||Human foot’’s structure is important regarding stands and walks. Abnormal foot state could make the lower limb easily weary and even lead to the pathological changes, resulting in unbalanced when walking. There are two common diseases: the flat foot and the high arch foot caused by abnormal arch height. Therefore, the arch height assessment of foot is essential in foot medical examination. There are many ways to detect arch height, including: x-ray examination, arch height measurement, footprint index parameters and foot pressure index (exp. Modified Arch Index; MAI) etc. In this study, we choose arch measurements, footprint index parameters (including AA, ALI, FI, TFI, SI, CSI and AI) and MAI with image processing and automated measurement system for detection as they are easy to access and the equipments are relatively cheap.|
33 participants with a complete footprint and without any foot pathological history were assumed to be normal and recruited in this study to give a total of 66 samples of footprints (22 male, 11 female, average height in 169±6.7cm, weight in 64±12.3 kg, age in 23±3 years). This is the normal control group. In addition, 10 participants with flat foot (8 male, 2 female; a total of 20 samples of footprints) and 10 participants with high arch foot (4 men, 6 women, a total of 20 samples of footprints) were recruited as the contrast group. The arch height,
seven footprint index parameters and MAI were measured and compared between groups and with data from literatures for cross validation in order to identify the best detection method.
The empirical results of the foot arch height detection experiments show that the average foot arch heights are 4.03±0.82, 2.45±0.14 and 5.47±0.26 cm for normal, flat foot and high arch foot, respectively.
The parameters that can best represent the arch height (highest correlation) is
MAI. The situation of MAI of normal foot which is 26%~30% on the middle foot, the distribution is uniform. The flat foot which is 33%~37% on the middle foot, the main distribution is on the middle foot. The high arch foot which is 18%~22% on the middle foot, the main distribution is on the front foot and the heel.
Among seven footprint index parameters, the Arch Index (AI) is most correlated with arch height and Arch Length Index (ALI) is lowest. Furthermore, the two-dimensional area ratio parameters (FI and TFI) are more related with arch height than one-dimensional length ratio parameters (SI and CSI).
In conclusion, we have indentified the best examine method: MAI among methods tested for abnormal arch height detection. As the method is capable of detecting abnormal foot arch and can provide useful and reliable information, we believe that it could predict the arch height before clinical x-ray foot arch examination.
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