A stiff knee is a common complaint, especially among older adults and those who are very physically active.
Several factors can contribute to knee stiffness, which is usually most noticeable after a brief period of sitting or inactivity. Injuries and conditions that affect the knee joint, like osteoarthritis or rheumatoid arthritis (RA), can cause your knees to feel stiff. Knee stiffness is characterized by a feeling of tightness in and around the knee joint, which can be accompanied by pain, difficulty moving the joint, and/or swelling.
Knee stiffness can occur as a result of poor flexibility or muscular imbalances in the legs. Injury and arthritis are other common causes of knee stiffness.
What Is A Stiff Knee?
A stiff knee occurs when you have difficulty moving the knee joint due to injury to or inflammation of the joint. Anything that leads to restricted movement of the knee joint may be considered to cause stiffness of the knee.
Four ligaments are important in maintaining the stability and function of the knee joint, the anterior and posterior cruciate ligaments, and the medial and lateral collateral ligaments. The menisci are two pieces of cartilage that permit the bones of the knee joint to move smoothly against one another. Injuries to these structures may restrict movement of the knee joint.
Other traumatic causes of stiff knee include fractures of bone, inflammation of tendons or bursae, or damage to the cartilage of the kneecap. Injuries may be sudden or may develop slowly over time.
The different forms of arthritis are the most common chronic diseases to affect the knee. Osteoarthritis results from wear and tear on the joint, while rheumatoid arthritis (chronic autoimmune disease characterized by joint inflammation) arises from a dysfunction of the body’s immune system. Rarely, tumors and infections of the knee joint and surrounding areas may produce a stiff knee.
A knee injury can require emergency care, and a sprain may be accompanied by more serious injuries to the joint. Seek immediate medical care (call 911) for serious symptoms, such as paralysis, loss of sensation, absent pulses in the feet, complete inability to move the knee joint, high fever (higher than 101 degrees Fahrenheit), severe bleeding, or uncontrollable pain.
Causes of Knee Stiffness
Most people experience knee stiffness after sitting for a long period of time. It’s usually the result of inflammation and fluid build-up in the knee joint, which causes swelling and decreases the ability to freely move the joint. A number of conditions can lead to inflammation, and subsequently, knee stiffness.
Bursitis is usually a temporary condition that occurs when the bursae become inflamed. Bursae are fluid-filled sacs that help reduce friction in the joints as they move. There are several bursae in each knee joint.
Overuse is the most common cause of bursitis. If you develop this condition, your knees can feel stiff after you sit for long periods of time.
Osteoarthritis, also known as wear-and-tear arthritis, can cause stiff knees. It is the most common form of arthritis, affecting 10% of men and 13 % of women in the 60-and-over demographic.1 However, if the knee joint is overused or injured frequently, osteoarthritis can affect young people as well.
RA, an autoimmune disease, is commonly associated with joint stiffness. Morning stiffness is a hallmark feature of RA. If you experience knee stiffness along with additional symptoms, like fever and fatigue, you may have RA.
Knee joint injuries can occur during athletic or everyday activities. Along with stiffness, you are likely to experience swelling and pain from the injury.
For example, a ligament injury can occur due to hyperextension of the knee or traumatic damage. Another common injury is a tear of the meniscus, a c-shape portion of cartilage that sits along the border of the knee joint, providing shock absorption. This can occur due to twisting the knee, and it is common in sports that require a lot of squatting, twisting, and changing positions. You would feel a pop if you tear your meniscus.
Patellofemoral Pain Syndrome
Patellofemoral pain syndrome (PFPS) causes pain in the front of the knee and around the patella (kneecap).2 PFPS is often the result of overuse or malalignment of the kneecap. It’s also referred to as runner’s knee or jumper’s knee because it’s most common in people who play sports. It affects women at a higher rate than men.
PMPS causes stiffness and pain in and under the kneecap, especially after sitting for long periods of time.
Surgery can cause a degree of postoperative knee stiffness. Arthrofibrosis, also called stiff knee syndrome, can happen after knee surgery. The body’s natural response to trauma, such as from injury or surgery, is to make scar tissues. Arthrofibrosis develops when there is too much scar tissue around the knee joint, causing the knee to tighten and stiffen.
