Tarsus and metatarsus Flashcards
Describe the bones of the tarsus
What are the components of the talus?
The body, neck and head.
Sesamoid bones are present at the level of what joint of the tarsus in 50% of Greyhounds?
The tarsometatarsal joint.
Describe the joints of the tarsus
The proximal intertarsal joint includes the talocalcaneocentral and calcaneoquartal joints. The distal intertarsal joint is the centrodistal joint.
Name the components of the lateral collateral ligament in the dog and their function in extension and flexion
Long component: loose in flexion, taught in extension.
Short components:
1. Tibiotalar (most substantial component of the medial collateral): Loose in extension and taught in flexion.
2. Tibiocentral: loose in flexion and taught in extension.
Name the components of the medial collateral ligament in the dog and their function in extension and flexion
Long component: loose in flexion, taught in extension.
Short components:
1. Talofibular: loose in extension, taught in flexion.
2. Calcaneofibular (most substantial component of the medial collateral): loose in flexion, taught in extension.
Which components of the lateral and medial collateral ligaments are given priority during surgical repair?
Medial: Tibiotalar
Lateral: Calcaneofibular
What are the components of the plantar ligaments of the tarsus?
Lateral, middle and medial.
What is the primary difference between the dog and cat in regards to ligamentous support of the tarsus?
The cat has no long components of the medial and lateral collateral ligaments.
What is the vascular supply to the tarsus?
Dorsal and lateral aspects: Branch of the cranial tibial becomes the dorsal pedal artery at the tarsocrural joint, and then forms the dorsal metatarsal arteries.
Medial and plantar: plantar branch of the saphenous artery.
Venous drainage: Medial and lateral saphenous veins
What is the primary innervation to the tarsus?
Two branches of the sciatic nerve: tibial nerve which becomes the medial and lateral plantar nerves, and the common peroneal nerve.
What are the three ligamentous components of the plantar ligaments?
Medial, middle and lateral
Is the fibrous joint capsule of the tarsus thickest on the dorsal or plantar aspect?
Plantar. Extends from the distal tibia to the proximal metatarsus.
What is the normal standing angle of the tarsus?
135-145 degrees in dogs, 115-125 degrees in cats
What is the typical range of motion of the tarsus in dogs and cats?
Dogs: 39 degrees in flexion, 164 degrees in extension
Cats: 22 degrees in flexion, 167 degrees in extension
Which joint of the tarsal joint contributes the majority of tarsal movement?
The tarsocrural joint (90%)
What surgical approaches can be used for access to the medial and lateral talar ridges for talar body fractures?
Osteotomy of the medial or lateral malleolus. Caudal approach has also been described.
Typically repaired using k-wires or small countersunk screws, or bioabsorbable rods.
How are fractures of the tarsal head or neck surgically repaired?
Small screws in lag fashion, traction and transarticular ESF.
What breed of dog is most likely to be affected by calcaneal fracture?
Greyhound, normally on the right side
What fracture frequently occurs in conjunction with calcaneal fracture?
Fracture of the central tarsal bone
What are the four described configurations of calcaneal fracture?
Slab fracture, midbody fracture, avulsion fracture (of palmar ligaments from the sustentaculum tali), avulsion of the apophysis (Salter Harris type 1)
What is typically observed with avulsion fracture of the palmar ligaments from the calcaneous?
Instability of the proximal intertarsal joint and pseudo-plantigrade stance
What surgical treatment options are described for calcaneal fracture?
Screws and K-wires (comminuted), pin and TBW or lateral plate (midbody), arthrodesis (avulsion fracture of plantar ligaments).
When placing a K-wire in the calcaneus care must be taken to avoid irritation of the digital flexors.
Prognosis is good for functional return, but poor for racing return.
Which breed of dog is most commonly affected by central tarsal bone fracture?
Greyhound, typically right sided
What fractures are commonly seen in conjunction with central tarsal bone fracture?
Calcaneal or fourth tarsal bone fracture due to loss of buttress support of the tarsus
What are the classifications of central tarsal bone fracture?
- Type I: Nondisplaced dorsal slab fracture
- Type II: Displaced dorsal slab fracture
- Type III: Large displaced medial fragment
- Type IV: Medial slab fracture with a dorsal slab fracture
- Type V: Comminuted fracture
Which classifications of central tarsal bone fractures are most common?
Type IV and V account for 75% of cases
What is the treatment for central tarsal bone fracture?
Lag screw fixation +/- augmentation with a medial plate (types IV or V).
External coaptation may also be appropriate for type I and II fractures provided a high level of function is not expected.
What type of tarsal fracture is shown?
