Here are some photos of a horse that is extremely “over at the knees”.
Notice how it appears the horse’s knees are buckled. This horse has the condition to the extreme and you sure wouldn’t want to buy one like this.
However, a horse that’s SLIGHTLY over at the knees, usually isn’t too big of a problem. If the horse was an exceptional performer and the price was right (low), I might consider him.
I’d definitely consult a veterinarian before I made my purchase, though.