Foot Positions Affect Knee and Ankle Proprioception, Balance, Vertical Jump, and Muscle Activity in Individuals With Flexible and Rigid Flatfoot and Chronic Ankle Instability

Inclusion Criteria: * The inclusion criteria were the presence of FF and chronic ankle instability in the dominant foot. Flexible and rigid flat feet were initially diagnosed by an orthopedist using a weight-bearing position with a standardized radiograph technique. The digital X-ray detector (film) and the X-ray tube (source) are 35-40 inches apart in lateral views of the foot. Then, Jack's test was performed to differentiate between the flexible and rigid FF. Jack's test is a valid test in assessing FF 10. Finally, people with flexible a second degree FF (Meary's angle between 15° to 30°) 3 were included in this study. The degree of flatfoot was determined by measuring the talus-first metatarsal angle on a lateral weight-bearing radiograph. This angle lies between a line drawn from the centers of the longitudinal axes of the talus and the first metatarsal. An angle that is greater than 4° convex downward is considered pes planus with an angle of 15° - 30° considered moderate, and greater than 30° severe 8. Chronic ankle instability was defined as the subject had a minimum of 2 acute ankle sprains, in the last 6 months, associated with pain, swelling, and a record of various ankle giving way. The determination of the dominant foot followed Vauhnik. \& ark, modified version which stated that the dominant foot should be used minimally in 2 of the 3 subsequent activities: (1) Using the leg to step over a spider toy, (2) Drawing a diamond figure on the ground and (3) Kicking a …