What is the radiographic technique for bones?
- low KvP (for high contrast)
- high mAs
Where is the marker placed on rads of extremities?
place L or R marker on the lateral side (cranially or dorsally on a lateral view)
Describe proper positioning of bones and joints.
- Bones: center on desired bone and include joint above and below
- Joints: center on desired joint
What surfaces of the bone/ joint are highlighted by a DLPMO radiograph?
plantarolateral and dorsomedial surfaces
What surfaces of the bone/joint are highlighted by the DMPLO radiograph?
plantaromedial and dorsolateral surfaces
With a hairline fracture [not large fracture line or displaced fractures], why is it important to take multiple views to find the fracture?
your x-ray beam must be tangential (parallel) to fracture line for it to show up; if the beam is perpendicular to fracture line, it will not appear on the films
If you see a relatively thin radiolucent area on the middle plantar/ medial aspect of a bone, what must you keep in mind?
this is the location of the nutrient foramen; if the animal is not lame/ not showing signs, consider that it is NOT a fracture
What are the salter-harris fracture classifications?
- I: physis
- II: physis and metaphysis
- III: physis and epiphysis
- IV: physis, metaphysis, and epiphysis
- V: crushing injury to the physis
Describe a transverse fracture.
perpendicular to the long axis of the bone
Describe oblique fractures.
- no longer perpendicular to the long axis, at some different angle
- can be short or long
What is a spiral fracture?
spirals around a long bone
Describe a comminuted fracture.
having multiple pieces
What is a compound fracture?
an open fracture in which the bone is sticking out past the margins of the skin
What is a pathologic fracture?
some disease process weakens the bone, making it easier to fracture with less trauma
What is a slab fracture?
starts on one margin of the joint and comes out the other edge of the joint
The proximal row of carpal bones contains the __________, and the distal row of carpal bones contains the ___________.
named carpal bones (ulnar, intermediate, and radial, acessory carpal bones); numbered carpal bones
Within the proximal row of carpal bones, the carpal bone that is projected most proximally on a lateral flexed carpal radiograph is the ___________.
intermediate carpal bone ("I is Hi")
Within the proximal row of carpal bones, the carpal bone that is projected most distally on a lateral flexed carpal radiograph is the ___________.
radial carpal bone
What is an avulsion fracture?
any piece of bone that’s attached to a soft tissue attachment (ligament/tendon) and is displaced by that ligament/ tendon
Describe a compression fracture.
- a bone that is pathologically weakened or fractures gets compressed/ becomes shorter
- common in young farm animals that have an infection that weakens the bones (ex. young cria with compressed C7 vertebra)
Describe a condylar fracture in a horse.
- articular fracture at the distal aspect of the cannon bone (metacarpal or metatarsus)
- common in athletic horses
Why do we take post-op radiographs? (3)
- document fixation
- anatomic alignment
- placement of implants (no implants in joints, engaging bone properly, etc)
Describe the aspects of secondary bone healing.
- most common way a bone heals
- occurs by callus formation: initially, hematoma and inflammation--> bridge gap with granulation tissue--> resorption of fracture margins--> mineralization of granulation tissue--> eventual bone remodeling
Describe the radiographic signs of secondary bone healing 5-10 days after reduction. (2)
- fracture fragments lose sharp margins
- demineralization of fracture margins, results in slight fracture line widening
Describe the radiographic signs of secondary bone healing 10-20 days after reduction. (3)
- formation of endosteal and periosteal callus
- decreasing size of fracture gap
- variable loss in opacity of free fracture fragments
Describe the radiographic signs of secondary bone healing >30 days after reduction. (2)
- fracture lines gradually disappear
- external callus increases in opacity and models
Describe the radiographic signs of secondary bone healing >3 months after reduction. (5)
- continued remodeling of external callus
- trabecular pattern may develop within the callus
- cortical shadow becomes visible through the callus
- medullary cavity continuity gradually re-established
- cortical remodeling along the lines of stress
What are factors affecting healing? (7)
- anatomic reduction
- viability of surrounding tissue- a lot of muscle will aid in healing b/c more blood supply
- specific bone involved
- fixation type
- misc- species, breed, age, nutrition
Describe primary bone healing. (3)
- no cartilaginous phase (no callus)
- excellent anatomic alignment
- rigid fixation
What are causes of lucency around a metallic bone implant?
infection and/or implant loosening
What is a classic sign of non-union?
smoothing/ rounding of edges of fracture margins that are not united
What is a malunion?
anything that doesn’t heal in its normal anatomic alignment
What is disuse osteopenia?
- bone opacity is decreased, thinned cortical margins, coarse trabecular pattern
- bone is resorbed d/t lack of loading of bone
What is synostosis?
when you have fractures especially with paired bones- sometimes they form one callus that incorporates both bones