Basic Sciences 2023, Jan, 25 | 12:00 am

Pseudogout

  • Pseudogout 

    • Deposition of calcium pyrophosphate dehydrate (CPPD) crystals in joints

    • Associated with lupus, renal dialysis, hemochromatosis,

      hyperparathyroidism, RA, Wilson disease

    • Chondrocalcinosis

    • Calcification within hyaline or fibrocartilage or menisci

    • Seen in pseudogout but also in other conditions

    • Genetic version: ANKH gene mutation

    • Increases extracellular pyrophosphate

    • Synovial fluid findings

    • Radiographic findings: fine linear calcification in hyaline cartilage and more diffuse calcification of menisci and other fibrocartilage (triangular fibrocartilage complex, acetabular labrum)

    • Treatment with NSAIDs and, potentially, steroid injection

  • Calcium hydroxyapatite crystal deposition disease

    • Apatite is primary crystal of normal bone.

    • Accumulates abnormally in areas of tissue damage or in hypercalcemic or hyperparathyroid states (chronic kidney disease [CKD])

    • Associated with

      • Acute attacks of bursitis/synovitis

      • Severe degenerative joint disease

      • Calcific tendinitis of rotator cuff and hip abductors

    • Destructive arthropathy can occur in the knee and shoulder.

      • Milwaukee shoulder: calcium phosphate deposition with cuff tear arthropathy

  • Calcium oxalate deposition

    • Primary oxalosis—rare genetic defect of liver enzymes

      • Alanine glyoxylate aminotransferase (AGT)

      • Glyoxylate reductase (GR)

    • Nephrocalcinosis, renal failure, and death by age 20 years

    • Treatment: liver/kidney transplantation

    • Secondary oxalosis—more common

      • Metabolic abnormalities of chronic renal insufficiency

      • Associated with calcium oxalate arthritis/periarthritis and nephrolithiasis

    • Diagnosis: synovial fluid usually contains fewer than 2000 WBCs/µL.

  • Hemophilic arthropathy ( Fig. 1.39)

    • X-linked recessive defect of factor VIII (A) or IX (B); discussed further in Chapter 3, Pediatric Orthopaedics

    • Decreased ROM and eventually ankylosis

    • Pathophysiology

      • Recurrent bleeds and chronic synovitis

      • Synovial hypertrophy/hyperplasia

      • Iron-laden phagocytic type A synovial cells

      • Synovium destroys cartilage

    • Radiographic findings

      • Flat condylar surface and widened notch in knee

      • Inferior patellar squaring

      • Talar flattening in ankle

    • Treatment

      • Early: prevention of bleeds/factor replacement

      • Radiation ablation of synovium with yttrium (Y) 90 microspheres and phosphorus (P) 32 colloid

      • Late: arthroplasty

         

         

         

        FIG. 1.38 Synovial fluid crystals. (A) Gout: yellow uric acid parallel to compensator, most common in first metatarsophalangeal joint. (B) Calcium pyrophosphate (dihydrate crystal) deposition disease (CPDD) or pseudogout crystals: blue rhomboid crystals (arrow) most common in knees and wrists.

        (C) Calcium oxalate crystals (arrow) are pyramidal and almost exclusively seen in patients with renal damage and oxalosis. (D) Platelike cholesterol crystals are rare and can be found in inflammatory synovial fluid and in fluids drained from bursas of patients with rheumatoid arthritis, systemic lupus erythematosus, and seronegative spondyloarthropathy. (E) Calcium apatite crystals from tumoral calcinosis on histology slide from tissue.

        From McPherson RA, Pincus MR, editors: Henry’s clinical diagnosis and management by laboratory methods, ed 21, Philadelphia, 2007, Saunders Elsevier; Firestein GS et al, editors: Kelley’s textbook of rheumatology, ed 8, Philadelphia, 2008, Saunders; Courtney P, Doherty M: Joint aspiration and injection and synovial fluid analysis, Best Pract Res Clin Rheumatol 23:161–192, 2013; Martínez-Castillo A et al: Synovial fluid analysis, Rheumatol Clin 6:316–321, 2010; and Topaz O et al: A deleterious mutation in SAMD9 causes normophosphatemic familial tumoral calcinosis, Am J Hum Genet 79:759–764, 2006.