Knee pain
The knee is built more intricately than any other joint: two bones, the kneecap, two menisci, four main ligaments, several tendons and bursae — and each of…
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Medicines commonly prescribed for Knee pain
For informational purposes only. Always consult a doctor before taking any medication.
Dosage form: GEL, 11.6 mg diethylamine diclofenac/gActive substance: diclofenacManufacturer: Haleon Spain S.A.Prescription not requiredDosage form: TABLET, 400 mgActive substance: ibuprofenManufacturer: Laboratorio Stada S.L.Prescription requiredDosage form: TABLET, 600 mgActive substance: ibuprofenManufacturer: Pharmaclan S.R.O.Prescription required
The knee is built more intricately than any other joint: two bones, the kneecap, two menisci, four main ligaments, several tendons and bursae — and each of those parts hurts in its own way. That is why the question "why does my knee hurt?" is close to useless on its own, and settles fairly quickly once a few things are pinned down. Three questions do most of the work: was there an injury and what kind, where exactly does it hurt, and what does the knee do — click, give way, lock, swell. Below comes first what cannot wait, then everything else. If other joints are sore as well and morning stiffness hangs around, the problem is no longer the knee: read the page on joint pain.
What must not be missed
Immediately, calling an ambulance on the single European number 112 or going to an emergency department:
- the knee swelled up within an hour of the injury. Large, rapid swelling nearly always means blood inside the joint, and that blood comes from a torn cruciate ligament, a fracture, or a meniscal tear in the part that has a blood supply. Swelling that builds slowly, by the next morning, works differently and is far less alarming;
- after the injury you cannot put weight on the leg or take even a few steps;
- the knee has changed shape, the kneecap has visibly shifted to one side, or the leg sits at an unnatural angle;
- the knee will not straighten fully, or is stuck bent — something is blocking the joint from inside, and that needs looking at, not working through;
- the knee is hot and red and you also have a temperature or shivering: that is how a joint infection presents, and the clock runs in hours;
- the leg below the knee has gone numb, pale or cold;
- pain behind the knee comes with a swollen, tender calf, especially after recent surgery, a long flight or a plaster cast.
The same day, not tomorrow: if a child has knee pain and is limping, if the knee has swollen with no injury at all, if you take anticoagulants and the joint swelled quickly, if the pain keeps you awake, or if the injury happened to someone with osteoporosis or after hormone treatment.
The knee after a twist or a blow
With a fresh injury, the mechanism tells you most — precisely how it happened.
- The foot stayed planted while the body turned: the classic mechanism for ligament and meniscal injury. If a pop was heard or felt at the time and the knee swelled within an hour, the anterior cruciate ligament is the first thought.
- A blow to the side of the knee. A knock from the outside stretches or tears the medial collateral ligament: it hurts on the inner side of the joint and complains when the knee is "opened out".
- Squatting or twisting under full load: the typical way a meniscus tears. Pain along the joint line on one side, swelling that appears gradually by the next day, and a knee that may start to lock.
- A direct impact against a dashboard or a fall onto a bent knee: this is how the posterior cruciate ligament and the kneecap get damaged.
- A sharp change of direction with the feeling that the knee "went out" and the kneecap visibly displaced sideways: a dislocated kneecap. It often goes back on its own as the leg straightens, but the knee still needs to be seen.
Bruises and sprains without any of the above heal by themselves and need rest in the first days, cold, and a gradual return to activity. But if two or three weeks on the knee is still unstable, giving way or not straightening, self-treatment has run its course.
When there was no injury
- Osteoarthritis. The commonest cause in middle-aged and older people. It hurts when walking and on stairs, especially going down, and is worse by evening; morning stiffness is short, about ten minutes. The knee swells a little, creaks and gradually loses its full extension. Often both knees are involved, though one more than the other.
- Pain beneath the kneecap in younger people. A dull ache in front of, around or under the kneecap, worse on stairs, when squatting and after long periods sitting with the knees bent — at the cinema, on a plane, driving. Commoner in teenagers, in young women and in anyone who has suddenly increased their running. Nothing is tearing; it is about how the kneecap travels in its groove and how well the thigh muscles cope. This is worth working through with a doctor or physiotherapist rather than with videos from the internet.
- Tendonitis. Pain at one precise point, most often in the patellar tendon between the kneecap and the shin. It turns up in people who jump and run, hurts at the start of exercise, then eases off and returns afterwards.
- Bursitis. A soft swelling directly above or below the kneecap, in people who spend a lot of time kneeling. If the skin over it reddens and warms and a temperature appears, the bursa has become infected, and that needs seeing urgently.
- Gout and pseudogout. Sudden severe pain with redness and swelling building over hours. It cannot be told from a joint infection by eye, so if there is a temperature it is treated as infection.
- Inflammatory arthritis. A swollen, warm knee, morning stiffness lasting over half an hour and other joints involved: that is no longer "the knee" but joint disease.
