Data from: Achilles tendon moment arm in humans is not affected by inversion/eversion of the foot: a short report

The triceps surae primarily acts as plantarflexor of the ankle joint.
However, the group also causes inversion and eversion at the subtalar
joint. Despite this, the Achilles tendon moment arm is generally measured
without considering the potential influence of inversion/eversion of the
foot during plantarflexion. This study investigated the effect of foot
inversion and eversion on the plantarflexion Achilles tendon moment arm.
Achilles tendon moment arms were determined using the centre-of-rotation
method in magnetic resonance images of the left ankle of 11 participants.
The foot was positioned at 15° dorsiflexion, 0° or 15° plantarflexion
using a Styrofoam wedge. In each of these positions, the foot was either
10° inverted, neutral or 10° everted using an additional Styrofoam wedge.
Achilles tendon moment arm in neutral foot position was 47.93 ± 4.54 mm
and did not differ significantly when the foot was positioned in 10°
inversion and 10° eversion. Hence, inversion/eversion position of the foot
may not considerably affect the length of the Achilles tendon moment arm.
This information could be useful in musculoskeletal models of the human
lower leg and foot and when estimating Achilles tendon forces during
plantarflexion with the foot positioned in inversion or eversion.