Background

High-pressure injection injuries occur when a high-pressure injection device such as a paint or grease gun injects into the operator. Commonly, this injury occurs in the dominant hand and the index finger of the operator.^[1] However, cases involving the arms, feet, abdomen, and even cervical spine have been reported.^{[2, 3]} Often, the injury may initially appear insignificant or benign. Future disability may be hidden behind a small, punctuate sore on the finger.^{[4, 5]}  The clinical effects of the high-pressure injection injury depend upon a number of variables, including the pressures involved, chemical toxicity, and the quantity of material injected and its temperature.^[6]

A high-pressure injection injury should be considered a surgical emergency. Immediate decompression and thorough cleansing of the offending material from the tissue is required to preserve optimal function.

Pathophysiology

Acute injury is caused by introduction of a foreign material, under high pressure between 2,000 and 10,000 psi, into the poorly distensible digital or palmar tissues. The pathophysiology involves direct trauma that may result in local tissue damage, acute and chronic inflammation, and foreign body granuloma formation. Damage results from the impact, ischemia due to vascular compression, chemical inflammation, and secondary infection. Highly viscous substances (eg, grease) require higher injection pressures than paint or solvents.

Hydrocarbon-based substances such as fuel, paint thinners, and organic solvents lead to the most severe inflammatory response with a high incidence of subsequent amputation.^[7] Grease- and oil-based compounds may lead to oleogranulomas with chronic fistula formation, scarring, and eventual loss of digit function.

Air and water injections also occur and are generally thought to be less serious because there is less resultant inflammation.

Epidemiology

Overall incidence of amputation approaches 48%.^[8] Morbidity is dependent to a large degree upon the material injected. Paint solvents appear to cause the greatest damage and result in amputation in 60-80% of the cases. Grease, the more common injectant, causes a less severe inflammatory response. Amputation is necessary in about 25% of these patients.^[9]

These injuries are rare in women. High-pressure hand injuries usually occur in young men while working, most often to their nondominant index finger. The average age at time of injury in one large review was 35 years (range, 16-65 y). These injuries occurred to the nondominant hand 76% of the time.^[9]