- Referred pain from the hip or the lower back: the knee examines normally, but turning the hip or shifting the back is what hurts.
Locking, catching and the feeling that the knee lets you down
These three complaints are worth separating, because they mean different things.
True locking is a knee that suddenly jams in a bent position and will not straighten until it is jiggled loose, after which it releases. That is how a flap of torn meniscus or a loose fragment of bone and cartilage caught between the joint surfaces behaves. A knee that has stopped straightening fully is a reason to be examined, not to be worked loose at home.
Pseudo-locking is a knee that will not straighten because of pain and swelling rather than a mechanical obstruction. The sensation is similar; the cause is not.
Giving way. If the knee slips out from under you on a turn or on uneven ground, this is usually ligament insufficiency after an old injury. If it gives way because of a stab of pain, that happens with pain beneath the kneecap and with osteoarthritis: the muscle lets go reflexly for a fraction of a second.
A word on clicks and creaking: painless creaking means nothing in itself and needs no treatment. What matters is a click with pain, and a click after which the knee stopped straightening.
A lump behind the knee
A soft, rounded swelling in the hollow behind the knee, more obvious with the leg straight, is usually a Baker's cyst. It is not a disease in its own right but a consequence: the joint produces extra fluid because of osteoarthritis, a meniscal tear or inflammation, and that fluid passes into the bursa behind the knee. It is a nuisance mainly because it tightens the back of the knee on full bending. What gets treated is not the cyst but whatever is filling it.
There is an important qualification, though. If pain behind the knee comes with swelling of the whole calf, tenderness, a bursting feeling, redness or warmth of the skin, this may be a deep vein thrombosis rather than a cyst. The same picture appears when a cyst ruptures, and the two cannot be separated without investigation. A swollen, painful calf is a situation in which help is needed the same day, particularly after recent surgery, a cast, a long spell of immobility, a long flight, in pregnancy or with cancer. Such a leg is not warmed, not massaged and not rubbed.
Knee pain in a child or teenager
A child with knee pain always has the hip examined too. This is the classic trap: the hip joint and the skin over the knee are supplied by sensory branches of the same nerves, so a child with a diseased hip complains about the knee, and the knee itself examines perfectly normally. That is how transient synovitis, Perthes' disease and, worst of all, a slipped upper femoral epiphysis in a teenager get missed — a slip through the growth plate that is treated for weeks as a "sprained knee" while the head of the femur moves further. If the child's knee looks healthy but they are limping or turning the foot outwards, look higher up.
Of the things that genuinely come from the knee at this age, the commonest are:
- Osgood-Schlatter disease, a tender lump on the shin just below the kneecap in an active teenager during a growth spurt;
- pain around the kneecap, worse on stairs and after long spells sitting;
- osteochondritis dissecans, a piece of cartilage with the bone beneath it that can separate and block the joint.
What should raise concern in a child: fever alongside joint pain, night pain that wakes them, refusing to bear weight, pain in several bones at once, unexplained weight loss, pallor and bruising. These are uncommon but serious, and they go to a doctor straight away.
What you can do and what the doctor will do
While the cause is unclear, this is sensible: in the first days after an injury, rest the knee and apply cold through a cloth rather than to bare skin; when walking, take weight off the leg and, if needed, lean on a stick held in the opposite hand; for pain, paracetamol or a non-steroidal anti-inflammatory by mouth or as a gel, with the choice agreed with a doctor or pharmacist. There is no need to immobilise the knee for long: without movement the thigh muscle weakens within days, and a weak muscle means an unstable knee and more pain. Do not warm a hot, red knee, and do not rub a leg with a swollen, tender calf.
The doctor will start with the history and the examination: where it hurts along the joint line, whether there is an effusion, whether the knee fully straightens and bends, whether the ligaments are stable, whether the kneecap is tender — and will always check the hip and the way you walk. An X-ray is needed after an injury and where osteoarthritis is suspected; ultrasound shows fluid and a cyst well; a scan is needed when menisci, ligaments and cartilage are in question, but not for every knee. If the joint has swollen for no reason or infection is suspected, fluid is drawn off for analysis. After that, anything from exercise tailored to the specific cause through to injections into the joint or surgery — and all of it is decided after the diagnosis, not instead of one.
Online consultation
The knee is precisely the case where a sensible conversation saves weeks. The Oladoctor doctor will ask about the mechanism of the injury, how fast the knee swelled, where exactly it hurts, whether it locks and whether it gives way, and from those answers will say what it most likely is and how urgently a face-to-face examination is needed. They will help you make sense of scans and reports you already have, explain what "degenerative changes" in a report actually mean and whether they warrant worry, and advise which specialist to see and what to ask. And they will flag the situations where there is nothing to discuss and you should go to hospital: a knee that swelled within an hour of an injury, a locked knee and a hot knee with a temperature cannot wait.
This material is for information only and does not replace medical advice.
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