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Differential Diagnosis of Musculoskeletal Disorders

Approach to Arthritis!!navigator!!

mnemonic: ABCDE'S

  • Alignment
  • Bone mineralization
  • Cartilage loss
  • Distribution
  • Erosion
  • Soft tissues

Signs of Arthritis!!navigator!!

Prevalence of arthritis: 15% of population in USA

Conventional x-ray:

  • narrowing of radiologic joint space:
    1. uniform = inflammatory arthritis
    2. nonuniform = degenerative arthritis
  • evidence of disease on both sides of joint:
    • osteopenia
    • subchondral sclerosis
    • erosion
    • subchondral cyst formation
    • malalignment
  • joint effusion
  • joint bodies

NUC:

  • increase in regional blood flow (active disease)
  • distribution of disease

MR:

  • bone marrow edema = predictor of erosions
  • Gd-DTPA enhancement of synovium (active disease)
  • radiographically occult extraarticular inflammation = tenosynovitis + enthesitis
  • irregularity + narrowing of articular cartilage

Classification of Arthritides!!navigator!!

  1. SEPTIC ARTHRITIS
    1. Tuberculous
    2. Pyogenic
    3. Lyme arthritis
    4. Fungal arthritis: Candida, Coccidioides immitis, Blastomyces dermatitidis, Histoplasma capsulatum, Sporothrix schenckii, Cryptococcus neoformans, Aspergillus fumigatus

    N.B.: Tuberculous + fungal arthritis show Phemister triad
    1. prominent osteoporosis,
    2. slower rate of destruction, and
    3. less joint narrowing than a pyogenic infection
  2. COLLAGEN / COLLAGEN-LIKE DISEASE
    1. Rheumatoid arthritis
    2. Ankylosing spondylitis
    3. Psoriatic arthritis
    4. Rheumatic fever
    5. Sarcoidosis
  3. BIOCHEMICAL ARTHRITIS
    1. Gout
    2. Chondrocalcinosis
    3. Ochronosis
    4. Hemophilic arthritis
  4. DEGENERATIVE JOINT DISEASE = Osteoarthritis
  5. TRAUMATIC
    1. Secondary osteoarthritis
    2. Neurotrophic arthritis
    3. Pigmented villonodular synovitis
  6. ENTEROPATHIC ARTHROPATHY
    1. INFLAMMATORY BOWEL DISEASE
      1. Ulcerative colitis (in 10–20%)
      2. Crohn disease (in 5%): peripheral arthritis increases with colonic disease
      3. Whipple disease (in 60–90% transient intermittent polyarthritis: sacroiliitis, spondylitis)
      • Resection of diseased bowel is associated with regression of arthritic symptomatology!
    2. INFECTIOUS BOWEL DISEASE
      Infectious agents: Salmonella, Shigella, Yersinia
    3. after intestinal bypass surgery

Spondyloarthritis with Positive HLA-B 27 Histocompatibility Complex

  1. Ankylosing spondylitis 95%
  2. Reiter disease 80%
  3. Arthropathy of inflammatory bowel disease 75%
  4. Psoriatic spondylitis 70%
  5. Normal population 10%

Monoarthritis!!navigator!!

Destructive Monoarthritis

  • Any destructive monoarthritis should be regarded as infection until proved otherwise!
  1. Septic arthritis
  2. Monoarticular presentation of a systemic arthritis
    1. Rheumatoid arthritis
    2. Gout
    3. Amyloidosis
    4. Seronegative arthritis
  3. Joint tumor
    1. PVNS
    2. Synovial chondromatosis
    3. Articular hemangioma

Nonseptic Monoarthritis

  1. Gout
  2. Milwaukee shoulder
  3. Rapidly destructive articular disease
  4. Amyloid arthropathy
  5. Hemophilic arthropathy
  6. Primary synovial osteochondromatosis
  7. Pigmented villonodular synovitis
  8. Neuropathic arthropathy
  9. Foreign-body synovitis

Arthritis without Demineralization!!navigator!!

  1. Gout
  2. Neuropathic arthropathy
  3. Psoriasis
  4. Reiter disease
  5. Pigmented villonodular synovitis
    mnemonic: PONGS
    • Psoriatic arthritis
    • Osteoarthritis
    • Neuropathic joint
    • Gout
    • Sarcoidosis

Arthritis with Demineralization!!navigator!!

mnemonic: HORSE

  • Hemophilia
  • Osteomyelitis
  • Rheumatoid arthritis, Reiter disease
  • Scleroderma
  • Erythematosus, systemic lupus

Deforming Nonerosive Arthropathy!!navigator!!

  1. Collagen-vascular disease, especially SLE
  2. Rheumatoid arthritis (rare)
  3. Rheumatic fever (Jaccoud arthritis) (rare)

Arthritis with Periostitis!!navigator!!

