Page 217 - Adams and Stashak's Lameness in Horses, 7th Edition

Examination for Lameness 183

VetBooks.ir Calcaneal
bursa

Long digital
Medial extensor
malleolus tendon Distal
of tibia
Tarsocrural intertarsal
joint joint
Tarsocrural
Sustentaculum joint Head of
tali fourth
Distal Tarsometatarsal metatarsus
intertarsal joint
joint Superfical
Superficial Tarsal sheath digital flexor
digital flexor tendon
tendon Deep digital
flexor tendon
Figure 2.189. Injection site for the medial approach to the
DIT joint. Figure 2.190. The dorsolateral approach to the DIT joint is
2–3 mm lateral to the long digital extensor tendon and approximately
6–8 mm proximal to a line drawn perpendicular to the axis of the
6–8 mm proximal to a line drawn perpendicular to the third metatarsal bone through the head of the fourth metatarsal
axis of the third metatarsal bone through the head of the bone. This is usually distal to the palpable lateral trochlear ridge of
fourth metatarsal bone. This is usually distal to the pal­ the talus. The needle is directed plantaromedially at an angle of
pable lateral trochlear ridge of the talus. The needle is approximately 70° from the sagittal plane until bone is contacted.
directed plantaromedially at an angle of approximately
70° from the sagittal plane until bone is contacted
(Figure 2.190; Video 2.38). This approach is safer for those described for insertion of the arthroscope into the
the clinician because it is performed on the lateral aspect calcaneal bursa: 1 cm dorsal to the SDFT and 1 cm distal
of the tarsus but may be even more technically difficult to the medial or lateral aspect of the SDFT retinaculum
36
than the medial approach. (Figure 2.191). Approximately 8–12 mL of anesthetic
is used to block the bursa.
Cunean Bursa

The cunean bursa is located on the medial surface of Stifle Joint
the distal tarsus between the medial collateral ligament The stifle joint is composed of three synovial compart­
of the tarsus and the medial branch of the tibialis crania­ ments: the femoropatellar and the lateral femorotibial
lis (cunean) tendon. The bursa is relatively small and is (LFT) and medial femorotibial (MFT) joints. Contrast
not routinely anesthetized or treated alone because it studies have shown that the frequency of communication
often communicates with the DIT joint. A 1‐inch between the femoropatellar and the MFT joint is approx­
27
(2.54‐cm), 22‐gauge needle is inserted under the distal imately 60%–65%. 54,80 The communication, however, is
border of the cunean tendon and directed proximally to variable and appears to depend on the direction of flow
enter the bursa. Some clinicians treat the cunean bursa of the injectable agent, the amount of joint inflammation,
concurrently when medicating the DIT joint in horses and anatomic variation. Communication between the
with distal tarsal OA. femoropatellar and the MFT joint is observed more fre­
quently when the MFT joint is injected than when the
Calcaneal Bursa femoropatellar joint is injected. Communication between
the femoropatellar joint and the LFT joint occurs rarely,
The calcaneal bursa is located between the SDFT and and communication between the MFT and LFT joints
the caudal aspect of the calcaneus. When distended, the does not occur under normal situations. Some clinicians
bursa has synovial outpouchings medial and lateral to feel that each synovial compartment of the stifle should
the tendon both proximal and distal to the SDFT reti­ be injected separately to ensure accurate distribution of
naculum. These can often be seen as four distinct pock­ local anesthetic. However, greater diffusion of local
75
ets of fluid surrounding the point of the hock‐in horses anesthetic between compartments of the stifle probably
with bursal distension. Synovial aspiration is best per­ occurs than what has previously been assumed based on
formed using the lateral synovial outpouchings either anatomic, latex injection, and contrast arthrography
above or below the SDFT retinaculum with the horse studies. 27,48 The majority of the injection approaches to
weight‐bearing. A 1‐inch (2.5‐cm), 20‐gauge needle is all compartments of the stifle are performed in the
angled proximally within these outpouchings to avoid weight‐bearing limb, and approximately 20–30 mL of
the SDFT. The sites for needle placement are the same as anesthetic is usually recommended in each joint.