Overview of the disease
Due to pyrophosphatase deficiency, calcium pyrophosphate dihydrate crystal deposition in tendons, ligaments, joint capsules, synovial membranes and cartilage caused by a disease, clinically, the elderly women are more common, male: female 1:2-3, manifested as acute, subacute or chronic arthritis and other symptoms. Symptoms. Calcium pyrophosphate dihydrate crystalline deposits (CPPD) have been found for more than 30 years. Before CPPD crystals were confirmed, it was often called “gout”; after that, it was also called “pseudogout”, and because of the calcification of the articular cartilage on X-ray, it was also called “chondrocalcinosis”. Chondrocalcinosis” is also known as “chondrocalcinosis” because of the calcification of articular cartilage on X-ray. However, this disease may not show cartilage calcification, so it is now generally called “pyrophosphate arthropathy”.
Causes
1. Hereditary
2. Sporadic (idiopathic)
3.Associated with metabolic diseases
Hyperparathyroidism, familial hypocalcemic hypercalcemia, hemochromatosis, ferrous hemoflavin deposition, hypothyroidism, gout, hypokalemia, hypophosphatemia, amyloidosis.
4. Associated with joint trauma and surgery
Symptoms
1. Pseudogout
(1) Different joint parts This disease is most common in large joints. The knee joint is the most common, accounting for about half of the affected parts. It is followed by shoulder, elbow, wrist, ankle, and other synovial joints including the first metatarsophalangeal joint. True gout, on the other hand, most often involves the first metatarsophalangeal joint, and the involvement of large joints is uncommon.
(2) The nature of the pain is different. In true gout, the pain is obvious when there is inflammation. In true gout, the pain is obvious during inflammation, while in this disease, the pain is mild. Although joint swelling is obvious, the pain can be relieved immediately after aspiration of joint fluid.
(3) Inflammatory process is different True gout response to triggering factors (trauma, mercury diuretics, etc.) the incubation time is longer, it takes a few days to appear red and swollen reaction. If there is a gout stone, it may break out. In contrast, the disease takes less time to respond to triggers, with an inflammatory response occurring in a few hours. Joint swelling is obvious, but the pain is not dramatic, the inflammatory process is shorter, never ulcerated.
2. Pseudorheumatoid arthritis
Pseudorheumatoid arthritis accounts for 5% of CPPD patients and shows symmetrical multiple joint involvement. Although the symptoms are mild, they last for a longer period of time and are characterized by morning stiffness, fatigue, synovial thickening, flexion contracture, and increased blood sedimentation. About 10% of the patients are positive for IgM rheumatoid factor, and about 1% of the patients are very similar to rheumatoid arthritis, which often leads to misdiagnosis.
3. Pseudo-osteoarthritis
Pseudoarthritis is characterized by progressive polyarticular degeneration. Knee joints are most commonly affected, followed by wrist joints, metacarpophalangeal joints, hip joints, shoulder joints, elbow joints and ankle joints. Although there is cross-over with the type of joint involvement in primary osteoarthritis (e.g., knee, hip), the arthritic nature of CPPD is different, with the distal and proximal interphalangeal joints showing Heberden’s nodes and Bouchard’s nodes, and the first carpometacarpal joints less frequently involved. The joints involved in CPPD often develop flexion contractures, and the knee joint is often valgus.
4. Pseudoneurotrophic joints
Pyrophosphate arthropathy may manifest as severe destructive arthropathy, but neurologic examination, mostly in the normal range. It is estimated that about 5% of CPPD patients develop spondyloarthropathic neurotrophic arthropathy.
5. Asymptomatic
CPP crystals are deposited on X-ray and joints show CPP calcification without clinical symptoms. Asymptomatic cases account for 20% of all cases.
Examination
1. Blood calcium and phosphorus are normal, alkaline phosphatase is normal.
2. Joint fluid is exudate, containing CPP crystals, which are inside leukocytes in acute inflammation; in the late stage of acute inflammation, both inside and outside the cells; in the chronic inflammation stage, outside the leukocytes, the crystals are in the form of rods or rhombuses, and the staining of alizarinreds shows a weakly positive doubly refractile crystals. The leukocyte count is increased and is predominantly neutrophilic. Synovial fluid should be stained and cultured for bacteria to exclude infectious inflammation. Sometimes the joint fluid is bloody, which cannot be regarded as simple traumatic joint effusion, and there is still a possibility of CPPD.
3. Pyrophosphate arthropathy is often associated with certain metabolic disorders, so routine tests should include: serum magnesium, serum iron, ferritin and iron binding capacity, as well as uric acid and thyroid function (TSH, T3, T4) measurements. If there is any abnormality, further examination should be done.
4. Typical X-ray findings are dots and lines of radiodense shadows on the articular fibrocartilage or hyaline cartilage tissue. When the shadow is typical and clear, it has diagnostic value. However, when the changes are not obvious or atypical, further detailed X-rays should be taken in thin areas (e.g., hands) and spot films should be taken in hypertrophic areas (e.g., knees). If X-rays show early calcification deposits in the articular cartilage, further anteroposterior X-rays of the knees, hips, and pubic symphysis, and posterior-anterior films of both hands should be taken; if no crystalline deposits are found, chondrocalcinosis is unlikely. On the contrary, CPP crystals may be detected in the joint fluid of joints with negative X-ray findings, especially in those with extensive joint stenosis.
5. Calcified deposits may also occur in the joint capsule, ligaments, and tendons. Deposits in the synovium can be so large that they can be mistaken for chondromatosis. This kind of deposition, and can be manifested as tumor-like growth, there have been reports of tumor-like calcium pyrophosphate deposits in the finger.
Diagnosis
Based on the manifestations of gout and arthritis, combined with X-ray examination, the diagnosis can be made.
1. Clinical manifestations similar to gout, rheumatoid arthritis, osteoarthritis, neurotrophic arthropathy.
2. Imaging examination shows point-like and line-like radiodensity shadows on the articular fibrocartilage or hyaline cartilage tissue. If X-ray shows early calcification deposits in the articular cartilage, further anteroposterior X-ray of both knees, hips and pubic symphysis, and posterior-anterior films of both hands can be made, and if there is no crystal deposition found, chondrocalcinosis is unlikely. On the contrary, CPP crystals may be detected in the joint fluid of joints with negative X-ray findings, especially in those with extensive joint stenosis.
Treatment
It is not currently possible to remove CPP deposits from cartilage and the joint capsule. CPP crystals that have been deposited are not reabsorbed in response to treatment-related metabolic disturbances. On the contrary, certain treatments may interfere with calcium homeostasis and contribute to an acute joint attack, such as pseudogout when parathyroidectomy or other treatments result in a rapid decrease in blood calcium concentration. Low thyroid function, treated with thyroid hormone replacement, may also precipitate an attack.
During an acute attack, symptomatic management can be provided. Non-steroidal anti-inflammatory agents applied alone or in combination with intra-articular injections of corticosteroids, or aspiration of joint fluid to relieve intra-articular pressure can lead to a rapid reduction in inflammation. Intravenous colchicine is also useful for pseudogout, but oral administration is not as effective as for gout. For patients with chronic recurrent attacks, oral administration of small doses of colchicine can significantly reduce the attack profile and attack duration.
During the chronic interval, triggers such as trauma, surgery, strong twisting and prolonged walking should be avoided. Because all of these actions or events can cause cartilage friction, drainage of microcrystals and cause an acute attack of arthritis.