What Causes Stiff Knees After Sitting?

Several factors can contribute to knee stiffness, which is characterized by tightness in the joint and may be accompanied by pain, difficulty moving the joint, and swelling. This problem usually occurs after a period of sedentary or inactivity. Injuries and conditions that affect the knee joint, such as osteoarthritis or rheumatoid arthritis (RA), can make knee stiffness worse.

This article explains why your knee may feel stiff, how your doctor will determine the cause, and treatment options for different conditions.

Why is my knee loose?

Causes of Stiff Knee

Most people experience stiffness in their knees after sitting for long periods of time. This is usually the result of inflammation and fluid buildup in the knee joint, which can cause swelling and reduce your ability to move the joint freely. Many conditions can cause inflammation and stiffness in the knee.


Bursitis Usually a temporary situation that occurs when Bursa of Fabricius, inflammation of the sac that protects the joint. There are several bursae in each knee joint.

Typically, the bursa creates a cushion inside the knee so that bone and other tissues don’t rub against each other. This reduces friction to prevent wear.

Overuse is the most common cause of bursitis. If this happens to you, your knees may feel stiff after sitting for long periods of time.


Osteoarthritis, also known as wear-and-tear arthritis, can cause stiffness in the knee. It is the most common form of arthritis, affecting 10% of men and 13% of women 60 and older. However, osteoarthritis can also affect young people if the knee joint is overused or frequently injured.

Rheumatoid arthritis is an autoimmune disease often associated with joint stiffness. Morning stiffness​​ is a hallmark feature of RA. If you have stiffness in both knees and other symptoms such as fever and fatigue, you may have rheumatoid arthritis.

Symptoms of Rheumatoid Arthritis


Competitive sports or everyday activities can put stress on the knee or force you to twist it incorrectly, which can lead to injuries with accompanying stiffness. Stiffness is more likely if the injury causes swelling and pain.

A common injury is a ligament injury. This problem can occur if you bend your joint beyond its normal range of motion. Ligament injuries can also occur during accidents or other types of traumatic injuries.

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A meniscus tear is another common injury. The meniscus is a C-shaped piece of cartilage that sits between the bones of the knee joint. It acts like a shock absorber.

If the knee is twisted the wrong way, it can tear the cartilage. This is a common problem in sports that require a lot of squatting, twisting, and changing positions. When your meniscus is torn, you may feel a thump in your knee.

Learn about the different types of knee injuries

Patellofemoral Pain Syndrome

Patellofemoral joint Pain Syndrome (PFPS) causes pain in the front of the knee and around the patella or kneecap. PFPS is often the result of overuse or poor alignment of the kneecap.

It’s also known as runner’s knee or jumper’s knee because it’s most common among athletic people. It affects women more than men.

PMPS can cause stiffness and pain under the kneecap, especially after prolonged sitting.

runner’s knee exercises


Postoperative knee stiffness, or stiffness that occurs after surgery, is not uncommon. joint fibrosisalso known as stiff knee syndrome, is a postoperative problem.

This condition is the result of the body’s natural process of forming scar tissue in response to surgery or trauma. With arthrofibrosis, excess scar tissue builds up around the knee joint, causing the knee joint to tighten.

Joint fibrosis can occur after common knee surgery, including:

  • total knee replacement
  • Anterior Cruciate Ligament (ACL) Reconstruction
  • knee arthroscopy
  • knee ligament repair
  • tendon repair
  • fold excision

low flexibility or strength

Maintaining flexibility throughout your body can help prevent some types of knee stiffness.

To avoid stiffness from tight muscles, add stretching to your fitness program and prioritize strength-building exercises.

  • Gentle stretching can improve the joint’s ability to move through the normal range of motion while minimizing restriction and tightness.
  • Strengthening the muscles around the knee joint can also make them less prone to injury.

