Summary

Our study summarized the characteristics of the hindfoot joint in stage II adult acquired flatfoot

Abstract

Objective

To make a comparison of the kinematic characteristics of hindfoot joints during stance phase in stage II adult acquired flatfoot and normal foot obtained by the technology of 2D-3D registration and one-plane fluoroscopy, thus to provide research basis to the pathogenesis ,diagnosis and treatment of flatfoot.

Methods

A RSA technology was firstly used to determine the accuracy and repeatability of the technology of 2D-3D registration within one-plane when applying into the hindfoot joints movement analysis. Then seven normal volunteers and eight volunteers with stage II flatfoot were recruited to take the CT scans for their bilateral feet in neutral positions, after that their lateral dynamic X-ray data during stance phase were collected including fourteen normal feet and ten flatfeet. A computer-aided simulated light source for three-dimensional CT model was applied to obtain a virtual image, and it is matched with the dynamic X-ray images to make a registration in “Fluo” software, by which finally the spatial changes during the stance phase can be calculated. Then the data of hindfoot joints were analyzed and compared on each axis.

Results

During the early stance phase, the calcaneous was more dorsiflexed, everted, rotated externally relative to talus in flatfoot compared with normal foot, the statistic difference is significant(p<0.05).During the Mid-stance phase, the calcaneous was more dorsiflexed, everted relative to talus in flatfoot compared with normal foot, the statistic difference is significant(p<0.05);while the rotation in both group were not significantly different (p>0.05). During the late stance phase, he calcaneous was more plantarflexed, while less inverted and rotated internally relative to talus in flatfoot compared with normal foot, the statistic difference is significant (p<0.05).During the early and mid-stance phase, the navicular was more dorsiflexed, everted, rotated externally relative to talus in flatfoot compared with normal foot, the statistic difference is significant (p<0.05).During the late stance phase, the navicular was more plantarflexed, while less inverted and rotated internally relative to talus in flatfoot compared with normal foot, the statistic difference is significant (p<0.05) .There was no difference between the motion of cuboid in both group during the whole stance phase( p>0.05) .

Conclusion

During the early and mid-stance phase, there is excessive motion in the subtalar and talonavicular joints in stage II adult acquired flatfoot. During the late stance phase, the motion of subtalar and talonavicular joints is in the decompensated state. During the whole stance phase, the motion of calcaneocuboid joint has no significant difference in both normal foot and stage II adult acquired flatfoot.