Equine Foot

sihirlifil's version from 2017-12-10 21:27


Question Answer
Which radiographic views are used?Lateral (lateromedial)
Dorsoproximal-palmarodistal Oblique = DP60PaDiO (Upright pedal, oxspring, Navicular views)
Obliques for palmar processes P3
Palmaroproximal-palmarodistal oblique = PaPrPaDiO (Skyline or Flexor view)
Lateromedial: what is 'good conformation'?Straight line through P1, P2, and P3
How is the lateromedial projection taken?Beam: Lateral
Cassette: medial aspect of limb on the ground, foot (or both feet to get square) on blocks (dont need blocks for P2 & above)
Include toe & heel bulb
Orange: Extensor process P3
Teal: Distal interphalangeal joint
Black: P3
Pink: Palmar processes of P3
Blue: navicular bone
What's the problem here?
Enthyseophytes in extensor tendon suggesting trauma to the tendon proximal to its attachment on P3
Normally can have biphasic shape, undulation in middle
What is foot balance? How do you calculate?Drop a line to the ground in the center where the 2 condyles of P2 are. The distance between this point and the toe should be the same as from from the point where the heel touches the ground
Dorsal hoof wall parallel to the dorsal aspect of P3 and the palmar aspect of the bulbs of the heel
Solar angle in some horses 3-11 degrees (angle from distal P3 to the bottom of foot)
What's the problem?
Foot balance pushed caudal, affecting breakover (horse has to lift foot higher)
DP of phalanges: how is the projection taken?Beam: Horizontal from front
Cassette: palmar, parallel to pastern
Center on P3 (foot on block) or fetlock (foot on ground)
Must include solar hoof margin!
Dorsoproximal-Palmarodistal Oblique (Oxspring view): 2 variants?Upright pedal (foot on Hickman block, lifted off ground)
High coronary (foot on ground, placed on tunnel on cassette)
Upright pedal: how do the vascular channels look?Get wider as they move to the periphery
High coronary: how does P3 look?Elongated distortion of shape, because machine & cassette are not parallel (x-ray beam not parallel to P3)
High coronary: really good in what situations?If horse has really sore feet & doesn't want to pick it up for upright pedal
Also done if you have no help
DProx-PDistO: technique for P3?Centering on coronary band
No grid
Horizontal beam
DProx-PDistO: technique for navicular bone?Centering 1cm proximal to coronary band
Increased exposure
Closer collimation (heel bulbs are dense, generate scatter)
Frog can be packed to displace air in frog
Make sure feet are even (pastern drops and pushes up navicular bone if foot taken behind the weight-bearing one)
Can views be taken with the shoe still on?Yes BUT have to say "can't comment on this radiograph" because it can cover pathology at solar margins
What's going on?
Air in sulcus of frog! NOT FRACTURE! (straight line through joint, so can't be)
What's this?
Always dead center, radiolucent, bilaterally symmetrical
What's this?
Synovial fossa
Found on DISTAL BORDER OF NAVICULAR BONE and nowhere else!
Abnormal ones associated with navicular syndrome
PaPrPaDiO: how is this projection taken?Beam: From back of foot high to low 65*
Cassette: placed in tunnel, on ground
Center: between heel bulbs
Machine placed level with elbow
MAY need pain relief: pulling on DDFT to bring foot back
PaPrPaDiO: good to see what?Profile navicular bone clear of the phalanges (P2 & P3)
Normal navicular bone should look how?Distinct cortico-medullary junction
Obliques for palmar processes of P3: how is the projection taken?Place foot in upright pedal foot block, taken 45* angle from lateral & medial aspects of foot
DL45PaMO: machine directed horizontally to the limb
L45PrMDO: machine angled distally towards the ground from back & lat of the foot (still 45*), profiles medial aspect of P3
Radiographic signs of laminitis:Progressive separation of hoof & pedal bone
Rotation of P3
Sinking of P3
Progressive deformity of the distal dorsal tip of P3 (chronic)
What's this? what's it for?
(Laminitis) Lead strip placed just below the coronary band. Put in the same place every time radiographs are taken to detect sinking of P3 (extensor process gets further away from lead strip)
Also shows when P3 rotates (not parallel anymore)
What's the thumbtack for?
(Laminitis) Placed at the point of the frog to see where P3 tip is located, for the farrier (avoid pushing P3 through the sole. Farrier makes sure shoe stays clear of P3 tip)
Acute laminitis
Severe rotation of P3 with close apposition to the sole of the hoof
Radiolucency between sensitive laminae & horny laminae (vaccuum phenomenon)
Chronic laminitis
Modelling of the tip of P3 (ski tip extension)
(no periosteum, just laminae interdigitating, sensitive laminae pull against horny parts)
If you get this radiograph, which other projection should you take?
Upright pedal! This horse also had articular fracture of P3 with its chronic laminitis!
Which synovial fossae are normal?
A, C, F
Radiographic signs of navicular syndromeWidening of synovial fossae
Enthyseophytes on the wings
Navicular syndrome
Abnormal synovial fossae, sclerosis of NB
Which condition? arrows?
Navicular syndrome: Osseous cyst-like lesions in navicular bone
Can be in medullary cavity OR flexor surface (which can cause adhesions with DDFT)
This scan is showing what?
Hotspot on navicular bone
The other limb is taking more weight, so it's hotter
What's wrong with C & D?
Poor cortico-medullary definition between flexor border & med cavity
(white arrowheads = sulci of frog, black arrow = palmar surface P2)
Can you see navicular syndrome on the lateral view?Not usually! Sclerosis of NB
Disruption of flexor cortex
Sclerosis of NB, loss of cortico-medullary definition
(Nail goes through frog, bursa, inxn gets in --> lysis)
Osteitis (infection on P3)
Discrete eccentric lysis, NOT central (so can't be crena)
Bone cyst of P3 (Osseous cyst like lesion)
Weakens P3, predisposes to fracture
Causes lameness if connects to joint
Rounded smooth radiolucent defect due to lysis affecting periphery of P3
May see deformation of adjacent hoof wall (iceberg, mostly extends inward)
Important to know about a P3 practure for prognosis?Articular or not
WHy is it important to take more than one view if suspecting P3 fracture?Important to assess whether or not they are articular
Whats the difference in these images?
Left: chronic articular (smooth edges. don't callus, just become sclerotic)
Right: Palmar process fracture (DL45Pr60PaMDiO)
**Bilateral round separated fragments may represent congenital anomaly/separate center of ossification**
Whats the difference in these images?
Left: Bipartite
Right: true sagittal fracture, sharp edges
What is quittor?Infection of the collateral cartilage of P2
Often discharge of the coronary band or sole of the foot
ST swelling, radiolucent defect in palmar process of P3
What is sidebone?Ossification of the collateral cartilages (significant if mineralization extends proximal to upper border of navicular bone)
Not clinically significant unless fracture (affects concussive mechanism)
Sidebone (** = prox edge NB)
Compare to normal:
Ginormous side bones
Infection at the toe- white line disease
Gas dissecting proximally in hoof wall
Pyramidal disease =Proliferative new bone formation around extensor process of P3
+/- OA of P2-P3 joint

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