Crush injuries

The result of severe physical trauma from prolonged compression of the torso/limbs

Pathophysiology

Severe compression results in direct trauma to local muscle/nerve
Failure of sodium-potassium pump and sodium-calcium exchanger on sarcoplasmic membrane -> influx of water, sodium and calcium to myocytes -> cellular swelling and death -> rhabdomyolysis
Rhabdomyolysis and compartment syndrome is common
Systemic manifestations result from reperfusion and myonecrosis

Pre-treat casualties with prolonged crush with 1-2L normal saline before releasing the crushing object, whenever possible
If not possible, consider maintaining tourniquet to crushed limbs until IV hydration is commenced
Monitor closely for compartment syndrome

Defined as a severely injured limb with significant risk of amputation
- Especially type III open fractures
MESS - most common scoring system - score >7 correlated well with primary amputation
- Severity of skeletal or soft tissue injury
- Severity and duration of limb ischaemia
- Severity of shock
- Patient age

Benefits of amputation
- Pain relief
- Better functional outcome than an impaired native limb
- Negate the need for multiple reconstructive procedures
- Avoid risk of systemic complications
Decision-making
- Immediate
  - Amputate only if the limb is causing compromised physiology and it is unfeasible to stabilise and revascularise
  - Specifically - haemodynamic instability, major haemorrhage, or inability to revascularise without risk of death
  - Guillotine amputation is commonly done, as distal as possible
- Early
  - Terminate limb salvage if there is - necrosis of plantar skin requiring free flaps and grafts; severe foot crush fractures especially combined with open tibial fractures; other complex decisions made in conjunction with orthopaedic surgeons