Emergency fractures in the horse

Question 1

How are fractures classified?

Answer 1

▪ Location (which bone involved, and where, e.g. metaphysis, diaphysis,
epiphysis)

▪ Structures involved (articular vs non articular)

▪ Contamination (open vs closed)

▪ Extent of damage (complete vs incomplete, simple vs comminuted)

▪ Size of fragment (chip vs slab vs shaft fracture)

▪ Fracture configuration (transverse, oblique, spiral, avulsion, growth plate)

▪ Displacement, fracture fragments and margins

Question 2

How to tell whether a fracture is acute or chronic

Answer 2

• acute = sharp margins
• chronic = smooth margins
• also look at the soft tissues surrounding the fracture (swelling indicates more acute)

Question 3

Why is determining whether there is articular involvement really important?

Answer 3

• this determines whether synovial sepsis or OA are possible complications, both of which have major impacts on outcome

Question 4

Causes of fractures in the horse

Answer 4

• trauma
• developmental
• secondary to other dz

Question 5

Traumatic causes of fractures

Answer 5

• most common cause
• can be acute trauma (e.g. kick, fall)
• or chronic repetitive trauma (e.g. stress fractures in racehorses, general wear and tear in any horse)

Question 6

Developmental causes of fractures

Answer 6

• most commonly fragments due to OCD or other developmental orthopaedic disease

Question 7

Secondary causes of fractures (secondary to other dz)

Answer 7

• e.g. neoplasia or infection
  – uncommon in the horse, but keep on differential list

Question 8

Common sites of kick injuries causing fractures

Answer 8

• splint bones
• stifle bones
  (tibia, patella)
• olecranon
• head

Question 9

Common sites of trauma/falls causing fractures

Answer 9

• head
• vertebrae
• long bones (femoral or cannon fractures in anaesthetic recovery)
• joints during competitions (patella fractures from hitting fences)

Question 10

Common sites of repetitive injury / wear and tear causing fractures

Answer 10

• distal phalangeal (pedal) bone
• middle phalangeal (pastern) bone
• distal sesamoidean (navicular) bone
• in the average horse more commonly in the distal limb

Question 11

Common sites of stress fractures in racehorses

Answer 11

Anywhere but most common are:
- carpal bones (radius, radiocarpal and third carpal)
- third metacarpal bone
- middle phalangeal (pastern) bone
- proximal sesamoid bones
- radius
- tibia
- pelvis
- vertebrae

Question 12

Why are racehorses especially prone to stress fractures?

Answer 12

• the high forces, stresses & strains on the bone can exceed the bones capacity to remodel and repair within a short time frame

Question 13

Clinical signs of fractures in the horse

Answer 13

▪ Range from mild / subtle to marked / severe

▪ Acute, severe or displaced fractures will have obvious conformational abnormalities, severe lameness, pain and crepitus at the fracture site

▪Non-displaced fractures (including stress fractures) and small chip fractures may have minimal lameness and localising signs

▪Articular fractures normally have joint effusion

Question 14

Major red flags for fractures

Answer 14

• history of trauma (e.g. kick or fall)
• acute onset severe lameness
• acute onset joint effusion
• heat
• pain
• swelling
• palpable crepitus

Question 15

How may non-displaced stress fractures present?

Answer 15

• acute onset lameness following exercise, which resolves over a few days

Question 16

What can happen to non-displaced repairable fractures if they’re not recognised and treated appropriately?

