Page 144 - Adams and Stashak's Lameness in Horses, 7th Edition

110 Chapter 2

Palpation of the stifle joints for effusion should always be
compared to the opposite limb. In general, abnormalities
VetBooks.ir vial effusion. Effusion of the femoropatellar and MFT
within the stifle joint are usually accompanied with syno­
joints can be associated with a variety of clinical prob­
lems (see the stifle section in Chapter 5 for details).
The patella and patellar ligaments should be palpated
for parapatellar inflammation and pain, crepitation, and
displacement. The patellar displacement test involves
pushing the patella proximally (upward) and laterally
(outward) in an attempt to engage the medial patellar
ligament over the medial trochlea. Most horses object to
this manipulation, but if the patella is easily displaced
upward with apparent locking, it may suggest intermit­
tent upward fixation of the patella. With complete
upward fixation, the horse will be unable to flex its stifle
or hock and may drag its limb behind in extension
(Figure 2.92).
Manipulative tests may also be performed on the sti­
fle to assess the cruciate ligaments and medial collat­
eral ligament. These tests are very subjective and only
15
used in those horses when other clinical signs suggest
injury to these structures. The cruciate test can be per­
Figure 2.90. Effusion can be seen and palpated within the formed from either the caudal or cranial aspect of the
femoropatellar joint cranial to the patella ligaments (arrow). limb. With the caudal approach, the examiner stands
behind the horse with his/her arms brought around the
limb and the hands clasped together at the proximal
end of the tibia (Figure 2.93). The examiner’s knees or
knee should be in close contact with the plantar aspect
of the calcaneus, and the examiner’s toe is placed
between the bulbs of the heels. This positioning helps
to stabilize the limb. In this position the examiner pulls
the tibia sharply caudally and releases it to go cranially,
feeling for looseness and crepitation that may suggest
cruciate ligament damage. With a cranial cruciate liga­
ment rupture, the looseness is felt as a sliding move­
ment in a cranial direction (cranial drawer sign).
However, a generalized looseness within the stifle is
often the only definitive finding because it is difficult to
identify the phase (caudal or cranial) in which the
movement occurs.
With the cranial approach, the examiner stands in
front of the affected limb with one hand placed on the
proximal tibial tuberosity. The other hand is used to
pull the tail to that side to force the horse into weight‐
bearing. The tibia is pushed caudally as quickly and for­
cibly as possible, which is thought to stress the cranial
and caudal cruciate ligaments (Figure 2.94). This may
Figure 2.91. Visible and palpable effusion within the medial be repeated multiple times, after which the horse may
femorotibial joint is present just behind the medial patella be trotted off and the degree of lameness observed.
ligament (arrow).
An increase in lameness may indicate a sprained or
ruptured cruciate ligament, but is not specific for this
more difficult. These ligaments should be easily palpable injury. 15
across the dorsal aspect of the stifle and are the land­ The medial collateral ligament test is performed by
marks to locate the three synovial pouches of the stifle. placing the shoulder or outside hand over the lateral
The patella ligaments should be palpated for evidence of aspect of the stifle and abducting the distal limb with the
thickening and pain suggestive of desmitis. Fluid disten­ other hand (Figure 2.95). Increased lateral movement of
sion of the femoropatellar pouch may indicate pathology the distal limb indicates complete rupture of the medial
within the femoropatellar joint or within the MFT joint collateral ligament. The opposite approach may be per­
because they communicate with each other. The MFT formed to test the integrity of the lateral collateral liga­
joint pouch is located medial to the medial patella liga­ ment, but injuries to this ligament are uncommon. If a
ment directly above the tibial plateau. The lateral femo­ sprain to the ligament is suspected, the limb may be
rotibial joint is located lateral to the lateral patella repeatedly abducted several times, after which the horse
ligament, and effusion within this joint is rarely detected. is trotted off and the degree of lameness assessed.