Calcium pyrophosphate dihydrate crystal deposition disease

Introduction to calcium dicalcium pyrophosphate crystal deposition Calcium pyrophosphatedihydratedepositiondiseaes (CPPD) has been found for more than 30 years. It is often called "gout" before CPPD crystallization is confirmed; it is also called "pseudogout", and because of its Articular cartilage calcification is present on the X-ray, so it is also called chondrocalcinosi. However, this disease can be free of cartilage calcification, so it is currently called "pyrophosphatearthropathy". basic knowledge The proportion of illness: 0.0025% Susceptible people: no special people Mode of infection: non-infectious complication:

Causes of calcium dicalcium pyrophosphate crystal deposition

Metabolic disorders (30%):

In 1988, McCarty divided it into several types, indicating that the disease is related to many factors, hereditary, non-hereditary; related to metabolic disorders, and also related to joint trauma, according to relevant statistics, 80% The above patients were over 60 years old; 70% of patients had a history of joint damage; young (<50 years old) patients were mostly associated with metabolic disorders.

Parathyroid muscle hyperthyroidism (25%):

Familial hypocalciuria hypercalcemia, hemochromatosis, hemosiderin deposition, hypothyroidism, gout, hypocalcemia, hypophosphatemia, amyloidosis, mechanism of CPPD crystal deposition are unknown, most believe It is associated with a decrease in local non-destructive inorganic pyrophosphate (PPi) and a decrease in the inhibition of PPi deposition by cartilage glycoprotein. Under normal conditions, nucleoside triphosphate (NTP) is decomposed into a single phosphate core by nucleoside triphosphate pyrophosphate hydrolase (NTP). Glycoside (NMP) and PPi, and then PPi is decomposed into inorganic phosphoric acid (Pi) by inorganic pyrophosphatase (PPiase).

Tissue damage (25%):

If the activity of nucleoside triphosphate pyrophosphate hydrolase is increased, the activity of inorganic pyrophosphatase is decreased, and the inhibition of local tissue deposition is weakened, which can cause the deposition of inorganic pyrophosphoric acid, which is said to increase with age or tissue damage. The inhibition of sedimentation will gradually weaken, so CPPD deposition occurs mostly in the elderly and increases with age; it is also seen in the tissue injury site, so the incidence of knee joint is high, and metabolic disorders also change the physical and chemical properties of local tissues. Conducive to the deposition of CPPD crystals, such as iron ions in hemochromatosis, on the one hand directly change the performance of cartilage, on the other hand inhibit inorganic pyrophosphatase, thereby enhancing the deposition of CPPD, these hypotheses, can explain the mechanism of CPPD deposition, currently It is not clear, but recently it has been proved that patients with CPPD deposition have higher ATP concentration in joint fluid than other arthritis concentrations. ATP can be hydrolyzed by NTPPase to AMP and PPi; others have proved that pyrophosphatase is soluble in calcium phosphate. The lysis is stimulated by Mg++ and inhibited by Ca++. Fam also proves that the ATP level of the joint fluid is higher than that of other CPPD patients. Joint inflammation was high, and is related to the concentration of PPi.

Prevention of calcium dicalcium phosphate crystal deposition

There is no special prevention method for this disease, and physical exercise should be strengthened to increase self-immunity.

Complications of calcium dicalcium phosphate crystal deposition Complication

Pain

2. Joint deformity: common types of common types of joint deformities, as follows:

(1) Button fancy joint deformity: proximal interphalangeal joint flexion, distal knuckle overextension.

(2) Telescope malformation: due to the large absorption of the metacarpal bone end, the fingers are obviously shortened, the finger skin has obvious organ-like wrinkles, the finger joints are slack and unstable, and there is abnormal lateral activity. The affected finger can be stretched or shortened, like a telescope.

(3) clubbing deformity: refers to the incomplete extension of the flexor tendon, which causes the tendon to prolong and form the flexion deformity of the distal interphalangeal joint.

(4) "goose neck" deformity: metacarpophalangeal joint flexion, proximal interphalangeal joint overextension, distal interphalangeal joint flexion, looks like a goose's neck from the side.

Symptoms of calcium pyrophosphate crystal deposition syndrome Common symptoms Calcification Diuretic heat pain Synovial thickening Joint swelling Morning zombie nodules

CPPD crystallized in tendons, ligaments, joint capsules, synovium and articular cartilage, mostly in asymptomatic quiescent state, but "active" can be acute or chronic degenerative pathological changes, inflammation and degeneration, can appear in turn, or overlap Existence, the clinical symptoms are manifested in diversity, acute, subacute, chronic or intermittent seizures, making clinical symptoms similar to other various joint diseases, making diagnosis difficult.

Pseudo gout

About one-fourth of patients with pyrophosphate arthritis have pseudogout symptoms, and there are more male patients. Joint inflammation often occurs with single or multiple joints, showing joint swelling and pain, lasting for several days, and self-relieving. During the remission period, there is no symptom, the whole inflammatory process is like gout, but unlike true gout,

1 joint parts of the disease is most common in large joints, the most common knee joint, accounting for about half of the affected part, followed by shoulders, elbows, wrists, ankles, and other synovial joints including the first metatarsophalangeal joint, and True gout, most often involving the first metatarsophalangeal joint, large joint involvement is not common,

2 The nature of pain is different from true gout. The pain is obvious during inflammation, but the pain is mild or "small" pain. Although the joint swelling is obvious, the pain can be relieved immediately after aspiration of joint fluid.

3 inflammatory process different true gout response to the induced factors (trauma, mercury diuretics, etc.) latency is longer, it takes several days to appear redness and swelling reaction, if there is tophi, can break out, and the disease takes time to induce the cause Shorter, an inflammatory reaction can occur in a few hours, joint swelling is obvious, but the pain is not dramatic, the inflammatory process is short, and no ulceration occurs.

