If one knee hurts more than the other, you may wonder whether the difference is normal or a sign of an underlying problem. In many cases, one-sided knee pain can be related to previous injury, osteoarthritis, overuse, inflammation, or differences in the way you move and distribute weight between your legs.

The important point is that one knee hurting more than the other is a symptom, not a diagnosis. The cause can range from a relatively minor strain to a condition that needs medical evaluation.

Why Does One Knee Hurts More Than the Other?

The two sides of the body do not always experience exactly the same amount of stress. One knee may have experienced an old injury, developed more cartilage changes, or simply be exposed to greater loading during certain activities.

Research has also found that structural changes such as joint-space narrowing and cartilage defects can be associated with knee pain in people who have symptoms in only one knee.

Other possible explanations include:

• Previous knee injury
• Osteoarthritis
• Meniscus damage
• Overuse or repetitive activity
• Tendon or bursa inflammation
• Gout or another inflammatory joint condition
• Differences in muscle strength or movement
• Problems involving the hip, ankle, or foot that change how you walk

9 Possible Causes When One Knee Hurts More Than the Other

1. Knee Osteoarthritis

Osteoarthritis is one of the most common causes of knee pain, particularly in adults as they get older. It can affect one knee more severely than the other. Symptoms may include pain with movement, stiffness, swelling, reduced flexibility, and discomfort when walking or using stairs. Osteoarthritis does not necessarily develop at the same rate in both knees. A previous injury, differences in joint loading, activity patterns, and other factors may contribute to one knee becoming more symptomatic.

2. A Previous Knee Injury

An old injury may explain why one knee hurts more than the other, even if the original injury happened years ago. Previous ligament injuries, meniscus tears, fractures, sports injuries, or knee surgery can change how the joint functions. Some injuries can also increase the likelihood of developing degenerative changes later. If your more painful knee has a history of injury, tell your healthcare professional when describing your symptoms.

3. Meniscus Injury or Tear

The menisci are pieces of cartilage that help distribute load and absorb shock within the knee. A meniscus can be injured during a twisting movement, particularly when the knee is bearing weight. Possible symptoms include localized pain, swelling, clicking, catching, or a sensation that the knee is locking. A meniscus problem commonly affects one knee rather than both at the same time.

4. Overuse or Repetitive Stress

Sometimes, one knee hurts more than the other because it is doing more work.

You may repeatedly favor one leg when:

• Climbing stairs
• Running or playing sports
• Kneeling
• Squatting
• Standing for long periods
• Performing repetitive work

A sudden increase in exercise or repetitive knee movement can also contribute to pain.

5. Bursitis or Tendon Problems

Bursae are small fluid-filled sacs that help reduce friction around joints. When one becomes inflamed, it can cause localized pain and swelling. Tendons around the knee can also become irritated following repetitive loading or overuse. The location of the pain can provide useful clues. For example, pain at the front of the knee may have different causes from pain behind or along the inner or outer side of the joint.

6. Gout or Other Inflammatory Conditions

Sudden, intense pain accompanied by swelling, warmth, or redness can sometimes be related to an inflammatory condition such as gout. Other inflammatory diseases, including rheumatoid arthritis, can also affect the knee. A swollen knee has numerous possible causes, including osteoarthritis, rheumatoid arthritis, gout, infection, bursitis, and injury.

Because several conditions can produce similar symptoms, persistent or severe inflammation should be medically assessed rather than diagnosed based on symptoms alone.

7. Differences in Strength, Movement, or Alignment

Your legs do not necessarily move in perfectly identical ways. Differences in muscle strength, flexibility, balance, or movement patterns may change the forces placed on each knee. Problems elsewhere in the lower limb may also influence knee loading.

For example, a problem affecting the hip, ankle, or foot can alter your walking pattern and potentially change the stress experienced by one knee.

8. A Baker’s Cyst

If the discomfort is mainly behind one knee, a Baker’s cyst is another possibility.

A Baker’s cyst is a fluid-filled swelling behind the knee. It can cause tightness or pain, particularly when bending or fully straightening the knee. It is often associated with an underlying knee problem such as arthritis or cartilage damage.

