Joint Pain

Joint pain can occur for a number of reasons. For many people, it is due to arthritis (joint inflammation), of which there are several types. For others, such as those with fibromyalgia or an underactive thyroid, pain occurs with no underlying inflammation at all. Joint pain may range from a mild ache to a severe, burning or sharp sensation in one or several joints. In some instances, joint pain is associated with other symptoms, like joint swelling and stiffness, overlying red and warm skin, and whole-body symptoms like fatigue, weight loss, or fever
Causes
Due to the multiple causes of joint pain, it is perhaps best to separate them into two classes— joint pain from arthritis versus joint pain unrelated to arthritis.

Arthritis-Related
Joint pain related to arthritis indicates that inflammation is occurring within the joint space. There are several types of arthritis and their causes differ.

Osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis. OA develops as a result of age-related breakdown of cartilage, which serves as a cushion between the bones of a joint. This type of arthritis tends to affect the knees, hips, neck, lower back, and fingers.

The pain of OA, which often progresses from a sharp, intermittent pain to a constant aching, worsens with movement and eases with rest. Joint stiffness and a restricted range of motion are also characteristic of OA joint pain.

While classic OA is actually a non-inflammatory arthritis (even though it is still classified as an arthritis), an aggressive subtype of OA, called erosive osteoarthritis, is inflammatory. Erosive OA is most common in postmenopausal women and causes a gradual onset of joint aches, stiffness, and swelling in multiple finger joints.

Gout


Gout is a type of inflammatory arthritis that occurs in some people with high levels of uric acid in their blood. As the uric acid builds up, it may form crystals in certain joint spaces, like the big toe, ankle, or knee.

A classic gout attack refers to a sudden episode of severe, often burning joint pain that usually occurs in one joint (for example, the big toe). The joint pain of a gout attack is often extreme and associated with redness, swelling, and warmth of the joint. Without treatment, the episode will remit on its own, often within a week's time.

The "why" behind gout joint pain is attributed to the rapid, inflammatory response of the body's immune system to digest the unwanted and foreign crystals.


Pseudogout

Pseudogout, also known as calcium pyrophosphate deposition disease (CPPD), is a type of inflammatory arthritis that occurs as a result of calcium crystal buildup in certain joints, most commonly the knee, wrists, shoulders, ankles, feet, and elbows. Like gout, the pain of an acute pseudogout joint attack is sudden, severe, and associated with other symptoms like joint swelling and warmth. Unlike gout, the attacks of pseudogout may last longer before remitting.

Septic Arthritis

With septic arthritis, a joint becomes infected, most commonly with a bacteria and rarely with a fungus (for example, Candida) or mycobacteria (for example, tuberculosis).

Septic arthritis tends to affect a single joint, usually the knee, ankle, wrist, or hip. The affected joint is swollen, warm, and stiff, and a fever is also present. In most cases, septic arthritis is caused by a bacterial infection in the blood that then travels to the joint space. Less commonly, joint surgery or trauma (for example, a tick bite) may be the culprit.

Viral Arthritis

Several different viruses may cause arthritis. The most common ones include hepatitis B and C, parvovirus B19, and alphavirus (viruses transmitted by mosquitoes), such as the Chikungunya virus (CHIKV) found in the Caribbean.

Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, autoimmune disease that develops gradually over a period of weeks to months. While the disease predominantly affects the joints, early symptoms may not involve them, but instead include fatigue, muscle pain, low-grade fever, weight loss, and numbness and tingling in the hands.

When the joints become affected, which is a gradual process, small joints on the same side of the body—such as the joints in the fingers and toes—tend to be affected first. Eventually, other joints follow suit like the wrists, elbows, hips, and spine.

In addition to joint pain, stiffness, warmth, redness, and swelling occur. Unlike osteoarthritis, the stiffness of joint pain in RA tends to be worse in the morning (lasting for more than an hour) and improve with movement.

