Fractures Flashcards
What is the definition of a fracture?
A complete or incomplete break in the continuity of bone and/ or cartilage
What are bone fractures usually accompanied by?
- Variable degree of soft tissue injury
- Locomotor dysfunction
- Maybe accompanied by significant injury to other body systems
What three aspects does the osseous blood supply have?
Afferent
Intermediate
Efferent
Describe the afferent blood supply of the bone…
- Principal nutrient artery
- Metaphyseal and Periosteal arteries are in association with muscle attachments
- Epiphyseal arteries separate the blood supply from the metaphysis
Describe the intermediate blood supply of the bone…
Fine system of little tiny vessels that run through the bone
Describe the Efferent blood supply of the bone…
Venous drainage at the periosteal surface
Where does the inside 2/3 of the bone get all of its blood supply from?
From the interior of the bone
In most significant injuries, which artery is damaged?
The Nutrient artery
- Less important than other vessels
What is the Secondary Bone healing sequence…
- Haemorrhage & clot formation
- Inflammation & Oedema
- Proliferation of cells
- Cartilage & Bone formation (callus)
- Remodelling
What are the two types of fracture healing?
Primary
Secondary
Describe Primary Bone Healing…
Direct production of new bone with no precursor
- No callus
- Requires perfect anatomical reduction and rigid fixation
- Osteoblasts lay new lamellar bone if theres a gap
- Plates take the weight and load share with the bone
What is a bone callus?
When the body creates a whole lot of extra bone
- Stabilises the fragments to allow lamellar bone to grow and fill the fracture gap
- Size of callus is related to the stability of the fracture - more callus= less stable
- Not good within or around a joint - need primary healing here without callus production
- Initially stronger than primary
- Three types of callus
What do osteoblasts do in primary bone healing?
If there is a gap between bone, osteoblasts will lay lamellar bone perpendicular to the long axis followed by cutting cores
Describe the fracture vascular supply…
Afferent artery hypertrophies
Extraosseous vessels are the most important in repair.
What is the most important blood supply in fracture repair?
Extraosseous blood supply
What is the most important thing about fracture repair?
Preserving the blood supply!
Vascular response is imperative!
What will affects the vascular response to a fracture?
- Nature of the Trauma
- Surgical Handling
- Inadequate reduction
- Inadequate stabilisation
What are the three types of bone callus that can form?
- Periosteal
- Medullary
- Endosteal
What are 5 clinical signs seen in animals with fractures?
- Dysfunction
- Pain
- Blood loss
- Nerve Injury
- Perforation of adjacent organs
What do we use to classify fractures?
- Location, direction & number of fracture lines
- Displacement of major bone fragments and stability
- Open or Closed
- Whether the fracture fragments can be reconstructed to provide load sharing
Why are fractures classified?
- Allows detailed & concise communication between vets
- Allows comparison of techniques when similar fractures are treated
- Allows assessment of the forces that lead to injury and affects the stability of repair
- Helps predict diagnosis, likelihood of infection & difficulty, complications of treatment
Describe a descriptive classification of fractures…
- Complete vs. Incomplete
- Displacement
- Single vs. Complex
- Open vs. Closed
- Bone involved
- Region of bone involved
What is a complete fracture?
Cortex fracture circumferentially
What is an incomplete fracture?
One cortex cracked, one bent
OR…
Fissure extending down the shaft, with the periosteum intact
What is a fissure?
A crack running down from the break
What does a wound over a fracture tend to mean?
- Contamination
- Soft tissue injury
- Devitalised tissue
- Dead space/ foreign matter
= risk of infection
What is important in preventing infection of an open wound from a fracture?
Aggressive early internal fixation
- granulation tissue resists infection but is disturbed by motion
What type of urgency is an open fracture?
A Surgical Emergency!
How do you classify open fractures?
Grade I: skin penetrated inside to out. Wound 1cm diameter without extensive st damage or flaps. In to out or out to in. Foreign material may be carried into the wound
Grade III: wounding from the outside with extensive skin, subcutaneous and muscle injury with neo-vascular injury
What is the prognosis for the three grades of open fractures?
Grade I and II: good prognosis
Grade III: require extensive and expensive treatment. Risk of infected nonunion is high.
Alternative is amputation but should attempt repair
Transverse Fracture…
Straight across
Short Oblique Fracture…
Small angled break all the way through
Long Oblique Fracture…
Large angled break all the way through
Spiral Fracture…
Oblique fracture that appears different on either side
What is a comminuted fracture?
A fracture with three or more fragments
Use mild, moderately or highly in the description
Certain types: butterfly, comminuted, segmental
What is a segmental, comminuted fracture?
Where there are two single fractures in the same bone that don’t meet
When does a comminuted fracture become non-reconstructible?
