Equine Carpus

sihirlifil's version from 2017-11-19 00:57


Question Answer
Which standard views are taken for the equine carpus?Lateromedial (LM)
Dorsopalmar (DP)
How is the DP taken?Horizontal beam (careful with radiation!)
Cassette: palmar to leg
Center: Intercarpal joint
(Accessory carpal superimposed on CBs, outline of Mc2 & 4)
Arrow? (1y.o. foal)
NORMAL oblique physis of distal radial epiphysis (lateral aspect)
Remnant of styoloid process of ulna (may persist for life)
NORMAL radiolucent area in distal radius (fossa)
High kVp can exacerbate (technical error)
How is the LM taken?Horizontal beam
Cassette: Medial
Center: middle carpal joint
(CBs superimposed)
Something to note about the growth plates?None at proximal metacarpus! Only at distal!!! (trauma can lead to marked ALD)
Intra-articular fat pads
May be displaced dorsally or completely by intra-articular swelling
Why take a flexed lateral?Joint space opens up (antebrachiocarpal & middle carpal) Easier to see chip fractures
How is the DLPMO taken?Cassette: on palmaro-medial aspect of leg
Beam: from dorsolateral, 45-60* angle (varies with shape of horse & amt of swelling)
DLPMO highlights what?DorsoMEDIAL aspect: useful for chip fractures
PalmaroLATERAL aspect
Hints for recognizing DLPMOIncomplete joint between 4th carpal bone & Mc4 (doesnt fully articulate)
Accessory carpal bone juts out, is foreshortened
Problem? where is the swelling?
Chip fracture off of proximo-dorsal aspect of 3rd carpal bone
Fat pads are NOT VISIBLE = intra-articular swelling
How is the DMPLO taken?Cassette: on palmarolateral aspect
Beam: 45-60* angle
DMPLO highlights what?DorsoLATERAL aspect
PalmaroMEDIAL aspect
Hints for recognizing DMPLOComplete joint between 2nd carpal bone & Mt2
Accessory carpal bone superimposed
Sometimes see 1st carpal bone!
Chip fracture off dorsolateral distal aspect of 3rd carpal bone
How is the dorsoproximal-dorsodistal oblique (DPrDDiO/Skyline) view taken?Vertical beam
55 degrees for proximal row
35 degrees for distal row
(Might be difficult to flex if animal is painful)
35* DPrDDiO: best view to highlight what?Slab fractures
Sagittal fractures
Sclerosis of 3rd carpal bone
35* DPrDDiO: how should the 3rd carpal bone look?Clearly defined cortiomedullary junction
What's wrong here? (2)
Non-displaced slab fracture of 3rd carpal
Poorly defined corticomedullary junction of 3rd carpal bone: Sclerosis (predisposes bone to fractures)
Abnormalities of the equine carpusAngular limb deformity (ALD)
Degenerative joint disease (DJD)
Fractures (chip, slab)
Sclerosis of 3rd carpal bone
Incomplete ossification of carpal bones
Osseus cyst-like lesions (OCLL)
Valgus = Lateral deviation of the limb distal to the carpus
Most common
Varus = Medial deviation of the limb
Where can ALD originate?At radial physis
Radial epiphysis
Incomplete ossification of CBs (=worse prognosis) (cartilage not converting to bone, excessive growth medially)
How is ALD measured?Rads taken to detect "pivot point" & degree of deviation. Where lines cross = source of deviation
Moderate to severe if angle >12
Why are radiographs taken for ALD?Detect "pivot point" & degree of deviation
Assess cuboidal bones
Assess physis
Assess progress after therapy (farriery, periosteal stripping, transphyseal bridging)
Where is the source of the ALD?
Antebrachiocarpal joint
Where is the source of the ALD?
Distal radial physis
Medial aspect of metaphysis is widened resulting in ALD
Problem? what's the pin for?
Large prominent bone production at distolateral aspect of radial metaphysis, severe wedging of epiphysis
Screws & wire compress medial physis to try and restrict its growth
New bone formation, intra-articular STS, obliteration of fat pad
Periarticular entheseophytes
Obliteration of fat pad
Carpitis (DJD)
Severe new bone formation & ST swelling (green arrows)
((sky blue RCB, red TCB, purple UCB, yellow Mc3, white displaced C1)
Chronic carpitis (DJD)
Blue = new bone formation on distal radius
Yellow = chip fracture off ICB
Red = ICB, green = ST swelling, sky blue = RCB (new bone formation)
Chronic carpitis (DJD)
Remodeling of proximal row of carpal bones (confirms OA)
Problem? what to note about the views? (DLPMO & lateral)
Slab fracture, fragment displaced dorsally
If you see slab fractures of the 3rd carpal bone on LM & flexed LM, what else do you have to do?TAKE SKYLINE! Can show other non-displaced fractures
What's the problem with these 3 images?
Left: Sclerosis & 3CB fracture
Mild sclerosis: indistinct CM junction
Severe sclerosis! NO CM JUNCTION! (compare 3CB & 4CB)
Small, sclerotic rim, away from joint space (=unlikely to be clinically significant, but still mention it!)
Infectious osteomyelitis
Large radiolucent defect (red) with sclerotic margins in distolat radial metaphysis
Disruption of radial epiphysis due to lysis & collapse (yellow)
Most common source of infectious osteomyelitisUmbilical infection (joint ill)

Random Cow

Question Answer
Anatomical difference between horse & cow antebrachiumCow has full ulna
Infectious osteomyelitis/OA
Large intra-articular ST swelling with gas in the joint
Blue = subtle lysis extending into joint (=OA)
(calves in feedlots, not caught early enough)
Common source of infectious osteomyelitisSalmonella enteritis, 2ry to umbilical infection
Infectious osteomyelitis
Mineralized material in the joint space
Traumatic pepriostitis/OA
Severe new bone formation on distal row of carpal bones & Mc3/4, cellulitis, periosteal reaction
(US is really useful here for tap)