Effect of foot orthoses on 3-dimensional kinematics of flatfoot: a cadaveric study.
OBJECTIVE
To test in cadaveric feet the hypothesis that prefabricated foot orthoses will improve arch alignment in flatfoot deformity.


METHODS
Experimental, paired comparisons.


METHODS
Biomechanics laboratory.


METHODS
Nine cadaveric lower-extremity specimens with no abnormalities.


METHODS
To evaluate the performance of 2 orthoses specimens were tested in 4 combinations: intact, flatfoot, flatfoot with shoe and orthosis 1, and flatfoot with shoe and orthosis 2. To simulate the midstance phase of gait, loads were applied to 5 tendons and an axial load equivalent to two thirds of the standing load was applied to the foot's plantar surface.


METHODS
Arch height and tarsal bone positions before and after a flatfoot deformity created by ligament sectioning; tarsal bone positions determined with a magnetic tracking system.


RESULTS
After ligament sectioning, the average decrease in arch height with a shoe applied was 4.6+/-1.6mm (8%); with orthosis 1, mean arch height increased 0.7+/-0.6mm (P=.008); with orthosis 2, it increased 0.3+/-0.5mm (P=.05). With both orthoses, arch height after sectioning was significantly less than that of the normal arch. Compared with the flatfoot condition, metatarsal-talar alignment improved in plantar flexion and inversion with both orthoses but did not approximate normal with either orthosis. Calcaneal-tibial position did not improve with either orthosis and was markedly different from that in the intact foot with either orthosis. No difference was found between the 2 orthoses except for metatarsal-talar motion in external rotation (P=.014) and eversion (P=.026).


CONCLUSIONS
Arch alignment improved significantly but to a limited degree (<2%) in cadaveric feet with the use of orthoses. Hindfoot valgus malalignment did not consistently improve by the use of shoe inserts.
Kitaoka
Harold B
HB
Department of Orthopedics, Mayo Clinic, Rochester, MN 55905, USA.
Luo
Zong-Ping
ZP
Kura
Hideji
H
An
Kai-Nan
KN
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005413:Flatfoot / Q000503:physiopathology / Q000534:rehabilitation*; D005529:Foot Bones / Q000502:physiology; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D009989:Orthotic Devices