Advances in the Canine Cranial Cruciate Ligament, 2nd edition

(^19) Stifle Ultrasonography
Cristi R. Cook
The normal stifle joint
Canine stifle joint disorders have been fre-
quently diagnosed based on physical examina-
tion findings, radiographs, and arthrography
(Reedet al. 1995; Krameret al. 1999; Soleret al.
2007). More recently, ultrasonography, com-
puted tomography and magnetic resonance
imaging have been used to further evaluate
the stifle joint (Gnudi & Bertoni 2001; Samii &
Long 2002; Soleret al. 2007). Musculoskeletal
ultrasound is commonly performed in humans.
Canine stifle ultrasound has become a more
common diagnostic modality to evaluate the
intra-articular structures of the stifle joint over
the last decade (Krameret al. 1999; Gnudi &
Bertoni 2001; Samii & Long 2002; Soleret al.
2007; Arnaultet al. 2009; Mattoon & Nyland
2015; Cook 2016). Notably, it is useful in eval-
uating the intra-articular soft tissues and the
supporting extra-articular structures.
Stifle ultrasound examination is best per-
formed using a 10–18 MHz high-resolution,
linear transducer (Krameret al. 1999). To mini-
mize any artifacts, the hair along the stifle joint
should be clipped and ultrasound coupling
gel applied to the skin surface. The linear
transducer is most appropriate for imaging
superficial structures with high detail while
minimizing the artifacts from anisotropy; the
latter occurs when the fibers of the tendon or
ligament are not perpendicular to the ultra-
sound beam (Figure 19.1A,B). Off-angle artifact,
or anisotropy, appears as a hypoechoic area
within the tendon or ligament, but when the
same structure is oriented perpendicular to the
ultrasound beam the fibers will reappear (Reed
et al. 1995; Krameret al. 1999). It is important to
look at potential lesions in both the longitudinal
and transverse planes to confirm the lesion is
real or artifact, while making sure the trans-
ducer face is perpendicular to the structure of
interest (Reefet al. 1998; O’Connor & Grainger
2005).
The cranial joint space is imaged with the
transducer interface along the patellar tendon.
The patellar tendon is seen in both transverse
and sagittal planes as a superficial structure
with low to moderate echogenicity and lin-
ear hyperechoic interstitial fibers (Reedet al.
1995; Kramer et al. 1999; Soler et al. 2007).
In the transverse imaging plane, the patellar
tendon is ovoid with hyperechoic, pinpoint
foci representing the interstitial fibers. The
peritendinous tissue should be a thin, hypere-
choic line (Krameret al. 1999; Soleret al. 2007)
(Figure 19.2). Deep to the patellar tendon is the
infra-patellar fat pad, which is hypoechoic to
Advances in the Canine Cranial Cruciate Ligament, Second Edition. Edited by Peter Muir. © 2018 ACVS Foundation.
This Work is a co-publication between the American College of Veterinary Surgeons Foundation and Wiley-Blackwell.
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