Calcium pyrophosphate dehydrate (CPPD) deposition, also known as acute CPP crystal arthritis, chondrocalcinosis, pyrophosphate arthropathy, or pseudogout, is a metabolic, inflammatory joint disease. It is characterized by the periarticular deposition of CPP crystals, typically occurring in the triangular fibrocartilage (TFCC) and hyaline cartilage and most commonly affecting the knees, wrists, and/or shoulders. Pseudogout demonstrates various clinical manifestations, ranging from an asymptomatic state to destructive arthropathy, in which arthritic attacks can last up to several weeks and cause a variety of painful symptoms in the wrist (eg, swelling, tenderness, stiffness, or joint effusion). Treatment is typically conservative and used to reduce the severity of symptoms during attacks, primarily consisting of non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections, joint aspiration, and/or splinting. Surgical intervention may be recommended if conservative efforts fail, and options depend on the specific location of the disease and degree ogf joint destruction.1-4,9,10
Pathophysiology
- Pseudogout may occur sporadically or be inherited in an autosomal dominant fashion with a variable penetrance5
- Patients with pseudogout have an increased production of inorganic pyrophosphate and decreased levels of pyrophosphatases in the cartilage, and crystals form as pyrophosphate combines with calcium.3. Crystals first appear in the synovial fluid, and are then deposited in the synovial membrane, the wrist ligaments and fibrocartilaginous structures, and then in the articular cartilage. Calcium pyrophosphate crystals localize in and around joints, and crystal deposition at the wrist can cause pseudotumours that bulge into the carpal canal
- The classic feature that is most specific for pseudogout is calcification of the triangular fibrocartilage complex (TFCC) with calcification in 73% of the wrist X-rays in one study.9
- Isolated scapho-trapezio-trapezoidal (STT) joint disease is also specific to pseudogout, and the scapholunate (SL) joint is the next most frequently involved joint, followed by the distal radioulnar joint (DRUJ), then the lunotriquetral (LT), isolated midcarpal, radiolunate, and pisotriquetral joints5
- Pseudogout has also been found to affect the metacarpophalangeal and interphalangeal joints1
- When pseudogout spontaneously causes pain and swelling of the wrist or thumb, it is often due to an acute inflammatory episode that may be mistaken for a joint infection or an attack of gout; these attacks may be precipitated by recent trauma, surgery, or a rapid decrease in serum calcium, which can cause CPPD deposits to infiltrate and weaken ligaments and cartilage3,5
- Risk factors for pseudogout include advanced age, osteoarthritis, rheumatoid arthritis, previous joint injury, metabolic disease, hyperparathyroidism, and familial predisposition1,4
- Tumoral pseudogout appears to contain CPPD crystals that form a tumor-like mass in an extra-articular location, and the mechanism of this development is not well known1
Related Anatomy
- TFCC
- STT joint
- SL joint
- DRUJ
- LT joint
- Midcarpal joint
- Radiocarpal joint
- Radiolunate joint
- Pisotriquetral joint
- Carpal tunnel
Incidence
- The incidence of pseudogout in the US is 275 cases per 100,000 people, which is roughly half the incidence of gout6,7
- Pseudogout most commonly develops between ages 50-70, and its male-to-female ratio is 1.5:17,8
- Carpal tunnel syndrome (CTS) is the initial presentation in 14% of pseudogout cases, and both wrists are affected in 66% of patients5
Related Conditions
- Symmetric synovitis
- Carpal tunnel syndrome
- Hyperparathyroidism
- Gout
- Rheumatoid arthritis
- Osteoarthritis
- Hemochromatosis
- Systemic lupus erythematosus
- Wilson's disease
- Hemophilia
Differential Diagnosis
- Gout
- Rheumatoid arthritis
- Osteoarthritis
- Osteoarthritis with pseudogout (pseudo-osteoarthritis)
- Cellulitis nephrolithiasis
- Septic arthritis
- Hungry bone disease
- Charcot neuroarthropathy
- Seronegative arthritis
- Cellulitis
- Hyperparathyroidism
- Hypothyroidism
- Hydroxyapatite deposition disease
- Ochronosis
- Acromegaly
- Paget's disease
- Hypomagnesemia