The first thing you need to do is to teach him not to jump up on furniture and off! Get stairs or a ramp and teach him to use them. Every time he jumps off of something he is adding more stress to his knees.
Not every pup with LP needs surgery!
Good luck and listen to the others. Start stashing money just in case because you just never know what can crop up with these little ones. As for knees, I seriously doubt it is so serious that surgery must be done right away! I would encourage you to spend a few extra dollars and get the opinion of a board certified surgeon. They usually do not operate on LP unless it is a constant and serious problem! You can ask your vet for a referral or find one at:
www.acvs.org