[gemy]

Drive is inherited and Drive is what you want in a puppy destined for agility or for that matter other performance sports. Make sure you mention to any breeder what you hope to do with your puppy. Given the inheritability it would be ideal to source a puppy from a breeder who also works with her dogs in some performance sport.

While knees are very important quite frankly the whole structure of the body is key to have a happy and healthy performance dog. Hips elbows a straight topline etc.

There is a stickey on here on How to Evaluate.Assess a Puppy which you might find helpfull.

The AKC listing as someone else mentioned is a good starting point but so is attending shows especially those with obedience rally and or agility trials which are held concurrently.

Good luck with your search.