Arthrofibrosis can occur after common knee surgeries, including:
- Total knee replacement
- ACL reconstruction
- Knee arthroscopy
- Knee ligament repair
- Tendon repair
- Plica excision
Low Flexibility or Strength
Maintaining flexibility throughout the body can help prevent some types of knee stiffness.
To avoid stiffness from tight muscles, add stretching to your fitness routine and prioritize strength-building exercises.
- Gentle stretching: Can improve the ability of your joints to move through their normal range of motion with minimal restriction and tightness.
- Strengthening: Strong muscles around your knee joints can also make them less prone to injury.
What Other Symptoms Might Occur With A Stiff Knee?
Stiff knee may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. Conditions that cause stiff knee may also lead to symptoms in other body systems.
Knee symptoms that may occur along with a stiff knee
Stiff knee may accompany other symptoms affecting the knee including:
Bleeding or bruising
Deformity of the joint
Instability of the joint
Muscle weakness or spasm
Pain, whether at rest or during specific movements, that may be described as dull, sharp, burning, stabbing or aching
Redness, warmth or swelling
Other symptoms that may occur along with a stiff knee
Stiff knee may accompany symptoms related to other body systems including:
Pain or swelling in other joints
Symptoms that might indicate a serious condition
if you, or someone you are with, have any of these serious symptoms including:
Coldness of the feet, with weak or absent pulse
High fever (higher than 101 degrees Fahrenheit)
Loss of sensation in the lower leg
Obvious breakage or deformity of the bones
Paralysis or inability to move a body part
When you are seen and evaluated for knee stiffness, your doctor will take a history of your symptoms and ask about any recent injuries.
Tests to diagnose the underlying cause of stiff knees can include:
- Blood tests to look for signs of arthritis
- X-rays to investigate a possible fracture or significant arthritic changes
- MRI, which can detect stress fractures or soft tissue injuries, such as ligament or tendon tears
The treatment options for a stiff knee depend partly on the cause.
If the cause is a minor injury, the following home treatments may be enough to alleviate pain and stiffness until the injury heals:
- resting the knee
- applying an ice pack to the knee at regular intervals
- taking over-the-counter (OTC) nonsteroidal anti-inflammatory drugs
- wearing a knee brace to stabilize the knee and help prevent further injury
For more severe injuries and knee stiffness that is severe or persistent, a person may need to see their doctor. The doctor will work to diagnose the cause of knee stiffness and will recommend appropriate treatments.
Depending on the cause of the knee stiffness, these treatments may include:
- taking prescription pain medications
- using corticosteroids
- taking rheumatoid arthritis medications, such as disease-modifying antirheumatic drugs and biologicssurgery
- physical therapy, to improve knee function and overall mobility
Exercises And Stretches That May Help
In some cases, people with a stiff knee should avoid exercising. Some knee injuries need time to heal and would benefit from rest instead of exercise.
However, a stiff knee that occurs due to a form of arthritis may benefit from exercise. The Arthritis Foundation state that different exercises and stretches could help in different ways:
- Strengthening exercises: Increasing muscle strength around the knee reduces the stress on the joint. Examples of these exercises include leg lifts and hamstring curls.
- Range-of-motion exercises: Stretches and exercises that increase the knee’s range of motion keep the joint moving to reduce stiffness. Examples of these exercises include heel slides and stretching with a yoga strap.
- Aerobic exercises: Cardio exercises can boost a person’s energy levels and reduce any excess weight that may put extra pressure on the knee. Examples of these exercises include cycling and swimming.
- Balance exercises: These exercises strengthen the muscles around the knee while also reducing the risk of falling, which could damage the joint further. Examples of these exercises include single leg standing and standing on a foam pad.
A person with a form of arthritis may want to discuss any new exercise plans or programs with their doctor before starting.
The following tips can also help prevent or alleviate knee stiffness and pain:
- avoiding stretching until sufficiently warmed up
- stretching the legs before and after exercise
- stretching slowly and not to the point of the pain
- using proper form when exercising
- making sure that the leg muscles are balanced in strength
- avoiding exercises that make the symptoms worse