A normal foot should arch so the middle of the foot does not touch the ground in standing. If it touches, you may have a flat foot or fallen arch. Having flat feet can contribute to posterior tibial tendon problems, but conversely, posterior tibial tendon can lead to the foot dropping.
Pain and/or swelling is common in the heel or arch. As we age or repetitively use the of the tendon, some of the strands of the tendon can degenerate or break, and the tendon may rapture. If you are unable to rise up on your toes you may have a ruptured tendon.
After a physical therapist looks at your feet, hip and knee alignment, observes your gait and the wear pattern of shoes, you may be given a brace, orthotics, hands on techniques for pain and swelling and exercises to strengthen the posterior tibialis and other muscles.
Learn more about common conditions of the foot here.