Fracture management in sports trauma Flashcards
What dictates whether primary or secondary bone healing occurs?
Fracture stability
Primary (no callous) only occurs if a fracture is adequately “fixed” through reduction, immobilisation, and rehabilitation.
Strain versus stress
STRAIN: percentage of change in length of the material in relation to original length (change in length / original)
STRESS: force per unit area ie pressure
Types of stress
- Tension
- Compression
- Shear forces
are the 3 stresses relevant to fractures
What calculation combines stress and strain?
Young’s modulus
Tells us how easily a bone can stretch and deform
stress/strain
Define yield strength
Lowest stress that produces a permanent deformity in a material
Describe the process of primary bone remodelling
- Osteoclasts form at the front of the cutting cone
- Closing cone of osteoblasts come behind it and lay down new bone in layers
What conditions are necessary in order to undergo primary bone healing?
1) Strain = <2%
- so fracture needs to be fixed very rigidly to prevent more than 2% change around fracture site
2) Fracture gap compressed <1mm
- so you need very stable opposition at the fracture site
ABSOLUTE STABILITY
Describe the process of secondary bone remodelling
1) HAEMATOMA FORMATION
2) SOFT CALLOUS
Movement around fracture site stimulates multipotent cells in periosteum to differentiate to osteoprogenator cells
3) BONY CALLOUS
- Soft calcified chondral cells become hard and mineralised
- At this point the fracture is solid, united and pain free
4) REMODELLING
- Once the bony callous has formed, tension is <2%
- organised new bone can be laid down that is no weaker than before
How much strain is necessary for secondary bone remodelling to occur?
2-10%
State some factors for non-union (secondary formation doesn’t occur despite attempt at callous formation)
- Smoking
- Nutrition
- Co-morbidities
- Drugs
- Poor blood supply (some fractures are more likely e.g. femoral head)
- Type of fracture- eg intra or extra capsular (extra = more likely to damage blood supply inc risk of AVN)
What are the pros and cons of callous formation?
If you can’t see it and function is good then it can be okay
If the callous forms into a joint there will be an irregular joint surface –> Early onset OA
Long term aims of fracture fixation
- Restore ROM
- Pain free
- Stable
What can occur if a fracture is incorrectly fixed?
- Malunion/deformity
- Abnormal joint loading –> OA
- post-traumatic OA
When is surgery indicated over a cast?
- Intraarticular- want primary bone healing
- Cannot maintain anatomical reduction with a plaster/splint
How do you manage intra-articular vs extra-articular fractures?
INTRA-ARTICULAR
- aim for absolute stability an avoid callous formation
- plates and screws around joint
EXTRA-ARTICULAR
- relative stability
- callus formation won’t affect the final outcome
Intramedullary nailing pros/cons
CONS
- Secondary healing – only 2 plates each end of a nail
- There will be >2% tension
PROS
- Allows for walking the next day post-surgery
- This allows for rehab, less atrophy, improved ROM, and return to normal function much faster than plaster
Which fixation methods lead to absolute stability?
- lag screw fixation
- tension band wiring
- plate and screws (can also be secondary)
External fixator primary or secondary bone healing?
far from fracture site
secondary
K wire fixation pros/cons
PROS
- better than plating because percutaneous less invasive procedure
- Good for fractures of small bones (eg, hand and foot)+ multiple small bony fragments.
CONS
- secondary bone healing
- less stable
intra-articular ankle fracture- what would you do to manage?
- Debride wound, Abx
- External fixator to hold wound in reduction
- come back a few days later for absolute reduction with plates and screws
