Knee Pain

Sudden or gradual: An injury points to ligament, cartilage or bone. A slow ache points to wear.
Swelling timing: Within an hour suggests bleeding in the joint. Next-day suggests irritation.
Most knees: Are treated without surgery, whatever the scan shows.

Did it start suddenly, or build up?

	After a twist, fall or tackle	Gradual, over months
Usual causes	Ligament tear, meniscus tear, fracture, dislocated kneecap	Osteoarthritis, kneecap pain, tendon problems, bursitis
Swelling	Often within an hour, and tense	Comes and goes with activity
What it does	Gives way, locks, or feels unstable	Aches after use; stiff after sitting
Typical age	Any, often younger and sporting	Usually over 45
First step	Examination and X-ray, MRI if a tear is likely	Examination and standing X-rays

Swelling within the first hour matters. A knee that balloons quickly after an injury usually has blood in it, which points to a ligament tear, a fracture or a dislocated kneecap. Swelling that appears the next morning is more often irritation than rupture.

The knee from the side, showing the quadriceps tendon, kneecap, patellar tendon and the cartilage on the joint surfaces. — The kneecap sits in the tendon that runs from the thigh muscle to the shin, which is why so much knee pain is felt at the front.

Pain at the front usually belongs to that chain: the quadriceps pulls through the kneecap and down the patellar tendon, and every stair or squat loads it.

What a side view cannot show is the inside of the joint. The menisci and the cruciate ligaments sit between the bones, which is where the twisting injuries and the catching and locking come from.

Where does it hurt?

Front, around the kneecap

Kneecap pain — aching on stairs, squatting, or after sitting a long time
Patellar tendon problems — sore just below the kneecap, common in jumping sports
Bursitis — a soft swelling over the front, often after kneeling

Inner side

Medial meniscus tear — catching, or pain on twisting
Osteoarthritis — the inner compartment wears first in most knees
Inner ligament sprain, after a blow to the outside of the knee

Outer side

Iliotibial band syndrome — a runner’s complaint, worse at a set distance
Lateral meniscus tear or outer ligament sprain

Deep inside, or at the back

Cruciate ligament injury — the knee gave way at the time, and swelled fast
A cyst behind the knee, often alongside wear or a tear inside the joint
Gout — sudden, hot, extremely painful; see gout

The three things worth reporting

Giving way. The knee buckles under you. Suggests a ligament problem, or weak thigh muscles after a long period of pain
Locking. The knee sticks and will not straighten, then releases. Suggests something loose or torn inside the joint
Swelling. How fast it came, and whether it returns after activity

A locked knee should be seen promptly, rather than left to settle. So should a knee you cannot put weight on after an injury, one that looks deformed, or one that is hot and swollen with a fever.

How knee pain is assessed

History. How it started, what it does now, what you can no longer do
Examination. Swelling, movement, ligament stability tests, meniscus tests and kneecap tracking
X-rays, standing. Weight-bearing films show the true joint space; lying down can hide the wear entirely
MRI. For ligaments, menisci and cartilage, where the result would change the plan
Blood tests or joint fluid sampling where gout or infection is possible

Knee pain treatment

Most knees improve without surgery. Strength around the joint does more than anything else, and that is true whether the problem is wear, a tendon or a tear.

First steps

Relative rest from what provokes it, a short course of anti-inflammatory medication, and quadriceps strengthening. Weight loss helps more than most people expect: the knee carries several times body weight with every step.

Physiotherapy

Targeted strengthening and movement retraining. For kneecap pain and early arthritis this is the treatment, not a preliminary to one.

Injections

A steroid injection can settle a painful flare enough to let rehabilitation work. Other injections are used in selected cases, and what suits depends on the diagnosis.

Surgery, when it is the answer

Keyhole surgery for a locked knee or an unstable tear, ligament reconstruction where the knee keeps giving way, and knee replacement for arthritis that no longer responds to anything else.

A tear on a scan is not automatically an operation. Meniscus tears and cartilage wear are common findings in people with no symptoms at all. What is treated is the knee in front of us, not the report.

Your surgeon

Knee problems here are seen by Dr Kelvin Tan Guoping, an orthopaedic surgeon whose subspecialty is hip and knee. He is a Fellow of the Royal College of Surgeons of Edinburgh, holds a Master of Medicine in orthopaedics, and is an Adjunct Assistant Professor at NUS. He consults in English, Mandarin, Teochew and Hokkien.

Most of the work is not surgery. Assessment, rehabilitation and injections come first; an operation is offered when the knee has stopped responding to them.
Robotic and computer-navigated replacement. He completed an international fellowship in Brisbane in 2017 under Professor Ross Crawford, and is a certified robotic trainer who teaches these techniques in Singapore and overseas.
Partial as well as total. His practice includes unicompartmental — partial — replacement, so a knee worn in one compartment is not automatically given a full one.
Complex and revision work. Previously with the Adult Reconstruction Service at Tan Tock Seng Hospital, he also handles revision surgery and peri-prosthetic fractures.

When to see someone about it

Pain lasting more than two or three weeks without improving
Swelling that keeps returning, or that came on fast after an injury
Giving way or locking
Difficulty with stairs, or getting out of a chair
Night pain, or pain at rest
Walking distance shrinking because of the knee

Why see us about it

Hip and knee is a subspecialty here. Dr Kelvin Tan is our knee pain specialist by training, including robotic and partial knee replacement.
Strength first. Rehabilitation is the treatment for most knees, not the consolation prize.
The scan is read against you, not instead of you.

Common questions

My knee swelled up straight after a twist. What does that mean?

Rapid swelling usually means bleeding inside the joint, which points to a ligament tear, a fracture or a dislocated kneecap. It is worth being examined rather than waiting for it to settle.

Why does it hurt going down stairs?

Descending loads the kneecap heavily. Pain there is typical of kneecap problems and of early wear behind the kneecap, and it usually responds to strengthening.

Do I need an MRI?

Not always. Examination and standing X-rays answer many questions, particularly for arthritis. MRI is arranged where a ligament or meniscus tear is suspected and the result would change the plan.

Is walking bad for a worn knee?

No. Activity within comfort helps, and strong thigh muscles protect the joint. What tends to aggravate an arthritic knee is sudden increases, deep squatting and stairs in quantity.

Will I end up needing a knee replacement?

Most people do not. Replacement is considered for advanced arthritis that limits walking and no longer responds to other treatment — see knee replacement.

Do I need a referral to see a knee pain doctor?

No. Bring any X-ray or MRI reports, and a note of what you can no longer do comfortably.

Related conditions

Knee replacement · Knee fracture · Gout · Osteoporosis · Rhabdomyolysis