Ch 64 - Tarsus and Metatarsus

Question 1

What breed may have sesamoids at the tarsometatarsal joint?
How frequently are they reported?

Answer 1

Greyhounds
- Lateral plantar sesamois in 50%
- Small medial intertarsal tarsometatarsal sesamoid 27%

Question 2

What percentage of tarsal movement occurs at the tarsocrural joint?

Answer 2

90%

Question 3

List the 6 main articulations of the tarsus

Answer 3

• tarsocrural
• talocalcaneal
• talocalcaneocentral
• calcaneoquartal
• centrodistal
• tarsometatarsal

Proximal intertarsal joint includes talocalcaneocentral and calcaneoquartal joints
Distal intertarsal joint includes the central tarsal and its articulation with the 1st, 2nd anf 3rd tarsal bones

Question 4

What is the tarsal canal?

Answer 4

A thickening of the plantar fascia medial to the calcanues and plantar to the talus, containing several important structures (plantar brances of saphenous artery and vein, medial and lateral plantar nerves, tendon sheath of flexor hallucis longus

Question 5

List the three compontents of the medial collateral ligament and specific whether they are taut in flexion/extension/both

Answer 5

Long part
- From medial malleolus to central tarsal bone (and talus and 2nd)
- Taut in extension

Tibiocentral (short)
- Taut in extension

Tibiotalar (short)
- Taut in FLEXION (runs 90 degress to the other two)
- Most substantial component of MCL

Question 6

List the components of the lateral collateral ligament and specific wheter each component is taut in extension of flexion

Answer 6

Long lateral ligament
- Taut in extension

Calcaneofibular short ligament
- Taut in extension
- Most substantial compontent of LCL

Talofibular (short)
- Taut in flexion

Question 7

List the three components of the plantar ligaments

Answer 7

Middle plantar ligament
- Base of calcaneus to 4th tarsal and to MT IV and V

Medial plantar ligament
- Sustentaculum tali to central tarsal bone and then to MT joint capsule

Lateral plantar ligament
- Leaves caudal surface of calcaneus and unites with long collateral before attaching to base of MT V

Question 8

What are the main differences in regards to the ligamentous anatomy of the tarsus?

Answer 8

Only have short collateral ligaments

MCL
- oblique tibiotalar
- straight talocentral

LCL
- Calcaneofibular
- talofibular

Question 9

What is the main arterial and nervous supply to the tarsus?

Answer 9

• Cranial tibial artery (becomes dorsal pedal and dorsal MT arteries)
• Plantar branch of saphenous artery (medial and plantar)
• Tibial nerve (becomes medial and lateral plantar nerves)
• Common peroneal nerve
• Saphenous nerve (sensation to dorsomedial tarsus and MT)

Question 10

What is the normal standing angle of the tarsus of the dog and cat?

Answer 10

• Dog: 135 - 145 deg
• Cat: 115 - 125 deg

Question 11

What are the four patterns of fracture of the calcaneus?

Answer 11

• Midbody
• Slab
• Avulsion
• Salter-Harris I

Question 12

What breed is perdisposed to calcaneal fractures?
What is a common concurrent injury
List some fixation options

Answer 12

Racing greyhounds
Commonly concurrent central tarsal bone Fx
Fixation options:
- Lag screws
- K-wires
- Pin and tension band
- Lateral bone plate
- Arthrodesis of calceneoquartal joint (avulsion fractures)

Question 13

What are they 5 types of central tarsal bone Fx?

Answer 13

• Type I: Nondisplaced dorsal slab fracture
• Type II: Displaced dorsal slab Fx
• Type III: Large displaced medial Fx
• Type IV: Medial slab fracture with dorsal slab Fx
• Type V: Comminuted

Question 14

What breed is predisposed to fracture dislocation of the central tarsal bone?

Answer 14

Border Collies - Associated with a fracture of the plantar process

Question 15

What are the main considerations when considering repair of shearing injuries?

Answer 15

• Contamination and possible infection
• Loss of vital structures
• Instability
• Is the remaining bone sufficient to attain a function outcome?

If more than 50% of the joint is intact, saving the joint is justified

Question 16

What is the reported outcome of shearing injuries of the tarsus?

Answer 16

91% good to excellent outcome

Question 17

What breed are predisposed to nontraumatic plantar instability of the proximal intertarsal joint? (Luxation/subluxation)?
What is the recommended Tx?

Answer 17

Middle-aged, overweight Shelties
Tx = Arthrodesis of calcaneoquartal joint
- Transfixation pin and tension band
- Single compression screw through cancaneus and into 4th tarsal bone
- Lateral plate

Question 18

What are the options for arthrodesis of the T-MT joints?

Answer 18

• IM pin and tension band
• Cross pins +/- IM pin
• Multiple pins from MTs into distal tarsal bones
• Lateral plate
• ESF

Question 19

What breed is overrepresented for external MT rotation?
How is it treated?

Answer 19

Bernese Mt Dog
Tx: correct rotational deformity and arthrodesis of proximal intertartsal joint

Question 20

What are the main parts of the common calcaneal tendon?

Answer 20

• Paired tendons of the gastrocnemius
• Common tendon of gracilis, semitendinosus and biceps femoris
• Superficial digital flexor tendon

Question 21

What breeds are predisposed to partial rupture of the common calcaneal tendon?

Answer 21

• Labradors
• Doberman Pinschers
• Old, female cats

Question 22

What novel prosthesis can be used for partial calcaneal ruptures?

Answer 22

Polyethylene terephthalate prosthesis
-Sutured at myotendinous junction of gastroc and attached to calcaneus with interference screw

Question 23

What is the reported outcomes of surgical repair of common calcaneal tendon repair in dogs and cats?

Answer 23

Dogs:
- Good to excellent in 72-94%
- Return to work 71%

Cats:
- 84% good outcome

Question 24

What breeds are overrepresented for luxation of the SDFT?
What dirction does it usually luxate?

Answer 24

• Shelties
• Collies
• Greyhounds

Usually occurs in a lateral direction. Can test by rotating metatarsus medially while flexing the tarsus

Question 25

What augmentation can be adding to a pantarsal arthrodesis?

Answer 25

• IM pins
• transarticular lag screw
• calcaneotibial screw

Question 26

What complication can be seen with medial plating for pantarsal arthrodesis?

Answer 26

Plantar necrosis with loss of soft tissue including MT pad

Question 27

What are the principles of arthrodesis?

Answer 27

Question 28

Describe the basic steps for a pantarsal arthrodesis

Answer 28

• Medial malleolar osteotomy
• Glide hole from medial tibia to medial side of tibial cochlea
• Cartilage on tibial removed at 90 degree to long axis
• Cartilage on talus removed at 45 degree
• Reduced (forms 135 degree angle)
• Holed drilled through glide hole into talus and lag screw placed
• Plate contoured for at least 4 screws in tibia and 2-3 in MT
• Calcaneotibial screw placed through the plate or seperately
• Cartilage removed from remaining joints and bone graft placed
• Dorsal or medial 3.5/2.7mm hybrid plate

Question 29

What is the reported complication rate after pantarsal arthrodesis?

Answer 29

30 - 70%
High complication rate mostly from attempts to arthrodese only the tarsocrural joint

Good outcome expected in more than 50 - 70%