Cannon bone & Ulnar Fxs

Question 1

Describe the fracture.
Also, what view is this??

Answer 1

Displaced parasagittal articular fracture
of the distal aspect of the 3rd metacarpal bone

aka:
closed lateral condylar fracture

Note how it’s propogated up from the articular surface
going laterally, up the limb

view: DP

Question 2

What is this view & why is it required?

Answer 2

Tangential view
{flexed fetlock}
highlights palmar aspect of bone to fully evaluate joint

fragmentation at the site decreases prognosis

Question 3

T or F:
TB→ MC III > 2x more common than MT III

SB→ MC III & MT III are ~the same

Answer 3

True.

In Thoroughbreds, front limb lateral condylar fractures {MC III} are at least 2x more common than hind limb lateral condylar fractures {MT III}.

In Standardbreds, they’re about the same…

Question 4

A race horse was just worked pretty hard & is now non-weight-bearing lame, has marked effusion in fetlock {MCP jt} & he’s painful on palpation. What type of fracture are we anticipating?

Answer 4

Acute displaced

Question 5

What is the treatment for lateral condylar fracture?

Answer 5

internal fixation w.transcortical screws in lag fashion…

​
usu only need 2 screws…
4.5mm or 5.5mm cortical bone screws
{5.5 have significantly greater pull-out strength}

1. place 1st one in epicondylar fossa of the cannon bone, closest to jt, in lag fashion
2. move up the Fx ~2cm & place the next one

Question 6

What type of Fx is this?

Answer 6

Salter Harris Type II
across the physis, thru the metaphysis
day {of the parent bone}

Question 7

What is the most common long bone fracture in horses?

Answer 7

cannon bone fractures
{diaphyseal Fxs of MC III & MT III}

Question 8

How would we manage a diaphyseal Fx in the field

Answer 8

• PVC pipe

{schedule/weight 40 has good rigidity but still workability}

• some sort of modified Robert Jones - need stout compression

Question 9

What aspects of the forelimb would we be placing a splint in a diaphyseal cannon bone Fx?

Answer 9

Lateral & dorsal

Kimzey splint can be helpful for this!

Question 10

What’s the optimal treatment/repair for cannon bone Fx?

Answer 10

the only way we can get enough support to this limb to bear this animal’s weight is a double plate fixation
{remember to always place plates on tension side!}

Question 11

Note the plate positioning…

​why is one plate longer than the other?

Answer 11

minimizing the risk of
“fulcrum effect” aka stress risers

Question 12

How can we attempt to repair this terribly comminuted Fx?

Answer 12

we’re going to need screws
{cortical bone screws most commonly}…

& place them in lag fashion
​to reduce all of these fragments…

to the point where we have:
2 main fragments that we can compress
& recreate a weight-bearing surface

Question 13

What’s different in the characteristics of the LC-DCP® hole design from that of the DCP hole?

Answer 13

LC-DCP® plate has a DCU hole: allows screws placed at 40º angle

vs.
DCP hole: allows 25º angle

Question 14

What purpose do combi-holes serve as a characteristic of the 5.5mm LCP®?

Answer 14

They permit the combination of a conventional {cortical} or locking screw…

locking screws: 4.0/5.0mm

cortex screws: 4.5/5.5mm

Question 15

What’s wrong with this horse?
What are the differentials you need to seriously consider?

Answer 15

Dropped elbow w/carpus in flexion

Typical presentation of an ulnar fracture

unable to extend carpus bc triceps {stay} apparatus is disrupted!

Remember similarly presenting dDx for ulnar Fx:

• Olecranon Fx
• Humeral Fx
• Radial n.paralysis
• neuro dz {WNV; rare}

Question 16

How would we manage an ulnar fracture with a splint?

Answer 16

Splint to fix the carpus in extension:

apply splint palmarly, ext. from fetlock → level of elbow
*need adequate padding*

Question 17

How are splints placed for olecranon fractures an exception to the rule?

Answer 17

​they do not span a jt above & a jt below…

olecranon Fxs only need 1 splint; straight up the back of the limb,
but you splint up as high as you can get,
so you need that padding to protect the elbow from the end of the splint

Question 18

What is the treatment of choice for olecranon Fxs?

Answer 18

*ORIF*

open reduction internal fixation

stall rest does NOT work!!

Question 19

Method of Fx Repair?

Answer 19

Bone plate
{DCP, LC-P/DCP}
contoured to fit over top of olecranon tuberosity
w.locking screws & cortex screws

Question 20

For olecranon fracture repair in foals <250kg, we can use _________; whereas in horses >250kg, we need __________.

Answer 20

tension band technique {screws & wires};

to use a plate

Question 21

In adult horses, how can we ensure rigid fixation when repairing an olecranon Fx?

Answer 21

distal screws can be inserted into the caudal cortex of the radius

remember:
*horses <1 year → distal screws should not engage radius*
may lead to elbow subluxation

Question 22

What’s the prognosis for ulnar Fx?

Answer 22

68-87%
{good w.ORIF}