Ch 64 - Tarsus and Metatarsus Flashcards
What breed may have sesamoids at the tarsometatarsal joint?
How frequently are they reported?
Greyhounds
- Lateral plantar sesamois in 50%
- Small medial intertarsal tarsometatarsal sesamoid 27%
What percentage of tarsal movement occurs at the tarsocrural joint?
90%
List the 6 main articulations of the tarsus
- 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
What is the tarsal canal?
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
List the three compontents of the medial collateral ligament and specific whether they are taut in flexion/extension/both
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
List the components of the lateral collateral ligament and specific wheter each component is taut in extension of flexion
Long lateral ligament
- Taut in extension
Calcaneofibular short ligament
- Taut in extension
- Most substantial compontent of LCL
Talofibular (short)
- Taut in flexion
List the three components of the plantar ligaments
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
What are the main differences in regards to the ligamentous anatomy of the tarsus?
Only have short collateral ligaments
MCL
- oblique tibiotalar
- straight talocentral
LCL
- Calcaneofibular
- talofibular
What is the main arterial and nervous supply to the tarsus?
- 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)
What is the normal standing angle of the tarsus of the dog and cat?
- Dog: 135 - 145 deg
- Cat: 115 - 125 deg
What are the four patterns of fracture of the calcaneus?
- Midbody
- Slab
- Avulsion
- Salter-Harris I
What breed is perdisposed to calcaneal fractures?
What is a common concurrent injury
List some fixation options
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)
What are they 5 types of central tarsal bone Fx?
- 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
What breed is predisposed to fracture dislocation of the central tarsal bone?
Border Collies - Associated with a fracture of the plantar process
What are the main considerations when considering repair of shearing injuries?
- 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
What is the reported outcome of shearing injuries of the tarsus?
91% good to excellent outcome
What breed are predisposed to nontraumatic plantar instability of the proximal intertarsal joint? (Luxation/subluxation)?
What is the recommended Tx?
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
What are the options for arthrodesis of the T-MT joints?
- IM pin and tension band
- Cross pins +/- IM pin
- Multiple pins from MTs into distal tarsal bones
- Lateral plate
- ESF
What breed is overrepresented for external MT rotation?
How is it treated?
Bernese Mt Dog
Tx: correct rotational deformity and arthrodesis of proximal intertartsal joint
What are the main parts of the common calcaneal tendon?
- Paired tendons of the gastrocnemius
- Common tendon of gracilis, semitendinosus and biceps femoris
- Superficial digital flexor tendon
What breeds are predisposed to partial rupture of the common calcaneal tendon?
- Labradors
- Doberman Pinschers
- Old, female cats
What novel prosthesis can be used for partial calcaneal ruptures?
Polyethylene terephthalate prosthesis
-Sutured at myotendinous junction of gastroc and attached to calcaneus with interference screw
What is the reported outcomes of surgical repair of common calcaneal tendon repair in dogs and cats?
Dogs:
- Good to excellent in 72-94%
- Return to work 71%
Cats:
- 84% good outcome
What breeds are overrepresented for luxation of the SDFT?
What dirction does it usually luxate?
- Shelties
- Collies
- Greyhounds
Usually occurs in a lateral direction. Can test by rotating metatarsus medially while flexing the tarsus
What augmentation can be adding to a pantarsal arthrodesis?
- IM pins
- transarticular lag screw
- calcaneotibial screw
What complication can be seen with medial plating for pantarsal arthrodesis?
Plantar necrosis with loss of soft tissue including MT pad
What are the principles of arthrodesis?
Describe the basic steps for a pantarsal arthrodesis
- 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
What is the reported complication rate after pantarsal arthrodesis?
30 - 70%
High complication rate mostly from attempts to arthrodese only the tarsocrural joint
Good outcome expected in more than 50 - 70%