Knee extension to keep you fit

when to see a doctor

While knee stiffness is common, it can also be a sign of serious illness. Call your healthcare provider right away if you experience the following symptoms:

  • swelling
  • hypoesthesia
  • Reduce the inability to move the knee joint
  • Decreased or absent pulse in the feet
  • cold or blue feet or toes
  • high fever
  • bleeding or bruising
  • uncontrollable pain
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Your doctor will first take a history of your symptoms and ask if you have been injured recently. To find out the cause of stiffness, several types of tests can be performed.

Tests to diagnose the underlying cause of knee stiffness include:

  • blood test to look for signs of arthritis
  • X-rays to diagnose possible fractures or obvious arthritic changes
  • Magnetic resonance imaging (MRI) to detect stress fractures or soft tissue injuries, such as ligament or tendon tears

How a blood test can help diagnose RA


Treatment depends on the cause of knee stiffness. Conditions such as osteoarthritis and rheumatoid arthritis require long-term treatment and follow-up with your healthcare provider.

Whether your stiffness in your knee is caused by a chronic disease or an injury, there are a number of ways you can relieve stiffness in your knee.

Self-Care Strategies

Self-care can be done at home to prevent or relieve stiffness in the knee.

These strategies include:

  • RICE (rest, ice, compression and elevation)
  • stretch before exercise
  • taking NSAIDs, such as aspirin or ibuprofen
  • wear knee pads
  • Strengthen the muscles around the knee joint
  • Incorporate walking and a standing desk into your routine
  • Opt for low-intensity exercise like yoga

Most importantly, listen to your body. Don’t overdo it.

Types of Surgery to Treat Knee Injuries

medical treatement

Depending on your situation, your doctor may recommend additional treatments along with self-care.

Treatment options include:

  • physical therapy
  • prescription pain medication
  • cortisone injection
  • joint lubricant injection
  • disease improvement antirheumatic drugs Medications to treat conditions such as rheumatoid arthritis
  • If knee surgery is required, refer to an orthopaedic surgeon

Even if you are sent for other treatments, you should continue to follow self-care strategies at home for best results.

How Physical Therapy Can Help Knee Pain


Stiff knees are often the result of overuse or injury, but diseases can also limit your mobility. To prevent problems, stretch and exercise your legs regularly.

Even if you are careful, you may find that your knee is still stiff. Other symptoms may also appear, such as swelling or fever. See your doctor for a physical exam, and be prepared to get some blood and imaging tests to find out what’s causing your stiffness in your knee.

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After a diagnosis, your doctor will develop a plan to help you return to full movement without pain, or to help you manage discomfort and physical limitations that cannot be reversed. Medications, physical therapy, and surgery are often used to treat stiffness in the knee.

VigorTip words

Stiff knees can be worrying and can interfere with your daily life. Whether it’s an injury or an underlying condition, your doctor can help you develop a treatment plan that’s right for you and relieves your symptoms.

The sooner you can identify what is causing your knee stiffness, the better your chances of restoring knee movement. So don’t ignore pain or changes in your ability to sit, stand, or move because of knee pain.

Frequently Asked Questions

  • Why do my knees hurt when I sit?

    Many people with Patellofemoral Pain Syndrome (PFPS) report pain in their knees when sitting, especially during prolonged sitting. This condition is usually identified by pain under and around the kneecap. Effective treatment of PFPS can take the form of physical therapy and exercises that focus on the quadriceps, hamstrings, and gluteal muscles.

  • How to prevent knee stiffness?

    There are several ways to help prevent knee stiffness. Before exercising or participating in physical activity, remember to stretch all parts of your body properly. Low-intensity exercises like yoga or hamstring curls can reduce stiffness and strengthen your knee muscles. If you work from home, stand up every 30 minutes to stretch your legs or install a standing desk to avoid prolonged sitting.

  • Why do I feel tightness in the back of my knee?

    Anterior cruciate ligament (ACL) tears, posterior cruciate ligament (PCL) tears, and Baker’s cysts are some of the conditions that can cause tightness in the back of the knee. ACL tears are generally considered sports injuries, but ACL and PCL tears can occur with any physical activity. The only way to diagnose tightness in your knee is to visit a healthcare provider.