About a month and a half ago, I slipped on ice and my feet flew completely out from beneath me. As I watched my legs go up in the air, I noticed a pop or snap sound. I hit the ground and was concerned with my back or arms but I did not notice much problem there. I tried to stand and noticed I could not without pain. After 10 minutes or so, I was able to stand and started walking around and continued on with my day. It was a good fall because I did not have bruises or much pain for days after the fall. About a week or so after the fall, however, I noticed an unusual indentation in my thigh muscle about 5 inches above the knee cap. I has not gone away even though I returned to my usual exercise routine. I am 62 but I have been walking for exercise for years [averaging about 11,000 steps per day]. That is why this is so noticeable; I have had well-developed thigh muscles for many years. .I also use weights 3 times a week with leg squats and I am a regular yoga participant. Can you give me some insight about what this indentation is?