Orthopedics Flashcards
What 4 factors make rabbit bones more brittle with a higher predisposition for fractures compared to dogs and cats?
- A smaller contribution of bony weight to whole body mass
- Thinner cortices
- Lower density/higher mineral composition
- Large muscle mass
What surgical fracture repair technique is generally preferred to other methods in rabbits due to versatility, minimal disruption of vasculature and low cost of equipment?
External skeletal fixation
Which bone is most commonly contaminated with fractures in rabbits?
The tibia
What are 3 indications for external coaptation?
- Fixation of closed fractures distal to elbow/stifle joints
- Temporary treatment pre-op to provide hemostasis, avoid further trauma, and keep the patient comfortable
- In combination with internal fixations such as IM pins to prevent rotational movement
What forces do IM pins not counter?
Rotational and shear forces
What are 5 potential risks of IM pin insertion?
Causing further fractures, cracking of affected bone, pin loosening, arthritis if placed through a joint, and interfering with the medullary blood supply
What makes up a ‘tie-in’ or hybrid external fixator?
An IM pin combined with an external skeletal fixator
What forces does ESF eliminate?
Bending, rotational and shear
What are potential complications of ESF?
Damage to the fixator, premature pin loosening, bending/breaking pins, pin-tract infections
When placing an ESF, why should distance between the limb and connecting materials be minimized?
To increase biomechanical stiffness and decrease fixator weight
What limitations prevent bone plating from being practical in ECM?
Small size of bones, thin cortices, technical difficulty & extra equipment, potential for disruption of periosteal blood supply, increase in risk of infection and prolonged surgical time
What complication can be seen in short-legged species such as guinea pigs and hedgehogs post amputation?
Decubitus and/or moist dermatitis of amputated lesions
In what circumstances will direct/primary fracture healing occur?
Only when fracture fragments are reduced anatomically and stabilized under interfragmentary compression with less than 2% interfragmentary strain
What does direct fracture healing mean?
Cortical bone is directly formed across fracture line with no evidence of callus formation
When does secondary/indirect bone healing occur?
When the interfragmentary strain is between 2 and 10%
