Leg problem in foster hound

Our new foster, Martina, has a very crooked foreleg. She does favor it a bit when walking, and the knee area appear knuckled over, while the foot itself is turned sharply outwards. Being as new to bassets as I am, I'm not sure what this might be. She has no pain in the leg that I can determine. Rescue said they see a great many of these, and it is a birth defect. Also, when she is walking, the kneecap area appears to be moving around. Any idea what this might be, and do I need to have it checked myself? The rescue organization had her vetted, but had no comment as to the leg. She runs fine, plays and jumps with no problems I can see. I know I'm a worrywart, but if it's something that needs to be fixed, I'd like to know.