Emergency fractures in the horse Flashcards
How are fractures classified?
▪ 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
How to tell whether a fracture is acute or chronic
- acute = sharp margins
- chronic = smooth margins
- also look at the soft tissues surrounding the fracture (swelling indicates more acute)
Why is determining whether there is articular involvement really important?
- this determines whether synovial sepsis or OA are possible complications, both of which have major impacts on outcome
Causes of fractures in the horse
- trauma
- developmental
- secondary to other dz
Traumatic causes of fractures
- 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)
Developmental causes of fractures
- most commonly fragments due to OCD or other developmental orthopaedic disease
Secondary causes of fractures (secondary to other dz)
- e.g. neoplasia or infection
– uncommon in the horse, but keep on differential list
Common sites of kick injuries causing fractures
- splint bones
- stifle bones
(tibia, patella) - olecranon
- head
Common sites of trauma/falls causing fractures
- head
- vertebrae
- long bones (femoral or cannon fractures in anaesthetic recovery)
- joints during competitions (patella fractures from hitting fences)
Common sites of repetitive injury / wear and tear causing fractures
- distal phalangeal (pedal) bone
- middle phalangeal (pastern) bone
- distal sesamoidean (navicular) bone
- in the average horse more commonly in the distal limb
Common sites of stress fractures in racehorses
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
Why are racehorses especially prone to stress fractures?
- the high forces, stresses & strains on the bone can exceed the bones capacity to remodel and repair within a short time frame
Clinical signs of fractures in the horse
▪ 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
Major red flags for fractures
- history of trauma (e.g. kick or fall)
- acute onset severe lameness
- acute onset joint effusion
- heat
- pain
- swelling
- palpable crepitus
How may non-displaced stress fractures present?
- acute onset lameness following exercise, which resolves over a few days
What can happen to non-displaced repairable fractures if they’re not recognised and treated appropriately?
- can progress to catastrophic irreparable fractures
Physical exam
▪ 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
Diagnostic tests
▪ Nerve or joint blocks
▪ Radiography
▪ Minimum of two views
▪ Ultrasound
▪ Gama scintigraphy
▪ CT
Use of nerve/joint blocks
- avoid if possible, only use is in chronic, mild, small fractures
Use of radiography
▪ 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
Use of US
- 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
Use of gamma scintigraphy
= 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
Use of CT
- gold standard but availability of facilities and cost limits use
- esp useful in imaging complicated fractures and neck lesions
Fracture complications
▪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