Spondyloarthritis

Spondyloarthritis is a family of inflammatory rheumatic diseases that includes the following four conditions:

Ankylosing spondylitis (AS): AS is an axial spondyloarthropathy because it affects mainly the back and neck (i.e. spine) and the sacroiliac joints (which connect the spine to the pelvis). The joint pain of AS tends to begin in early adulthood before the age of 45, come on gradually, and improve with activity (similar to rheumatoid arthritis, but the opposite of osteoarthritis). Morning stiffness that lasts longer than 30 minutes is also common in AS.
Psoriatic arthritis: Up to 30 percent of people with psoriasis—a chronic skin condition characterized by patches of thickened skin covered by silvery scales—have psoriatic arthritis. It most commonly affects the end joints of the fingers and toes, causing a throbbing pain, along with stiffness and swelling. Other symptoms may include swollen fingers and toes that look like sausages and nail problems (for example, pitted nail beds). Interestingly, the severity of a person's psoriasis does not correlate with the severity of their arthritis—and in about 15 percent of people, joint pain shows up before the psoriasis appears.
Reactive arthritis: This type is characterized by the development of joint pain and swelling one to four weeks after an infection in the urinary tract, genitals, or intestines. Specific bacterial organisms linked to the development of reactive arthritis include Salmonella, Campylobacter, Shigella, Yersinia, and Chlamydia. Typical joints involved in reactive arthritis are the knee, ankle, and foot.
Arthritis associated with inflammatory bowel disease (IBD): Throbbing joint pain and swelling, especially in larger joints like the knees and hips, may occur in people with inflammatory bowel disease (Crohn's disease or ulcerative colitis). The arthritis tends to be more active when bowel symptoms are flaring.
Systemic Lupus Erythematosus

Joint inflammation, especially of the knees, wrists, and finger joints, is common in systemic lupus erythematosus (SLE)—a chronic, autoimmune disease that may affect nearly every organ in the body.

Like RA, the same joints on the same side of the body tend to be affected in SLE. However, unlike RA, the morning stiffness does not last as long (minutes for SLE versus over an hour for RA), and the joint pain tends to be short-lived and migratory, moving from one joint to another within a 24-hour period.

Polymyalgia Rheumatica

Polymyalgia rheumatica (PMR) is an inflammatory joint disease that causes significant muscle and joints aches and stiffness in the shoulders, neck, and hips. Joint swelling and tenderness may also occur in the wrists and fingers, although it is usually mild. The feet and ankles are never affected, and the disease almost only affects people over the age of 50.

Interestingly, PMR is associated with another rheumatic condition called giant cell (temporal) arteritis, which is an inflammatory blood vessel disease that causes inflammation in the arteries of the head and scalp.

Other Systemic Rheumatic Diseases

Though it may be hard to believe, the above list is not exhaustive of all the different causes of arthritis. Other less common systemic (whole-body) illnesses may cause arthritis, a few examples being:

Systemic sclerosis
Sarcoidosis
Familial Mediterranea fever

Unrelated to Arthritis
These conditions may cause joint pain but are not related to an underlying disease or inflammatory process within the joint.

Fibromyalgia

The predominant symptom of fibromyalgia, a chronic pain condition, is widespread muscle tenderness, along with crippling fatigue. In addition to muscle pain, people often note joint aches and sometimes joint swelling, despite the lack of inflammation on physical exam.

Hemarthrosis

Hemarthrosis, when bleeding into a joint occurs, may occur for a number of reasons including trauma, a bleeding disorder like hemophilia, a postsurgical complication, or tumor growth, like a synovial hemangioma.

Hypothyroidism

The most common cause of hypothyroidism—an underactive thyroid gland—is Hashimoto's thyroiditis, which is when your body's immune system launches an attack on your thyroid. Hypothyroidism may cause numerous symptoms, including fatigue, weight gain, constipation, cold intolerance, and joint aches and stiffness.

Depression

You may be surprised to learn that a primary physical manifestation of depression is joint pain, and sometimes this is a person's only reported symptom. That said, other common symptoms of depression include a loss of interest in pleasurable activities, a change in appetite, sleep disturbances, difficulty concentrating, and feelings of hopelessness and/or guilt.