LA Ortho - Navicular Disease

Question 1

Features of navicular disease

Answer 1

Acute or usually chronic progressive, degenerative condition that effects one or more components of navicular apparatus

Question 2

Components of navicular apparatus

Answer 2

Navicular bone (digital sesamoid bone)
Navicular bursa
DDFT
Supporting ligaments (impair, suspensory ligament of navicular bone)

Question 3

Most common ancillary tendon involved in navicular apparatus

Answer 3

DDFT

Question 4

Side effect of navicular disease

Answer 4

Horses can develop short choppy strides due to the forces on the navicular bone during propulsion phase of strides

Question 5

Pathogenesis of navicular disease

Answer 5

Chronic, progressive, degenerative condition
Etiology is most likely mechanical
Results from a repetitive or excessive imbalance between applied force/stress to tissues & capacity of tissues to distribute / withstand stress

Question 6

Distribution of navicular disease

Answer 6

Forelimbs are more common that hind
Multi limbed or bilateral disease

Question 7

Use pathogenesis for disease development

Answer 7

Overuse - no recovery time
Erratic use - “weekend warriors”
Work on hard ground - concussive force
Overweight/obesity - too much force to accommodate for

Question 8

Pathogenesis due to conformation

Answer 8

Inferior or abnormal conformation can’t withstand reasonable applied loads resulting in abnormal loading of navicular region

Question 9

Examples of inferior conformation

Answer 9

Upright pasterns - angle of P1&P2, handle concussive forces differently
Broken back hoof pastern axis - common cause
Underrun heels - overloading heels can trigger BBHPA
Small feet to body size - common w quarter horses

Question 10

Matched hoof pastern axis

Answer 10

Comparing angular relationship of P1 and P2 to P3
Angle should intersect the middle of 1 2 3 smoothly

Question 11

History for diagnosis

Answer 11

May have a history of an insidious onset of lameness
Forelimbs effected almost exclusively
Often bilaterally lame
Tripping

Question 12

Clinical signs of navicular disease

Answer 12

Short choppy gait
Lameness is often exacerbated by work on hard ground /tight circles
Resent hoof tester pressure over navicular region
Lameness is markedly improved by anesthesia of the palmer digital nerves

Question 13

Importance of digital nerves

Answer 13

Blocking palmar digital nerves is important to confirm the source of lameness is very important for diagnosis

Question 14

Imagining for diagnosis

Answer 14

Radiography (LM, DP, navicular skyline, 65* navicular DP)
MRI
Nuclear scintigraphy
Ultrasound

Question 15

Radiographic changes

Answer 15

Indicates the disease have severally progress
Enlargement of synovial foramina - irregular shape
Medullary sclerosis
Enthesopathy
Distal boarder fragments
Lysis or irregularity of flexor cortex
Cystic formation

Question 16

MRI for navicular disease

Answer 16

Gold standard for imaging navicular apparatus
Can check for bone edema, irregularity, tendon/ligament lesions, cystic/erosive lesions

Question 17

Treatment for navicular disease

Answer 17

Depends on specific diagnosis
Inflammation vs flexor surface erosion vs DDFT lesions

Question 18

Treatment methods

Answer 18

Often multimodal approach
Trimming/shoeing to protect navicular apparatus
Intrasynovial therapies (steroids, HA)
Tendon/ligament (PRP, stem cells)
Bone resorption inhibitors
NSAIDS
Surgery (bursoscopy, tenoscopy)
Rest, controlled exercise, rehab