What is the principle of flat foot evaluation by plantar laser 3D scanner?

Traditional methods for evaluating flat feet include visual inspection, footprint method and so on.

However, these traditional evaluations are prone to large errors and inaccurate judgments. Moreover, they rely heavily on rich experience and involve strong subjective judgment.

The plantar laser 3D scanner adopts technical principles such as laser and white light scanning to conduct multi-dimensional scanning and measurement of the human sole. It performs automatic calculation and analysis through software, so as to obtain more than 20 key plantar data and 3D data in formats such as STL.

Data analysis is carried out through the software to accurately determine whether there is flat foot and give an accurate grade, such as mild flat foot, moderate flat foot and severe flat foot.



The process and principle of measuring and evaluating flat feet by the plantar laser 3D scanner are as follows:

1. Pre-measurement preparation work.

The subject shall first take off shoes and socks, keep the sole clean and dry. Meanwhile, roll up the trouser legs of both legs to above the ankles, and finally close to the knees.

Then stand in the scanning area of the device with both feet apart shoulder-width apart, look straight ahead, and make the center of gravity evenly distributed on both feet.

2. Data collection and measurement.

After the preparation is completed, operate according to the voice guidance of the device.

Some devices scan both feet at the same time, while some measure the left foot first and then the right foot.

During the measurement process, keep the body relaxed and natural with arms hanging down naturally, so that the feet are in a standard weight-bearing state.

The whole measurement process can be completed in about 10 to 30 seconds.

After the measurement, the measurement report can be exported directly. The report can display the foot size, foot type and other information, including the judgment result of flat foot.

3. Principle of flat foot judgment by plantar 3D scanner.

(1) Most current devices make judgments based on the Arch Index (AI).

After the data is generated, the software divides the sole into three areas: forefoot, midfoot and hindfoot, excluding the toe part.

AI value = Midfoot contact area ÷ Total plantar area.

When the AI value is between 0.21 and 0.26, it is judged as normal foot.

When the AI value is between 0.26 and 0.28, it is judged as mild flat foot.

When the AI value is between 0.28 and 0.30, it is judged as moderate flat foot.

When the AI value is greater than 0.30, it is judged as severe flat foot.

(2) Further judgment based on the medial longitudinal arch angle.

The medial longitudinal arch is the most critical and highest arch on the sole of the foot. It is longitudinally distributed along the medial side of the foot and jointly composed of calcaneus, talus, navicular bone, medial cuneiform bone and first metatarsal bone.

The medial longitudinal arch angle refers to the included angle formed by connecting three marked points in the 3D model: the lowest point of calcaneus, talar head and first metatarsal head.

The medial longitudinal arch angle of a normal foot arch ranges from 113° to 130°. If the medial longitudinal arch angle is greater than 130°, it is judged as flat foot. The larger the angle, the more serious the arch collapse.

(3) Judgment based on the height of the foot arch.

The plantar arch height refers to the vertical height from the highest point of the foot arch to the ground.

A foot arch height between 1cm and 2cm falls within the range of normal foot.

If the foot arch height is less than 1cm or even the foot arch disappears completely, it is judged as flat foot.

The above are several currently popular principles and methods for judging flat feet.