Db. Thordarson et al., DYNAMIC SUPPORT OF THE HUMAN LONGITUDINAL ARCH - A BIOMECHANICAL EVALUATION, Clinical orthopaedics and related research, (316), 1995, pp. 165-172
This study was designed to evaluate the dynamic support provided to th
e human longitudinal arch by the leg muscles active in the stance phas
e of gait and by the plantar aponeurosis. Ten fresh adult cadaveric sp
ecimens were mounted in a materials testing machine. The tendons of th
e posterior tibialis, flexor digitorum longus, flexor hallucis longus,
peroneus longus, peroneus brevis, and Achilles tendon were attached t
o force transducers. Plantar loads of 0, 350 and 700 N were applied, a
nd the tendons were tensioned individually. The Achilles tendon was te
nsioned an amount equal to the plantar load; the posterior tibialis, f
lexor digitorum longus, flexor hallucis tongus, peroneus longus, and p
eroneus brevis were tensioned a fractional amount (depending on the pr
oportion of the cross-sectional area to the gastrocsoleus complex). Th
e angular relationships between the first metatarsal, navicular, and t
alus were recorded using a 3-dimensional movement analysis system. An
additional series of measurements was obtained by positioning the ankl
e plantarflexed 10 degrees under a plantar load of 350 N. Dorsiflexing
the toes with the ankle in and 700 N permitted an evaluation of the e
ffect of the plantar aponeurosis. The plantar aponeurosis, via dorsifl
exion of the toes, contributed the most significant arch support in th
e sagittal plane with a 3.6 degrees between the first metatarsal and t
alus at 350 N and a 2.3 degrees increase at 700 N. The posterior tibia
lis tendon consistently provided arch support at plantar loads of 350
N acid 700 N. The peroneus longus consistently abducted the forefoot i
n the transverse plane at 350-N and 700-N load levels. The study provi
des further insight into the dynamic supporting and deforming forces o
f the longitudinal arch.