Fractures Flashcards
what do compression fractures look like?
what do tension fractures look like?
what do shear fractures look like?
what do bending fractures look like?
what do torsion fractures look like?
what are simple vs complex forces?
simple:
-compression
-tension
-shear
complex:
-bending
-torsion
what, generally, causes a fracture to occur?
- Occurs when load on bone exceeds the strength of the bone
Extrinsic forces:
* External forces acting on bone
> Cause the majority of fractures
Intrinsic forces
* Internal forces (tendon pull…)
> Less frequent, leads to specific fractures
how do we desribe a fracture (6 things)
- Bone involved
- Location within the bone
* Epiphyseal, Physeal, Metaphyseal, Diaphyseal
* Proximal, Middle, Distal - Fracture type or complexity
* Simple, Comminuted, Segmental - Fracture configuration
* Transverse
* Oblique (Short, Long)
* Spiral
* Wedge - Fracture characteristic
* Open, Closed - Displacement
simple vs comminuted fracture, and when does each occur
Simple:
-single fracture line
-Low energy trauma
-Minimal soft tissue trauma
Comminuted:
-multiple intersecting fracture lines
-High energy trauma
-High soft tissue damage
how do we desribe the segmental fracture configuration
- Segmental: multiple, non intersecting fracture lines
what is a transverse fracture, when does it occur
- Fracture line perpendicular to the long axis of bone
- Tensile loading
- Fracture angle 90° > x > 60° relative to long axis
what is an oblique fracture and what is short vs long? when do they occur?
- Short oblique: Fracture angle 60° > x > 30° relative to long axis
- Long Oblique: Fracture angle x <30° relative to long axis
- Compression loading
what causes a spiral fracture
- Torsional forces
- “Figure-of-eight” fracture line
- Very similar to a long oblique Fx
- One of the easiest fractures to get
> Playing…
when do we see a wedge fracture and what does its character depend on?
- Result from bending forces
- Size of wedge depends on loading
- Biomechanically important
when should we fix a fracture
as early as possible
advantages to early, accurate fixation
- Reduces pain
- Allows early return to function
- Reduces risk of non-union
- Eliminates risk of mal-union
Goals of fracture fixation:
Early ambulation and complete return to function
what are the categories of primary bone healing?
-Contact Healing
-Gap Healing
what are the properties of Primary Bone Healing – Contact Healing
- Absolute stability (< 2% strain)
- No or minimal gap (< 0.01mm)
- Bone heals without the formation of callus
- Weaker than 2* bone formation initially
- Slow process…
what are the properties of Primary Bone Healing – Gap Healing
- Absolute stability (< 2% strain)
- Small gap (< 1mm)
- Initial fibrin matrix with angiogenesis
- Within days-weeks lamellar bone fills gap
> Initially oriented perpendicular to long axis – weak
> 3-4 weeks > reoriented
what are the properties of secondary (indirect) bone healing? what is the proccess?
- Adequate stability
- Some gap may be present
- Formation of callus
- Transformation of tissue into another until bone is repaired
> Granulation
> Fibrous tissue
> Fibrocartilage
> Bone - Clinical union is relatively fast
5 steps of secondary bone healing
- Inflammation
- Intramembranous Ossification
- Soft Callus (chondrogenesis)
- Hard Callus (endochondral ossification)
- Bone Remodeling
fixation methods for broken bone
- Splint/Cast (coaptation)
- Intramedullary (IM) pin
- Cerclage wire
- Bone plate
- External fixator
- Interlocking nail
- Often used in COMBINATIONS!
how should casts be placed to help heal a fracture? when should they not be used?
- Must immobilize joint above and (all) joints below
- Cannot be used for upper extremities (femur, humerus)
- Some bones should not be casted (radius in miniature breeds)
disadvantages of using casts for fracture repair
- Never provide full stability
> Many fractures cannot be properly immobilized
> Mal-unions are VERY frequent - High morbidity!
> Morbidity quickly increases with duration
> Cheaper initially but cost of maintenance is high
when is it ok to use a cast to repair a fracture?
- Closed, non-displaced fractures below elbow or stifle
> Incomplete (Greenstick)
> Transverse (non- displaced/reduced) - Fractures that can be reduced closed and will be stable once reduced
- Good for small bones like toes and metacarpi
- Fractures that are expected to heal quickly
> Minimize fracture disease
> Often young animals
what type of fractures should never be casted?
MANY fractures should never be casted…
* Open
* Comminuted
* Non-reduced
* Unstable
* (Older dogs)
* Femurs
* Humerus
* Radius (miniature)
* etc
what is an external fixator?
there are several types, but all work by the same principle
Advantages of External Fixator
- Versatility!
- Minimally Invasive (reduced surgical approach)
> Good for open or infected fractures! - Can be deconstructed easily
- Reasonable cost
Disadvantages of External Fixators
- Technically demanding
> (although less than some other techniques) - Requires significant aftercare
> Daily cleaning - Pin tract infections/draining
- Cumbersome for the patient
Intramedullary Pins and Cerclage Wires advantages
- Inexpensive
- Minimal equipment
disadvatages of Intramedullary Pins? why do we use them with other devices?
- ONLY counteracts bending forces
- Cannot be used for radius
- Only for very specific fractures:
- Simple Long oblique or spiral
- Never used alone:
-use with cerclage wires to make sure things cant twist out of position - Can be used with plates for complex Fx
what is the interlocking nail and what are its advantages? what about disadvantages?
- Very good stability
> Counteract all forces
> locking bolts - Minimally Invasive technique
> Good for open fractures
> Good for comminuted fractures - Not for the radius!
- Technically difficult for small size bones
what are bone plates and screws used for? what are the advantages?
- Metal plates attached to the bone with bone screws.
- Can be used for all bones
> Probably the most used method for Fx - Very stable fixation
- Can be combined with many other fixation methods
disadvantages of bone plates and screws
- More invasive (large approach)
- Cause more bone trauma
- Expensive
> Large inventory and equipment
> Technically demanding
what are the 3 ways that a bone plate can be used?
A) Compression plate
* Transverse fractures only
* Bone supports most of the load
B) Neutralization plate
* Bone must be reconstructed
* Bone shares some of the load
C) Bridging plate
* Bone is NOT reconstructed
* NO load sharing
what is plate-rod fixation?, what is the advantage?
- Combination of plate and IM pin greatly increases the bending strength of the repair
- IM pin 35-40% of medullary canal
what is the ‘race’ for healing?
- Most implants are designed to allow weight bearing …but NEVER running, jumping etc
- Animals MUST ALWAYS be restricted until healing is confirmed
> Short leash walks only - “Implant failure is always a time dependent certainty”
> ie: if it does not heal in time, EVERY implant is going to eventually fail
what does a bone need to heal? what determines the type of healing?
- Bone needs blood supply and stability to heal
> Stability determines the type of healing
goal of fixation
- The goal of fracture fixation is Return to Full Function
Fixations should be designed to allow….
immediate use of the leg
intramedulary pin and circlage wires can never be used for what bone?
radius
intramedulary pin and circlage wires are only for what type of fractures?
simple long oblique, or spiral
initerlocking nail good for what type of fractures? cant be used where?
good for comminuted, open
do not use on radius