If the fragments are dimensionally less than a third of the bone diameter
What is the definition of bone reconstruction?
The ability to return the fragments to an anatomically correct and structurally intact state
- They can bear/ share weight along with the implant
What type of fractures can be load-sharing?
Transverse
Oblique (after implants are placed to prevent shear)
Reducible wedge
Segmental
Describe a Stable Fracture…
Doesn’t tend to displace after it has been reduced and mobilised.
Describe a Rotationally Stable Fracture…
Interlock when anatomically reconstructed
What are the complex fracture configurations?
Butterfly
Comminuted
Segmental
What is an extra-articular fracture?
Articular surface isn’t fractured but is separated from the diaphysis
- Metaphyseal in adults
- Physeal in growing animals
What is a partial articular fracture?
Involve only a section of the articular surface
What is a complete articular fracture?
The joint surface is fractured and separated from the diaphysis
Describe a type 1 salter-harris fracture…
Slipped
Fracture plane passes all the way through the growth plate and doesn’t involve bone
Describe a type 2 salter-harris fracture…
Above
Fracture passes across most of the growth plate and up through the metaphysis
Describe a type 3 salter-harris fracture…
Lower
Fracture plane passes along the growth plate and down through the epiphysis
Describe a type 4 salter-harris fracture…
Through
Fracture plane passes directly through the metaphysis, growth plate and down through the epiphysis
Describe a type 5 salter-harris fracture…
Rammed
Crushing type injury that doesn’t displace the growth plate but damages it by direct compression
Describe a type 6 salter-harris fracture…
Injury to perichondral surface
- Periosteal bridge stopped growth
Which side of the fracture are the germinal cells?
Epiphysis
- Can be more forceful with the metaphysis because it doesn’t have germinal cells
What fracture forces are countered?
Those that act on a bone during weight bearing
Force by muscle actions across joints
What are the 5 types of fracture forces that can be encountered?
- Bending
- Rotation
- Shear
- Tension
- Compression
Where are bending forces most significant?
Long bones
Where are rotation forces most significant?
Near joints
Where are shear forces most significant?
Most problematic for oblique fractures
What type of fractures are most susceptible to bending, shear forces and rotation?
Diaphyseal Fractures
Traction and Compression are secondary considerations
What type of fractures are most susceptible to bending and shear with rotation and tension as secondary considerations?
Metaphyseal fractures
Which fractures are primarily subjected to shear and tension?
Articular Fractures
What is the importance of identifying forces on a given fracture?
It allows evaluation as part of fracture planning
- i.e. some types of fixation are stronger in bending than others so would be used in a mid-diaphyseal fracture subject to significant bending stress
What is Stress?
The magnitude of force acting over a given area
Determined by:
- Weight-bearing loads
- Non-physiological loading
- Size of the bone
What is strain?
Measure of the change in the length of the fracture gap
- delta L/L%
- Cells in the gap, subjected to strain will form only fibrous tissue in high strain
- Bone requires low strain
What happens if inter-fragmentary strain is not reduced below 10%?
Fibrocartilage cannot form = fibrous non-union will develop
What do you have to be careful of when trying to reduce the gap between comminuted fragments?
It can actually increase the strain and delay or prevent healing if the implant system isn’t completely rigid
What happens if Strain is lower than 2%
Bone can form
What happens when a callus forms in a comminuted fracture gap?
Increases stability which decreases strain below 2% allowing bone to form
What is fracture assessment?
Pre-op analysis of the factors for and against a successful outcome
What are the three things that make up a fracture assessment?
- Mechanical Fracture Assessment
- Biological Fracture assessment
- Clinical Fracture assessment
What are the three major types of fracture repair systems?
- Limb splintage / external coaptation
- Bone splintage by external skeletal fixation
- Bone Splintage by internal fixation
What is external coaptation good for?
Weakest for all fracture forces
What is external skeletal fixation (ESFs) good for?
Bending and Rotation
- less in shear
What are IM pins good for?
Bending
- Poor in rotation without cerclage
What are plates good for?
Shear and rotation forces
- Bending is variable
What are Inter-locking nails good for?
Excellent in bending
- Weaker in shear
- Okay in rotation
What are four questions you should ask yourself when making decisions about fracture repair?
- Is fracture repair warranted? - Age, use, owners finances, animals general health
- Is the fracture site viable?
- Are the major nerves intact?
- Are the major blood vessels intact?
What should you consider when you have elected fracture repair?
- Optimum repair method first
- Then cost
- Then based on fracture forces
- Then age
- Then classification
What is a major feature of success of fracture repair?
Correct post-op management
- Rest and exercise restriction
- Early weight bearing
- Lead toileting for young and old animals
What is good about early progressive consolidation of fractures?
It causes a shift in relative load bearing toward healing bone and away from the implants
What do you do if you’re not going to treat a fracture immediately?
