A2 and A4 Flexor Pulley Biomechanical Analysis- Comparison among Gender and Digit

Gregory Charles Mallo & Yury Sless & Lawrence C. Hurst & Kevin Wilson
HAND (2008) 3:13–16
DOI 10.1007/s11552-007-9057-z

Abstract:
Rock climbing has become increasingly more
popular in the USA over the past two decades. Accordingly,
with increased participation comes an increase in climbingrelated
injuries. Rooks et al noted that three-quarters of elite
and recreational climbers will suffer upper extremity
injuries, approximately 60% involving the hand or wrist
and 40% divided evenly between the shoulder and elbow.
Most of these injures will be strains, microtrauma, and
tendonitis; however, 30–50% represent trauma to the
proximal interphalangeal region. The purpose of this study
was to investigate the biomechanical properties of the A2
and A4 pulley and compare biomechanical properties
among gender and digit. A specially designed materials
testing machine, shown in the included figure, measured
maximum breaking load, displacement and stiffness of the
A2 and A4 pulleys of ten cadaveric hands using an S hook
to apply a steady force until complete pulley rupture. The
A2 and A4 biomechanical properties of breaking load,
displacement, and stiffness did not significantly differ
among the index, middle, ring, and little fingers. Additionally,
there was no significant difference in A2 or A4 pulley
biomechanics between male and female specimens. The A2
and A4 pulleys among differing digits and genders have
similar biomechanical properties in regards to maximum
breaking load, displacement, and stiffness.