What Causes Knee Osteoarthritis and Who Is at Risk?

FAQ Series — The Pain Relief Clinic Singapore

What are the causes of knee osteoarthritis?
Knee osteoarthritis (OA) occurs when the cartilage cushioning your knee joint gradually breaks down. This leads to bone friction, inflammation, and pain. Common causes include:

• Age-related wear and tear
• Previous knee injuries (e.g., ligament tears, fractures)
• Repetitive stress from work or sports
• Obesity (increases joint load)
• Poor knee alignment or abnormal joint structure
• Joint instability over time

Why do I have knee arthritis?
You may have developed arthritis due to a combination of factors like previous injuries, age, genetics, body weight, or repetitive movements. In some cases, early arthritis appears without a clear trigger, especially if there is a history of family joint problems or past trauma.

What are the risk factors for knee osteoarthritis?
You may be more likely to develop knee OA if you:

• Are over 45 years old
• Are overweight or obese
• Have had past knee injuries (e.g., sports injuries, ACL tears)
• Frequently kneel, squat, or lift heavy objects
• Have weak thigh muscles
• Have a family history of arthritis
• Have other joint conditions (e.g., gout)

Can young people have knee osteoarthritis?
Yes. While knee OA is more common with age, it can affect younger individuals, especially after injuries like ACL or meniscus tears. Repetitive sports stress, poor joint alignment, or obesity can also contribute to early onset arthritis in the young.

What is the difference between osteoarthritis and rheumatoid arthritis?
Osteoarthritis is a degenerative joint condition caused by cartilage wear. It usually affects one or a few joints and worsens with activity.
Rheumatoid arthritis is an autoimmune disease where the body attacks joint lining. It often causes swelling in multiple joints, morning stiffness, and fatigue.
A proper diagnosis—often with blood tests and imaging—is needed to tell them apart.