Equine Musculoskeletal: Navicular Syndrome Flashcards

1
Q

how common is navicular syndrome?

A

most common degenerative disorder of the foot causing lameness

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2
Q

what makes up the podotrochlear apparatus?

A

navicular bone
collateral sesamoidean ligaments
impar ligament
deep digital flexor tendon
navicular bursa
coffin joint- partially

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3
Q

which horses are genetically predisposed to navicular syndrome?

A

quarter horses
thoroughbreds
warmbloods

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4
Q

what does increased stiffness of bone lead to?

A

overload of cartilage

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5
Q

what is history like with navicular syndrome?

A

mostly chronic front limb lameness, often intermittent
lameness can also be acute onset
most often bilateral front, can be unilateral

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6
Q

which radiograph views are used for the navicular bone?

A

lateral view
60 degree dorso-palmar view
proximopalmar-to-distopalmar tangential view- “skyline”

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7
Q

what changes can be seen with the proximopalmar-to-distopalmar tangtial view- “skyline”?

A

medullary sclerosis
loss of corticomedullary junction- flexor surface
irregularities along the flexor surface
may be normal

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8
Q

what does a nuclear scintigraphy bone scan show?

A

bony inflammation

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9
Q

what are some abnormal findings in an MRI for navicular syndrome?

A

navicular bone edema
deep digital flexor tendonitis
desmitis
navicular bursitis
adhesions within navicular bursa

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10
Q

how can navicular syndrome be medically managed mainly?

A

corrective shoeing
NSAIDs
intra-articular therapy
intra-bursal therapy
biphosphonates

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11
Q

when are biphosphonates used?

A

primarily in cases of primary navicular bone degeneration

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12
Q

what is the mode of action of biphosphonates?

A

biphosphonate is taken up by osteoclasts inducing inactivation or apoptosis

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13
Q

what are the surgical options for navicular syndrome?

A

navicular buroscopy
palmar digital neurectomy

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14
Q

when can palmar/plantar digital neurectomy be performed?

A

when medical treatment or buroscopy is unsuccessful
first option: in cases with navicular bone changes

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15
Q

where is the incision made for palmar/plantar digital neurectomy?

A

over ligament of ergot

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16
Q

what is navicular syndrome?

A

injury to one or several components of the equine podotrochlear apparatus

17
Q

what is the podotrochlear apparatus?

A

palmar/plantar structures of the foot around the navicular bone as fulcrum

18
Q

is navicular syndrome unilateral or bilateral?

19
Q

what conformation predisposes a horse to navicular syndrome?

A

narrow upright feet
straight or upright pastern
large body with small hoof size

20
Q

what does increased stiffness of bone lead to?

A

overload to cartilage

21
Q

what does upregulation of blood supply to navicular bone promote?

A

neovascularizatin

22
Q

what do new blood vessels in the medulla of bone leaking serum into the perivascular space lead to?

A

perivascular fibrosis
bone edema
obstruction of venules
intra-osseous pressure increase
bone pain

23
Q

what nerve block can help with identifying navicular syndrome?

A

palmar digital nerve anesthesia

24
Q

what changes can be seen with the 60 degree dorso-palmar view with navicular syndrome?

A

irregularities along the distal border
marginal osteophytes/enthesiophytes
cyst-like lesions
medullary sclerosis

25
what structures can be seen with ultrasound in looking for navicular syndrome?
deep digital flexor tendon navicular bursa parts of coffin joint collateral ligament of the navicular bone impar ligament bony line of navicular bone
26
where does radioisotope concentrate in nuclear scintigraphy?
areas of increased bony activity
27
what are the main abnormal findings in MRI for navicular syndrome?
navicular bone edema deep digital flexor tendonitis desmitis navicular bursitis adhesions within navicular bursa
28
what is done in corrective shoeing for navicular syndrome?
egg bar shoe with 2-3 degree wedge shorten toes and shoe with squared toe use shoe slightly wider than foot
29
when are biphosphonates used?
primarily in cases of primary navicular bone degeneration
30
when might a navicular bursoscopy be performed?
adhesions DDFT tears damage to flexor surface of navicular bone
31
when is a palmar/plantar digital neurectomy the first choice?
navicular bone changes
32
what is the most common reason a palmar/plantar digital neurectomy fails?
regeneration of the transected nerve