SAOP1- Fracture Complications

  1. How do you choose an appropriately sized bone plate?
    • there should be 3 screws proximal and distal to the fracture plane
    • no screws in the fracture plane
    • no empty holes
    • plate should span entire length of bone
  2. What is the AAAA scheme?
    • Alignment, Apposition, Apparatus, Activity (activity of the bone at the level of the fracture)
    • used to assess fixation of a fracture
  3. What are the major reasons for failure of a fracture repair? (3)
    • incorrect selection of implants
    • techical errors in application
    • inconsiderate tissue handling
  4. Describe the stabilization achieved with simple IM pin fixation.
    • only provides distraction to bending
    • NOT to compression, shear, or rotation
    • poor choice for complex/ comminuted fractures, not commonly used as sole fixator
  5. Why shouldn't you pin the radius in a small dog (or any dog)?
    • poor medullary blood supply, which is compromised by an IM device
    • may not even be able to get a pin in the small medulla
  6. What are the principals of cerclage? (5)
    • reconstruct complete circumference of bone
    • use large strong wires
    • make wires tight
    • space wires >1cm apart and space them evenly
    • place wires >0.5cm from fracture ends
  7. What are potential complications that can occur with cerclage wire?(3)
    • pin migration associated with fracture instability (do not use cerclage as a single device or alone with an IM pin because the cerclage will act as a fulcrum and the pin will start to migrate)
    • pin removal
    • loose cerclage inhibits union
  8. What are the 3 types of viable and 4 types of non-viable non-unions?
    • Viable: hypertrophic non-union (elephants foot callus), slightly hypertrophic non-union (horses hoof callus), oligotrophic non-union
    • Non-viable: dystrophic non-union, necrotic non-union, defect non-union, atrophic non-union
  9. What is pseudoarthrosis?
    specific type of non-union, where the fracture surface develops a synovial-like surrounding it and a cartilage-like surface; chronic complication
  10. What is stress protection?
    failure to load the limb after fracture fixation and atrophy of the bone
  11. What is the fracture risk post-op after repair of a fracture?
    • plate not long enough, creates a fulcrum and fracture distal to the plate [long lever arm]
    • stifle arthrodesis--> risk for tibia fracture
  12. What kind of clinical manifestations occur due to plate irritation, and how is it addressed?
    • near joint, where there is little soft tissue cover, lick granuloma
    • address by removing the implant
  13. What are the radiographic characteristics of osteomyelitis? (8)
    • soft tissue swelling
    • periosteal reaction (irregular or smooth)
    • cortical lysis/ sclerosis
    • lysis around implants
    • increased medullary density
    • sequestrum and involucrum
    • delayed union or non-union
    • gas shadows in soft tissue
  14. How do you address implant-associated osteomyelitis?
    • treat with antibiotics and remove implant
    • must remove implant because it will harbor biofilm, even if the infection responds to antibiotics successfully
    • address fracture with cancellous bone autograft and ex-fix (can be removed without further surgery)
  15. What are the types of implant failure, and in what patients does each usually occur?
    • acute material failure: single fatigue failure after a single massive load; occurs in equine
    • fatigue failure: implant fails after a time; common in small animal
  16. Describe how fatigue failure of an implant occurs.
    metal can fail in fatigue; if the fracture is repaired appropriately, the fracture will heal before the implant reaches its fatigue limit; if there is infection or the fracture is not repaired appropriately, it will continue to be loaded b/c fracture takes longer to heal, and be more likely to break in fatigue
  17. What type of IM pin is more stable?
    smooth pins are more stable; there is no benefit to using negative profile threaded IM pins (prone to fail at thread/ shaft junction)
Card Set
SAOP1- Fracture Complications
vetmed SAOP1