Knee pain: common causes and what helps

Where it hurts gives clues

The knee is a hinge joint between the thigh bone and shin bone, with the kneecap sliding in a groove at the front. Two C-shaped cartilage cushions (the menisci), four main ligaments and several strong tendons all play a part. Pain in different areas tends to point to different structures, although overlap is common.

• Front of the knee, around or behind the kneecap: often runner's knee, also called patellofemoral pain.
• Just below the kneecap: often patellar tendinopathy, sometimes called jumper's knee.
• Inside of the knee: a medial ligament sprain, a meniscus problem, or osteoarthritis.
• Outside of the knee: often IT band syndrome in runners and cyclists, or a lateral ligament or meniscus problem.
• Back of the knee: a Baker's cyst, a hamstring or calf tendon issue, or occasionally a blood clot.

Sudden injury or gradual build-up?

Knee pain generally follows one of two stories. Sudden injuries happen during a twist, landing, collision or awkward step. They may cause a pop, rapid swelling, difficulty straightening the knee or a feeling of the knee giving way, and they can involve a ligament such as the ACL or a meniscus tear.

Gradual-onset pain builds over weeks or months, usually because the load on the knee has risen faster than it can adapt: a new running plan, a HYROX block with lots of lunges and wall balls, a jump in squat volume, or a new job with lots of kneeling. Weight gain, low strength and poor sleep can all lower the knee's tolerance too.

Squats, lunges and running are not bad for healthy knees. Research consistently shows that well-dosed strength training and running are good for knee health. The problem is almost always the dose, not the exercise.

Common symptoms

• Pain on stairs, squatting, kneeling or running
• Stiffness after sitting or first thing in the morning
• Swelling that appears after activity
• Clicking or grinding, which is common and often harmless on its own
• Catching, locking or giving way, which needs assessment

Noises from the knee worry many people, but painless clicking and grinding are very common in healthy knees and do not mean damage. Pain, swelling and locking are more useful signs than noise.

What a physio assessment looks at

Your physio will take a careful history: how it started, where it hurts, whether it swells, and what your training and daily life involve. The examination looks at swelling, range of movement, ligament stability, meniscus tests and strength of the quads, hamstrings and hips. They will usually watch you squat, step down or hop, and they may check your hip and lower back, because pain can be referred to the knee.

Many knee problems can be diagnosed well without scans. X-ray or MRI may be recommended after significant injuries, when the knee locks or keeps giving way, or when symptoms are not improving with good rehab.

Bring any scan reports you already have. Terms like wear and tear or degenerative changes are very common on knee scans in people with no pain, so a physio will interpret them in the context of your symptoms rather than treating the image.

What usually helps

For most knee conditions, the treatment with the strongest evidence is progressive strengthening of the quads, hamstrings, hips and calves, combined with managing the load on the knee while it settles. That usually means adjusting rather than stopping: reducing depth or volume on squats, swapping running for cycling for a while, or changing lunges to a shorter range.

Manual therapy, taping and supports can ease pain in the short term for some people and make exercise easier. For people carrying extra weight, even modest weight loss reduces load on the knees, and our guide to losing weight with knee pain shows how to stay active while doing it.

What you can start with at home

1. Quad sets: sitting with the leg straight, tighten the thigh to press the back of the knee down, hold for 5 to 10 seconds, 10 times.
2. Sit to stand from a chair, 3 sets of 10, lowering the chair over time.
3. Glute bridges, 3 sets of 12 to 15.
4. Step-ups onto a low step, 2 to 3 sets of 8 to 10 each side.
5. Easy cycling or walking to keep the knee moving.

As the knee settles, build towards exercises like the goblet squat and split squats with gradually increasing load. Progress one variable at a time: range, then load, then speed.

Keep a short note of what you did and how the knee felt the next morning. After a couple of weeks, the pattern usually shows you which activities your knee tolerates well and which need more time, and that makes progression much less of a guessing game.

Recovery time and when to get urgent help

Overload problems often improve over 6 to 12 weeks with consistent rehab, while tendon problems, ligament injuries and arthritis may need longer. The on-site physio at Lycan Strength can assess your knee, with 20% off for members, and you can book a physio appointment online.

• Go to A&E if you cannot bear weight after an injury, the knee looks deformed, or it swelled up rapidly within a couple of hours of a twist or impact.
• Go to A&E if the knee is hot, red, very swollen and painful, especially with a fever.
• See a GP or physio promptly if the knee locks and you cannot straighten it, or it keeps giving way.
• Call NHS 111 or see a GP urgently for a swollen, warm, painful calf, which could be a blood clot. Call 999 if you also have chest pain or breathlessness.
• See a GP the same day if a child has knee or hip pain with a limp.

Questions