Comparison of foot kinematics and the morphology of intrinsic musculature of the foot using a foot-type classification based on function.
Shintarou Kudo, Kodai Sakamoto, Takeshi Shirakawa
PMID 32184540WHAT IT FOUND
Feet classified as flat but adducting during gait showed thinner abductor digiti minimi muscles and altered kinematics compared to normal arch feet.
However, flat feet that abducted during gait did not differ significantly from normal arches, suggesting static foot posture alone is an insufficient risk indicator.
Key findings
01The thickness of the abductor digiti minimi muscle was significantly thinner in the flat foot-adduction group compared to the normal arch-abduction group.
02Flat feet were more likely to be classified as adduction type, while normal arches were more likely to be abduction type.
03The flat foot-abduction type showed no significant kinematic differences from the normal arch group.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study did not measure muscle activity (EMG) during gait, so it cannot determine if the observed differences in muscle thickness are due to functional weakness or other factors. Skin movement artifacts were present in the motion capture data, which can affect the accuracy of foot kinematics. The participants were all healthy volunteers without lower limb pain, so the findings may not apply to patients with active overuse injuries. The study could not definitively link specific ground reaction force directions to arch deformation.
Declared interests
Funded by JSPS KAKENHI Grant Number 19K19815. Authors declared no conflicts of interest.
The easy way to misread this
Do not assume that all flat feet have abnormal mechanics or weak intrinsic muscles. The study found that flat feet which abducted during gait were kinematically similar to normal arches, while only those that adducted showed significant differences.