Hindlimb flexion and abduction tests have been described but are of limited
specificity in the identification of stifle pathology. A drawer test is virtually
never used to detect a cranial-cruciate-deficient stifle as it is too dangerous.
Lameness from stifle injury is highly variable and is not specific to the stifle.
However as the stifle is responsible for a considerable amount of the
protraction phase of the stride, the cranial phase of the stride is often reduced
and the lameness is usually as evident, or worse, on soft ground compared to
on hard ground. In some horses with stifle lameness, the limb is carried
forward in a position lateral to the expected position (i.e. abducted), which is
sometimes referred to as a “wet nappy trot”. In some horses with this limb
flight the limb swings outside the expected line of limb flight, only to strike the
ground near the expected position or by stabbing laterally.
Diagnostic analgesia of stifle lameness
We inject each joint compartment separately, since functional communication
between the different cavities is inconsistent and synovial inflammation may
be sufficient to block a previously existing natural communication (Reeves et
al. 1991). Needle placement for arthrocentesis is determined by the same
anatomical landmarks as previously described.
The femoropatellar joint is approached close to the distal border of the patella,
between the middle and lateral or middle and medial patellar ligaments,
aiming the needle slightly in a distoproximal direction. An alternative lateral
approach has been described immediately caudal to the lateral patellar
ligament and half-way between the lateral pole of the patella and the lateral
tibial condyle. The benefits of this latter approach include a lower risk of
iatrogenic cartilage damage and an increased likelihood of synovial fluid
aspiration. The medial femorotibial joint is entered, 1-2 cm proximal to the
medial horn of the medial meniscus, between the medial collateral ligament
and the medial patellar ligament. Needle entry to the lateral femorotibial joint
is gained through the combined tendon of the long digital extensor tendon and
the peroneus tertius into a cul-de-sac of the joint that extends distally in the
extensor groove between the tibial tuberosity and the lateral condyle of the
tibia, 2 to 4 cm distal to the level of the lateral tibial condyle. The tendon of the
long digital extensor muscle is readily palpable in the extensor groove (sulcus
muscularis) that lies between the tibial tuberosity and the lateral tibial condyle.
Twenty ml of mepivacaine hydrochloride is injected into each joint. Diagnostic
analgesia of all three joints should be performed in those cases were the
location of the lameness is unknown because of variable physical and
functional communication between the three separate stifle joint
compartments (Toth et al. 2014).
Diagnostic Imaging of stifle lameness
Diagnostic imaging should include a minimum of radiography (lateromedial,
caudocranial and flexed lateromedial views) and ultrasonography (cranial,
15-‐18
February
2016
East
London
Convention
Centre,
East
London,
South
Africa
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