Fracture management Flashcards
What are the main goals of fracture fixation?
- Early return to function
- Achieve stability
How are fractures classified?
- Bone affected
- Position within bone affected
- Fracture pattern
- Open or closed
- Additional features e.g. articular
- Over-riding
- Displacement of segments
- Degree of malalignment
- Soft tissue swelling
What is a simple fracture described as?
One with only 1 fracture line i.e. bone split into 2 pieces
What is required in order to classify a fracture?
Good radiographs, 2 orthogonal views minimum - need to be able to clearly see the bone and make a detailed examination
What is the classification for a fracture where the fracture line is less than 30˚ to the long axis of the bone?
Oblique fracture
What is meant by an interdigitating fracture?
One where the fracture surface is irregular with spikes and depressions on both ends of fractured bone that interlock/interdigitate with each other
What forces are transverse fractures stable and unstable to?
Stable to compression, unstable to rotation
What forces are interdigitating fractures stable to?
Compression and rotation
What classification is given to a fracture where the fracture line is >30˚ to the perpendicular to the long axis of the bone?
Oblique fracture
What is meant by a spiral fracture?
An oblique fracture that curves/spirals around the bone
When do spiral fractures most commonly occur and what is the importance of this?
- Usually low energy fractures i.e. little/no trauma
- Osteons debond
- Often pathologic fractures so need to look for underlying cause
What are comminuted fractures?
- More than one fracture line that connects
- May me multiple joining fractures
- Produce 3 or more pieces of bone
What are segmental fractures?
- Rare, specific types of comminuted
- 2 or more fracture lines that do not connect
- Each bone has a complete piece of cortex
- Produces 3 or more pieces of intact bone
- Wedge/butterfly
How do forces at a fracture site occur?
- Fragments form lever arms
- Coupled with normal loading generate shear, compression/tension and rotation at the fracure site
Explain how avulsion fractures occur
- Apophyseal bone avulses at pointof tendon or ligament insertion
- Usually puppies/kittens due to open growth plates being weaker than bone
- Often landing injury from jumping
- Tendon pulls apophysis away from bone when lands
When do physeal fractures occur?
In skeletally immature animals
What are the classifications for physeal fractures?
- Salter Harris classification type 1 to 5
- TI: complete across the physis
- TII: spur through metaphysis
- TIII: articularte fracture
- TIV: articular and chip in metaphysis
- TV: compression/crush injury of the growth plate
What are the 5 primary forces acting on normal bone?
- Axial compression
- bending
- Shear
- Torsion
- Tension (avulsion, only at insertion points of ligaments)
How do avulsive/tension forces occur on bones?
Tendons or ligaments apply a distractive force e.g. patellar tendon on tibial tuberosity
Give examples of common sites of avulsive fractures
- Patellar tendon on tibial tuberosity
- Gluteal insertion on geater trochanter of femur
- Triceps on olecranon
- Common calcaneal tendon on the calcaneus of the foot
Compare the effect of axial compression on transverse and oblique fractures
- Transverse: compression is stable,
- Oblique: produces shear force leading to over-riding and collapse of fracture
How do bending forces on bones occur?
- Caused by compression
- Bones not straight and not loaded centrally so compressive forces become bending
- Leads to bending on one side and tension on another
Where should plates be placed on a transverse fracture and why?
Should be placed on the tension side to minimise the bending of the bone due to compression
Which aspects of the following bones are the tension surfaces?
a: humerus
b: radius
c: femur
d: tibia
Humerus: lateral and cranial
Radius: cranial and medial
Femur: lateral
Tibia: medial and cranial
What is meant by shearing forces?
Forces that displace the bone perpendicularly
What are the fracture fixation options dependent on?
- Fracture type
- Patient factors
- equipment available
- Surgeon experience/confidence with fixation method
Against which forces are fracture plates stable?
- Compression
- Torsion
- Shear
- Tension
Against which forces are External Skeletal Fixators stable?
All forces
Against which forces are IM pins stable?
Bending and shear
Against which forces are interlocking nails stable?
Best against bending, moderate for compression and ok for torsion and shear forces
Against which forces are pins + tension band stable?
Only tension (moderate stability)
What is strain theory?
Measurement of the strain (% movement) at a fracture site
How is strain applied to a fracture calculated?
- % movement of a fracture
- Amount of movement divided by the original fracture length i.e. fracture 10mm that moves mm = 10% strain
Explain the application of strain theory to fracture repair
- Different healing tissue types can cope with different degrees of deformation
- Can reduce strain to increase chance of healing
- Increase distance between fracture ends and/or reduce fracture movement
List the tissues in bone healing from first to last
- Fracture haematoma
- Granulation tissue
- Fibrous tissue
- Cartilage
- Bone
Compare the strain limits of the healing tissue of bone
- Haematoma and granulation tolerate 100% strain
- Fibrous: 20% strain
- Fibrocartilage: 10% strain
- Woven/lamellar bone: 2% strain
Explain why having a large fracture gap minimises strain and when this method of reducing strain is used
- For comminuted fractures
- Large gap means movement creates low strain e.g. 50mm gap, 5mm movement is only 10% strain - tolerated all bone healing tissues
What are the most common causes of high strain on a fracture repair?
- Movement
- Small fracture gap
- Incomplete reduction leaving small gap (healing tissue ruptures)
What is meant by primary healing of bone?
Bone apposition and reduction used to create stability, ideally compression (contact or gap healing)
What is meant by secondary healing of bone?
Bone not apposed or reconstructed, relative movement instability, bone heals by callus formation