What Causes Indent On The Inside Of Both Ankles?

I have an indent on the inside of both ankles and was wondering if chemo treatments 6 yrs ago could be the cause? I also have weak ankles now. I am a 66 yr old woman, 5 ft 2 in, 190 pds. I cannot do strenous exercises or much walking because of copd, arthritis and I had lung cancer.