Diagnostic Anesthesia for Lameness of the Hindlimb

True or False: Everything up to the mid-pastern ring block or abaxial sesamoid block is the same in the forelimb and hindlimb.

True!

What are the SIX nerves blocked in a low six-point block?

Plantar nerves

Plantar metatarsal nerves

Dorsal metatarsal nerves

What are the landmarks for the plantar nerve in a low six-point block?

Proximal to tendon sheath between suspensory and DDFT

What are the landmarks for the plantar metatarsal nerves in a low six-point block?

Base of the splints at the buttons

What are the landmarks for the dorsal metatarsal nerves?

Dorsal cannon bone

Why do you NOT need to worry about blocking the ramus communicans in the hindlimb?

Rudimentary or nonexistent -> located much more distally if present

True or False: The contribution of the ramus communicans in relay of sensation can be ignored in the hindlimb if the structure is present there.

True!

What ADDITIONAL structures are blocked by a low six-point nerve block? (3)

Fetlock joint and below

Distal digital tendon sheath

Insertion branches of suspensory lig

What TWO conditions may respond to a low six-point block?

1. Fetlock conditions

2. Tendon sheath conditions

Why is it not uncommon for veterinarians to start with the low six-point block in the hindlimb?

Rare to have hoof and navicular issues in the hind

What nerves arise from the deep branch of the lateral plantar nerve?

Medial/lateral plantar metatarsal nn, nerves that supply proximal suspensory

How much the limb be positioned and what is the landmark when performing a block of the deep branch of the lateral plantar nerve block (DBLPN)?

Flexed 15mm distal to MTIV articular surface by resting on stool (push flexors medially to visualize MTIV)

How many mLs of anesthesia should be used to block DBLPN?

5-10cc

What major structure is blocked with a DBLPN block?

Proximal suspensory ligament

What are the THREE structures that can be inadvertently injected during a DBLPN block?

1. Tarsal sheath of DDFT

2. Tarsal metatarsal joint

3. Lateral plantar nerve

What nerve blocks the limb from the tarsus distally?

Tibial and peroneal nerve blocks

True or False: Blocking the tibial and peroneal nerves separately instead can localize pain more precisely.

True!

True or False: It is often difficult to distinguish lameness due to proximal suspensory desmitis vs osteoarthritis of the distal tarsak joints.

True!

Blocking the tibial and peroneal nerves separately is especially a good idea when you need to localize the site of pain in the --- region.

Hock

Lameness caused by proximal suspensory desmitis may improve after anesthesia of the ---------------- and lameness caused by osteoarthritis of the distal tarsal joints may improve after anesthesia of the -------------------.

TMT joint

Deep br. lateral plantar n

The tibial nerve is located (medially/laterally)

Medially

What nerves arise from the tibial nerve?

Medial and lateral plantar nerves

What is the landmark for the tibial nerve block?

Medial leg between calcaneal tendon and DDFT 10cm proximal to point of hock

Where/how should your needle be placed for a tibial nerve block?

Caudal surface of DDFT to lie close to neurovascular bundle

How much anesthesia is needed for the tibial nerve block?

15-20 mLs

Why will blocking the tibial nerve improve or abolish lameness caused by proximal suspensory desmitis?

Tibial n -> lateral plantar n -> deep branch of lateral plantar n -> innervates suspensory

What structure is very small compared to the forelimb on MSK ultrasound?

Inferior check ligament

What makes the peroneal nerve block different than others?

Has a superficial and deep portion

What is the landmark for the peroneal nerve block?

Lateral aspect of crus 10cm proximal to point of hock in groove between long and lateral digital extensors

How many mLs is needed to block the peroneal nerve?

10 cc each portion

What structure is specifically blocked with a peroneal nerve block?

Distal joints of the tarsus

What TWO major conditions respond to a peroneal nerve block?

1. Bone spavin

2. Fractures of small tarsal bones (T2, T3, T4, central tarsal)

What major motor issue can occur after a peroneal nerve block?

What should you always do with this block to minimize this risk?

Buckling fetlock joint (extensor paralysis)

Bandage

The peroneal nerve, when functional, flexes the --- and extends the ---.

Hock

Digits

What are the FOUR major tarsal joints in order from proximal to distal?

1. Tarsocrural

2. Proximal intertarsal (PIT)

3. Distal intertarsal (DIT)

4. Tarsometatarsal (TMT)

What joints of the hock ALWAYS communicate directly with one another (3)?

Tarsocrural, PIT, talocalcaneal

What TWO joints have a variable communication in the hock from 8.3-70%?

DIT and TMT

When do the DIT and TMT communicate functionally?

Mepivacaine or methylprednisone injected into TMT joint

What is the easiest pouch of the tarsocrural joint to inject?

