Calcium Pyrophosphate (CPP) Arthritis

The reason that CPP dihydrate crystals form in some people is unknown. The crystals often occur in people who have the following:

However, many people with CPP arthritis have none of these conditions. The disorder rarely can be hereditary.

Calcium crystals can 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. However, calcium deposits in a joint may not cause symptoms.

Symptoms of CPP 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 .

Compared to gout flares, attacks from CPP arthritis vary more in intensity, tend to last longer, and are often more difficult to treat. As in gout, CPP arthritis attacks 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 CPP arthritis rarely develop hard lumps of crystals (tophi).

Doctors suspect CPP arthritis in older people with arthritis, particularly when joints are intermittently 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 ). CPP 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 may show 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 CPP arthritis.

Often, the inflamed joints heal without any residual problems. However, in some people, chronic arthritis and permanent joint damage can occur over time, 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).

Unlike gout, chronic CPP arthritis is difficult to treat because there is no therapy that effectively eliminates or reduces the amount of CPP dihydrate crystals. People who have frequent flares, especially younger people, are often evaluated for underlying diseases Causes .

Treatment of acute CPP arthritis is similar to that for acute gout Treatment Gout is a disorder in which deposits of uric acid crystals accumulate in the joints because of high blood levels of uric acid (hyperuricemia). The accumulations of crystals cause flares (attacks)... read more . 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 can be injected into the joint to rapidly reduce the inflammation and pain.

Medications taken by mouth help treat CPP 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.

Colchicine (see table ) can be given by mouth in daily low doses (usually 1 or 2 pills) to try to limit the number of flares.

Corticosteroids taken by mouth are effective at treating acute CPP arthritis flares and are particularly useful for some people who should not take NSAIDs or colchicine.

If people cannot tolerate corticosteroids, NSAIDs, or colchicine, drugs that suppress the immune system and inflammation (such as anakinra daily injections) can be effective.

Unlike for gout, no specific effective long-term treatment of CPP arthritis is available. However, physical therapy (such as muscle-strengthening and range-of-motion exercises) may be helpful to maintain joint function.