External fixator
Principles
- Focus - area of bone supported (ie fracture)
- Segment - area of bone into which external fixator is inserted in order to control the focus
Components
- Pin (fix frame to bone)
- Screw-threaded half pins: applied to side of bone, low risk of neurovascular damage, but increased risk of loosening
- Transfixing pins: passes through all of bone to other side, better control of fracture site; disadvantage of neurovascular injury and risk of loosening - used only in simple constructs or temporary stabilisation of severely traumatized limbs
- Tension wired: passes through all of bone, tightened to support bone, less traumatic to blood supply, but more expensive and complicated to apply
- Frame
- Unaxial: half pi; frame adjacent to one side of pin only
- Circular: ilizarov frame
- Hybrid: supports one segment using rings and other segments using uni-axial constructs
- Pinless: metal clamps that tighten onto bone and therefore avoid interfering with medullary canal for lateral internal fixation
Indications:
- Polytrauma
- Peri articular fractures
- Intra articular fractures
- Open fractures
- Pelvic fractures (to reduce life threatening haemorrhage)
- Bone transport
Complications
- Pin-track infection
- Chronic pain
- Pin loosening and breakage
- Neurovascular damage
- Joint stiffness
Intramedullary nails
- Material
- stainless steel, titanium, titanium alloys
- Locking
- Screws inserted proximally and distally
- Provide longitudinal and rotational stability
- May be static or dynamic
- Dynamisation: process of removing one or more screws in order to allow collapse - increases the loading of the fracture site and hastens union
- Controversies of reaming
- Enlarges medullary canal - allows stronger, wider nail
- Weakness due to loss of endosteal bone
- Disturbance of medullary blood supply may cause cortical necrosis
- Time consuming
- May cause embolisation