What causes hip and knee pain?
The knee is an honest joint. It reports problems, but it rarely causes them. It sits between a hip that steers the leg and a foot that meets the ground, and when either of those does its job badly, the knee absorbs the difference. The hip is subtler about it: it hides its own restrictions until the back or the groin starts complaining. So the question is never only where it hurts. It is which link stopped contributing, and what has been quietly compensating ever since.
Pain around or under the kneecap that worsens on stairs, on hills and after long sitting is the most common knee complaint we see. The kneecap has to track through a groove, and the muscles controlling the thigh bone underneath it decide how well that goes. Weak or slow gluteal muscles let the thigh rotate inward and the kneecap runs off line. Strengthening the hip usually does more than anything aimed at the kneecap.
Pain on the outside of the hip, worse lying on that side at night and worse again after sitting cross legged, is usually the gluteal tendons rather than a bursa. Compression is the aggravator: positions that press the tendon against the bone keep it irritated day after day. The treatment is unloading those positions first, then progressive strengthening. Stretching it aggressively, which is most people's instinct, tends to make it angrier.
Joint changes on imaging are common and are a poor predictor of pain. Plenty of people have them and no symptoms at all. What determines how an arthritic joint feels is the strength around it, the range it has kept, and how much load it is asked to take at once. Strengthening reduces pain and improves function in arthritic hips and knees, and it keeps working as long as you keep doing it.
The meniscus spreads load across the knee. It can tear traumatically in a twist, or it can fray gradually with age, and the second kind often hurts without ever needing surgery. Locking, genuine giving way and a knee that will not straighten need imaging. A knee that aches under load and settles with rest usually responds to graded strengthening and a change in how the joint is being loaded.
When the hip loses rotation or extension, that movement has to come from somewhere, and the knee and the lower back are the nearest donors. You feel it as knee pain while the hip is the restricted joint, or as back stiffness after a long walk. Testing hip range on both sides and comparing them is often what finally explains a knee problem that has never made sense.
Tissue adapts to what you ask of it, provided the ask increases gradually. A new training block, a return to sport after a break, a house move or a job change that puts you on your feet all raise demand faster than tendon and cartilage can build tolerance. Nothing is damaged. Demand simply overtook supply. Fixing it means honest load management alongside the strengthening, not stopping altogether.
