeneous appearance of the postoperative
rotator cuf tendon (Fig. 24.20, Video 24.4). A gap within the
tendon and nonvisualization of the tendon owing to retraction
are the most reliable signs for a recurrent tear. 75,76 A thinned
tendon or one with subtle contour abnormality is considered
intact.
Muscle Atrophy
Ultrasound may also be used to assess for rotator cuf muscle
atrophy, which may occur in the setting of a subacute or chronic
rotator cuf tear. his is characterized by decreased muscle bulk
and increased muscle echogenicity (related to increased fat
interposed among muscle ibers 77 (Fig. 24.21). Ultrasound
appearances also include lack of clarity of the muscle contour,
and loss of visibility of the central tendon within the myotendinous