Knee pain: what is usually causing it, what actually helps, and when you need a scan

Knee pain is one of the most common reasons people in their thirties, forties and fifties first see a doctor, and one of the most common reasons people in their sixties and seventies keep seeing one. It arrives as a runner's niggle that never quite settles, a twinge on the stairs, a knee that gives way at the wrong moment, or a gradual stiffening that makes getting out of a chair a negotiation. At The Online GP by The Wellness, we assess knee pain by phone and video every week, and most cases follow recognisable patterns that point to a clear plan.

What is usually causing it

A few culprits account for most knee pain. Patellofemoral pain, sometimes called runner's knee, is the classic ache around or behind the kneecap that worsens on stairs, hills and after sitting with the knee bent. It is the most common knee problem we see in active adults under fifty and usually reflects load exceeding what the tissues are conditioned for, not damage.

Meniscus tears produce pain along the joint line, sometimes with swelling, catching or a feeling the knee locks. Degenerative tears in over-forties are common on scans and often settle without surgery. Ligament injuries, especially the ACL, usually come with a twist, a pop, rapid swelling and instability. Osteoarthritis brings gradual stiffness, morning creakiness that eases within half an hour, and aching after use. Gout can ambush a knee overnight with hot, red, exquisitely tender swelling, and so can a septic joint, which is the one genuine emergency on this list.

The red flags that change the urgency

Most knee pain is safe to manage with sensible first steps and a routine assessment. Some patterns need faster action. A knee that is hot, red and swollen with fever or feeling unwell could be a septic joint and needs same-day hospital assessment. A knee you cannot bear weight on at all after an injury, an obvious deformity, or a calf that is swollen and tender (possible DVT) all need urgent review. A locked knee that will not straighten at all should be seen promptly. Everything else, however annoying, can usually be assessed calmly over a day or two.

What helps at home, and what is a myth

For a fresh injury, the old RICE advice has evolved. Current guidance favours PEACE and LOVE: protect the knee for the first few days, elevate it, and avoid anti-inflammatory overkill in the first 48 hours, then load it progressively, stay optimistic, keep the blood flowing with movement, and exercise. Complete rest beyond a few days slows recovery for almost every knee condition.

Ice eases pain in the first day or two; heat often suits stiff, arthritic knees better. Paracetamol and short courses of ibuprofen help most people, used sensibly. Supportive footwear matters more than most expect, and knee braces are useful for some ligament and kneecap problems but are not a substitute for strengthening.

The strongest evidence for almost every chronic knee condition, from runner's knee to osteoarthritis, is targeted strengthening of the quadriceps, hips and glutes. Weight loss, when relevant, reduces knee load by roughly four pounds per pound lost. Neither is glamorous; both outperform most injections and gadgets over time.

When scans and injections enter the picture

An X-ray helps when arthritis or a fracture is suspected. An MRI earns its place for mechanical locking, suspected significant meniscus or ligament injury, or pain that defies a clear diagnosis after six weeks of sensible management. Scans for their own sake often muddy the water: most knees over forty show findings that are not the source of pain.

Corticosteroid injections can settle an inflamed arthritic knee for weeks to months and are reasonable in the right patient. Hyaluronic acid and PRP injections have mixed evidence. Surgery is the right answer for some problems, true locking from a bucket-handle meniscus tear or an ACL rupture in someone who wants pivoting sport, and the wrong answer for many others, including most degenerative meniscus tears.

A musculoskeletal assessment at a private London clinic typically costs £100 to £250 before any scan or injection. A phone or video consultation with The Online GP costs £59 for 15 minutes by phone or £150 by video, which is enough to examine how the knee moves and settles most diagnoses. An in-person assessment at our Marylebone clinic is £220. Book a same-day consultation and leave with a clear plan rather than a leaflet.

How a GP appointment helps

The useful output of a knee consultation is a working diagnosis and a sequenced plan: what to start now, what to avoid for two weeks, which exercises, whether a scan is genuinely needed, and when to expect improvement. Where referral is right, to physiotherapy, orthopaedics or rheumatology, we arrange it with a proper letter. Where it is not, we say so plainly.

If you are not sure whether your knee needs a doctor at all, message us on WhatsApp with a short description and we will tell you honestly.

Book your consultation or call 020 3951 3429. Phone consultations are £59, video £150, and in-person at Unit 4, 10 Portman Square, London W1H 6AZ is £220.

Frequently asked questions

Why does my knee hurt going down stairs but not up?

That pattern is the classic signature of patellofemoral pain, runner's knee. Descending loads the kneecap joint at several times body weight with the knee bent, which is exactly the position that aggravates it. It usually responds well to quadriceps and hip strengthening rather than rest.

Should I stop running if my knee hurts?

Not necessarily. Pain that stays mild, does not worsen during a run, and settles within 24 hours can often be trained through with reduced volume and a strengthening programme. Pain that climbs during a run, changes your gait, or swells afterwards means stop and get assessed.

My knee clicks. Is that a problem?

Clicking without pain, swelling or locking is almost always harmless and needs no treatment. Clicking with pain, catching or a knee that sticks needs assessment, as it can indicate a meniscus tear.

Do I need an MRI for knee pain?

Usually not as a first step. Most knee pain is diagnosed from the history and examination, and MRI is reserved for mechanical locking, suspected significant internal injury, or pain that has not declared itself after about six weeks of good management.

Is knee arthritis inevitable with age?

No. Joints change with age on scans, but pain and stiffness are not inevitable, and even established osteoarthritis improves measurably with strengthening, weight management and pacing. Age alone is not a reason to accept a painful knee.

Can knee pain be referred from the hip or back?

Yes. Hip problems, especially in children and teenagers, classically present as knee pain, and lower back problems can refer pain down the leg to the knee. A proper assessment always considers the joints above and below.

References

NHS. Knee pain. nhs.uk, reviewed 2024.

NICE Clinical Knowledge Summary. Osteoarthritis: diagnosis and management. NICE, 2022.

Dubois B, Esculier JF. Soft-tissue injuries simply need PEACE and LOVE. British Journal of Sports Medicine, 2020.

Written by The Wellness Team and medically reviewed by The Wellness Clinical Team. This article is for information only and does not replace a consultation. A hot, red, swollen knee with fever needs same-day hospital assessment.