Fracture class and assessment (Lewis) Flashcards
Strength of bone dependent on
- material properties
- structural properties
- rate of load applied
- viscoelastic
- Orientation of applied load
- anisotropic
Wolf’s law
Bone will form in response to forces it’s subject to
Fracture mechanics
Types of stress
- Tension
- attachments of ligments or tendons
- Compression
- aka: axial loading
- Shear
- think of it as eccentric loading (making a parallelogram out of a box)
- Bending
- Torsion
Tension
- Produces elongation
- Creates avulsion fractures
- Occurs at apophyses - traction physes (immature dogs)
- olecranon
- Calcaneus
- tibial tuberosity
Compression
- Opposite force of tension
- Not a common type of fracture
- can happen in vertebral bodies (cancellous bone)
- Tends to create short oblique fractures
- Bone is strongest in this mode of loading
Shear
- Eccentric loading of a bone’s surface
- Bone is weakest in this mode of loading
- lateral condylar fracture (when small dog jumps out of arms)
Bending
- Results in compressive and tensile forces
- Causes short transverse or short oblique fractures
- often with butterfly thingy
- Fracture initiates on tension surface
Torsion
- Rotational forces applied along long axis of the bone
- Results in spiral fractures
Descriptive fracture classification
Important because
- Good communication
- Complexity
- Equipment
- Prognosis
- Concurrent injuries
- Systemic dz
- Cost
Configuration
Incomplete fractures
- Greenstick: opposing cortices involved
- young animals
- bending or torsional forces
- can be oblique or spiral fractures
- Fissure: involves only one cortex
Configuration
Complete fractures
- Continuity of bone is disrupted
- Transverse
- Oblique
- Spiral
- Comminuted
- Segmental
Transverse fractures
*what force would bone be stable to if anatomically reduced?
- propagates perpendicular to bone’s long axis
- smooth or serrated fracture surfaces
- generally result of bending forces
- Some inherent stability
- Stable to
- shear forces
Oblique fracture
- Fracture line rund diagonally to bone’s long axis
- opposing fracture surfaces (cortices) are in same plane
- generally result of axial compression and bending nforces
- limited inherent stability: would succumb to all forces if reduced
Spiral fracture
- Fracture line runs diagonally to bone’s long axis
- Opposing fracture surfaces (cortices) are in different planes
- Generally result of torsional forces
- Inherently stable if reduced
Comminuted fractures
- At least three fracture segments
- Fracture lines intersect
- High(er) energy trauma
- Multiple forces involved
*think about damage to all the soft tissue when you see this: KE=1/2mv2
Segmental fracture
- At least three fracture segments
- will have a middle cylinder of bone
-
Fracture lines do not intersect
- very difficult to reduce and stabilize
- Bending and other forces
- May have a large avascular segment
- upsets main vascular medullary supply
*Not seen as frequently as people
Open Fracture Classification
- Type 1
- Type 2
- Type 3a
- Type 3b
- Type 3c
*used to be called compound fracture
Type I open fracture
- clean soft tissue laceration < 1cm
Type II open fracture
- Soft tissue laceration > 1 cm
- mild trauma, no flaps or avulsion
*Needs more aggressive treatment
Type IIIa open fracture
- Soft tissue available for wound coverage despite large laceration
- flaps or high energy trauma
Type III b open fracture
- Extensive soft tissue injury, loss
- Periosteum stripped and bone exposed
Type III c open fracture
- Arterial supply to the distal limb damaged
- Arterial repair indicated
*street pizza, establish prognosis and aggressive tx if trying to treat
Fracture classification
Anatomic location
- Diaphyseal
- cortical bone; haversion system; dense bone; slow healing; very little soft tissue
- Metaphyseal
- mainly cancellous bone; lots of soft tissue; faster turn over; less mechanical forces
- Physeal (Salter-Harris)
- impacts growth
- Epiphyseal
- usually also articular fractures
- Articular
- goal: anatomic reduction and rigid fixation
clnic question:
Articular fracture of the acetabulum, what do we want to do?
- Anatomic reduction
- Rigid internal fixation
Salter-Harris Classification
- Class I
- separation through the physis (epiphysis comes off)
- Class II
- comes through metaphysis, goes through physis
- Class III
- comes through epiphysis, goes through the physis
- Class IV
- comes through metaphysis, physis and epiphysis
- Class V
- compressive injury
*higher classification, worse prognostic indication for continued growth from growth plate (in humans), in vet med, most fractures cause growth plate to close
Growth from growth plate
- Starts at reserve zone at epiphysis
- cells mature and migrate to metaphysis
Boards question:
Through what layer of the growth plate to Salter Harris fractures occur
Zona hypertrophy
*growing cells bigger, mostly water, not strong
*dogs cats have complex physes, humans tend to have straight physes so maybe this is a trick question…
Articular Fracture
- Can be complete or incomplete
- Involves articular cartilage and subchondral bone
- very important to recognize
- demand anatomic reduction and rigid internal stabilization
Fracture description
INCLUDE:
- Open/closed
- Configuration
- Location
- Right/Left
- Bone
- Displacement: distal segment relative to proximal segment
Describe this fracture:
- Closed
- Spiral
- Distal (dia-) metaphyseal
- fracture of left humerus
- with caudal & lateral displacement
Fracture diagnosis
- History
- Dysfunction
- Pain
- Local trauma
- Abnormal conformation
- crepitus
- radiographs
Fracture diagnosis
Radiographic signs
- A disturbance or break in continuity
- Radiolucent line
- Summation
- or lack
- Always include the joint proximal and distal to the fracture
-
Always obtain two orthogonal views of the bone
- elbow
- sedate if necessary
Fracture assessment score
- Developed to assist surgeons in decision making
- Consider risk factors
- Assess a score based on risk
Clinical fracture assessment
- 1 end (caution)
- Poor client compliance
- Poor patient compliance
- Wimp
- High comfort level required
- 10 end (little risk)
- Good client compliance
- Good patient compliance
- Stoic
- Comfort level not a consideration
Mechanical Fracture Assessment
- 1 (caution)
- non-reducible fragments
- multiple limb injury
- Giant breed
- 5
- Reducible fragments
- Preexisting Clinical Disease
- Large Dog
- 10 (caution)
- Compression
- Single Limb
- Toy Breed
Biologic Fracture Assessment
- 1 (caution)
- old patient
- poor health
- poor soft tissue envelope
- Cortical bone
- High velocity injury
- Extensive approach
- 10 (minimal risk)
- juvenile
- excellent health
- good soft tissue envelope
- Cancellous bone
- low velocity injury
- closed
- reduction
Interpretation of fracture assessment
- Average all scores
- High scores better
- Low scores
- slow or complicated healing
- greater reliance on implants for longer periods of time
