A stiff knee is a common complaint, especially among older adults and those who are very physically active.
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.
In this article, learn more about the causes of knee stiffness. The article will also outline some treatments and home remedies that may help alleviate this symptom.
The following are some common causes of a stiff knee.
Injury to menisci
The menisci are two “C” shaped pieces of cartilage that sit inside the knee joint. Their role is to act as a cushion, or shock absorber, between the bones that make up the joint.
A person can injure or damage a meniscus by suddenly moving or twisting the knee. This is most likely to occur during sports or other types of physical activity.
The menisci are also prone to degeneration with age. Specifically, as the menisci degrade, they become more prone to tearing.
A person will likely hear or feel a “pop” when a meniscus tears. According to the American Academy of Orthopaedic Surgeons, the knee will then start to feel stiff. In many cases, people can still walk on the knee, though they may also experience symptoms such as:
- locking knee
- loss of full range of motion
- a feeling that the knee is giving out
Injury to ligaments
Ligaments are bands of fiber that connect bone to bone. Ligaments that run through the knee connect the thigh bone, or femur, to the lower leg bone, or tibia.
A person may sprain, tear, or rupture their knee ligaments. If this occurs, a person may experience:
- pain in the knee joint
- instability of the knee
- swelling in the knee
Arthrofibrosis, or stiff knee syndrome, occurs when an excessive amount of scar tissue forms around the knee joint.
It is not uncommon for people to experience arthrofibrosis following knee surgeries such as knee replacement or anterior cruciate ligament surgery. In fact, according to the Saint Alphonsus Rehabilitation Services, around 6% of people who have knee replacements experience arthrofibrosis.
Some additional symptoms of arthrofibrosis include:
- knee pain that worsens
- swelling and warmth around the knee
- walking with a bent knee
There are three common types of arthritis that can contribute to knee pain and stiffness. The following sections outline these in more detail.
Rheumatoid arthritis is the result of an autoimmune condition that causes the body to attack its own tissues. Rheumatoid arthritis typically affects both knees.
People with rheumatoid arthritis sometimes experience swelling of the synovial membrane, which is a thin membrane that covers the inner lining of the knee joint. Swelling of the synovial membrane causes knee stiffness and pain.
Osteoarthritis occurs as a result of wear and tear of the cartilage between bones. As the cartilage within the knee degrades, it causes the bones within the knee to rub against each other. The rubbing bones can cause bony growths called spurs. These can cause joint stiffness and pain.
According to one 2013 study, knee osteoarthritis is more common among people aged 55–64 years.
Injuries such as meniscal and ligament tears can increase the likelihood of further injury to the knee joint. Over time, this can lead to post-traumatic arthritis (PTA). PTA occurs years after a person sustains an injury to their knee.
People with PTA may experience the following symptoms:
- swelling in the knee joint, which may make it difficult to move the knee
- knee pain
- a feeling of weakness in the knee
- worsening of symptoms following physical activity
- worsening of symptoms during wet weather
A person should see their doctor as soon as possible if they suspect a torn or injured knee. Receiving prompt treatment will help reduce the risk of further injury.
A person should also see a doctor if knee stiffness is accompanied by other symptoms, such as pain or swelling.
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
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
Knee stiffness is a common issue. It is particularly common in people who are very physically active, as well as older adults.
Knee injuries and arthritis are among the most common causes of knee stiffness. In many cases, rest, ice, and OTC medications can help alleviate knee stiffness and associated symptoms.
However, a person should talk to their doctor if they have sustained a knee injury, or if their knee stiffness is accompanied by additional symptoms. People who suspect that they have arthritis in the knee should also see a doctor for a diagnosis and appropriate treatment.