Knee
The knee carries your body weight almost every time you stand or walk, which is why knee problems are so common — from age-related wear to sports injuries. Where the knee hurts, and when it hurts, often points to different causes.
ACL injury
A cruciate ligament torn on a twist. The knee swells fast and gives way.
Knee osteoarthritis
The cartilage lining the knee thins: pain, stiffness, harder walking.
Knee pain
Many causes. Where and when it hurts points to which one.
Meniscus root tear
A tear at the meniscus anchor, so it no longer spreads load.
Meniscus tear
A torn pad of cartilage: pain, catching, or a knee that locks.
Pain at the front of the knee
Pain around the kneecap, worse on stairs and after sitting bent.