Navicular degeneration Flashcards
What is the navicular bone
distal sesamoidean bone
What is the typical conformation of a horse with navicular degeneration
long toe low heel
broken back Hoof pastern axis
how does a broken back HPA + collapsed heel lead to navicular degeneration?
increases pressure applied on navicular bone
which ligament supports the navicular bone
distal sesamoidean ligaments (impar ligament)
where does the impar ligament insert
proxiamally to the DDFT on P3
True/false the impar ligament and suspensory ligament are involved in navicular degeneration
True
List 4 changes that are seen in navicular degeneration
Focal loss of the medullary architecture
Fibrocartilagenous change of the flexor surface of the bone
Traumatic fibrillation of the deep digital flexor tendon
Enthesiophyte formation on the proximal and distal borders of the bone
Outline the 2 possible causes of navicular degeneration?
Unknown but most likely biomechanical
Possibly some vascular component
List 3 risk factors for navicular degeneration
genetic component
typically older horses >10 yr
foot conformation very important
How to horses with navicular degernation typically presented
Insidious onset bilateral forelimb lameness- Initially intermittent and possible Change in performance
Sound in straight line but Lame on lunge
Rarely positive to hoof testers
Describe how to diagnose navicular degeneration
PDNB- complete resolution- if bilateral lameness will switch to other leg
navicular bursae block- more specific
why is navicular bursa block less commonly used than PDNB for navicular degeneration diagnostics even though it is more specific?
harder to do
needle goes through DDFT In one of the approaches
required radiographic guidance and contrast to confirm placement
What is the main diagnostic imaging tool for navicular degeneration
radiographs
List the radiographic views we need to take to diagnose navicular degeneration
LM
DoPr, PaDi 60 oblique
PaPr PaDi 45 oblique
what changes would we see in a LM view of a horse with navicular degeneration
enthesiophyte –> spur like projection
what changes would we see in a upright navicular of a horse with navicular degeneration
synovial invaginations = round areas of reduced density on the border
± cysts in the bone
what do we need to do before radiographing the foot
fill up the frog (play dough)- if we don’t do this then will get air artefact which could be mistaken for fracture
List 3 advantages of using MRI for navicular degeneration diagnosis
Diagnosis of multiple pathologies
Early diagnosis of bone pathology
shows soft tissue change
What is a possible disadvantage for using MRI to diagnose navicular degeneration
cost
expernsive
what is a STIR image
think it is like an MRI but only shows water -> will show bone oedema
Describe how we manage navicular degeneration cases
via conservative management - no cure for it
Describe conservative management of navicular degeneration
- analgesia: bute ± paracetamol
- corrective farriery (esp in horses with poor conformation)
- steroids into bursa or coffin joint
- biphosphonates (prevents bone resorption by osteoclasts)
what may we do in terms of corrective farriery for navicular degeneration
wedges- reduce extension of DIP (if broken back)
rolled toe- eases break over
bar shoes
what surgical treatment might we give for navic degeneration?
palmar digital neurectomy
What is the main aim of doing palmar digital neurectomy
provide pain relief
List 2 problems with doing palmar digital neurectomy
Nerve sensation will eventually restore
Complications include neuroma and catastrophic DDFT breakdown, pedal osteitis/foot penetrations
