Knock-knee or genu valgum is a condition in which the knees angle in and touch each other when the legs are straightened. Individuals with a severe condition are unable to touch their feet together while standing straight.
Knock knees cause your knees to get out of alignment with the ankle and this puts more pressure on the inside of the knees. They can have a ripple effect on the feet and get the arches to collapse as well.
Insoles for knock knees have medial arch support so that the foot is supported medially and the arches are held up in place. When the arches are held in place, some of the excessive pressure on the knees is reduced and this results in pain relief in the knees.