  1. Juvenile rheumatoid arthritis
  2. Psoriatic arthritis
  3. Reiter syndrome
  4. Infectious arthritis

Premature Osteoarthritis!!navigator!!

mnemonic: COME CHAT

  • Calcium pyrophosphate dihydrate arthropathy
  • Ochronosis
  • Marfan syndrome
  • Epiphyseal dysplasia
  • Charcot joint = neuroarthropathy
  • Hemophilic arthropathy
  • Acromegaly
  • Trauma

Synovial Disease with Decreased Signal Intensity!!navigator!!

= blooming” artifact of low SI on gradient-echo pulse sequences ← magnetic susceptibility artifact of hemosiderin

  1. Pigmented villonodular synovitis
  2. Rheumatoid arthritis
  3. Hemophiliac arthropathy
  4. Synovial hemangioma

Chondrocalcinosis!!navigator!!

mnemonic: WHIP A DOG

  • Wilson disease
  • Hemochromatosis, Hemophilia, Hypothyroidism, 1° Hyperparathyroidism (15%), Hypophosphatasia, Familial Hypomagnesemia
  • Idiopathic (aging)
  • Pseudogout (CPPD)
  • Arthritis (rheumatoid, postinfectious, traumatic, degenerative), Amyloidosis, Acromegaly
  • Diabetes mellitus
  • Ochronosis
  • Gout

mnemonic: 3 C's

CrystalsCPPD, sodium urate (gout)
Cationscalcium (any cause of hypercalcemia), copper, iron
Cartilage degenerationosteoarthritis, acromegaly, ochronosis

Subchondral Cyst!!navigator!!

= SYNOVIAL CYST = SUBARTICULAR PSEUDOCYST

= NECROTIC PSEUDOCYST = GEODES

Etiology: bone necrosis allows pressure-induced intrusion of synovial fluid into subchondral bone; in conditions with synovial inflammation

Cause by mnemonic: COORS

  • CPPD
  • Osteoarthritis
  • Osteonecrosis
  • Rheumatoid arthritis
  • Synovial tumor
  • size of cyst usually 2–35 mm
  • may be large + expansile (especially in CPPD)

DDx:

  1. Giant cell tumor
  2. Pigmented villonodular synovitis
  3. Metastasis
  4. Intraosseous ganglion
  5. Brown tumor of hemophilia

Periarticular Calcified Mass!!navigator!!

  1. Calcinosis of chronic renal failure = uremic tumoral acalcinosis = secondary tumoral calcinosis = tumoral calcification
  2. Tumoral calcinosis

Periarticular Cyst!!navigator!!

= cyst located in the vicinity of a synovial joint

  1. Ganglion
    = mucin-containing cyst arising from tendon sheath / joint capsule / bursa / subchondral bone lined by flat spindle-shaped cells
  2. Synovial cyst
    = cyst continuous with joint capsule lined by synovial cells (term is used by some synonymously with ganglion)
  3. Meniscal cyst
    = associated with meniscal tear, in >90% of a tear with horizontal component
  4. Bursa
    = synovial lining, forms in area of friction, may communicate with joint

Loose Intraarticular Bodies!!navigator!!

  1. Osteochondrosis dissecans
  2. Synovial osteochondromatosis
  3. Chip fracture from trauma
  4. Severe degenerative joint disease
  5. Neuropathic arthropathy

Rice Bodies

= subset of loose bodies as a nonspecific response to chronic synovial inflammation resembling polished rice

  1. Rheumatoid arthritis
  2. Juvenile rheumatoid arthritis
  3. Tuberculous arthritis

Pathogenesis:

  1. microinfarction of synovium / detachment of hypertrophied synovium → sloughed synovium falls into joint space → coated with fibrinogen
  2. precipitate of fibrin + fibronectin / core of mononuclear cells, blood cells and amorphous material

MRI:

  • well-defined nodules of intermediate SI on T1WI + relatively low intensity on T2WI

DDx:

  1. Synovial osteochondromatosis (monoarticular, large joint, hyperintense cartilage components on T2WI)
  2. Pigmented villonodular synovitis (monoarticular, large joint, hemosiderin deposition)

Intraarticular Mass!!navigator!!

  1. PROLIFERATIVE SYNOVIAL PROCESS
    1. Lipoma arborescens
    2. Synovial osteochondromatosis
    3. Pigmented villonodular synovitis
    4. Rheumatoid arthritis
  2. INFECTIOUS GRANULOMATOUS DISEASE
    1. Tuberculous arthritis
    2. Coccidioidomycosis arthritis
  3. DEPOSITION DISEASE
    1. Gout
    2. Amyloid arthropathy
  4. VASCULAR MALFORMATION
    1. Synovial hemangioma
    2. Arteriovenous malformation
  5. MALIGNANCY
    1. Synovial chondrosarcoma
    2. Synovial sarcoma
    3. Synovial metastasis: primary lung cancer
  6. Peculiar joint anatomy
    1. Cyclops lesion

Intraarticular Process with Cortical Erosion!!navigator!!

