Pastern

What is the most common fracture configuration of P2?

Comminuted

Where on P2 are comminuted fractures most common?

Proximal articular surface

T/F: Comminuted P2 fractures often start with a single oblique fracture line extending into the DIJ that progresses to multiple fracture planes.

True!

What common name is given to comminuted P2 fractures that are held together only by periosteum?

Ice bag fractures

What TWO types of horses are most predisposed to comminuted P2 fractures? Why?

Western performance and Arabs -> bending and torsional forces from stops and direction changes

What are the TWO major clinical signs of comminuted P2 fractures?

1. Severe non-weight-bearing lameness

2. Palpable instability and distal limb crepitus

What splint is often used for a comminuted P2 fracture?

Level 1

What TWO imaging modalities confirm the configuration of a comminuted P2 fracture?

Rads and CT

What is the most frequent configuration of comminuted fractures?

Both sagittal and transverse planes with added comminution on palmar/plantar aspect

T/F: Comminuted P2 fracture treatment is selected based on the extent of the fracture and possibility of adequate repair.

True!

What is the most important decision to make when presented with a comminuted P2 fracture?

Treat or euthanize

What is the major prereq for repairing a comminuted P2 fracture?

Intact piece of bone from PIP to DIP

T/F: It is important to inform the owner that a comminuted P2 fracture is career-ending and a horse will never be able to return to full level of work and would only be pasture sound at best.

True!

What THREE situations would indicate euthanasia is best in a horse with a comminuted P2 fracture?

1. Inadequate DIP reconstruction

2. Severely comminuted and unlikely to be successfully repaired with plates/screws

3. Concurrent navicular or coffin bone fracture (adds to instability)

What is vital and what is advantageous in the "humpty dumpty" surgery for comminuted P2 fracture?

Vital: reconstruct distal articular surface of P2 in coffin joint

Advantageous: reconstruct proximal articular surface of P2 in pastern joint

What is the preferential treatment for comminuted P2 fracture?

What is one major downside?

Two narrow compression plates (fuse P2 to P1)

Compromised vascular supply to soft tissue

T/F: Pre-op immobilization in a supporting splint is important for long-term outcome in comminuted P2 fractures. Infection is also a risk, and local and systemic antibiotics are used to minimize bacterial growth.

True!

What is the downside to using locking compression plates for a comminuted P2 fracture?

Limits screw insertion angle (must go in perpendicular)

What is an alternative, less expensive treatment when a client does not want to elect for euthanasia or if not repairable by internal fixation alone?

Transfixation cast

Transfixation casts involve large pins through the cannon bone in different planes to pick up force before bearing weight on the fracture site and prevent the limb from ---.

Hyperextension

The selection of fixation for a comminuted P2 fracture should provide the earliest return of comfortable weight on the fracture to minimize ---.

Laminitis

When might you get residual lameness after a comminuted P2 fracture repair?

Inadequate reduction of fracture fragments in DIP joint

What is the most common osteoarthritis called that is seen around the PIJ?

High ringbone

High ringbone affects multiple breeds, especially those with a ------------ conformation.

Short upright pastern

What TWO populations of horses are more prone to high ringbone? State why for each.

Western and showjumpers- quick stops and turns

Young horses- osteochondrosis

What are the THREE major clinical signs of high ringbone?

1. Grade II to III/IV lameness

2. Palpable enlargement/heat of PIP joints

3. Pain on pastern flexion

High ringbone lameness is usually --- and exacerbated by increased ---.

Chronic

Work

What nerve block is best to localize high ringbone?

Abaxial sesamoid

What is the best way to diagnose high ringbone?

Radiographs

What is the best short-term treatment for high ringbone?

What is needed with progression to fulminant osteoarthritis if the horse wants to continue an athletic career?

Intra-articular corticosteroids or orthobiologics

Arthrodesis of pastern joint

What is the prognosis for riding soundness with proper treatment of high ringbone?

Fair to favorable

Typically, high ringbone does better in the (forelimbs/hindlimbs)

Hindlimbs (bear less weight)

Dorsal P1 osteochondral fractures are common in --- and --- horses.

Racing

Sport

What is the etiology of dorsal P1 osteochondral fractures?

Hyperextension of metacarpal joint -> proximodorsal aspect of P1 hits dorsal cannon bone -> wedge fracture

T/F: Preexisting subchondral bone disease predisposes dorsal P1 osteochondral fractures.

True!

What are the TWO major clinical signs of dorsal P1 osteochondral fractures?

1. Moderate lameness with synovial effusion

2. Pain on flexion of affected joint

What is the most common location of a dorsal P1 osteochondral fracture?

