Crystals accumulate in the fluid and cartilage of the joints, and cause varying degrees of inflammation and tissue damage.
The diagnosis is confirmed by finding calcium pyrophosphate crystals in joint fluid.
Treatment is with nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine, and sometimes injection of corticosteroids into joints.
Calcium pyrophosphate arthritis usually occurs in older people and affects men and women equally.
Causes of Calcium Pyrophosphate Arthritis
The reason that calcium pyrophosphate dihydrate crystals form in some people is unknown. The crystals often occur in people who have the following:
A joint injury (including surgery)
Accumulations of an abnormal protein in various organs and tissues (amyloidosis Amyloidosis Amyloidosis is a rare disease in which abnormally folded proteins form amyloid fibrils that accumulate in various tissues and organs, sometimes leading to organ dysfunction, organ failure, and... read more )
An abnormally high calcium level in the blood caused by a high level of parathyroid hormone (hyperparathyroidism Hyperparathyroidism In hypercalcemia, the level of calcium in blood is too high. A high calcium level may result from a problem with the parathyroid glands, as well as from diet, cancer, or disorders affecting... read more )
An abnormally low magnesium level in the blood (hypomagnesemia Hypomagnesemia (Low Level of Magnesium in the Blood) In hypomagnesemia, the level of magnesium in blood is too low. (See also Overview of Electrolytes and Overview of Magnesium's Role in the Body.) Magnesium is one of the body's electrolytes,... read more )
A rare disorder that causes an abnormally low alkaline phosphatase level in the blood (hypophosphatasia)
However, most people with calcium pyrophosphate arthritis have none of these conditions. The disorder rarely can be hereditary.
The calcium crystals frequently occur in joints affected by osteoarthritis Osteoarthritis (OA) Osteoarthritis is a chronic disorder that causes damage to the cartilage and surrounding tissues and is characterized by pain, stiffness, and loss of function. Arthritis due to damage of joint... read more for unclear reasons.
Symptoms of Calcium Pyrophosphate Arthritis
Symptoms of calcium pyrophosphate arthritis vary widely. Some people have attacks of painful joint inflammation (arthritis) similar to gout flares, usually in the knees, wrists, or other relatively large joints. Other people have lingering, chronic pain and stiffness in joints of the arms and legs, which may be similar to rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis is an inflammatory arthritis in which joints, usually including those of the hands and feet, are inflamed, resulting in swelling, pain, and often destruction of joints.... read more or osteoarthritis Osteoarthritis (OA) Osteoarthritis is a chronic disorder that causes damage to the cartilage and surrounding tissues and is characterized by pain, stiffness, and loss of function. Arthritis due to damage of joint... read more .
Sudden painful (acute) attacks are usually less severe than those of gout, but, as in gout, attacks in calcium pyrophosphate arthritis can cause fever. Some people have no pain between attacks, and some have no pain at any time, despite large deposits of crystals.
Unlike in gout, where collections of crystals often occur in tissues near joints, people with calcium pyrophosphate arthritis rarely develop hard lumps of crystals (tophi).
Diagnosis of Calcium Pyrophosphate Arthritis
Microscopic examination of joint fluid
Sometimes x-rays or ultrasonography
Doctors suspect the diagnosis of calcium pyrophosphate arthritis in older people with arthritis, particularly when joints are swollen, warm, and painful. Doctors confirm the diagnosis by removing a fluid sample from an inflamed joint through a needle (joint aspiration Joint aspiration (arthrocentesis) A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more ). Calcium pyrophosphate dihydrate crystals are found in the joint fluid. They can be distinguished from uric acid crystals (which cause gout) using a special microscope with polarized light.
X-rays X-rays A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more are done when doctors cannot obtain fluid from the joint. Seeing masses of crystals in a joint's cartilage suggests the diagnosis. Ultrasonography Ultrasonography A doctor can often diagnose a musculoskeletal disorder based on the history and the results of a physical examination. Laboratory tests, imaging tests, or other diagnostic procedures are sometimes... read more of the joint may show crystals in joint cartilage and strongly suggests the diagnosis of calcium pyrophosphate arthritis.
Prognosis of Calcium Pyrophosphate Arthritis
Often, the inflamed joints heal without any residual problems. However, in some people, chronic arthritis and permanent joint damage can occur, with some joints so severely destroyed that they can be confused with neurogenic arthropathy Neurogenic Arthropathy Neurogenic arthropathy is caused by progressive joint destruction, often very rapid, that develops because people cannot sense pain, continually injure joints, and thus are not aware of the... read more (Charcot joints).
Treatment of Calcium Pyrophosphate Arthritis
Drainage of joint fluid and injection of a corticosteroid
Nonsteroidal anti-inflammatory drugs
Colchicine to help prevent attacks
Usually, treatment can stop acute attacks and prevent new attacks but cannot reverse changes in already damaged joints. Excess joint fluid can be drained and a corticosteroid suspension can be injected into the joint to rapidly reduce the inflammation and pain.
Drugs taken by mouth help treat calcium pyrophosphate arthritis. Most often, nonsteroidal anti-inflammatory drugs Nonsteroidal Anti-Inflammatory Drugs Pain relievers (analgesics) are the main drugs used to treat pain. Doctors choose a pain reliever based on the type and duration of pain and on the drug's likely benefits and risks. Most pain... read more (NSAIDs) are used to promptly stop the pain and inflammation of acute attacks.
Unlike for gout, no specific effective long-term treatment of calcium pyrophosphate arthritis is available. However, physical therapy (such as muscle-strengthening and range-of-motion exercises) may be helpful to maintain joint function.