Dorsomedial pouch

What is the landmark for the dorsomedial pouch of the tarsocrural joint?

Medial or lateral to the saphenous vein

What is the landmark for the lateroplantar pouch of the tarsocrural joint?

Distension between calcaneus and the lateral malleolus of the tibia

How can you make the lateroplantar pouch more obvious?

Apply pressure to the dorsomedial pouch

How much anesthetic is administered to the lateroplantar pouch of the tarsocrural joint?

10-20 mLs

What THREE joints are blocked by a tarsocrual joint block?

1. Tibial tarsal joint

2. Talocalceneal joint

3. Proximal intertarsal joint

What THREE condition may respond to a tarsocrural joint block?

1. Osteochondrosis distal intermediate ridge of the tibia

2. Malleolar fractures of tibia

3. Trochlear ridge fractures

Why is the DIT rarely blocked?

Challenging, inaccurate, and often not necessary since functional communication with TMT

What is the landmark for the medial approach to the DIT?

Gap formed between fused 1+2, third, and central tarsal bones

You should insert your needle for a medial approach of the DIT near the point where the distal border of the ----------- crosses the horizontal depression between the proximal and distal rows of tarsal bones.

Cunean tendon

What is the landmark for the DIT joint block from the dorsolateral approach?

2-3 mm lateral to long digital extensor and 6-8 mm proximal to a line drawn perpendicular to the axis of MTIII through the proximal end of MTIV

What is often useful in the DIT to confirm accurate arthrocentesis due to high frequency of inaccuracy?

Contrast arthrography

What is the landmark for the plantarolateral approach to the TMT joint?

0.25 in above the lateral splint bone and 0.5 in lateral to lateral SDFT

How is the needle directed in a plantarolateral approach to the TMT joint?

Downward toward the dorsomedial aspect of the tarsus

True or False: The TMT is above the splint, while the DBLPN is below the splint.

True!

What can occur when forcing a large volume of solution into a joint?

Does this mean its in the joint?

Distinct pop and loss of resistance

No, often means accumulating SQ, especially if the DIT

What is blocked in a tarsometarsal joint block?

Tarsometatarsal joint +/- DIT

You should hold the hub to avoid accidental blow out of product when injecting what joint of the hock?

TMT joint

What major condition should respond to a TMT joint block?

Bone spavin

What TWO major conditions may respond if diffusion of anesthetic is outside the TMT joint?

1. Proximal suspensory desmitis

2. Stress remodeling of plantar MTIII

Name the joints of the stifle and any compartments they may have.

Femoropatellar

Femorotibial -> medial and lateral compartments

What is the largest stifle joint?

Femoropatellar

The femoropatellar joint communicates ---% with the ----------- joint and rarely with the -----------------.

65%

Medial femorotibial

Lateral femorotibial

Although each compartment and joint of the stifle can be injected altogether, what are TWO reasons why this could be a disadvantage?

1. Uncertainty of communications

2.Inflammation of joints may result in communication obstruction

What is the landmark for the intrapatellar ligament approach in the femoropatellar joint?

Between the middle and medial patellar ligaments 2.5-4 cm proximal to tibial tuberosity

How many mLs are put into the femoropatellar joint?

20 mLs

What is the landmark for the lateral cul-de-sac approach to the femoropatellar joint?

What is contacted and then slightly retracted from?

5cm proximal lateral tibial condyle caudal to lateral patellar ligament lateromedially

Abaxial side of lateral trochlear ridge of femur

True or False: Synovial fluid is often seen in the injection of the femoropatellar joint.

True!

What is the landmark for the major approach to the medial femorotibial joint?

Between medial patellar ligament and medial collateral femorotibial ligament proximal to medial meniscus

What is one downside to the major approach to the medial femorotibial joint?

Synovial fluid rarely aspirated

What is the landmark for the alternative approach to the medial femorotibial joint?

Between medial patellar ligament and tendon of sartorius muscle about 2.5 cm proximal to tibial plateu

What are TWO advantages to the alternative approach to the medial femorotibial joint?

1. Synovial fluid consistently recovered

2. Needle not directed toward medial meniscus or articular cartilage (less likely to have pain reaction)

What are the landmarks for the lateral femorotibial joint?

1-4 cm distal to proximolateral edge of tibia directly through center of tendon of long digital extensor muscle until tip of needle contacts bone

Is synovial fluid generally aspirated from the lateral femorotibial joint?

No

When is injection of the lateral femorotibial joint easier?

When not fully weight bearing

With the lateral femorotibial joint, --------- is a sign of correct needle placement and accuracy of the technique is high.

Ease of injection

What is the landmark for when you inject all three compartment of the stifle at once?

Between the lateral and middle patellar ligaments

What modality is good at looking at bones and is best used in orthopedic cases or of the head, including teeth and sinuses?

Radiograph