9. Your Body May Be Compensating for Another Problem

If one knee becomes painful, you may unconsciously change the way you walk to protect it.

That altered movement can place additional demands on the opposite leg, hip, ankle, or back. This does not necessarily mean the original knee problem is causing a new disease elsewhere, but persistent changes in movement are worth discussing with a healthcare professional.

What Does the Location of One-Sided Knee Pain Mean?

The location of your pain can help a healthcare professional narrow down possible causes, although pain location alone cannot establish a diagnosis.

A proper assessment considers the location together with your age, activity level, injury history, swelling, range of motion, and other symptoms.

When Should You See a Doctor for One Knee Pain?

Consider arranging a medical evaluation if one knee hurts more than the other and the pain:

• Persists or keeps returning
• Is getting progressively worse
• Causes significant swelling
• Limits walking or normal activities
• Makes the knee feel unstable
• Causes painful clicking, catching, or locking
• Develops after an injury
• Is associated with persistent stiffness

You should seek urgent medical attention if the knee becomes very swollen, hot, or red, particularly when accompanied by fever, or if you cannot bear weight after a significant injury. A hot, discolored knee can be a sign of an infection and should not be ignored.

How Is One-Sided Knee Pain Diagnosed?

A healthcare professional will usually start by asking about your symptoms and medical history and examining the knee.

They may want to know:

• When the pain began
• Whether it started suddenly or gradually
• Where the pain is located
• Whether the knee is swollen
• Whether there was an injury
• What activities make it worse
• Whether you experience stiffness, locking, or instability
• Whether you have pain elsewhere in the body

Depending on the findings, additional testing may be considered. This can include an X-ray or, in selected situations, MRI or other imaging.

Importantly, imaging findings do not always perfectly correspond with the amount of pain a person experiences. Your symptoms and physical examination remain important parts of the assessment.

What Can You Do for One Knee That Hurts?

Treatment depends on the underlying cause.

For mild pain without significant injury or concerning symptoms, temporarily reducing activities that aggravate the knee may help. Gradually returning to appropriate movement and exercise can be preferable to prolonged inactivity.

Depending on the diagnosis, treatment may include:

• Physical therapy
• Strength and flexibility exercises
• Activity modification
• Weight management when appropriate
• Pain-relief medication when medically suitable
• Treatment of an underlying inflammatory condition
• Injections in selected cases
• Surgery for certain injuries or advanced joint disease

There is no single treatment that is appropriate for every type of knee pain.

Can One Knee Hurt More Than the Other Without a Serious Problem?

Yes. One knee hurting more than the other does not automatically mean you have a serious disease.

Knee pain is common, and many cases are related to overuse, minor injuries, or degenerative changes. However, persistent, worsening, or unexplained one-sided pain deserves attention because different conditions can produce similar symptoms.

FAQ

The Bottom Line

If one knee hurts more than the other, there are several possible explanations. Osteoarthritis, previous injuries, meniscus problems, overuse, inflammation, and differences in movement are among the possibilities.

The amount of pain alone cannot tell you exactly what is wrong. If symptoms persist, worsen, or interfere with walking and everyday activities, a qualified healthcare professional can assess the knee and determine whether further investigation or treatment is needed.

Citation

• Javaid, M. K., et al. “Individual Magnetic Resonance Imaging and Radiographic Features of Knee Osteoarthritis in Subjects with Unilateral Knee Pain: The Health, Aging, and Body Composition Study.” Arthritis & Rheumatology, vol. 64, no. 10, 2012, pp. 3246–3255. Wiley, https://pubmed.ncbi.nlm.nih.gov/22736267/
• Duong, Vicky, et al. “Evaluation and Treatment of Knee Pain: A Review.” JAMA, vol. 330, no. 16, 2023, pp. 1568–1580. JAMA Network, https://pubmed.ncbi.nlm.nih.gov/37874571/
• Adams, Bryan G., Megan N. Houston, and Kenneth L. Cameron. “The Epidemiology of Meniscus Injury.” Sports Medicine and Arthroscopy Review, vol. 29, no. 3, 2021, pp. e24–e33. Wolters Kluwer, https://pubmed.ncbi.nlm.nih.gov/34398119/