Crystalline Arthropathies Flashcards
What are the three main crystal types in crystalline arthropathies?
Basic calcium phosphate (BCP)
Calcium pyrophosphate dihydrate (CPPD)
Monosodium urate (gout)
Where do basic calcium phosphate crystals deposit?
Soft tissues (acute calcific periarthritis), joints (BCP arthropathy), and tendons (calcific tendinitis)
What is acute calcific periarthritis?
Deposition of BCP crystals in soft tissues leading to joint swelling, tenderness, warmth (similar to cellulitis, gout, pseudogout, septic arthritis, etc). Intense local inflammation wtih juxta-articular deposition of hydroxyapatite.
Where are acute calcific periarthritis depositions most commonly located?
Shoulders, greater trochanters of hips, elbows, wrists, and digits. First MTP common in women
What is BCP arthropathy?
Severe degenerative, destructive arthritis of the shoulder joint, leading to loss of rotator cuff (cannot abduct arm, huge swelling), BCP crystals in synovial fluid, and destructive changes on X-ray.
Who is most commonly affected by BCP arthropathy?
Women > 70 years old
What is Milwaukee Shoulder Syndrome?
BCP arthropathy of the shoulder joint
What joints are most commonly affected by BCP arthropathy?
Shoulder, knees, hips, finger. Bilateral involvement common.
What is calcific tendinitis?
BCP depositions in tendons, mostly in the shoulder, that causes frozen shoulder
What muscles are affected by shoulder calcific tendinitis?
Rotator cuff: supraspinatus, infraspinatus, subscapularis
What joints besides the shoulder can be affected by calcific tendinitis?
Hand, wrist, hip, knee, foot, and neck
What is the microscopic appearance of BCP?
Shiny coins on LM, not birefringent on polarized light, can see individual crystals on EM (diagnostic)
What are the treatments for BCP conditions?
NSAIDs, PT, intra-articular corticosteroid injections, surgery
What are the ABCs of BCP arthropathy?
A: acute calcific periarthritis, alizarin red stain, atypical gout
B: BCP arthropathy, not birefringent
C: calcific tendinitis, cuff (supraspinatus), coins “shiny” on light microscopy
What is calcium pyrophosphate dihydrate deposition disease?
A disease with CPPD deposits in cartilage that occur mostly in knees and wrists, and can be asymptomatic or symptomatic
What do CPPD crystals look like?
Positively birefringent rhomboids under polarized light
What is pseudogout?
A disease where CPPD crystals deposit in joint spaces, leading to fever, malaise, acute onset of joint pain, swelling, erythema/tenderness/warmth over joints that mostly affects large joints.
How is pseudogout diagnosed?
Aspirate joint fluid to look for inflammatory fluid and crystals within PMNs
What are the clinical associations of CPPD?
Advanced age (> 50)
Osteoarthritis
Long-term consequences of mechanical knee joint trauma
Associated with systemic metabolic disease
What is the treatment for CPPD crystal deposition diseases?
NSAIDs, intraarticular steroid injections, IL-1 inhibitors, glucocorticoids
How are attacks of CPPDs prevented?
They cannot be prevented, only treatment is for acute attacks after they happen
What is the sex distribution of gout?
More men than women (3 or 4:1) until menopause (1:1 after) because estrogen breaks down the crystals
What are gout risk factors?
- prevalence increases with age
- obesity
- diet rich in purines (meat, shellfish, beer, soda)
- thiazides, cyclosporins, low dose ASA
- renal insufficiency
- organ transplantation
- inborn errors of metabolism
What is hyperuricemia?
Due to overproduction and under excretion of uric acid, treated to prevent acute flair-ups of gout.
Treatment goal < 6.0 mg/dL
What are the treatments for uric acid underexcretors?
CANT LEAP
Cyclosporine
Alcohol
Nicotinic acid
Thiazide
Lasix
Ethambutol
Aspirin (low dose)
Pyrazinamide
What condition can lead to uric acid overproduction?
Cancer (causes increased cell turnover)
What are the four stages of gout?
Asymptomatic hyperuricemia
Acute gouty arthritis
Intercritical gout (asymptomatic intervals between acute attacks)
Chronic tophaceous gout (uric acid deposits in small tissues)
How is gout diagnosed?
Aspiration of joint showing monosodium urate crystals that are negatively birefringent (yellow when parallel to polarizer, needle shaped)
What disease is this?
Gout
What is the acute treatment of gout?
generally goal = reduce body’s inflammatory attack on crystals
- Colchicine
- NSAIDs
- Steroid injection (especially for monoarticular)
- Initiate prophylactic agent like allopurinol (chronic uric acid lowering therapy)
What are indications for chronic gout therapy?
- >2-3 gout attacks within 1-2 years
- Renal stones
- Tophaceous gout
- Erosions on xray
What are gout recurrence prevention strategies?
- dietary changes (reduce meat, beer, extra frutose consumption)
- xanthine oxidase inhibitors (allopurinol)
- Uricosurics - prevent renal tubular resorption (probenicid)
- Uricases
What kind of crystal is this?
BCP
What kind of crystal is this?
CPPD
