My family has two long-time friends afflicted with the same birth defect, they are both now in their mid-sixties, are both British, but are of no relation to each other. What they have in common is their birth defects. They each have a malformed leg as their malformed legs cannot support them on their own as one lady uses a stick and when they were both children, they both spent plenty of time in hospital and had several surgeries on their legs. As a matter of fact one of the friends has to swim daily in the sea or pool to keep her leg functioning as much as it can otherwise without swimming, the leg would definitly seize up!
About a year ago this swimmer had an accident and fell and broke her other leg; i.e. the one which is the good leg; but as her malformed leg cannot support her, instead of using crutches like most other people with now leg deformities, she had to spend several in a wheelchair until the other leg healed. As a matter of fact she had nails inserted the other leg as maybe her bones are getting thin over time.
My point is: what are the causes of these malformed legs? I would appreciate if you would give me all the right answers as soon as possible as this birth defect is bugging me as I cannot find any real cause of it. Thank you.