  1. Pigmented villonodular synovitis
  2. Synovial osteochondromatosis
  3. Rheumatoid arthritis
  4. Gout
  5. Synovial hemangioma
  6. Lipoma arborescens

Erosions of DIP Joints

  1. Inflammatory osteoarthritis
  2. Psoriatic arthritis
  3. Gout
  4. Multicentric reticulohistiocytosis
  5. Hyperparathyroidism
  6. Frostbite
  7. Septic arthritis

Articular Disorders of Hand and Wrist!!navigator!!

  1. Osteoarthritis = degenerative joint disease = abnormal stress with minor + major traumatic episodes
    Target areas: DIP, PIP, 1st CMC, trapezioscaphoid; bilateral symmetric / asymmetric
    • joint space narrowing
    • subchondral eburnation
    • marginal osteophytes + small ossicles
    • radial subluxation of 1st metacarpal base
    • Radiocarpal joint normal unless history of trauma
  2. Erosive osteoarthritis = inflammatory osteoarthritis
    Age: predominantly middle-aged / postmenopausal women
    • acute inflammatory episodes

    Target areas: DIP, PIP, 1st CMC, trapezioscaphoid; bilateral symmetric / asymmetric
    • central erosions combined with osteophytes = subchondral “gull wing” erosions
    • joint space narrowing + sclerosis
    • rare ankylosis
  3. Psoriatic arthritis
    = rheumatoid variant / seronegative spondyloarthropathy; peripheral manifestation in monoarthritis / asymmetric oligoarthritis / symmetric polyarthritis
    Target areas: all hand + wrist joints (commonly distal); bi- / unilateral asymmetric polyarticular changes
    • “mouse ears” marginal erosions
    • intraarticular osseous excrescences
    • new bone formation ± fusion
    • osteoporosis may be absent
  4. Rheumatoid arthritis
    = synovial proliferative granulation tissue = pannus
    • Target areas: PIP (early in 3rd), MCP (earliest changes in 2nd + 3rd), all wrist joints (early in RC, IRU), ulnar styloid; both hands in relative symmetric fashion
    • fusiform soft-tissue swelling
    • regional periarticular osteoporosis
    • diffuse loss of joint space
    • marginal + central poorly defined erosions
    • joint deformities
  5. Gouty arthritis
    • monosodium urate crystals in synovial fluid
    • asymptomatic periods from months to years

    Target areas: commonly CCMC + all hand joints
    • development of chronic tophaceous gout = lobulated soft-tissue masses
    • well-defined eccentric erosions with overhanging edge (often periarticular) + sclerotic margins
    • preservation of joint spaces
    • absence of osteoporosis
    • most extensive changes in common carpometacarpal compartment:
      • scalloped erosions of bases of ulnar metacarpals
  6. Calcium pyrophosphate dihydrate crystal deposition disease = CPPD
    • Target areas: MCP (2nd, 3rd), radiocarpal; bilateral symmetric / asymmetric changes
    • chondrocalcinosis + periarticular calcifications:
      • calcification of triangular fibrocartilage
    • “degenerative changes” in unusual locations:
      • narrowing ± obliteration of space between distal radius and scaphoid ± fragmentation of surfaces
      • scapholunate separation
      • destruction of trapezioscaphoid space
    • no erosions
    • + large osteophytes = hemochromatosis
  7. SLE
    • = myositis, symmetric polyarthritis, deforming nonerosive arthropathy, osteonecrosis
    • Target areas: PIP, MCP
    • reversible deformities
  8. Scleroderma = progressive systemic sclerosis (PSS)
    • Target areas: DIP, PIP, 1st CMC
    • tuft resorption
    • soft-tissue calcifications

Arthritis Involving Distal Interphalangeal Joints!!navigator!!

mnemonic: “POEM”

  • Psoriatic arthritis
  • Osteoarthritis
  • Erosive osteoarthritis
  • Multicentric reticulohistiocytosis

Ankylosis of Interphalangeal Joints!!navigator!!

mnemonic: “S - Lesions”

  1. Psoriatic arthritis
  2. Ankylosing spondylitis
  3. Erosive osteoarthritis
  4. Still disease

Arthritis of Interphalangeal Joint of Great Toe!!navigator!!

  1. Psoriatic arthritis
  2. Reiter disease
  3. Gout
  4. Degenerative joint disease

Outline