This is a collapse of your foot's arch. It happens over time, usually in just one foot but sometimes in both. As your arch collapses, the bones of your foot may gradually shift out of alignment. This can cause pain and other problems.
This condition is most often caused by a problem with the posterior tibial tendon. That's a tendon that travels from your calf to the inner side of your foot. It holds your foot's arch up. If this tendon is weak or injured, it can't support your arch. An arch can also collapse as a complication of rheumatoid arthritis or diabetes. And, it can be caused by a fracture, dislocation, or ligament injury in your foot.
A collapsed arch can cause pain, swelling, and redness along the inner side of your foot and ankle. It may be hard for you to walk or to stand for long periods of time. As the collapse gets worse, your heel bone may shift out of alignment. Your foot may turn outward and your ankle may roll inward. Without proper care, you may develop bony bumps in your feet, or ulcers in the skin of your feet.
There are several treatment options for this condition. You may need to wear a walking boot to let your tendon heal. You may benefit from a custom shoe insert or a brace to help support your arch. Losing weight may help. If these aren't helpful, you may need surgery to correct your arch. Your healthcare provider can create a plan that's right for you.