Osteoarthritis of the knee is very common. This is probably because your knee has to take extreme stresses, twists and turns. Osteoarthritis can affect the main surfaces of your knee joint and also the cartilage underneath your kneecap (patella).1  You’re most likely to feel pain at the front and sides of your knee.steoarthritis of the knee is very common. This is probably because your knee has to take extreme stresses, twists and turns. Osteoarthritis can affect the main surfaces of your knee joint and also the cartilage underneath your kneecap (patella). 1  You’re most likely to feel pain at the front and sides of your knee.