Knee Pain Causes

A practical guide to common knee pain causes, warning signs, and next steps.

Knee pain causes physiotherapy assessment of kneecap and knee joint line — Knee assessment helps identify likely causes.

Knee pain causes include ligament injuries, meniscus tears, kneecap pain, tendon overload, bursitis, arthritis, and less common referred or inflammatory pain. The likely cause becomes clearer when you review pain location, swelling, locking, giving way, and movement triggers.

If your symptoms started after sport, twisting, jumping, kneeling, or a training increase, match your symptoms with the most likely cause. This page supports our broader knee pain guide and links to common diagnoses seen in active and everyday patients.

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Quick symptom guide

Front knee pain often points to kneecap pain or tendon overload.
Joint line pain may suggest a meniscus injury.
Immediate swelling after a twist can suggest ligament or internal joint injury.
Pain below the kneecap often fits patellar tendinopathy.
Morning stiffness may fit knee arthritis.

What are the most common knee pain causes?

The most common knee pain causes are kneecap pain, meniscus injuries, ligament sprains, tendon overload, bursitis, and knee arthritis. Your symptoms, movement pattern, swelling response, and activity load help guide the likely cause.

In practice, knee pain often falls into four groups: sudden injury, repeated overload, age-related joint change, or nearby soft tissue irritation. A physiotherapist helps narrow this down through your history, movement tests, strength tests, and load response.

Common causes of knee pain

Ligament injuries

ACL injuries, MCL injuries, LCL injuries, and PCL injuries often follow twisting, pivoting, sudden stopping, or impact. These injuries may cause fast swelling, giving way, pain with turning, or poor confidence when changing direction.

Meniscus injuries

Meniscus tears often cause joint line pain, clicking, catching, locking, or pain with deep bending. Symptoms commonly start after a twist, pivot, squat, or awkward landing.

Patellofemoral pain

Patellofemoral pain syndrome usually causes pain around or behind the kneecap. It often worsens with stairs, squats, lunges, hills, running, or long sitting with bent knees.

Tendon overload

Patellar tendinopathy is common in jumping and sprinting sports. Pain usually sits just below the kneecap and often flares with repeated loading or sudden training increases.

Arthritis

Knee osteoarthritis often causes stiffness, swelling, deep aching, and reduced walking tolerance. Symptoms often build slowly and may feel worse after rest, in the morning, or after longer weight-bearing tasks.

Bursitis

Knee bursitis can cause local swelling and tenderness. It often follows kneeling, direct pressure, or repeated irritation around the front or inner side of the knee.

Other important causes

Other knee pain causes include ITB syndrome, plica syndrome, Osgood-Schlatter disease, and Sinding Larsen Johansson syndrome. In children and teenagers, growth-related overload problems are common. They usually respond best to smart load change rather than complete rest.

Knee pain causes step-down assessment checking kneecap and joint line control — Step-down testing shows knee control.

Where your knee pain sits can guide diagnosis

Pain location gives useful clues about the likely diagnosis. Front knee pain behaves differently from inner-knee pain, outer-knee pain, or a deep joint ache, so location helps guide the next step.

Location	Likely cause	Common trigger
Front	Kneecap pain or patellar tendon overload	Stairs, squats, lunges, running
Inner	MCL injury or medial meniscus irritation	Twisting, side force, deep bending
Outer	ITB syndrome or lateral meniscus irritation	Running, downhill, cutting
Deep ache	Arthritis or wider joint irritation	Long walks, standing, repeated loading

Diagnosis pathway

Pain location and symptom behaviour guide the first diagnosis. Swelling, locking, giving way, strength loss, and movement tests then help confirm whether the main problem is ligament, meniscus, tendon, arthritis, or another overload condition.

How is knee pain diagnosed?

Knee pain is usually diagnosed through your symptom history, movement testing, swelling pattern, and load response. Imaging helps in selected cases, but many common knee pain causes can be assessed first through a detailed clinical assessment.

Your physiotherapist may assess walking, squatting, step-down control, ligament stability, meniscus signs, strength, balance, hopping, and training load. For broader public information, Healthdirect provides a clear overview of knee pain and when medical review may be needed.

