Abstract
This study investigated the biomechanical responses of neonatal piglet brachial plexus
(BP) segments—root/trunk, chord, and nerve at two different rates, 0.01 mm/second
(quasistatic) and 10 mm/second (dynamic)—and compared their response to another peripheral
nerve (tibial). Comparisons of mechanical responses at two different rates reported
a significantly higher maximum load, maximum stress, and Young's modulus (E) values
when subjected to dynamic rate. Among various BP segments, maximum stress was significantly
higher in the nerve segments, followed by chord and then the root/trunk segments except
no differences between chord and root/trunk segments at quasistatic rate. E values
exhibited similar behavior except no differences between the chord and root/trunk
segments at both rates and no differences between chord and nerve segments at quasistatic
rate. No differences were observed in the strain values. When compared with the tibial
nerve, only mechanical properties of BP nerves were similar to the tibial nerve. Mechanical
stresses and E values reported in BP root/trunk and chord segments were significantly
lower than tibial nerve at both rates. When comparing the failure pattern, at quasistatic
rate, necking was observed at maximum load, before a complete rupture occurred. At
dynamic rate, partial rupture at maximum load, followed by a full rupture, was observed.
Occurrence of the rate-dependent failure phenomenon was highest in the root/trunk
segments followed by chord and nerve segments. Differences in the maximum stress,
E values, and failure pattern of BP segments confirm variability in their anatomical
structure and warrant future histological studies to better understand their stretch
responses.
Keywords
Neonatal Brachial Plexus - injury mechanism - biomechanical properties - stretch rates
