The goal of this clinical trial is to investigate the effect of a semirigid foot insole on radiological angle correction in people with asymptomatic flexible flat feet. The X-ray will be performed while standing barefoot one time and the other while standing on the insole from 2 views.

This study will be conducted on 30 male and female subjects with flexible pes planus. Clinical diagnosis for flexible pes planus will be made through the navicular drop test (NDT) and the Foot Posture Index (FPI). The study included asymptomatic people with flexible pes planus. If the pain is greater than 3 out of 10 on the numeric pain rating scale in the last 3 months, aged 18-35, and BMI max 29.9 kg/cm². The subjects will be excluded if they have osteoarthritis of the joints of the foot (excluded by x-ray), foot deformities (e.g., hallux valgus), old fractures of the foot, previous injuries to the ankle, or previous surgeries to the lower limb. Calcaneal Spur, Foot and Ankle Ligament Tear, Systemic diseases such as rheumatoid arthritis (gouty arthritis, an autoimmune disease) and neurological diseases. The X-ray is the gold standard for assessment of adult-acquired flat foot deformity. Two views are used: anteroposterior (AP) and lateral views. A ruler and protractor will be used for manual measurements of X-ray foot. The subject will stand barefoot, and a weight-bearing X-ray will be taken from lateral and AP views once, without an insole, and another photo will be taken with an insole. The subject will stand barefoot, and a weight-bearing X-ray will be taken from lateral and AP views once, without an insole, and another photo will be taken with an insole.

The angles will be measured:

The gathered angles aim to evaluate the alignment of the foot's three arches. In the lateral view, the following angles will be measured and evaluated with without the insole: the lateral talo-1st metatarsal angle, the calcaneal inclination angle, the angle of Hibbs, the calcaneal-5th metatarsal angle, and the navicular height.

In the AP view, the following angles will be measured and evaluated with without the insole: The lateral talo-1st metatarsal angle, Talo-2nd metatarsal angle, The talocalcaneal angle, Talonavicular coverage angle and First-fifth metatarsal angle

Inclusion Criteria:

1. Asymptomatic people with flexible pes planus. If the pain is greater than 3 out of 10 on the visual analog scale in the last 3 months, the patient is considered to have symptomatic flat feet (Mahdiyar et al., 2021).
2. Aged 18-35.
3. BMI max 29.9 kg/cm².

Exclusion Criteria:

1. Osteoarthritis of the joints of the foot (excluded by x-ray).
2. Foot Deformities (e.g. Hallux Valgus)
3. Old fractures of the foot.
4. Previous injuries to the ankle.
5. Previous surgeries to the lower limb. 6. Calcaneal Spur. 7. Foot and ankle ligaments tear.

8- Systemic diseases such as rheumatoid arthritis. (Gouty arthritis, autoimmune disease) 9. Neurological diseases.

Obtaining the patient privacy, however the data will be available with the original author uopn request