Dorsomedial eminence of P1

You are presented a lame horse and take films of the fetlock. You notice a round, 5-6 mm chip but there is no synovitis and the flexion was negative. Should you remove the chip?

What could you do to rule it out?

No- there are many other possibilities that could be the cause and this is likely a chronic change and not the issue

Block out the fetlock joint

What is the treatment for a dorsal P1 osteochondral fracture?

Arthroscopic removal

How do treatment guidelines change if the chip is small (

Small: rapidly recovered by synovial tissues and may heal without causing symptoms

Moderate to large dorsal: remove to prevent synovitis, cartilage degeneration, and chronic proliferative synovitis

Large: erosion of opposing metacarpal condyle; persistent lameness

A horse can return to training in ---------- dependent on joint inflammation with dorsal P1 osteochondral fractures.

6-8 weeks

T/F: Removal of osteochondral fractures also may be useful even when moderate levels of osteoarthritis is present.

True!

Most diaphyseal P1 fractures initiate at the ---------------------- and propagate (proximally/distally).

Midsagittal groove

Distally

What is a P1 diaphyseal fracture line initiated by?

Torsion from sagittal ridge of cannon bone to sagittal groove of proximal P1

T/F: Most axial fractures of P1 occur in the sagittal plane and propagate distad from the articular surface of the MCP/MTP joint.

True!

What are the five fracture types seen in diaphyseal P1 fractures?

1. Short incomplete

2. Long incomplete

3. Complete uniarticular

4. Complete biarticular

5. Dorsal complete biarticular

Diaphyseal fractures are most common in --- horses and most occur in the (forelimb/hindlimb).

Racing

Forelimb

T/F: Diaphyseal P1 fractures are seen more commonly in the left limb, as this is the inside limb horses race on and experience more torsion.

False! There is no tendency for left or right limb predisposition

(did i get you on this one i feel like that sounded so legit)

What diaphyseal P1 fracture type is considered "stress fracture" in Warmbloods? Why are they prone to this?

Short incomplete sagittal

They are fat spooky little bastards (i'm a warmblood person)

T/F: Short incomplete sagittal P1 fractures in Warmbloods are often accompanied by osteoarthritis with a poor prognosis.

True!

Describe the clinical sign/timeline of a diaphyseal P1 fracture in order of type and severity.

Short incomplete: no pain until next workout

Long incomplete: no pain until coolout

Complete uniarticular: no pain until coolout

Complete biarticular: immediate pain at injury

Dorsal complete biarticular: immediate pain at injury

T/F: Fractures extending the full length of P1 and those that tend to comminute result in non-weight-bearing lameness and moderate swelling of the pastern.

True!

What diaphyseal P1 fracture type is sometimes difficult to isolate through a routine lameness exam and radiographs might miss, as the fracture may only extend 0.5-2 cm?

Short incomplete

What could be a problem if done to diagnostically work up a horse with suspect short incomplete diaphyseal P1 fracture? Why?

Nerve blocks- increases risk of worsening fracture lines

What should you do if you suspect a short incomplete P1 fracture and rads did not show it?

Wait and take rads again in 10 days

In diaphyseal P1 fractures, several different DP projections are needed to localize and short sagittal fractures are often detected using ---------- when radiographs are inconclusive.

Nuclear scintigraphy

--- can elucidate the exact P1 fracture configuration and be useful if screw fixation if performed.

CT

Conservatively, short incomplete fractures that are incomplete and stable can be surgically repaired after ------ if not healed by then.

3 months

What technique induces primary bone union and reduced the chance of further propagation of P1 fracture?

Screw stabilization

T/F: Screw fixation of a P1 fracture can allow racehorses to return to training more quickly and have an excellent prognosis.

True!

The extent of fracture planes and stability can considerably vary where CT imaging can increase the success of surgical reconstruction in what kind of P1 fractures?

Long incomplete and other non-displaced

What is the prerequisite for selecting screw reconstruction of P1 fracture over transfixation casts or external fixator devices?

Intact bone from fetlock to PIP

--- where us where a P1 fracture is and allows an understanding of how to place screws to ensure they are perpendicular to the fracture plane.

CT

In a long incomplete P1 fracture, the limb is cast after surgery to the proximal aspect of the cannon bone for recovery and is maintained for the next ---------. Radiographic evaluation is used to determine the appropriate cast time required.

3-6 weeks

T/F: Implant removal is required in long incomplete P1 fractures.

False! Implant removal is NOT required.

What are the FOUR indications of P1 fracture screw removal?

1. Lysis beneath screw head

2. Excessive periosteal reaction around screw head

3. Drainage from incision

4. Excessively long screws