2. pseudo rheumatoid arthritis

This type accounts for about 5% of patients with CPPD. It is characterized by symmetry and multiple joint involvement. Although the symptoms are mild, the duration is longer. After a few winds and rains or months, it is characterized by morning stiffness, fatigue, and thickening of the synovial membrane. Flexion contracture, increased erythrocyte sedimentation rate, etc., about 10% of patients with IgM rheumatoid factor positive, about 1% of patients very similar to rheumatoid arthritis, often lead to misdiagnosis.

3. Pseudo osteoarthritis

This type of progressive multi-articular changes, the knee is most often involved, followed by the wrist, metacarpophalangeal joint, hip joint, shoulder joint, elbow joint and ankle joint, although this performance and primary osteoarthritis The types of joint involvement (such as knees and hips) have overlapping overlaps, but the arthritis of the cochlear acid joint disease is different. The distal, proximal interphalangeal joints show Heberden nodules and Bouchard nodules and the first carpometacarpal joint. Less involved, the jointability of CPPD develops symmetrically, but some joints, especially joints with severe lesions or fractures, have more severe degeneration, and flexion contracture often occurs in CPPD-affected joints, and knee joints often have valgus deformity.

4. Pseudo-neurotrophic joints

Pyrophosphate arthropathy can be characterized as severe destructive joint disease, but most of the neurological examinations are in the normal range, but there are reports of mild spinal cord spasm associated with knee joints and complex CPP crystal deposition. About 5% of patients with CPPD occur in spastic neurotrophic joint disease of the spinal cord.

5. Asymptomatic CPP crystal deposition

On the X-ray, the joints showed CPP calcification, but no clinical symptoms, and asymptomatic cases accounted for 20% of the total cases.

6. Other

In some patients, especially those with a family history, the spine becomes straight and hard, similar to ankylosing spondylitis. It has been reported that the joint is really skeletal, and some patients have misunderstood due to the transient acute arthritis. "Rheumatism", some episodes are mild, and are considered "psychotic symptoms" and so on.

Examination of crystal precipitation of calcium pyrophosphate dihydrate

Blood calcium, normal phosphorus, and alkaline phosphatase are normal.

The joint fluid is an exudate containing CPP crystals. This crystal is in the white blood cells during the acute inflammatory phase; in the late stage of acute inflammation, both inside and outside the cells; in the chronic inflammatory phase, outside the white blood cells, the crystals are rod-shaped or rhomboid. Alizrin red s staining is weakly positive double-refractive crystal, the number of white blood cells is increased, from thousands of cells to 100,000 cells per cubic millimeter. It is mainly neutrophil, and the synovial fluid should be stained and cultured by bacteria. In addition to infectious inflammation, sometimes the joint fluid is bloody, can not be considered as simple traumatic joint hemorrhage (hemarthrosis), there is still the possibility of CPPD.

Because pyrophosphate arthropathy is often associated with certain metabolic disorders, routine tests should include: blood magnesium, serum iron, ferritin and iron binding, and uric acid and thyroid function (TSH, T3, T4), if abnormal Should be further checked.

X-ray findings: typical X-ray findings are a bit of a linear and linear radiographic density shadow on articular fibrocartilage or hyaline cartilage. The shadow is typical and clear, and has diagnostic value, but when the change is not obvious or atypical, Further detailed X photos in thin parts (such as hands), and spot examination in hypertrophic parts (such as knee joints), such as X-ray showing early calcification deposition of articular cartilage, can further be used for bilateral knee, hip and pubic symphysis The X-slice, the posterior anterior slice of the hands, if there is no crystal deposition, the possibility of cartilage calcification is not great. On the contrary, the joints with negative X-ray findings may have CPP crystals in the joint fluid, especially the extensive joint cavity. The difference between stenosis and gouty arthritis: gout is mainly characterized by small lesions on the articular surface and bone end, which is different from the calcification of articular cartilage in this disease. When pseudo-neurotrophic joint disease occurs in Charcot's joint disease, only The X-ray performance of the potential pressure can not be identified, but the "truth" Charcot's joint has no pain, and the disease has pain.

Calcification deposits can also occur in joint capsules, ligaments and tendons. The deposition of synovial membrane can be very large, which can be mistaken for chondromatosis. This deposition can be expressed as tumor-like growth. There is a tumor-like pyrophosphate in the country. The report of depression.

Diagnosis and differential diagnosis of calcium dicalcium pyrophosphate crystal deposition

diagnosis

Acute false gout

More common in the elderly, often secondary to metabolic or endocrine diseases, such as diabetes, hyperparathyroidism, brown yellow disease, acromegaly and hypophosphatemia, seizures similar to gout, acute onset, 12 to 36 hours of climax, usually monoarthritis or a small number of arthritis, most often involving the knee joint, followed by sputum, wrist, elbow and hip joints, affected joints, swelling, heat and dysfunction, dysfunction, X-ray examination see affected Calcification of articular cartilage, showing parallel or fine-grained calcified plaques on the surface of the subchondral bone. Synovial crystals can be seen in the synovial fluid. Diamond or brick-like shapes of different sizes are also observed under polarized light microscopy. Double refraction.

2. Chronic false gout

Often secondary to osteoarthrosis, due to the continuous deposition of pyrophosphate in the joint cavity of the degenerative cartilage, X-ray examination showed osteoarthritis lesions and cartilage calcification, the diagnosis was based on synovial fluid to detect pyrophosphate crystals .

Differential diagnosis

The disease should be distinguished from the following diseases:

1. True gout;

2. Rheumatoid arthritis;

3. Primary osteoarthritis;

4. Rheumatic fever;

5. Chondroma disease.

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