Fracture Healing Flashcards
What is a fracture?
Disruption in the cortical continuity of a bone
How does direct trauma cause a fracture?
- The force is applied at or near to the point of fracture.
- The degree and direction of the force determine the fracture pattern
- Increased soft tissue damage as a result of impact and energy dissipation following fracture
Name some example causes of pathological fractures
- Neoplasia
- Incompletely healed fracture
- Systemic disease e.g. Osteopenia, Hyperparathyroidism
What are some characteristic features used to classify fractures?
- Open/closed
- Bone
- Position
- Fracture line
- Degree of displacement
- Reconstructable?
Position of a fracture is can occur at what points?
- Articular
- Epiphyseal
- Growth plate
- Diaphyseal
What are the 5 different fracture line types?
- Transverse
- Oblique
- Spiral
- Comminuted
- Segmental
How is a transverse fracture classified?
Any fracture across the bone up to an angle of 30 degrees
Describe the 3 classifications of an open fracture
- Grade I - bone ends have pierced skin and retracted
- Grade II - Fracture ends exposed
- Grade III - Major soft tissue loss and trauma
70-80% of the blood supply to bone is provided by which vessel?
Medullary artery
20-30% of the blood supply to bone is provided by which vessel?
Periosteal arteries
How is the blood supply to bone different when there is a fracture?
- Extraosseous arteries
- From tissues around the fracture
- Can be disturbed by fixation method
Describe the features of primary (direct) fracture healing
- Gap less than 1mm
- Rigid stabilisation
- Cutting cones
- No/limited callus
- Works at a cellular level
- No intermediate cartilage stage
- Reduced and compression fractures only
Describe the features/steps of secondary (indirect) fracture healing
- Haematoma
- Granulation tissue
- Connective tissue
- Fibrocartilage
- Bone formation-callus
- Callus remodelling
Does primary or secondary fracture healing work faster?
Secondary
What are the positive healing influencing factors for fracture healing?
- Young patient
- Healthy
- Closed fracture
- Low energy
- Single injury
- Closed reduction
- Non articular
What are the negative healing influencing factors for fracture healing?
- Old patient
- Systemic/local disease
- High energy
- Open
- Multi-trauma
- Open reduction with implants
- Articular (OA/fracture disease)
What are some complications which may lead to failure of a fracture to heal in the time or manner as expected?
- Infection
- Instability- unsuitable fixation
- Implant failure
- Vascular compromise
Complications in fractures healing are nearly always due to..?
Poor surgical technique
Why are young dogs (under 8 months) favourable for fracture repair?
Bone has a high rate of turnover
What is external coaptation?
Casts
When is it suitable to use a cast?
- Small/medium size, non-performance, young dogs (some cats)
- Diaphysis of long bones
- Transverse fractures
- Simple, inherently stable, closed fractures
- Distal limb (but not near joints)
- MUST be reducible to >50% bone contact in two planes (demonstrated radiographically)
What are the advantages of using IM pins?
- Good at resisting bending (only force they oppose)
- In neutral axis of bone
- Often relatively inexpensive
- Should be used with other fixation devices e.g. plate
What are the disadvantages of using IM pins?
- Poor at resisting rotation
- Poor at resisting shear
- Interferes with medullary blood supply
- Difficult in chondrodystrophic dogs
What are the two techniques of IM pinning?
Indirect and direct
What is cerclage wire used for?
Used in combination with IM pins for long oblique fractures
- Must be tight to provide compression: primary bone union
- Can slip along diaphysis
What are the 3 uses of positional screws?
- To maintain relative position of two bone fragments
- To hold plate to bone
- To anchor wire or suture to bone
What are the advantages of using lag screws?
- Lag screw produces static interfragmental compression
- Lag screw is the most efficient method of creating compression
What are external skeletal fixators?
- Pins placed within the bone which span the fracture
- Pins are connected by a thick connecting bar
- External scaffold
- Can transverse joints to stop motion of the joint
What are the advantages of external skeletal fixators?
- Negates all the fracture forces
- Rigid fixation with minimal invasion of injured area
- Allows access to open wounds during fracture repair
- Can maintain limb length, if bone defects exist, while secondary bone healing occurs
- Allows for gradually increasing loads to be applied to the healing bone
- Materials are inexpensive
What are the disadvantages of external skeletal fixators?
High complication rate: • Iatrogenic interference • Catches on clothing/furniture • Pin tract infections - Can weaken/loosen over time
What are some principle points of articular fractures?
- Common e.g. single humeral condylar fracture
- Require primary bone healing
- Require rigid fixation
- Early return to full function
What are some principle points of avulsion fractures
- Associated with strong avulsion force at a muscle/tendon/ligament attachment to bone
- Tibial tuberosity = Quadriceps
- Lateral malleolus = Lateral Collateral Ligament
- Unique challenges of negating avulsion force