Need to apply fracture support or patient restraint
- Minimises pain and prevents trauma to soft tissues
When not treating a fracture immediately… Should you stabilise fractures above the elbow/ stifle?
Additional temporary stabilisation is unnecessary and may be detrimental
- Stabilised by surrounding musculature and post-fracture haematoma
When not treating a fracture immediately… Should you stabilise fractures below the elbow/ stifle?
Yes
- Splints OR…
- RJB
What is an open fracture repair?
Operation in which skin and overlying muscle is opened
What is a closed fracture repair?
Operation in which implants are placed through stab incisions away from the fracture
What is important about open/ closed fracture repair?
It doesn’t dictate what is biologic or anatomic repair
What is fracture reduction?
Process of returning fracture fragments to their anatomic position
- Performed by open or closed methods
What occurs if a fracture isn’t reduced within 3 days?
The inflammatory reaction brings about more permanent contraction
- Harder to attempt reduction
What are the AO principles in fracture repair?
- Anatomical reconstruction
- Stable fixation
- Preservation of the blood supply to the bone
- Early, pain-free mobilisation
What is biological fixation?
An attempt to stimulate synergy between implants and the body’s inherent manner of repairing and healing bone
What is the ultimate form of biological strategy?
Limb splintage
- some can be performed with minimal open or closed reduction
How are some methods of plating (e.g. bridging osteosynthesis) also biologic strategies?
Rigid fixation can be achieved without disturbing the fracture site by making no attempt to reduce fragments
What are the 5 principles of treating open fractures?
- Prevent further contamination
- Thorough cleansing and aseptic surgical debridement
- Careful preservation of blood vessels and nerves
- Stable fixation
- Early active mobilisation of the limb
What are the best ways to take care to prevent further bugs?
- Aseptic handling
- GA/sedation to perform cleansing
- Sterile KY jelly on wound before clipping
- Surgically prep surrounding skin
- Flush with saline, 0.05% chlorhexidine
- Staged debridement
- Small bone fragments without blood supply can be removed if contaminated
What are splints and casts only appropriate for?
Stable distal antebrachial or lower limb first degree open fractures treated within 6 hours
Powdered Local Antibiotics…
Aren’t effective at reducing infection and can be harmful
Local gentamicin Antibiotics…
Impregnated PMMA beads can be placed in the wound
Systemic Antibiotics…
For efficacy against staph or from results of culture from wound swabs
What is the ideal fixation for open fractures?
ESF
- avoids placing implants in a contaminated site
Prophylactic Antibody use…
To have high levels at the site of surgery
- IV high dose
- Delivered at induction
Most commonly cephalosporins
What are the three major fracture complications?
- Implant loosening
- Instability
- Osteomyelitis
What do the fracture complications lead to?
- Malunion (alters bone function)
- Delayed union
- Non-union (never heals)
- Sequestrum/ Involucrum (death of a fragment)
Implant failures…
Premature loosening Premature failure Infection Excessive movement Damage to blood vessels
How are fracture complications classified?
- Fracture site
- Displacement of fractures
- Any infection
- Biological activity
Describe biological activity…
Hypertrophic: Abundant callus
Moderately Active: Moderate Callus
Oligotrophic: Little/ No callus
What does an active non-union hypertrophy indicate?
Lack of instability is the cause of the non-union
- Apply rigid fixation and compression without removal of the callus
When can an active but infected non-union occur?
- Surgical infection
- Open fractures
What type of non-unions are rarer?
Biologically inactive ones
- impaired blood supply and thus healing
What are some causes of active non-unions?
- Inadequate stabilisation
- Loss of blood supply
- Infection
- Excessive gap
- Severe comminution
- Inappropriate post-op management
- Excessive compression
- Excessive implants
- Improper implants
- Systemic Disease
What are some clinical signs of delayed/ non-union?
- Inadequate progression of weight bearing
- Pain/instability on palpation
- Lack of radiographic evidence of bridging callus to the extent expected
- Lack of expected fracture and remodelling
- Sclerotic bone fragments
- Sealed medullary cavity
- Lysis around implants
- Broken implants
- Lysis of bone + soft tissue swelling
How do you treat delayed unions?
- If rads show delay, but viable fracture ends then reduce motion by cage rest and external coaptation
- Do serial rads to assess
- ESF (closed) can be placed for additional stability
How do you treat viable hypertrophic non-unions?
Closed ESF for stability
How do you treat viable oligotrophic non-unions?
ESF or (Dynamic compression plate) DCP after bone grafting
How do you treat non-viable non-unions?
Resect inactive fracture site and DCP with bone graft
How do you treat infected non-unions?
- Culture and Sens from FNS or biopsy sample
- Antibiotics
- Delayed grafting and ESF
- Implants away from the site
