It means that you have had no significant knee injury in the past and that you have no evidence, whether by X-ray, MRI or physical examination, of arthritis or cartilage damage in the knee.

CNN: Will jogging hurt an obese person's joints?

Inventor and author Ray Kurzweil claims we are living in the knee of the curve: the sharp bend upward.

FORBES: How The Cheap Revolution Confuses Policymakers

Norris Cole scored 15 points and Ray Allen added 14 for the Heat, who played without Wade, held from the lineup because of right knee soreness the team believes is minor.

NPR: Heat Set To Hit The Road Riding 26-Game Win Streak