Understanding the causes of knee pain, warning signs, and when to seek medical care can help prevent long-term damage and improve recovery.
This article explores five common causes of knee pain, explains when knee pain is serious, and outlines when to see a doctor for knee pain.
1. Knee Osteoarthritis (Wear and Tear)
Knee osteoarthritis is a degenerative joint condition caused by gradual breakdown of cartilage. It is one of the most frequent causes of chronic knee pain, especially in adults over 40.
Common symptoms
- Pain that worsens with walking, climbing stairs, or standing
- Morning stiffness lasting less than 30 minutes
- Swelling or a grinding sensation in the knee
- Reduced range of motion
When to worry
- Pain is increasing despite rest
- Knee stiffness interferes with daily activities
- Knee feels unstable or deformed
When to see a doctor
See a doctor if knee pain lasts more than a few weeks, limits mobility, or does not improve with basic treatments like rest and pain relief. Early treatment can slow disease progression and reduce pain.
2. Ligament Injuries (ACL, MCL, PCL)
Ligament injuries often occur during sports, sudden twisting movements, or falls. A torn ACL (anterior cruciate ligament) is a common cause of acute knee pain in athletes.
Common symptoms
- Sudden pain after injury
- Swelling within hours
- Knee instability or ‘giving way’
- Difficulty bearing weight
When to worry
- Rapid swelling after injury
- Knee feels unstable or buckles
- Inability to fully straighten or bend the knee
When to see a doctor
You should seek medical attention immediately after a significant knee injury, especially if there is swelling, instability, or difficulty walking. Early diagnosis helps prevent further joint damage.
3. Meniscus Tear
The meniscus is a shock-absorbing cartilage in the knee. Tears often occur during twisting movements or gradually due to aging.
Common symptoms
- Pain along the joint line
- Swelling or stiffness
- Locking or catching sensation
- Pain when squatting or twisting
When to worry
- Knee locks and cannot move freely
- Swelling persists for several days
- Pain worsens with daily activities
When to see a doctor
Consult a doctor if knee pain follows a twisting injury or if your knee locks or catches. Imaging tests (e.g. an MRI) may be needed to confirm a meniscus tear.
4. Patellofemoral Pain Syndrome (Runner’s Knee)
This condition causes pain around the front of the knee and is common in runners, cyclists, and people who sit for long periods.
Common symptoms
- Dull pain around or behind the kneecap
- Pain when climbing stairs or sitting for long periods
- Clicking or popping sounds
When to worry
- Pain does not improve with rest
- Knee pain affects exercise or daily movement
- Swelling around the kneecap
When to see a doctor
If knee pain persists for several weeks or limits physical activity, see a doctor. Early treatment can prevent chronic knee problems.
5. Knee Bursitis (Inflammation)
Knee bursitis occurs when fluid-filled sacs (bursae) around the knee become inflamed due to pressure, repetitive kneeling, or infection.
Common symptoms
- Localised swelling
- Warmth and tenderness
- Pain with movement or pressure
When to worry
- Redness and warmth with fever
- Rapid swelling
- Severe pain at rest
When to see a doctor
Seek medical care if there are signs of infection, such as fever or increasing redness. Non-infectious bursitis that does not improve with rest should also be evaluated.
When Knee Pain Is an Emergency
Seek urgent medical care if:
- You cannot bear weight on your knee
- There is severe swelling or deformity
- Knee pain follows a major accident
- You have fever with knee swelling
Final Thoughts
Knee pain has many causes, ranging from minor injuries to chronic joint conditions. Recognising warning signs of serious knee pain and knowing when to see a doctor can prevent complications and improve outcomes. Early evaluation and proper treatment are key to maintaining healthy knee function.
If knee pain is persistent, worsening, or affecting your quality of life, consult a doctor for an accurate diagnosis and personalised treatment plan.
