External fixators Flashcards
What do external fixators consist of?
Pins drilled into the bone to hich a metal beam is attached in parallel to the long axis of the bone
What are the advantages of external fixation?
Stabilises fracture
Allows access to soft tissues
Name 5 uses of external fixation in orthopaedics
Limb lengthening Limb shortening Joint fusion (arthrodesis) Correction of angulatory or rotatory deformity Bone segment transportation
How is post trauma use of external fixators divided?
Temporary
Definitive
What type of fractures is temporary use of external fixators indicted? Why?
When there is extensive soft tissue damage - to maintain stability of the bone whilst allowing access to soft tissues - also allows easy way to elevate the limb
What happens after the soft tissues have healed in temporary external fixation?
May be changed for another treatment such as nailing (surgical) or cast bracing (non-surgical)
Examples of how external fixation is used in a temporary situation
Unstable pelvic fractures (to prevent blood loss)
Polytrauma
What is dynamisation?
The sliding of one fracture fragment relative to another to stimulate callus formation
Which bone is external fixation of open fractures particularly useful? Why?
Tibia - there is usually a great deal of soft tissue damage and the bone has a relatively poor blood supply
What are the 2 principles used when constructing external fixation frames?
Bone/frame construct should be stable
Pin placement must not tether soft tissues or restrict access to wounds
What is a bilateral frame?
When bone pins are positioned so they cross both cortices and pass through the skin and soft tissues on both sides
What is the downside of bilateral frames?
They cause unacceptable soft tissue tethering and limiti limb motion (painful and limits rehab so joints become stiff)
What is a unilateral frame?
Pass through the skin on one side of the limb, enter the proximal cortex and end by just passing through the opposite cortex
What are A or V frames and when are they used?
If unilateral system does not confer adequate stability (if bone is very soft)
Pins are sited at right angles to eah other through the same side of the limb (is a compromise between sot tissue tethering and stability)
Should be reserved for rare difficult situations
What 6 factors determine the stability of a fracture?
Configuration of the frame Degree of contact between bone ends Extent of the soft tissue injury The quality of the bone/pin interface The degree to which clamps have been properly tightened The total number of pins used
