Background: The plantar aponeurosis is known to be a major
contributor to arch support, but its role in transferring Achilles tendon
loads to the forefoot remains poorly understood. The goal of this study was to
increase our understanding of the function of the plantar aponeurosis during
gait. We specifically examined the plantar aponeurosis force pattern and its
relationship to Achilles tendon forces during simulations of the stance phase
of gait in a cadaver model.
Methods: Walking simulations were performed with seven cadaver feet.
The movements of the foot and the ground reaction forces during the stance
phase were reproduced by prescribing the kinematics of the proximal part of
the tibia and applying forces to the tendons of extrinsic foot muscles. A
fiberoptic cable was passed through the plantar aponeurosis perpendicular to
its loading axis, and raw fiberoptic transducer output, tendon forces applied
by the experimental setup, and ground reaction forces were simultaneously
recorded during each simulation. A post-experiment calibration related
fiberoptic output to plantar aponeurosis force, and linear regression analysis
was used to characterize the relationship between Achilles tendon force and
plantar aponeurosis tension.
Results: Plantar aponeurosis forces gradually increased during
stance and peaked in late stance. Maximum tension averaged 96% ± 36% of
body weight. There was a good correlation between plantar aponeurosis tension
and Achilles tendon force (r = 0.76).
Conclusions: The plantar aponeurosis transmits large forces between
the hindfoot and forefoot during the stance phase of gait. The varying pattern
of plantar aponeurosis force and its relationship to Achilles tendon force
demonstrates the importance of analyzing the function of the plantar
aponeurosis throughout the stance phase of the gait cycle rather than in a
static standing position.
Clinical Relevance: The plantar aponeurosis plays an important role
in transmitting Achilles tendon forces to the forefoot in the latter part of
the stance phase of walking. Surgical procedures that require the release of
this structure may disturb this mechanism and thus compromise efficient