Musculoskeletal - Joint - Metabolic Disease Flashcards
Monosodium Urate Gout
- Term gout represents all of the various forms of crystal-induced deposition diseases of the joints. These diseases can be subdivided into three common types based on the type of crystals found in the synovial fluid:
(1) monosodium urate (MSU)
(2) calcium pyrophosphate dihydrate (CPPD)
(3) calcium hydroxyapatite (HA)
(4) calcium oxalate (CaOx) - very rare, primary oxalosis.
Note: some texts use term “pseudogout for CPPD form. These forms are of endogenous origin, however, numerous exogenous substances can also crystalize in a joint to span an arthritic situation.
AKA - MSU gout, Gout, Podagra (when confined to great toe); gouty arthropathy
Monosodium Urate Gout - History
- In western cultures, 10% of total population has hyperuricemia.
- Gout affects less than 0.5% of the total population; however, the incidence can be higher in some families.
- In families affected by the disorder, the incidence is 6-80%
- males beging experiencing gout at 18; women after menopause
- Gout is an end point of a group of disorders resulting in hyperuricemia
- Plasma urate levels above 7 mg/dl is considered hyperuricemia
- Lack of the enzyme hypoxantine guanine phosphoribosyl transferase can elevate uric acid production
- Precipitation of monosodium urate crystals into the joint cavity
- distal joint most effected due to lower temperatures
- Crystals are chemotaxic to leukocytes
- cytokines released and joint inflammation follows
- Phagocytosis of crystals, cell rupture and release of lysosomal enzymes
- Repeated attacks lead to chronic gouty arthritis
- Tophi (aggregates of crystalline monosodium urate) accumulate in teh synovium)
Monosodium Urate Gout - Risk Factors
- Age
- Genetics
- Alcohol consumption
- Obseity
- Drugs (thiazides)
- Lead toxicity
Monosodium Urate Gout- Presentation
- Acute onset over a few hours of moderate to severe monoarthritic joint pain
- Attack is usually at night and typically involves the first metatarslphalangeal joint
- Heat, (intense) redness and swelling surround the joint
- Hyperalgesia to touch
- Synovial effusion and periarticular cellulitis
- Intercritical periods tend to become shorter with time.
- Repeated attacks (>10 year period) can lead to tophi formation termed chronic tophacceous gout
Monosodium Urate Gout - Diagnostic Testing
- DIagnosed in part by clinical presentation
- CBC, ESR, and C-reactive protein
- Serum uric acid levels
- Aspiration:
-monosodium urate crystals seen under polarizing light microscopy - Gram-stain and culture
*Radiographic studies - PA and lateral views of the joint; findings include: - soft tissue calcifications
Bony overhangs from the edges of joints, can be very deforming - Erosion cysts in the periarticular bone
Monosodium Urate Gout
- American College of Rheumatology criteria:
- More than one attack of acute arthritis
- maximum inflammation developed within 1 day
- Monoarthritis attack
- Redness observed over joints
- First metatarsophalangeal joint painful or swollen
- unilateral first metatarsalphalangeal joint attack
- unilateral tarsal joint attack
- tophus (proven or suspected)
- hyperuricemia
- asymmetric swelling within a joint on x-ray
- subcortical cysts without erosions on x-ray
- monosodium urate monohydrate microcrystals in joint fluid during attack
- joint fluid culture negative for organisms during attack
Monosodium Urate Gout - treatment
- Prove joint is not septic
- Relieve pain and swelling; NSAIDS when appropriate
- Oral and intra-articular corticosteroids
- colchicine
- Triamcinolone if not oral medication is possible
- joint aspiration
Management with complications: Prophylaxis with colchicines or allopurinol when appropriate
Preventions: lifestyle changes
Calcium Pyrophosphate dihydrate-induced arthritis
- pseudogout
- CPPD is a calcium salt that is deposited into articular cartilage and released as crystals into the joint space.
AKA - Calcium pyrophosphate dihydrate-induced arthritis (CPPD arthritis); Chondrocalcinosis; Pseudogout
Calcium Pyrophosphate dihydrate-induced arthritis (pseudogout) - History
- CPPD is a common condition that occurs with aging in all races
- Usually occurs in people over 50
- About 4% of the adult population has articular CPPD deposits at the time of death
- Nearly 50% of people older than 85 years have radiologic evidence of chondrocalcinosis
- Three categories of CPPD:
- idiopathic form
- Hereditary form
- Secondary form
- Hereditary form is associated with a mutation in the ANKH Gene
- transmembrane inorganic pyrophosphate transport channel
- Secondary form is associated with:
- previous joint damage
- hyperparathyroidism
- hypomagnesemia
- hemochromatosis
- hypothyroidism
- Ochronosis
- Diabetes Mellitus
- crystal first form in the articular matrix, menisci and intervertebral joint
- Seeding of the joint space induces chemokines initiating a neutrophil invasion
- Free radicals and cytokines are released and macrophages move in to the joint with associated fibrosis.
- Individual crystals are small (0.5 - 5 mm in size)
- Knee > wrist (triangular fibrocartilage) > elbow > shoulders > ankles
- Depositions of CPPD are usually bilateral in nature
Calcium Pyrophosphate dihydrate-induced arthritis (pseudogout) - Presentation
- Can be asymptomatic
- Can produce acute, subacute or chronic arthritis
- Can be monoarthicular or polyarticular
- Rapid onset of painful swelling in the joint
- Warmth, swellng and joint effusion
- Can mimic any of the following: Gout, RA, OA, Charcot joint
Calcium Pyrophosphate dihydrate-induced arthritis (pseudogout) - Diagnostic Testing
- Arthrocentesis and aspiration
* Culture of the aspirate and examination by polarized by polarized light microscopy
Hydroxyapatitie arthritis (HA)
- Calcium apatite arthritis
AKA - Basic calcium phosphate hydroxyapitie deposition disease; Chondrocalcinosis; Calcium hydroxyapatitie
Hydroxyapatitie arthritis (HA) - History
- No known association with the ANKH mutation
- A very destructive form afflicts the shoulder in the elderly (termed Milwaukee shoulder)
- crystals are often deposited on vessels
- Basic calcium phosphate crystals can be found in the synovial fluid of 30-60% of patients with osteoarthritis
Hydroxyapatitie arthritis (HA) - Presentation
- Can be asymptomatic
- Can be acute, subacute or chronic in onset
- Acute synovitis, bursitis, or tendinitis
- Chronic destructive arthropathy, typically shoulder or knee
Hydroxyapatitie arthritis (HA) - DIagnostic Testing
- Radiographic studies non-specific
* Synovial analysis necessary to rule out infection
