Page 216 - Adams and Stashak's Lameness in Horses, 7th Edition

182 Chapter 2

the same side of the horse. Fifteen to 20 mL of local
anesthetic is recommended. Calcaneal
VetBooks.ir joint may be used for arthrocentesis, especially if signifi­ bursa
The medial or lateral plantar outpouchings of the TC
cant synovial effusion is present (Figures 2.186 and
2.187). The palpable landmarks of the lateral plantar
pouch are bordered by the tuber calcis caudally, the cau­
dal aspect of the distal tibia cranially, and the proximal
aspect of the lateral trochlear ridge of the talus distally
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(Figure 2.187; Video 2.35). Confirmation that fluid Long digital
swellings in this location are part of the TC joint can be extensor tendon
determined by applying finger pressure to the swellings Tarsocrural
and feeling the dorsal pouches of the TC joint distend. joint
A 1‐inch (2.5‐cm), 20‐gauge needle is inserted perpen­ Distal intertarsal Head of
dicular to the skin at the site of the effusion with the joint fourth
limb weight‐bearing. Tarsometatarsal metatarsus
joint
Superficial
Tarsometatarsal (TMT) Joint digital flexor
tendon
The TMT joint is best approached from the plantaro­
lateral aspect of the tarsus with the limb weight‐bear­
ing. It is an easy joint to inject with an accuracy rate of Figure 2.188. Injection site for the TMT joint proximal to the
96% in a recent report. The landmarks for injection head of the lateral splint bone.
69
are the proximal head of the fourth metatarsal (MT IV)
bone and the lateral edge of the SDFT. A 1‐ to 1.5 inch
(2.5‐ to 3.8‐cm), 20‐ to 22‐gauge needle is inserted in around the tendons of the tibialis cranialis and fibularis
20
the small palpable depression 0.25 inch (0.5–1 cm) tertius when using this approach. A more difficult
proximal to the head of MT IV (Figure 2.188; Video alternative approach to the TMT joint is from the
2.36). The needle is directed toward the dorsomedial distomedial aspect of the tarsus. The site for injection is
aspect of the tarsus in a slightly downward direction to approximately 0.5 inches (1–2 cm) distal to the site used
a depth of 0.5–1 inch (1–3 cm). 47,48 Synovial fluid is for the medial approach to the DIT joint. 75
often observed in the needle hub, and 3–5 mL of anes­
thetic is used for diagnostic purposes. Injecting the anes­ Distal Intertarsal (DIT) or Centrodistal Joint
thetic under pressure was thought to force anesthetic
into the DIT joint, but instead it just causes it to accu­ The site for injection of the DIT joint is on the
mulate in the subcutaneous tissues. In addition, the distomedial surface of the tarsus. The injection is per­
48
anesthetic may enter the tarsal sheath and extend formed from the opposite side of the horse with the
limb weight‐bearing. It is a difficult joint to inject with
an accuracy rate of only 42% in a recent report. One
69
technique is to draw an imaginary line between the pal­
pable distal tubercle of the talus and the space between
Calcaneal the second and third metatarsal bones (MT II and III) at
bursa
their proximal limits. 57,75 A small depression can often
be felt with a fingernail just distal to the cunean tendon
along this imaginary line. Another approach is to iden­
tify the medial eminence of the talus and medial emi­
nence of the central tarsal bone. The site for injection is
halfway between these landmarks and 0.5 inch (1 cm)
Long digital
48
extensor distal to the eminence of the central tarsal bone. A 1‐
tendon inch (2.5‐cm), 22‐ to 25‐gauge needle is directed per­
Tarsocrural joint pendicular to the long axis of the limb (or slightly
caudally) to enter the joint space between the combined
Distal intertarsal Head of first and second tarsal bones, the third, and the central
tarsal bones. The needle is advanced to about 0.5 inches
joint fourth (1 cm) and 3–4 mL of local anesthetic is injected
Tarsometatarsal metatarsus
joint (Figure 2.189; Video 2.37). The needle is determined to
Superficial be within the DIT joint by low resistance to injection
digital flexor without developing a subcutaneous swelling and the
48
tendon ability to aspirate the injected contents of the syringe.
The DIT joint is thought to communicate frequently
with the cunean bursa. 27
Figure 2.187. Injections sites for the dorsolateral (distal needle) The DIT or centrodistal joint can also be entered
38
and the lateral plantar (proximal needle) approaches to the using a dorsolateral approach. The injection site is
tarsocrural joint. 2–3 mm lateral to the long digital extensor tendon and