Equine Musculoskeletal: Navicular Syndrome Flashcards
how common is navicular syndrome?
most common degenerative disorder of the foot causing lameness
what makes up the podotrochlear apparatus?
navicular bone
collateral sesamoidean ligaments
impar ligament
deep digital flexor tendon
navicular bursa
coffin joint- partially
which horses are genetically predisposed to navicular syndrome?
quarter horses
thoroughbreds
warmbloods
what does increased stiffness of bone lead to?
overload of cartilage
what is history like with navicular syndrome?
mostly chronic front limb lameness, often intermittent
lameness can also be acute onset
most often bilateral front, can be unilateral
which radiograph views are used for the navicular bone?
lateral view
60 degree dorso-palmar view
proximopalmar-to-distopalmar tangential view- “skyline”
what changes can be seen with the proximopalmar-to-distopalmar tangtial view- “skyline”?
medullary sclerosis
loss of corticomedullary junction- flexor surface
irregularities along the flexor surface
may be normal
what does a nuclear scintigraphy bone scan show?
bony inflammation
what are some abnormal findings in an MRI for navicular syndrome?
navicular bone edema
deep digital flexor tendonitis
desmitis
navicular bursitis
adhesions within navicular bursa
how can navicular syndrome be medically managed mainly?
corrective shoeing
NSAIDs
intra-articular therapy
intra-bursal therapy
biphosphonates
when are biphosphonates used?
primarily in cases of primary navicular bone degeneration
what is the mode of action of biphosphonates?
biphosphonate is taken up by osteoclasts inducing inactivation or apoptosis
what are the surgical options for navicular syndrome?
navicular buroscopy
palmar digital neurectomy
when can palmar/plantar digital neurectomy be performed?
when medical treatment or buroscopy is unsuccessful
first option: in cases with navicular bone changes
where is the incision made for palmar/plantar digital neurectomy?
over ligament of ergot
what is navicular syndrome?
injury to one or several components of the equine podotrochlear apparatus
what is the podotrochlear apparatus?
palmar/plantar structures of the foot around the navicular bone as fulcrum
is navicular syndrome unilateral or bilateral?
bilateral
what conformation predisposes a horse to navicular syndrome?
narrow upright feet
straight or upright pastern
large body with small hoof size
what does increased stiffness of bone lead to?
overload to cartilage
what does upregulation of blood supply to navicular bone promote?
neovascularizatin
what do new blood vessels in the medulla of bone leaking serum into the perivascular space lead to?
perivascular fibrosis
bone edema
obstruction of venules
intra-osseous pressure increase
bone pain
what nerve block can help with identifying navicular syndrome?
palmar digital nerve anesthesia
what changes can be seen with the 60 degree dorso-palmar view with navicular syndrome?
irregularities along the distal border
marginal osteophytes/enthesiophytes
cyst-like lesions
medullary sclerosis
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
where does radioisotope concentrate in nuclear scintigraphy?
areas of increased bony activity
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
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
when are biphosphonates used?
primarily in cases of primary navicular bone degeneration
when might a navicular bursoscopy be performed?
adhesions
DDFT tears
damage to flexor surface of navicular bone
when is a palmar/plantar digital neurectomy the first choice?
navicular bone changes
what is the most common reason a palmar/plantar digital neurectomy fails?
regeneration of the transected nerve
