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Equine LA Sx > Selecting Cases for Fracture Repair > Flashcards

Selecting Cases for Fracture Repair Flashcards

1
Q

What do you worry about with a highly comminuted articular fracture at distal MT3 and P1?

A
  • Leg can hyperextend
  • Suspensory apparatus gives away
  • Palmar vessels and nerves can stretch and
  • due to endothelial damage
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2
Q

Challenges with fracture repair to consider

A
  • Size of the horse
  • Disposition of the horse
  • Expectations (going back to soundness; breeding stallion)
  • Cost
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3
Q

What influences prognosis for a fracture?

A
  • Size
  • Location
  • Open vs closed
  • Complete vs incomplete
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4
Q

Fractures in a horse <150 kg

A
  • Prognosis will increase
  • Treat similarly to large small animals
  • Protect joints and growth plates
  • Residual lameness not okay in most cases
  • Fairly easy to repair
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5
Q

Criteria to repair fractures in adults

A
  • Minimal comminution (internal fixation)
  • Closed fracture
  • Adequate blood supply
  • Calm/sensible horse
  • Suitable equipment
  • Expeditious surgery
  • Adequate recovery room/pool
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6
Q

Closed vs open fracture prognosis

A
  • Open fracture will get infected 90% of the time

- Decreases your prognosis 50%

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7
Q

What are the rules of repairing comminution?

A
  • 6 cortices proximal and distal to the fracture (go across with 3 screws)
  • 180 degrees of cortices to carry weight axially
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8
Q

P1 fracture requirement

A
  • Must have an intact strut of bone spanning the fetlock and pastern joints for internal fixation
  • Otherwise they will crush it down
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9
Q

Lag screw fixation

A
  • Drill a hole on the side of the fracture that has the head i nit to the diameter of the OUTSIDE of the thread of the screws (e.g. 5.5 mm, 4.5mm, or 5.0 mm)
  • Drill a hole on that side so the screw doesn’t engage there
  • On the other side they drill to a core diameter and tap it (create the threads that it will screw into
  • Slides through the first part not touching or engaging and twist the screw onto the second part to engage the threads
  • As you tighten it,the head of the screw will bring the two pieces together quite nicely
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10
Q

Benefits of lag screw fixation

A
  • Minimizes motion at the fracture line

- Anchors the pieces together

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11
Q

Lag screw fixation method (short)

A
  • Drill glide hole (outside diameter of the screw, e.g. 4.5, 5.0 or 5.5)
  • Drill thread hole (core diameter of the screw e.g. 3.2, 4.0, or 4.3)
  • Measure
  • Tap (create threads in far cortex)
  • Place and tighten screw
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12
Q

Core diameter of 4.5 mm screw

A
  • 3.2
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13
Q

Core diameter of 5.5 mm screw

A
  • 4.0
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14
Q

Core diameter of 5.0 mm locking screw

A
  • 4.3
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15
Q

Which screw is the strongest?

A

5.0 with core diameter 4.3

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16
Q

Locking compression plate (LCP)

A
  • These plates are used a lot now
  • Tighten it down, the bottom of the screw will engage the bone, and the head of the screw will engage the plate
  • Plate is almost like an external fixature (rigid structure that holds itself together and holds the fracture together)
  • The plates
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17
Q

Dynamic compression plate

A
  • Screws don’t actually attach it to the plate

- They hold it by compressing it against the bone

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18
Q

What is “the race” of fracture repair?

A
  • Open fractures (communication of fracture with skin) have increased risk of infection
  • Decreased rate of healing
  • Increased risk of implant failure
  • Majority of horses with open fractures will have implant infection
  • Decreases prognosis by at least 50%
19
Q

Adequate blood supply and fracture repair

A
  • No blood no healing
  • Fractures through nutrient foramen
  • Loss of both palmar digital vessels = loss of the foot
20
Q

Fracture recovery

A
  • Need to have a place to recover the animal
  • If they slam their legs down
  • Recover long-bone fractures with a pool
  • GO in a sling, lower the floor
  • Float in the pool until they are awake enough
  • Allow the floor to come up until they can get on their feet
  • Then they lift them up
21
Q

Indirect bone healing

A
  • Callus formation
  • Occurs in fractures that have an unstable mechanical environment caused by motion
  • This is how most bones heal
22
Q

What is fracture strain?***

A
  • Ratio of the change in gap width to the total width of the gap
  • Motion at fracture site causes change in the width of the gap between fragments
  • Particular tissues will not proliferate under strain conditions that exceed the tissues limits of deformation
23
Q

What can decrease fracture strain?

A
  • In a comminuted fracture and move it the same amount, that movement will be equally distributed
24
Q

Stages of fracture healing?

A
  1. Hematoma
  2. Granulation tissue (fibroblasts and endothelial cells)
  3. Connective tissue (blood vessels regress out of the fibrous stump)
  4. Then it will make a jump to fibrocartilage
  5. Fibrocartilage will be converted to cancellous bone
  6. Then remodeling
25
Q

How much strain can a hematoma handle?

A
  • 100%
26
Q

How much strain can granulation tissue handle?

A
  • 100%
27
Q

How much strain can connective tissue handle?

A

20%

28
Q

How much strain can fibrocartilage handle?

A

10%

29
Q

How much strain can cancellous bone handle?

A

<2%

30
Q

What happens if you have too much strain in a fracture?

A
  • No healing
  • Will stop at whatever point
  • Often gets stuck in the progression from granulation tissue to connective tissue
  • Non-union
31
Q

Biological mechanisms to decrease strain

A
  • Fragment end resorption
  • Number of fracture lines decreases strain on any individual fracture line
  • Sequential formation of stiffer tissues in the fracture gap
32
Q

What does fragment end resorption do?

A
  • Increases width of gap which decreases ratio of change thus decreasing strain
33
Q

Which fractures are most difficult to repair?

A
  • Displaced, comminuted fractures of the femur, humerus, proximal tibia and proximal radius
  • Can heal with conservative treatment (AKA stall confinement with cross ties)
34
Q

What part of the limb has best blood supply?

A
  • Proximal
35
Q

What part of the limb has the worst blood supply?

A
  • Distal
36
Q

Pelvic fractures

A
  • Can do well
  • Limiting factor is acetabulum
  • If not involving the acetabulum, they may be lame for 4-6 months and heal on their own
  • If they do involve the acetabulum, may not be worth putting the horse through that
37
Q

Proximal fractures of the femur and humerus

A
  • Conservative management
38
Q

Arthodesis on a coffin joint?

A
  • Does not arthrodese well
39
Q

P1 fracture

A
  • Need an intact struct of bone

- Absent of that, think about an external fixator to hold it so you don’t get crush

40
Q

Lateral condylar fractures

A
  • Quite common
  • Break out through lateral cortex 3-5 in up the leg
  • Not often catastrophic
  • Need to repair quickly so you avoid arthritis
  • If minimally displaced, pretty good chance of healing
41
Q

What can you have help you if you’re unable to get six cortices spanning the fracture line?

A
  • A plate
42
Q

What about a very highly comminuted fracture with significant proximity to the joint?

A
  • Cannot get enough screws in on the proximal bit to hold it together
  • He would try and put the pieces back together and do a trans-articular pin
  • Put pins above the joint and below it and rely on external fixator
43
Q

Ulnar fracture

A
  • Non-weight bearing
  • Just re-establish tension band and re-engage the tricep
  • Elbow drops so they can’t lock the carpus in place
  • Curve the plate around to engage the top part of the bone

Equine LA Sx (4 decks)

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