Arterial Zone of Injury After Different Mechanisms of Traumatic Finger Amputation

This study aimed to describe how the pattern of arterial damage in traumatically amputated digits changes with increasing distance from the site of injury (SOI), how different mechanisms of injury affect that pattern, and to assess the viability of fresh, unembalmed, unfrozen cadavers for the histologic analysis of injuries.

Using fresh cadavers (5 specimens), the index, middle, and ring fingers were injured via knife laceration, chisel crush amputation, or miter saw amputation. The severed proper palmar digital arteries were dissected out and cross-sectioned every 3 mm from the SOI for histologic evaluation of the percent of intima attached at the line dividing the tunica intima from the tunica media (tunica intima/media junction [TIMJ]).

There was an increase in intima attachment with increased distance from the SOI in saw- and chisel-injured digits. Additionally, there were distinct patterns of intima injury resolution with increased distance from the SOI between mechanisms. Significant linear regression models found that, on average, chisel-injured digits achieve 100% TIMJ attachment at 8.8 mm (P = .002) from the SOI and saw-injured digits achieve 100% TIMJ attachment at 11.3 mm (P = .00002). The knife regression was not significant (P = .08).

Chisel- and saw-injured digits show distinct patterns of separation at the TIMJ. Saw-injured digits have greater TIMJ separation at the SOI and require a greater distance to return to complete attachment. The knife injury damage relationship is likely too minute to discern using these methods.

Although this study does not tell surgeons exactly how much to shorten vessels during digit replantation, it does show that different injury mechanisms have distinct patterns of damage resolution. Further study using fresh cadaveric histology for injury analysis will continue improving surgical guidance for digit replantation and help characterize injuries at other sites of microvascular surgery.