Fractures

• Fractures are classified by…

  • Location (which bone involved, and where, e.g. metaphysis, diaphysis, epiphysis)
  • Structures involved (articular vs non articular)
  • Contamination (open vs closed)
  • An open fracture is a contaminated one
  • Extent of damage (complete vs incomplete, simple vs comminuted)
  • Size of fragment (chip vs slab vs shaft fracture)
  • Fracture configuration, the shape and direction of the fracture lines (transverse, oblique, spiral, avulsion, growth plate)
  • Displacement, fracture fragments (identify the number of fragments) and margins
• Articular involvement is really important as this determines whether synovial sepsis or osteoarthritis are possible complications, both of which have a major impact on outcome
• There are also specific classifications for the key fracture sites in the horse, these key sites are the pedal bone, navicular bone, olecranon, sesamoid bones and growth plates. The classifications help us both plan what the repair or treatment options are, but also what the prognosis is.
• The causes of fractures are…

  • Trauma (Acute or chronic)
  • Developmental e.g., OCD
  • Secondary to other diseases e.g., neoplasia (uncommon)
• Racehorses are especially prone to stress fractures as the high forces, stresses and strains on the bone can exceed the bone’s capacity to remodel and repair within a short time frame
• fill in the blanks

  A) kick

  B) falls

  C) repetitive

  D) stress

  
• The problem is that the fractures themselves vary from small and minimal structural impact to major, so remember this variation when you assess (signs can range from mild/subtle - marked/severe). Look for classic signs of heat and pain, but also feel for the crepitus, grating sound or feel of bone ends grinding against each other. Check surrounding structures and especially joints

  • A small fracture in a joint can have a big impact, articular fractures normally have a joint effusion
• Non-displaced fractures including stress fractures) and small chip fractures may have minimal lameness and localising signs
• Acute, severe or displaced fractures will have obvious conformational abnormalities, severe lameness, pain and crepitus at the fracture site
• Non-displaced stress fractures may present as acute onset lameness following exercise, which resolves over a few days
• • Crepitus due to air/gas under skin is usually diffuse and non-painful.
  • Crepitus due to bone fragments is painful and localised.
• In terms of diagnostic test, commonly radiography is performed using at least two orthogonal views. In the horse, some regions are difficult or impossible to radiograph, including the scapula and pelvis.

  • Some fractures are non-displaced so may not show up on radiographs.

  Ultrasound is very useful for identifying loss of continuity of the bone in proximal regions of the limb, such as the pelvis.
• You can reduce the risk of complications right from when you first see the horse, don’t make things worse, don’t nerve block or exercise, do support, splint and protect wounds. It is imperative at the first examination you recognise a 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
• Articular fractures are pretty common treatment follows two very simple concepts…

  • if the fractures are small, unstable and do not form a major part of the weight-bearing surface, they need to be removed to avoid continuing synovitis and eventual arthritis.
  • If the articular fragments are larger and form a major part of the weight-bearing surface, then they need to be put back into place with a screw or plate.

  Arthrodesis or fusing of the joint is an option for some joints in the horse such as the pastern, carpometacarpal and distal tarsal joints)
• Contamination of a fracture site, leading to infection is a major concern in the horse. Open fractures frequently end up infected (hence internal fixation fails), and a major part of first aid is cleaning and protecting the site as quickly as possible.

  • Identify, flush and protect any wounds and possibly administer antibiotics
• Sometimes the fracture itself is not the main problem as soft tissue involvement may be a limiting factor in some cases e.g., laceration to the SDFT and DDFT
• You should consider euthanasia in the following cases…

  • Fracture is irreparable
  • Open comminuted long bone fractures
  • Complete fractures of the scapula, humerus, radius, femur and tibia in horses over 500kg
  • 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 treatment
  • Horse will not tolerate box rest / rehabilitation (pre-existing conditions, temperament/behaviour)
  • Horse will not return to previous work (depending on owner’s circumstances)
• fill in the blanks

  A) degenerative joint disease

  B) contamination

  C) soft tissue involvement

  D) malunion

  E) sequestrum

  F) laminitis

  
• What is the correct term for this radiographic view?


  flexed lateromedial

  
• what view is this image?

  dorsoproximal palmarodistal 60 oblique view

  
• AO principles of fracture repair

  1. Fracture reduction and fixation to restore anatomical relationships
  2. Fracture fixation providing absolute or relative stability as the "personality" of the fracture, the patient, and the injury requires
  3. Preservation of the blood supply to soft tissues and bone by gentle reduction techniques and careful handling
  4. Early and safe mobilization and rehabilitation of the injured part and the patient as a whole
• Lag screws achieve compression which is essential for direct healing

  • The hole is drilled as the same diameter as the screw, this is known as the glide hole as the screw doesn’t engage with the bone
  • A drill sleeve is placed in the glide hole and a smaller drill enters further into the far cortex creating a thread hole.
  • Countersink the screw, and measure the length of the screw required. Tap (Same diameter as the screw) the far screw hole and insert the screw.
• what are the three types of screws?

  lag, plate and positon screws
• Each screw size has two drill diameters associated with it:

  • Thread hole diameter (core diameter)
  • Glide hole diameter (nominal diameter - outside diameter so is larger than the thread hole diameter)
• Complete parasagittal intra articular pedal bone fracture can occur due to kicking a wall or stamping too hard

  
• what image is this?

  dorsopalmar of the first phalanx

  
• what image is this?

  dorsolateral palmar medial oblique

  
• what view is this?

  dorsoproximal dorsodistal oblique

  
• Complications of fracture repair (internal fixation) include…

  • Osteomyelitis (infection)
  • Screw loosening
  • Implant failure
  • Delayed / non union
  • Ring sequestrum
  • Support limb laminitis
  • This is an overload laminitis as the horse may be standing on one leg for prolonged periods due to the pain from the damaged limb.
• Ring sequestrum is a thermal injury from drilling causing the bone to die off

  • This can result in screw loosening and infection. Hence it is important to regularly clean drill bits and lubricate them.