Carpus, Tarsus, and Pes

Question 1

describe the skeletal anatomy of the carpus (2)

Answer 1

1. 7 carpal bones held together by a variety of ligaments: intermedioradial carpal bone, ulnar carpal bone, accessory carpal bone, and 1st-4th carpal bones
2. 3 levels of hinge joints:
   -antebrachiocarpal: 90% of movement
   -intercarpal
   -carpometacarpal

Question 2

describe the skeletal anatomy of the tarsus (2)

Answer 2

1. 7 bones held together by a variety of ligaments: talus, calcaneus
   -central and 4th tarsal bone
   -1st, 2nd, and 3rd tarsal bone
2. 4 levels of hinge jointsL
   -tibiotarsal: 90% of movement
   -proximal intertarsal
   -distal intertarsal
   -tarsometatarsal

Question 3

describe the ligament support of the carpus (5)

Answer 3

main support comes from the
1. joint capsule
2. flexor retinaculum- not reparable
3. palmar fibrocartilage- not reparable
4. in dogs, the medial collateral ligament has a straight and an oblique component
5. in cats, the medial collateral ligament only has a straight component, so carpal luxation can occur with disruption of the MCL alone!

Question 4

describe the ligament support of the tarsus

Answer 4

all collateral ligaments have a long part that is taut in extension and a short part that is taut in flexion

it is important to assess mediolateral stability in both positions!

Question 5

what are 7 common conditions of the carpus, tarsus, and pes?

Answer 5

1. fractures
2. carpal hyperextension injury
3. traumatic antebrachiocarpal and tarsocrural luxation
4. traumatic antebrachiocarpal and tarsocrural subluxation (collateral ligament injury)
5. intertarsal and tarsometatarsal subluxation
6. achilles tendon injury
7. tarsal OCD

Question 6

describe clinical evaluation of the carpus, tarsus, and pes

Answer 6

1. pay attention to standing angle, compare to contralateral; look for dropped hocks and hyperextension
2. swelling may localize an injury with accuracy because there is only sparse soft tissue coverage in these areas; compare to contralateral
3. many injuries result in instability, so systemic and careful palpation is carried out with the joint stressed in mediolateral, dorsoplantar, and rotatory planes; compare to contralateral
4. repeat exams when patient is sedated or anesthetized; may resist or be tense when awake!

Question 7

describe diagnostic evaluation of carpus, tarsus, and pes

Answer 7

1. orthogonal radiographs augmented with stress views, oblique views, and contralateral views
2. CT is more sensitive than radiographs for fracture eval
3. both/all may be required for accurate diagnosis!

Question 8

describe carpal and tarsal fractures

Answer 8

1. typically secondary to trauma and more common in active dogs
2. often articular

Question 9

describe 3 treatment options of carpal and tarsal fractures

Answer 9

1. primary repair: pins, lag screws, plate and tension band wire, plate fixation
2. arthrodesis: partial carpal/tarsal, pancarpal/pantarsal
3. external coapatation not recommended; joint incongruity and OA can lead to persistent lameness

Question 10

describe metacarpal and metatarsal fractures

Answer 10

1. traditionally surgery is recommended if
   more than 2 are fractured, MC3 and MC4 and fractured, marked displacement, base of MC II and V are fractures (don’t know criteria)
   -can place small bone plates, little IM pins ALONE!!, of ESF but almost always protect with coaptation anyways
2. in reality: many cases can be managed successfully with coaptation

Question 11

describe carpal hyperextension injuries (5) in general

Answer 11

1. most common carpal inujury
2. damage to flexor retinaculum and palmar fibrocartilage
3. injury can occur at any joint level
4. common is medium/large breed dogs
5. typically involved jump/fall from height

Question 12

describe acute versus chronic carpal hyperextension injuries

Answer 12

acute
1. non weight bearing
2. carpal swelling
3. pain on manipulation

chronic:
may present weight bearing with a hyperextended carpus

Question 13

describe diagnostics of carpal hyperextension

Answer 13

stress radiographs are very important! look for areas of maximum angular change and compare to contralateral

Question 14

describe treatment of carpal hyperextension injuries (3)

Answer 14

1. conservative treatment is rarely successful
2. surgical treatment is arthrodesis: partial or pancarpal because cannot repair the structures!, +/- postop copatation with palmar splint
3. if sx not an option, can do orthotics; like a brace for exercise to get reasonable quality of life; can become comfortable despite instability but will develop arthritis likely

Question 15

describe antebrachiocarpal luxation

Answer 15

see luxation lecture; remember is due to major trauma in dogs, and less severe trauma in cats

Question 16

describe trasocrural luxation

Answer 16

see luxation lecture; just remember often a malleolar fracture in conjugation with luxation and shearing injuries are common