See a physiotherapist or doctor promptly if:

your knee swells quickly after a twist or collision
the knee locks or will not fully straighten
the knee gives way when walking or turning
you cannot weight bear properly
the joint is red, hot, or linked with fever

How can physiotherapy help knee pain causes?

Physiotherapy helps identify the main pain source, settle irritation, improve movement, and rebuild strength. The best plan depends on the diagnosis, because arthritis, meniscus irritation, jumper’s knee, and ligament injuries each need different management.

Treatment may include swelling control, activity changes, strength work, balance retraining, landing mechanics, running or sport progressions, taping, bracing when appropriate, and clear return-to-activity planning.

Can I keep exercising with knee pain?

You can often keep moving if pain stays mild, settles after activity, and does not cause swelling or giving way. Reduce speed, hills, jumping, deep bending, or volume if these trigger symptoms.

Stop and seek advice if pain increases, your knee swells, locks, gives way, or remains worse the next day. A guided knee exercise plan can help rebuild strength and load tolerance safely.

Load management for knee pain causes

Load management means reducing painful loads, rebuilding strength, then progressing activity again. This approach helps many knee pain causes because the knee often reacts to sudden spikes in walking, running, stairs, gym work, kneeling, or sport.

Reduce the main painful activity during a flare-up.
Keep gentle movement that does not increase symptoms.
Rebuild strength with a gradual knee exercise plan.
Avoid sudden jumps in running, hills, stairs, or sport.
Check how the knee feels over the next 24 to 48 hours.

What should you do if knee pain keeps returning?

Recurring knee pain often means the knee is still being overloaded, underprepared, or both. This can happen when strength has not recovered, training rose too quickly, or the first diagnosis did not match the true pain source.

If symptoms keep returning, it often helps to review return to sport timing, rebuild strength slowly, and improve exercise load instead of resting until pain settles again.

When should you worry about knee pain causes?

You should be more concerned if knee pain follows a major twist or collision, causes fast swelling, locks the joint, prevents weight bearing, or makes the knee give way. These signs may point to a more significant injury.

You should also seek help if pain lasts beyond a few days, keeps returning with activity, wakes you at night, or stops you from walking, working, training, or managing stairs with confidence.

Knee pain causes FAQs

What causes knee pain most often?

The most common knee pain causes are kneecap pain, meniscus injuries, ligament sprains, tendon overload, bursitis, and arthritis. The likely cause depends on where the pain sits, how it started, whether swelling is present, and which movements trigger symptoms.

How do I know if my knee pain is from a meniscus tear?

Meniscus pain often sits along the joint line. It may come with clicking, catching, locking, or pain during twisting and deep bending. However, other knee injuries can feel similar, so a proper assessment is still important.

Can knee pain settle without surgery?

Yes. Many knee pain causes improve with physiotherapy, load management, strengthening, movement retraining, and time. Surgery is usually reserved for selected cases such as major ligament injuries, certain locked meniscus tears, fractures, or advanced joint disease.

Do I need a scan for knee pain?

Not always. Many common knee pain causes can be assessed from your history and physical tests. Scans are more useful when there is major swelling, suspected fracture, locking, strong instability, infection concern, or poor recovery despite care.

Can children and teenagers get knee pain too?

Yes. Young active people often develop knee pain from growth-related overload conditions such as Osgood-Schlatter disease or Sinding Larsen Johansson syndrome. These problems usually improve with smart activity change, strength work, and gradual reloading.

When should I see a physiotherapist for knee pain?

You should see a physiotherapist if your knee pain lasts more than a few days, keeps returning, follows a sporting injury, or affects walking, stairs, gym work, running, or sport. Early assessment often makes recovery more efficient.

What to do next

If you are unsure which knee pain cause fits your symptoms, book a physiotherapy assessment. A clear diagnosis, early load advice, and the right exercise plan can help you settle pain and return to daily activity or sport with more confidence.

If your knee has swollen quickly, locked, buckled, or become hard to weight bear, arrange prompt assessment. The earlier the real cause is identified, the easier it is to choose the right treatment path.