- high pressure grease and paint guns are most common cause of injury, & site of injury is often the pad od the thumb or index finger;
- severity of injury is often underestimated due to the small punctate entrance wound;
- injected substance passes rapidly thru the subcutaneous tissue and enters the flexor tendon sheath;
- from there it passes into one or more of the deep spaces of the hand
Wheeless' Textbook of Orthopaedics

In 1937, Rees published the first reported case of a high-pressure injection (HPI) injury to the finger. This injury involved diesel fuel. Prior to Rees's report, Hesse had described a similar injury in 1925.
Although over 100 case reports of HPI injuries of the hand can be found in the literature, the incidence of these kinds of cases is difficult to assess. Nonetheless, a group from the University of Colorado described an estimated incidence of 1 in 600 hand injuries seen in their emergency department. These numbers suggest that HPI injuries to the hand are relatively common, given the widespread use of pressure machinery.
Synonyms and related keywords: HPI injury, hand injury, finger injury, paint gun injury
Arneja et al 2008