Normal knee alignment spreads the forces of weightbearing evenly across both sides of the knee.
Unfortunately, knock knees
(aka valgus knees) and bowlegged knees (aka varus knees) overloads the lateral side (outside) and the medial side (inside), respectively. This overload can cause early wear of the cartilage
as well as causing dysfunction of the patellofemoral joint (kneecap).