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%
What are the 3 phases of bone healing?
Reactive, reparative and remodeling
The phases of rehabilitation closely match the stages of ___. The 3 stages are:
Healing;
1. Inflammatory stage
2. Reparative (fibroblastic) stage
3. Remodeling (maturation) stage
What are the four main interventions in a rehabilitation program?
- Ergonomics
- Manual therapy
- Therapeutic exercise
- Electrophysical (therapeutic) modalities
How does cryotherapy work on injured tissue?
Reducing or delaying infiltration of white blood cells and subsequent inflammatory cytokines in injured tissue
What are the three phases of rehabilitation?
Inflammatory, transition and strength/function
What does the functional evaluation consist of in a rehabilitation assessment?
Passive and active assessments
Give examples of passive assessments in physical rehab (7)
Passive range of motion, end-feel, goniometry, joint play, flexibility, muscle girth, myofascial exam
Give examples of active assessments in physical rehab (4)
Posture, Gait/mobility, Transfer, Strength (muscle) test
What are the basic goals in the inflammatory stage of rehabilitation?
Protect healing tissues, relieve pain, reduce inflammation, maintain joint ROM
What are the goals in the reparative stage of healing/subacute/transition stage of rehab?
Promote weight bearing/joint function, reeducation of muscle, regain ROM, regain flexibility/strength
What are the goals in the remodeling stage of healing/ chronic or strength/function stage of rehab?
Restore full ROM/flexibility, improve muscle mass/strength, improve proprioception, regain endurance, return functional activity
Which is typically the longest phase of the rehabilitation process? How long does it typically last?
The chronic or strength/function phase; For bone - 12 wks+; for tendon/ligament - 1 yr+
How does pulse electromagnetic field (PEMF) energy work?
A flow of electricity runs through a coil or antenna, which in turn generates a magnetic field that can be directed at tissues for therapeutic effects
When is PEMF particularly helpful?
Nonunion fractures and neurologic injury
What are the four main skeletal tissues found in vertebrates?
Cartilage, bone, enamel, dentine
What is the approximate composition of skeletal bone?
75% inorganic (water and minerals) and 25% organic (extracellular matrix and cells)
What are the most common complications in fracture healing?
Infection, sequestration, delayed union, nonunion, malunion
When can periosteal proliferation be detected on radiographs after infection of a fracture?
7-10 days
What are potential reasons for delayed union of a fracture?
Disuse, instability, poor fracture reduction, poor vascular irrigation, poor nutrition, MBD, old age, infection, sequestrum, or underlying pathology s/a neoplasia
When should nonunion be considered?
After 12 weeks, especially if no evidence of radiographic healing in sequential radiographs
What is the most frequently fractured bone in the ferret and guinea pig?
The femur
What is the most common traumatic fracture in chinchillas? What type of fracture usually occurs?
Tibia; short spiral or transverse
Where is the most common site for vertebral fractures in rabbits?
LS junction (L7)
How much bone loss must occur before being radiographically evident?
30-60%
What area do osteosarcomas in rabbits more commonly affect?
The skull
What is the most common spinal curvature malformation in small mammals?
Scoliosis
