= CPPD = PSEUDOGOUT = FAMILIAL CHONDROCALCINOSIS

= metabolic arthropathy characterized by deposition of calcium pyrophosphate dihydrate crystals in articular + periarticular tissues

• Most common crystalline arthropathy

Chondrocalcinosis = term for intra-articular calcifications with involvement of hyaline articular cartilage and fibrocartilage

Types:

1. Osteoarthritic form (35–60%)
2. Pseudogout = acute synovitis (10–20%) mimicking gout attack
3. Rheumatoid form (2–6%)
4. Pseudoneuropathic arthropathy (2%)
5. Asymptomatic with tophaceous pseudogout (common)

Associated with: hyperparathyroidism, hypothyroidism, hemochromatosis, hypomagnesemia

Prevalence: widespread in older population; increasing with age; M÷F = 3÷2

• calcium pyrophosphate crystals in synovial fluid + within leukocytes (characteristic weakly positive birefringent rhomboid foci)
• acute / subacute / chronic joint inflammation

• polyarticular chondrocalcinosis (in fibro- and hyaline cartilage)
• large subchondral cyst (HALLMARK)
• numerous intraarticular bodies (fragmentation of subchondral bone)
• coalescing CPPD crystals → tophus-like deposits (rare) → significant articular destruction

Site: involvement of tendons, bursae, pinnae of the ear

• painful mass

• joint space narrowing + extensive subchondral sclerosis
  • CPPD arthropathy resembles osteoarthritis!

• Hand
  • Distribution: 1 CMC; 2^nd + 3^rd MCP joints; bilateral symmetric
  • resembling degenerative joint disease (without DIP and PIP involvement)
  • small hook-like osteophytes at radial aspect of metacarpal heads 2 & 3
• Wrist
  Distribution: triangular fibrocartilage in distal radioulnar joints bilaterally, proximal carpal row joints at lunotriquetral + scapholunate ligaments
  • calcification (chondrocalcinosis) of triangular fibrocartilage
  • extensive narrowing / obliteration of joint space between distal radius + scaphoid → destruction of trapezioscaphoid space:
    • incorporation of scaphoid into articular surface of radius
    • prominent cysts
  • scapholunate separation (= ligament tear) → scapholunate advanced collapse (SLAC
• Knee
  Distribution: especially meniscus + cartilage of patellofemoral joint
  • medial femorotibial + patellofemoral compartments commonly involved simultaneously (as in osteoarthritis) but with greater osseous destruction + fragmentation
  • disproportionate narrowing of patellofemoral joint
• Spine
  • chondrocalcinosis / calcifications of outer fibers of annulus fibrosus of lumbar spine resembling syndesmophytes; NEVER in nucleus pulposus
    DDx: ochronosis (in nucleus pulposus)
  • vertical radiodense line in symphysis pubis
  
  Other locations:
  • pelvis (sacroiliac joint, symphysis)
  • shoulder (glenoid), hip (labrum), elbow, ankle, acromioclavicular joint