Knee injuries are so common partly because of how complex the joint is. The knee is the joint where the thighbone, shinbone, and kneecap (patella) connect. In addition to these bones, the knee includes cartilage, ligaments, menisci and tendons.
Cartilage is a slippery substance on the ends of the bones in the knee. It lets the bones rub smoothly over one another as the leg bends and straightens.
Ligaments are the connective tissues that hold the bones of the knee together and give the knee its stability. The menisci are the cushions between the femur and tibia that also act as shock absorbers. There is one along the outer aspect called the lateral meniscus and one along the inner aspect called the medial meniscus.
Tendons are the connective tissues that attach the muscles in the leg to the bones they control. When all these pieces work together, the knee works as it is supposed to. It protects the bones from impact and allows people to move around freely.
When the components of the knee are not working properly, people are likely to experience pain, inflammation, and many of the other symptoms of chronic knee pain.
Long-lasting knee pain can be caused by injuries such as bone fractures and torn ligaments.
There are many things that can contribute to knee pain. Though the outcome is the same, the causes are very different.
Knowing what is causing chronic knee pain can help people properly treat it.
The common causes of chronic knee pain include:
- degenerative tissue disorders
- connective tissue disorders
Traumatic knee injuries are usually caused by accidents, falls, and physical activities. Traumatic injuries usually happen because the knee has been put under extreme strain. Falling from a height, being hit directly on the knee, or making a sudden change in direction are all causes of traumatic knee injuries.
Common traumatic knee injuries include bone fractures, dislocated kneecaps, and torn ligaments.
Metabolic disorders are illnesses that affect how the cells of the body convert food to energy. There may be a metabolic connection to chronic knee pain.
People with metabolic disorders like gout may often experience knee pain. This is because gout causes uric acid crystals to build up in the joints. The result can be painful inflammation, which can also affect how the knee moves.
Degenerative tissue disorders
According to the Arthritis Foundation, osteoarthritis is the most common chronic condition of the joints. It is a degenerative disease, caused by the "wear and tear" of the joints over time.
Common symptoms are pain and stiffness after long periods of rest. The knees may also get swollen after extended activity.
Osteoporosis is another common disorder. Osteoporosis also damages the cartilage and connecting tissues of the knee because the supporting bone is lost.
Bacterial infections such as cellulitis can also cause sudden knee pain. Cellulitis occurs when bacteria that are normally on the surface of the skin make their way underneath the skin's protective surface.
Cellulitis around the knee can cause the joint itself to become infected if left untreated. This causes redness, swelling, pain, and stiffness. In turn, this can produce chronic knee pain.
Connective tissue disorders
Rheumatoid arthritis (RA) is the most common connective tissue disorder that causes knee pain. It is a disease that causes the body's immune system to attack its own tissues. In the case of knee pain, RA attacks the tissues of the knee.
Stretching before physical activity is very important for preventing knee injuries.
A doctor may ask questions about lifestyle to help diagnose the cause of chronic knee pain. The different causes of chronic knee pain have different risk factors associated with them.
- Trauma: Physical activity without proper stretching can put you at risk for a traumatic knee injury. Intense sports like basketball and football can also put people at risk for traumatic injury.
- Metabolic disorders: Disorders like gout may be caused by lifestyle choices or genetics. Excessive alcohol use, obesity, and dietary factors may contribute to knee pain caused by metabolic disorders.
- Degenerative disorders: Degenerative disorders are commonly linked to an aging body, though there are other factors. The risk of osteoporosis increases with age, specific genes, lack of exercise, and dietary factors.
- Obesity puts people at a higher risk for osteoarthritis, especially in the large joints such as the knees. Other possible factors include age, overuse of the joints, and genetics.
- Bacterial infections: Risk factors that can lead to cellulitis include a weakened immune system, skin conditions, long-term swelling in the arms and legs, using drugs that require needles, and obesity.
- Connective tissue disorders: Risk factors for RA include a family history of RA, being over 40, smoking, and obesity. Women are also more likely to develop RA than men.
Treatment for chronic knee pain may come in the form of prescription drugs or an exercise plan. In the case of injuries and serious degenerative conditions, surgery may be needed.
No matter what the diagnosis, patients will likely be given immediate measures to take to begin reducing symptoms. These can include using anti-inflammatory drugs to reduce the pain and swelling, resting the knee, and doing low-stress exercises.
Preventing or reducing chronic knee pain in the long term is a simple commitment. It is as easy as taking care of the body and making healthy lifestyle choices.
Swimming is a good way to exercise without putting strain on the knees.
Adjusting lifestyle to reduce the risk of chronic knee pain can also help care for knee and joint conditions.
Reducing alcohol intake and quitting smoking may reduce the risk of many disorders that lead to knee pain.
Obesity is a risk factor for many of the disorders that cause chronic knee pain. Because of this, keeping body weight in check can greatly reduce the risk of chronic knee pain.
Adequate exercise is an important part of life. Daily exercise directly decreases the risk of many diseases, including heart disease, cancer, diabetes, high blood pressure, depression, obesity, and osteoporosis.
Exercise is one of the best ways to prevent or reduce the symptoms of many diseases. When coping with chronic knee pain, people should be sure include exercises that strengthen the knees.
Low-stress exercises such as swimming, cycling, and walking are best for caring for or preventing chronic knee pain.
Some types of pain, for example, osteoarthritis, can be worse at night. Tips for getting a better night's sleep include:
- finding a comfortable position, with a pillow between your legs
- use a long-lasting anti-inflammatory, for example, 12 hours duration
- avoiding substances such as alcohol, as it will not help you sleep all night
- maintain good sleep hygiene, with regular times for going to bed and getting up
- avoid sleeping aids as you will need a higher dose if you use them regularly
- do low-impact exercise to help with both pain and sleep
- use a firm mattress, possibly with a foam pad on top to help distribute your weight
Chronic knee pain can be caused by a variety of things. Some risk factors can be controlled, and there are many preventive options. People can take steps toward pain-free knees by seeing a doctor and taking care of their bodies.
In addition to the pain caused by a chronic knee injury, there are usually other accompanying symptoms. These symptoms may include:
- Weakness of the knee; inability to stand properly or fully lengthen out the knee
- Popping sounds as the knee flexes or straightens out
- Swelling and stiffness around the knee
- Redness or warm sensations throughout the knee
While it is important to know what may be causing chronic knee pain, people should always rely on the experience of a licensed doctor. If someone is uncertain what may be causing their pain, a full physical examination can help their doctor diagnose it for them.
After accounting for risk factors, an X-ray or magnetic resonance imaging (MRI) is often needed to diagnose the cause of chronic knee pain. Laboratory work is usually necessary also.