Diagnostics and gold standard
Pseudogout can be suspected as early as the imaging stage. Radiographs visualize chondrocalcinosis, which is specific calcification of cartilaginous structures.
Typical sites of deposition:
- Menisci of the knee joint.
- Triangular fibrocartilage complex of the wrist.
- Acetabular labrum of the hip joint.
- Annulus fibrosus of the intervertebral discs.
However, the gold standard for diagnosis is arthrocentesis (joint aspiration) with mandatory synovial fluid analysis. The obtained aspirate must be sent for leukocyte count with differential, crystal analysis, Gram staining, and bacterial culture.
Synovial fluid analysis: how to distinguish from gout
In inflammatory arthritides (which include gout and pseudogout), synovial fluid becomes turbid, and its leukocyte count increases. Meanwhile, Gram staining and culture remain negative (unlike infectious processes).
A key step is polarized light microscopy:
- Pseudogout: calcium pyrophosphate crystals (CPPD) are detected. They have a characteristic rhomboid shape and demonstrate weak positive birefringence.
- Gout: monosodium urate crystals are identified. They are needle-shaped and show negative birefringence (appearing yellow when aligned parallel to the polarization axis and red when perpendicular).
Epidemiology and risk factors
Pseudogout is predominantly a disease of older age groups. In young patients, it rarely acts as a primary isolated pathology without concomitant systemic disorders.
Calcium pyrophosphate dihydrate crystal deposition is often associated with the following conditions:
- Hemochromatosis and Wilson's disease.
- Hyperparathyroidism.
- Systemic lupus erythematosus (SLE) and rheumatoid arthritis.
- True gout.
- Hemophilia.
- Long-term dialysis.
Interestingly, asymptomatic chondrocalcinosis is an incidental finding in approximately 7% of the general population.
Differential diagnosis
A pseudogout attack must be differentiated from several other diseases affecting joints and periarticular tissues:
- Septic arthritis: clinically very similar to crystalline arthropathies. Synovial fluid is turbid or purulent, leukocytes exceed 50,000/mm³, culture is positive. Important: the finding of pyrophosphate or urate crystals does not rule out concurrent septic arthritis.
- Osteoarthritis: may have a similar clinical picture and frequently occurs concomitantly with pseudogout. Requires careful history taking, examination, and radiography.
- Cellulitis: skin infection with superficial erythema and edema that may extend beyond the joint (proximally or distally).
- Bursitis: presents with local swelling and pastosity directly over the affected joint.
- Intra-articular fractures: reliably ruled out using radiography.
Principles of treatment
Pseudogout management largely overlaps with gout treatment and is divided into acute attack management and chronic control.
Acute attack management: Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids are the mainstay.
- NSAIDs (e.g., indomethacin, naproxen, sulindac) inhibit crystal phagocytosis and reduce the inflammatory response.
- Intra-articular corticosteroid injections provide rapid relief. However, they are strictly contraindicated if septic arthritis is suspected and require caution in patients with diabetes mellitus (due to the risk of hyperglycemia).
Chronic form control: Colchicine is used to prevent relapses. This drug suppresses the acute inflammatory response by inhibiting inflammatory mediators and reducing neutrophil motility. Colchicine is most effective if taken within the first 24 hours of symptom onset.
Briefly: answers to topical questions
What radiographic features, aside from chondrocalcinosis, are characteristic of chronic pyrophosphate arthropathy?
In addition to chondrocalcinosis, pyrophosphate arthropathy is characterized by joint space narrowing, bone remodeling, and ligamentous dysfunction.
The main radiological signs include:
- Joint space narrowing — characteristic of the patellofemoral joint.
- Bone remodeling — observed in the distal metaphysis of the femur.
- Crystal deposition — occurs in the synovial membrane.
- Ligamentous dysfunction — leads to scapholunate (scapholunate) and triquetrolunate (triquetrolunate) diastasis.
Erosions of articular surfaces are not a characteristic feature of this disease.
What are the absolute and relative contraindications to intra-articular corticosteroid injections?
An absolute contraindication to intra-articular corticosteroid administration is septic arthritis.
Glucocorticoids are used with caution or under certain limitations:
- in uncontrolled type 2 diabetes mellitus — due to the risk of hyperglycemia;
- in the presence of high blood pressure readings — due to the risk of elevation.
Course administration should be avoided; injections should be performed no more often than once every 3 months. Secondary osteonecrosis and exacerbation of articular cartilage degradation are possible.
To avoid confusing the optical properties of crystals on microscopy: Pseudogout — Positive birefringence (weak), Gout — Negative.
Class and exam questions
Can infectious arthritis be ruled out if crystals are found in the punctate?
No. The presence of crystals in synovial fluid does not rule out concomitant septic arthritis. A cell count, Gram stain, and culture are always needed to rule out infection.
Which structures are most commonly calcified in pseudogout?
Typical locations: menisci of the knee joint, triangular fibrocartilage complex of the wrist, acetabular labrum of the hip joint, and intervertebral discs.
At what age does pseudogout most frequently manifest?
The disease is typical for elderly patients. In young individuals, it is rare and usually associated with severe underlying conditions (hemochromatosis, hyperparathyroidism).
What else to study on this topic
- Detailed algorithm for knee joint arthrocentesis
- Differential diagnosis of synovial fluid in various arthritides
- Pathogenesis of calcium pyrophosphate crystal formation
- Association of microcrystalline arthropathies with hemochromatosis and hyperparathyroidism
- Peculiarities of basic urate-lowering therapy (allopurinol, febuxostat) in classical gout
Master the entire topic in the "Traumatology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete guideline on the topic "Pseudogout" and 812 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 35 video lessons on the subject
Other Topics in "Orthopedics"
Entire "Orthopedics" SectionPrepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.