Type I fracture of the central tarsal bone.
What is the treatment for fracture dislocation of the central tarsal bone?
Lag screw fixation and external coaptation (only reported in 3 border collies).
How are fractures of the 2nd, 3rd, and 4th tarsal bones typically treated?
Lag screw fixation for 2nd and 3rd bones. For fractures of the 4th bone (which typically occur in conjunction with central tarsal bone fracture), stabilization of the central tarsal bone is typically adequate to allow healing
How can surgical repair of fractured malleoli be achieved?
Pin and TBW or lag screw.
Post-op protection of the repair recommended with a short lateral splint or transarticular ESF.
How are injuries to the collateral ligaments of the tarsus surgically repaired?
Avulsion from the tibia or fibula may allow reattachment of the ligament with a small pin or screw, or suturing through a bone tunnel.
Mid body strains are repaired primarily (locking loop) with augmentation via an internal splint, or use of internal splint alone if primary repair not possible.
Internal splint best achieved by use of bone screws/washers and monofilament suture/nylon at locations of short and long components of collateral ligaments. Alternatively bone tunnels or anchors can be used.
Post-operative support with a splint or transarticular ESF for 4-6 weeks is required.
Following shearing injury how much of the joint should remain intact to consider attempts at saving the joint?
50%
What causes luxation/subluxation of the proximal intertarsal joint?
Rupture of the plantar ligaments of the tarsus.
What is the treatment for plantar subluxation of the proximal intertarsal joint?
Calcaneoquartal arthrodesis (transfixation pin and TBW, single compression screw, laterally placed plate).
Which bones are frequently fractured in conjunction with tarsometatarsal luxation/subluxation?
4th tarsal bone, and metatarsal bones II and V
What techniques can be used to augment primary repair of a ruptured calcaneal tendon during healing?
Calcaneotibial screw, transarticular ESF, splint/cast.
These tend to be responsible for more complications than the primary tendon repair.
What is the most common signalment of dogs with partial rupture of the common calcaneal tendon?
Medium to large breed active dogs (particularly labradors and dobermans).
What are common radiographic findings associated with degenerative rupture of the common calcaneal tendon?
Tendon swelling, enthesophytes near the attachment of the tendon to the tuber calcanei.
Describe the basic principles of surgical arthrodesis
What surgical techniques have been performed in conjunction with pantarsal arthrodesis for augmentation of the repair?
Intramedullary pins, transarticular screws in lag fashion, calcaneotibial screws.
What is the ideal length of a dorsal pantarsal arthrodesis plate?
Should allow placement of 4 screws in the distal part of the tibia, and 2-3 screws in the appropriate metatarsal bone (typically III or IV).
What are the surgical options for arthrodesis of the calcaneoquartal joint?
Lag screw, pin and TBW, lateral plate.
A soft splinted support bandage or half cast should be used to protect the limb for 2-4 weeks following surgery.
According to Luescher 2020 in Vet Surg which of the following repairs of the medial collateral ligament in cats was the most biomechanically similar to the intact tarsi?
1) Bone tunnel with polyethylene
2) Bone tunnel with polypropylene
3) Knotless anchor technique with polyethylene
Knotless anchor technique with polyethylene.
In a study by Gunstra 2019 in JAVMA, prosthetic ligament repair was used for which direction(s) of tarsometatarsal luxation? What complications were reported?
Medial or dorsomedial luxations (intact plantar structures).
Complications included wire breakage or bandage related complications. Owners generally reported satisfactory outcomes.
In a study by Easter 2021 in VCOT, what surgical technique was used for stabilization of comminuted central tarsal bone fractures in non-racing dogs?
Medial plating.
Limb function was acceptable in all cases and only minor complications were reported (SSI, contact of plate with medial malleolus, loosening of talar screw).
In a study by Holroyd 2023 in VCOT, at what level of the metatarsal was the intermetatarsal channel delineating the passage of the dorsal pedal artery located? What is the significance of the dorsal pedal artery in tarsal arthrodesis surgery? Is lateral or medial pantarsal arthrodesis more likely to result in plantar necrosis?
The intermetatarsal channel is a shallow sulcus located between metatarsals 2 and 3, in the proximal 25%.
Disruption of the dorsal pedal artery or perforating metatasal artery is thought to contribute to plantar necrosis (although screw position in this study did not impact incidence of plantar necrosis, and therefore other factors may be implicated).
Traditionally medial plating has been associated with a higher risk of necrosis, however, in this study lateral plating had more instances (13% compared to 0% for medial).
The results of this study recommended careful placement of the first metatarsal screw on medially plated arthrodeses and the first two screws when laterally plated.
