SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
choice of transducer selection and the standoff provide optimal image quality to
evaluate these structures. This transducer or a high frequency microconvex is excellent
for evaluating the cranial horn of the meniscus and the cranial meniscal tibial ligament
when the joint is flexed. A 6.0 or 5.0 MHz microconvex transducer may be needed to
evaluate the deeper portions of the stifle when the joint is flexed, such as looking at
the cranial cruciate ligament. An even lower frequency 2.5 – 5.0 large convex
transducer is needed to image the caudal stifle to achieve the best resolution with
needed penetration. If using a machine with variable focusing, the focal zone should
be centered in the tendon or ligament being examined.
Scanning Technique
The optimal images are obtained with the transducer held perpendicular to the
structures being evaluated. This maximizes the amount of reflected ultrasound from the
tendons and ligaments. The tendons and ligaments should be scanned in two mutually
perpendicular planes from their origin to insertion. Ultrasonographic examination of the
stifle should be performed in a systematic fashion to be sure that all structures are
examined. The entire joint and periarticular structures should be examined
ultrasonographically. While most of the structures can be scanned with the horse
weight bearing, the cranial horn of both menisci, the cranial meniscal tibial ligament
and the cranial cruciate ligament have to be examined with the limb flexed.
One systematic approach starts cranially at the middle patellar ligament and extends
medially around the joint to the medial patellar ligament, the medial femorotibial joint,
the medial meniscus and the medial collateral ligament. Returning to the cranial
stifle, the lateral patellar ligament is then scanned along with the femoropatellar joint,
followed by the lateral femorotibial joint and the combined peroneus and long digital
extensor tendon, as one progresses laterally around the stifle. The lateral digital
extensor tendon is imaged next as one progresses caudally around the lateral
aspect of the joint followed by the popliteal tendon, lateral meniscus and lateral
collateral ligament. All tendons and ligament should be scanned in their entirety in
long and short axis.
Normal Sonographic Anatomy of the Stifle
Normal Ultrasonographic Appearance of Bone
The normal bone surface echo is a smooth uniform thickness hyperechoic line
that casts an acoustic shadow from its near surface. Within the joint, the articular
cartilage is a thin anechoic space overlying the hyperechoic subchondral bone.
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