The exact cause of most types of arthritis is unknown. Gout is the only type of arthritis where the cause is fully understood. Gout is caused by an accumulation of urate crystals in the affected joint. These crystals form as the result of too much uric acid in the blood.

While it’s not clear exactly how you get arthritis in most cases, there are factors that can increase the risk of developing the condition. These include:
Excess weight – People who are overweight are at an increased risk of certain types of arthritis due to excessive pressure and stress on the joints.
Joint injuries – Joints that have been injured are more prone to certain types of arthritis due to long-term damage.
Smoking – People who smoke are at an increased risk of certain types of arthritis due to the joint-damaging effects of cigarettes.

While arthritis symptoms vary between individuals and depending on the type of arthritis, common symptoms include pain and stiffness of a particular joint or multiple joints. The area may be tender and sore to the touch and in many cases, range of motion is limited. Swelling is also common. There are specific symptoms associated with different type of arthritis:

Gout – This type of arthritis most commonly affects the big toe. The pain usually comes on suddenly and severely with swelling and redness at the base of the big toe.
Lupus – This type of arthritis typically causes joint pain and swelling along with tiredness and other potential symptoms such as headaches, sensitivity to light and mild fever. People with certain types of lupus may also experience skin issues such as sores, rashes and hair loss.
Osteoarthritis – The most common type of arthritis, osteoarthritis causes pain and swelling in the joints, especially after a long, active day. Stiffness is also common, most notably after long periods of rest or after waking up in the morning. Muscle weakness and reduced range of motion are also common. Many people with osteoarthritis report a cracking or clicking sound when bending the affected joints.
Rheumatoid arthritis – This type of arthritis tends to affect multiple joints, causing pain, swelling and inflammation. Stiffness is common after waking up in the morning, and it can last a half hour or even longer.
Psoriatic arthritis – Also called PsA, psoriatic arthritis can cause a number of joint issues including pain, tenderness, swelling and stiffness. Fingers and toes that are affected often swell up to a point where they look like sausages. PsA can also cause fatigue as well as eye symptoms such as redness and discomfort. In some cases, those with PsA will notice changes in their toenails and fingernails. The nails may crumble or form dents. They may also change color, becoming yellow or brown.

Arthralgia is the term for discomfort (such as pain and stiffness) of a joint or multiple joints of the body such as the knees, hips and joints of the toes and fingers. Arthritis is a common cause of arthralgia.

There is no way to prevent arthritis completely. However, there are ways to reduce the risk of developing certain types of arthritis. These include:
Maintain a healthy weight since excess weight can put pressure on the joints, leaving them more susceptible to arthritis.
Don’t smoke since smoking can cause joint damage which can contribute to or worsen arthritis.
Take care when exercising or engaging in any activity that makes you prone to joint injuries.
Consider protective attire and equipment such as toe protective shoes along with elbow and knee pads. When possible, avoid sports and activities that have a high risk of injury.

There is a genetic link with certain types of arthritis such as rheumatoid arthritis, lupus and osteoarthritis. Although it’s not entirely clear how genes play a role, people are more likely to develop some types of arthritis if a parent or a sibling has had the disease.

Symptoms of rheumatoid arthritis include joint pain and stiffness that can last for a significant period of time, several weeks or even longer. More advanced cases of rheumatoid arthritis can cause swelling and even visible redness of affected joints. Stiffness is most common in the morning after first getting out of bed. The stiffness can last 30 minutes or longer in some cases. Rheumatoid arthritis usually affects multiple joints. The smaller joints of the hands are often the first to experience symptoms. It’s common for joints on both sides of the body to be affected. Some people also experience tiredness and a mild fever. The symptoms of rheumatoid arthritis often come and go.

Arthritis does not always produce visible symptoms and when it does, the symptoms will vary depending on the severity and type of arthritis. There are visible symptoms that are typically associated with specific types of arthritis. These include:
Gout – The joint at the base of the big toe is the most commonly affected joint in people who have gout although other joints can be affected as well. The base of the big toe will usually become red and swollen.
Lupus – Some people with lupus will develop a rash on the face or body. Depending on the type of lupus, the rash can take on different shapes and affect different areas of the face and body. Some people with lupus develop a distinctive butterfly-shaped rash that covers the cheeks along with the bridge of the nose. Rashes associated with lupus are usually red and scaly, and they can be triggered or made worse by sunlight and fluorescent lights. If the rash affects the scalp, hair loss can occur.
Osteoarthritis – While in its early stages osteoarthritis might not produce visible symptoms, as it progresses, it can cause swelling, bumps and deformities of the affected joints. For example, if the hands are affected, they can appear unusually large and misshapen.
Rheumatoid arthritis – The hands are usually the first body parts to be affected by rheumatoid arthritis and it’s common for both hands to be affected. The wrists and knuckles may appear swollen at first but as the disease progresses, the fingers may become deformed, appearing in a twisted fashion. If the feet are affected, they may develop bumps and the toes may become deformed. Rheumatoid arthritis can also cause redness in the eyes.
Psoriatic arthritis – A common visual symptom of psoriatic arthritis is significant swelling of the fingers or toes. Some people report that their swollen digits look like sausages. Nail issues are also associated with psoriatic arthritis. The nails of fingers and toes may become discolored and crumble or develop pits or dents. Psoriatic arthritis can also cause red eyes.

Yes, in some cases, joint pain can be a symptom of COVID-19. However, joint pain is one of many symptoms associated with COVID-19 and is not usually a sole indicator of an infection.

There are a number of solutions for arthritis, from lifestyle changes to doctor prescribed treatments. These include:

Physical activity – Many people with arthritis shy away from exercise because it can be painful. However, exercise actually helps joint pain. Be sure to consult with your healthcare provider before starting an exercise plan.
Lose weight – If you’re overweight, ask your healthcare provider for help achieving a healthy weight as this can take pressure off of painful joints.
Orthotics – Shoe orthotics can improve the body’s alignment and provide extra support to reduce pressure on painful, arthritic joints.
Over-the-counter treatments – OTC pain relieving oral medications and topical creams are available to help relieve arthritis pain. Some of these products are also effective for inflammation. Ask your healthcare provider before considering any OTC medications.
Prescription treatments – In some cases doctors will prescribe stronger medications in order to relieve pain and reduce joint inflammation.

Symptoms associated with arthritis in the knee will vary depending on the individual affected, the type of arthritis, and how advanced the condition is.

Osteoarthritis is the most common type of arthritis that affects the knee although other types of arthritis can also involve the knees. Osteoarthritis is often referred to as wear and tear arthritis because it typically occurs in people over 50 following decades of wear on the joints. As cartilage breaks down, the bones of the knee may rub together which can be painful.

Arthritic knees can also become stiff and swollen, and it’s common to experience a reduced range of motion. People with arthritis in the knee may find that their knees lock or buckle during certain types of movement such as bending. The pain and stiffness in the knee may be worse after getting up in the morning or following periods of rest. It may also be worse following intense physical activity.