Physiologic amputation prevents myoglobinuria from lower extremity myonecrosis

Myoglobinuria secondary to myonecrosis is a proven cause of renal failure, especially in critically ill patients. Physiologic amputation or cryoamputation has been used at our institution for the past two decades as a safe and effective treatment for lower extremity infection, intractable rest pain, and irreversible myonecrosis. We retrospectively studied five critically ill patients with myonecrosis of lower extremities associated with myoglobinuria. The etiology of myonecrosis included preexisting peripheral vascular disease or crush injury to the lower extremities. It was determined that all five patients were too ill to undergo emergency amputation. Myoglobinuria was documented in all five patients and cleared within 24 hours of physiologic amputation in four patients. All five patients had elevated creatine phosphokinase levels (mean 20,270 mU/mL, range 12,090 to 43,164 mU/mL) that significantly decreased within 48 hours of physiologic amputation (mean 6,488 mU/mL, range 2,250 to 13,580 mU/mL). Mechanical ventilation and cardiovascular support were required in four patients. All patients had transient episodes of renal insufficiency with two progressing to anuric renal failure and requiring dialysis. One patient's renal failure resolved after 56 days, but the other patient died of a cerebrovascular accident 22 days after initiation of physiologic amputation. The mean duration of physiologic amputation was 15.6 days (range 5 to 32 days) with no significant complication due to physiologic amputation. All five patients had surgical amputation successfully. Three patients survived. The two deaths in the study were due to a cerebrovascular accident in one patient and a cardiopulmonary arrest in another. Physiologic amputation is a treatment option that halts myonecrosis, prevents myoglobinuria, and lessens the risk of associated acute renal failure. Physiologic amputation may be appropriately used in patients with myoglobinuria due to extremity myonecrosis who are deemed too critically ill to survive emergency amputation.