Advances in the Canine Cranial Cruciate Ligament, 2nd edition

Stifle Ultrasonography 137

Figure 19.3 Zoomed image of the normal cranial
cruciate ligament in the full flexion technique with
proximolateral-distomedial rotation of the transducer. The
normal longitudinal fiber pattern is identified (arrows). F,
femur; T, tibia.

Improved viewing of the CrCL in the longi-
tudinal axis has been shown with maximum
flexion of the stifle and rotation of the ultra-
sound probe in a proximolateral to distomedial
direction (Naysehet al. 2015) (Figure 19.4). This
allows more of the ligament to be imaged and
allows an improved alignment (anisotropy) of
the ligament fibers. This would also improve
the likelihood of identifying subtler interstitial
tears of the ligament. The caudal cruciate liga-
ment (CaCL) is not easily visible with any cra-
nial imaging technique due to the large mus-
cle mass along the caudal joint (Krameret al.
1999). The femoral attachment of the CaCL has
been imaged in multiple studies with the use of

Figure 19.4 Normal image of the cranial cruciate
ligament (arrows) attachment along the tibial cortex
(arrowheads).

Figure 19.5 Normal meniscus. Note the abaxial surface

of the meniscus positioned along the femoral and tibial

cortical margins (arrows). The asterisks outline the normal

medial meniscus. F, femur; T, tibia.

a water bath, with the stifle in extension or full

flexion (Reedet al. 1995; Gnudi & Bertoni 2001;

Samii & Long 2002; Seonget al. 2005).

The medial and lateral menisci are best seen

on sagittal plane images. Each appears as a tri-

angular, echogenic structure that is fairly homo-

geneous (Reedet al. 1995; Krameret al. 1999;

Soleret al. 2007). The apex of the triangle points

axially, conforming to the femoral condyle and

tibial plateau (Figure 19.5). The cranial, cen-

tral, and caudal regions of the medial menis-

cus are visible, whereas the different sections of

the lateral meniscus are more difficult to iden-

tify routinely and are dependent on the individ-

ual patient. The different sections of the menisci

are based on their location to the collateral lig-

aments (i.e., the cranial horn of the meniscus is

found cranial to the collateral ligament; the cau-

dal horn, caudal to the ligament and the cen-

tral region, adjacent to the collateral ligament).

Normally, there is a thin fluid line between the

meniscal and osseous surfaces.

The abnormal stifle joint

The most common abnormality of the stifle joint

is cruciate ligament rupture (CR). In acute cases,

the joint effusion can be mild to severe and

potentially have echogenic fluid if there is a sig-

nificant hemarthrosis with imaging in the early

phase of the rupture. The rupture of the lig-

ament may be identified if it is near the tib-

ial attachment, and may not be visible if it is