Answer 16

• can progress to catastrophic irreparable fractures

Question 17

Physical exam

Answer 17

▪ Careful and detailed palpation for heat, pain, swelling and crepitus.
▪ Crepitus due to air/gas under skin is usually diffuse and non painful. Crepitus due to bone fragments is painful and localised.
▪ Administer sedation and analgesia as needed until horse is calm and can be examined thoroughly
▪ If attending event / accident and examine immediately, then consider re-examining later. Exhausted or excited horses may mask some of the signs initially. Swelling and heat can take a few hours to appear.
▪ Consider what underlying / associated structures

Question 18

Diagnostic tests

Answer 18

▪ Nerve or joint blocks
▪ Radiography
▪ Minimum of two views
▪ Ultrasound
▪ Gama scintigraphy
▪ CT

Question 19

Use of nerve/joint blocks

Answer 19

• avoid if possible, only use is in chronic, mild, small fractures

Question 20

Use of radiography

Answer 20

▪ First line approach for most fractures
▪ Minimum of two views
▪ Some regions may not be accessible for
radiography
▪ Non-displaced fractures may not show any radiographic changes

Question 21

Use of US

Answer 21

• main use is in pelvic fractures in racehorses
  – it’s useful for identifying loss of continuity of the bone in the proximal regions of the limb

Question 22

Use of gamma scintigraphy

Answer 22

= bone scans
- valuable for non-displaced stress fractures (e.g. tibia, radius, humerus) and regions which cannot be accessed / imaged well with radiography (e.g. vertebrae, ribs, scapula, pelvis)
- hot spots associated with fracture and remodelling

Question 23

Use of CT

Answer 23

• gold standard but availability of facilities and cost limits use
• esp useful in imaging complicated fractures and neck lesions

Question 24

Fracture complications

Answer 24

▪Articular involvement –> degenerative joint disease
▪Contamination -> osteomyelitis, synovial sepsis, soft tissue infection
▪Soft tissue involvement -> tendon, ligament, muscle or neurovascular damage
▪Unstable -> non-healing or malunion
▪Damage to periosteal vascular supply -> sequestrum formation ▪Mechanical overload of contralateral limb -> laminitis

Question 25

How to avoid fracture complications at the first examination

Answer 25

▪ Recognise fracture promptly and provide
adequate stabilisation
▪ Do not nerve block or exercise if risk of fracture
▪ Provide adequate support / splinting to prevent further damage
▪ Provide adequate support / splinting if moving or transporting the horse for further assessment
▪ Cover and protect open wounds

Question 26

How to avoid fracture complications at first diagnostics

Answer 26

▪Assess carefully for involvement of other structures
▪Radiography for articular involvement
▪Ultrasound to assess soft tissues
▪Neuro exam for suspected nerve damage ▪Further diagnostic as required
▪Get the full picture to enable you to plan treatment options and advise on prognosis

Question 27

How to avoid articular fracture complications

Answer 27

▪ Remove small unstable articular fragments which are not an integral part of the articular surface and will cause trauma if left
– would cause continued synovitis and eventual arthritis
▪ Stabilise large fragments which are an integral part of the articular surface (screw, plate etc)
▪ Arthrodesis is a viable option for low option joints (pastern, carpometacarpal, and distal tarsal joints)

Question 28

How to avoid contamination

Answer 28

▪Internal fixation of open fractures is rarely
successful
▪Open contamination / infection of a major fracture is a major complication
▪Identify, flush and protect and any wounds ▪Administer systemic antibiotics

Question 29

What is the biggest challenge in fracture management for horses?

Answer 29

• mechanical load
• hence failure of implants and overload of the contralateral limb are important potential complications that can limit outcome

Question 30

Which fractures should you euthanase?

Answer 30

▪Open comminuted long bone fractures
▪Complete fractures of the scapula, humerus, radius, femur and tibia in horses over 500kg

Question 31

When should you consider euthanasia?

Answer 31

▪ Fracture is irreparable
▪ Horse cannot be stabilised / transported for appropriate treatment
▪ Quality of life in long term will be poor (e.g. articular damage leading to arthritis)
▪ Owner cannot afford
▪ Horse will not tolerate box rest / rehabilitation (pre-existing conditions,
temperament/behaviour)
▪ Horse will not return to previous work (depending on owner’s circumstances)

Question 32

Where can’t you radiograph?

Answer 32

• scapula
• pelvis