Why Does One Knee Hurt More Than the Other?
Wondering why one knee hurts more than the other? Learn about common causes, what patterns may mean, and when it is worth getting checked.
It can be confusing when both of your knees do roughly the same job, but only one of them seems to complain.
Maybe your right knee hurts when you walk upstairs. Perhaps your left knee feels sore after a long day on your feet. Or one knee has gradually become more uncomfortable even though you cannot remember doing anything to injure it.
Pain in just one knee does not automatically point to one specific problem. Knee pain can have many causes, ranging from a temporary strain to an injury or a longer-term joint condition. The details of the pain, including where it occurs, when it started, and what makes it better or worse, can provide useful clues.
One knee does not always experience the same stress as the other
Although your knees may seem symmetrical, they do not necessarily go through exactly the same movements and forces every day.
You may naturally put more weight on one side when walking, climbing stairs, standing, or getting up from a chair. An old injury, muscle weakness, or a change in the way you move can also affect how force is distributed through your legs.
Sometimes this happens without you consciously noticing it.
For example, if one leg or hip has been bothering you, you may gradually shift more of your weight onto the other side. Over time, that extra workload can contribute to discomfort.
This does not mean that every case of one-sided knee pain is caused by an imbalance. It simply helps explain why two knees can have different experiences even in the same person.
A past injury can still matter
An old knee injury can sometimes have lasting effects.
Previous damage to structures such as ligaments, tendons, or the meniscus can change how the knee moves or how force passes through the joint. Even after an injury appears to have healed, the affected knee may not behave exactly like the other one.
According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, a history of joint injury is one of the factors that can increase the likelihood of osteoarthritis. Osteoarthritis can also begin in one or a few joints rather than affecting every joint equally.
That is why a knee injury from years ago may still be relevant when discussing new or gradually worsening pain.
Of course, pain in a knee that has been injured before does not automatically mean that osteoarthritis or another long-term problem has developed. It is simply one part of the bigger picture a healthcare professional may consider.
The location of the pain can offer clues
Where you feel the pain can sometimes be useful.
Pain at the front of the knee may feel different from pain on the inside, outside, or back of the joint. Certain activities may also trigger discomfort depending on which part of the knee is involved.
For example, pain around or behind the kneecap may become more noticeable during activities that put extra pressure on that area, such as climbing stairs, squatting, kneeling, or getting up from a chair.
Pain that begins after twisting, overstretching, repetitive exercise, or a direct injury may have a different pattern. The NHS notes that knee symptoms can have several possible causes, including sprains, strains, tendon problems, ligament injuries, and cartilage damage.
The important point is that location alone cannot diagnose the cause. Two people can have pain in the same area for completely different reasons.
Could osteoarthritis affect only one knee?
Yes, it can.
Osteoarthritis often develops gradually and can affect people differently. Symptoms may include pain, stiffness, swelling, and changes in how easily a joint moves. Previous injury, age, excess body weight, repetitive stress, and other factors can influence risk.
One knee may become more affected than the other, particularly if it has experienced a previous injury or has been exposed to different stresses over time.
Osteoarthritis is not simply a matter of a joint being “worn out.” It involves changes in the tissues within the joint, and symptoms can vary considerably from person to person.
If knee pain is persistent, a healthcare professional can assess the symptoms and determine whether osteoarthritis or another condition may be involved.
Your hips, feet, and muscles may also play a role
The knee does not work alone.
Walking and other everyday movements involve the hips, thighs, lower legs, ankles, and feet. Changes in strength, movement, or stability elsewhere can affect how the knee is loaded.
Muscles around the knee also help support movement. If they become weak, particularly after a period of inactivity or injury, everyday activities may feel different.
This is one reason treatment or rehabilitation plans often focus on more than the painful spot itself. Depending on the cause, strengthening and movement exercises may be used to improve function and support the joint.
The right approach depends on the individual and the cause of the pain, so an exercise that is helpful for one person may not be appropriate for someone else.
When the pain appears matters too
Try to notice the pattern.
Does your knee hurt only after exercise? Does it feel worse after sitting for a long time? Is walking downstairs more difficult than walking upstairs? Does the pain appear suddenly, or has it slowly developed over months?
These details can be useful.
A sudden injury followed by swelling, instability, or difficulty straightening the knee is different from discomfort that gradually develops with everyday movement. Likewise, pain that comes and goes after activity may need a different evaluation from pain that is constant or worsening.
Keeping track of these patterns can make it easier to explain your symptoms if you decide to speak with a doctor or physical therapist.
What can you do when one knee is sore?
If the pain is mild and not related to a serious injury, a few simple steps may help while you monitor how things develop.
You might consider temporarily reducing activities that clearly make the pain worse rather than pushing through significant discomfort. At the same time, completely avoiding movement for long periods may not always be helpful.
The NHS recommends simple measures such as resting the affected joint when needed, using an ice pack wrapped in a towel for short periods, and seeking advice about appropriate pain relief. It also advises against completely stopping movement of the affected joint.
Regular physical activity can also play an important role in joint health. For people with osteoarthritis, exercise may help improve pain, stiffness, flexibility, and muscle strength when performed safely and appropriately.
If excess weight is a concern, weight management may reduce stress on weight-bearing joints such as the knees.
There is no single solution that works for every type of knee pain. The best approach depends on what is causing the problem.
When should you get your knee checked?
It is worth seeking medical advice if knee pain is persistent, keeps returning, is getting worse, or is interfering with normal activities or sleep.
Some symptoms deserve more urgent attention. The NHS advises seeking urgent help if you cannot move the knee or put weight on it, if it is badly swollen or has changed shape, or if it becomes hot and red along with symptoms such as fever or feeling unwell.
A healthcare professional can consider your medical history, examine the knee, and decide whether further tests or treatment are needed.
The bottom line
One knee hurting more than the other is not unusual, and there is no single explanation for it.
A difference in how you move, an old injury, repetitive stress, muscle weakness, or a condition such as osteoarthritis could all be relevant. Sometimes the cause is relatively minor and improves with time. In other cases, persistent or worsening symptoms deserve a closer look.
Rather than trying to diagnose the problem based on one symptom alone, pay attention to the full pattern. When did the pain begin? Where is it located? What activities trigger it? Is there swelling, stiffness, instability, or difficulty moving?
Those details can help you make a more informed decision about whether simple self-care is reasonable or whether it is time to speak with a healthcare professional.
Sources
National Institute of Arthritis and Musculoskeletal and Skin Diseases, Osteoarthritis