Question 17

describe antebrachiocarpal/tarsocrural collateral ligament injury

Answer 17

1. sprains of collateral ligaments can cause varyin degrees of lameness, often with lcoal soft tissue swelling, pain on palapation, but if just a sprain, instability is unlikely
2. rupture of ligament leads to mediolateral instability
3. diagnosis is usually confimred by joint space widening on stressed views
4. palpation and radiographs of the unaffected limb can be helpful comparison

treatment options:
1. coaptation: if mild instability; splint bandage, immobilize tarsus/caprus for fibrosis to occur
2. surgical reconstruction with prosthethic ligament if more severe
3. arthrodesis

Question 18

describe assessment of collateral ligament injury of antebrachiocarpal joint

Answer 18

1. assess carefully for hyperextension
2. isolated collateral ligament in carpus is uncommon! (need to rule out hyperextension)

Question 19

describe assessment of collateral ligament injury of tarsus joint

Answer 19

1. medial ligament disrupted more frequently than antebrachiocarpal
2. not uncommon for both medial AND lateral structures to be damaged
3. may have concurrent malleolar fracture (intra-articular, avulsion); so should provide anatomic reduction and rigid fixation (internal fixation with pin +/- tension band wire or lag screw)

-and/or shearing injury , often affecting the medial aspect of the joint; treatment options depend on underlying injuries (fractures, ligament disruption); primary concerns are delayed wound healing from instability and increased risk of infection
-trans-articular ESF may be useful for shearing injuries: provide stability, allow for wound management, but complications
-prognosis: good for weight bearing but will have decreased ROM and may require arthrodesis in the future

Question 20

describe intertarsal/tarsometatarsal subluxation

Answer 20

1. plantar instability most common and clinically significant; often secondary to trauma, concurrent fractures are common
2. treatment:
   -splinting typically not successful, partial tarsal arthrodesis recommended (intertarsal joints and tarsometatarsal joint, will not affect overall joint function that much bc low movement here)

Question 21

describe plantar instability: achilles tendon injuries

Answer 21

1. five components of achilles tendon (Good Sailors Build Good Ships)
   -gastrocnemius
   -SDFT
   -combined tendon of: biceps femoris, gracilis, and semitendinosus
2. two common presentations:
   -traumatic: penetrating wound, midsubstance tear, complete disruption
   -atraumatic: (chronic tendinopathy slowly tears over time): medium/large active dogs, tear at calcaneal insertion, start as partial and can progress to full tear

Question 22

describe traumatic rupture of the achilles tendon (5)

Answer 22

1. acute severe lameness
2. swelling, apin, bruising
3. wound is not always present or obvious
4. will have a palpable defect though (skin on skin between fingers, not tendon feeling)
5. dropped hock due to inability to extend tarsus

Question 23

describe atraumatic rupture of achilles tendon (4)

Answer 23

1. acute/chronic lameness
2. tendon thickening, often bilateral so won’t always have a comparison
3. varying degrees of plantigrade stance
4. clenched toes: partial disruption of intact SDFT; SDFT gets stretched and flexes digits

Question 24

describe diagnostic imagng of achilles tendon rupture

Answer 24

1. radiographs: swelling/thickening, avulsion fragment, entehsophyte formation, mineralization
2. ultrasound: useful for ID specifics: site/level of injury, structures involved

Question 25

describe treatment options of achilles tendon rupture (2)

Answer 25

dependent on severity and location

1. low grade strain/partial rupture (LONG PROCESS):
   -can try non surgical approach
   -external support to keep in extension (splint/custom orthotic)
   -exercise restriction strict for 4 weeks
   -physical therapy to promote gradual tendon loading (UWTM)
   -adjunctive therapies to stimulate healing: PRP, stem cells, US, laser, shock wave
2. complete or failed conservative management or traumatic tear:
   surgical repair recommended: tendon suture pattern + immobilization

Question 26

describe temporary immobilization of surgical repair of rupture of achilles tendon (3)

Answer 26

1, critical to protect the repair
2. different methods: cast/splint, calcaneotibial screw, ESF- all have complications
3. how long: 6-12 weeks, maximum 4 weeks of rigid stabilization, incrementally decrease amount of support (long recovery process)

Question 27

what is the last resort of treatment of a ruptured achilles tendon?

Answer 27

pantarsal arthrodesis:
if tendon repair has failed or is not possible; relatively high risk of complications but can yield good to excellent outcomes

Question 28

describe tarsal OCD; include location, clinical presentation, diagnosis, treatment options, and prognosis

Answer 28

1. more common in dogs, on the medial or lateral trochlear ridges of talus (medial more common)
2. clinical presentation:
   -young, 4-8 months
   -large and giant breed dogs
   -lameness, pronounced effusion, crepitus
3. diagnosis:
   -radiographs: oblique craniocaudal, flexed views)
   -CT best
4. treatment options:
   -medical (always)
   -surgical (arthroscopy): flap removal + arthroplasty or total ankle replacement/arthrodesis (end stage OA)
5. prognosis: guarded
   -dogs may improve with surgery
   -many have residual/progressive lameness