Advances in the Canine Cranial Cruciate Ligament, 2nd edition

Stifle Ultrasonography 139

Figure 19.9 Meniscal tear. There is flattening of the
tibial side of the meniscus with adjacent fluid (arrow).

of the meniscus (Figure 19.9) (Mahnet al. 2005).
Occasionally, axial splitting of the meniscus is
identified in some patients with radial tears.
Small radial tears or fraying of the meniscal
edges may be too small to see specific changes
with ultrasound, but other characteristics of
meniscal tears are usually present. The complex
meniscal tears and the macerated meniscus are
usually seen as an irregular, hyperechoic mass
of tissue with no specific shape (Figure 19.10).
Fluid accumulation is often seen adjacent to
the meniscal tear, and may be the only visible
fluid within the joint. The normal meniscal
echogenicity is relatively hyperechoic to the
surrounding muscles with a fine echotexture.

Figure 19.10 Macerated meniscus. The meniscal tissue
has a mottled appearance with an abnormal shape
(arrowhead). F, femur; T, tibia.

Figure 19.11 Bucket-handle tear of the medial

meniscus. Note the abaxial displacement of the abaxial

margin of the medial meniscus (arrows). F, femur; T, tibia.

In the presence of a meniscal tear, the meniscus

may appear hypoechoic or mottled (Kramer

et al. 1999). Occasionally, there may be a hyper-

echoic appearance adjacent to the tibial side

of the meniscus. This has been confirmed

with arthroscopy as hypertrophied synovium

along the meniscus. Meniscal displacement

may be the most difficult feature to evaluate.

There is a faint, hyperechoic line between

the medial meniscus and the joint capsule

that is used as a reference for the meniscal

position. Normally, this line is adjacent to the

surface of the femoral and tibial cortices (see

Figure 19.5) (Mahnet al. 2005). Caution should

be used if there are large osteophytes adjacent

to the joint, as the meniscus can appear falsely

displaced (abaxially). With further evaluation,

the osteophytes are the cause of the apparent

displacement. Abaxial displacement has been

associated with a displaced bucket-handle

tear, following confirmation with arthroscopic

evaluation (Figure 19.11).

Patellar tendon abnormalities are most com-

monly associated with rupture (incomplete or

complete) or tendonitis associated with a previ-

ous surgical treatment. In acute patellar tendon

injuries, it will appear hypoechoic and thick-

ened when compared to normal (Krameret al.

1999). The fibers may be visible, but not parallel;

disrupted with a distinct peritenon; disrupted

fibers and peritenon; or complete rupture of the

tendon and peritendon (Figure 19.12). Chronic

patellar tendon injuries appear hyperechoic,

focally narrowed, with or without dystrophic

mineralization within the tendon or entheso-

phytes at the tibial crest.