What do synovial joints do?
They allow for gliding movement facilitated by lubricated cartilaginous surfaces
What is the function of hyaline cartilage on articular surfaces?
Elastic shock absorber that spreads weight across surface of joint; friction free surface
What is hyaline cartilage composed of?
Type 2 collagen Water Proteoglycans Chondrocytes Avascular
What makes up the synovial cavity?
Synovial cells -- cuboidal cells, 1-4 layers thick
What happens in the synovial cavity?
1. Synovial fluid is produces 2. Debris is removed (phagocytic function) 3. Movement of solutes, electrolytes and proteins from capillaries to synovial fluid is regulated
What is synovial fluid made of?
Viscous filtrate of plasma containing hyaluronic acid Lubricant Provides nutrients to articular cartilage
What types of crystals are involved in inflammatory mono arthritis?
Monosodium urate (gout) Calcium pyrophosphate (pseudogout)
What types of things may cause inflammatory mono arthritis?
Trauma Crystals Septic joint
Clinical assessment of inflammation
Morning stiffness > 1 hour Erythema and warmth (usually with crystal arthritis and septic arthritis) Synovitis-- thickening of synovium around joints; tender upon firm palpation
What lab tests can help diagnose inflammation?
Inflammatory markers -- erythrocyte sedimentation (ESR), C reactive protein (CRP) Peripheral blood leukocytosis (septic arthritis) Joint fluid analysis
What radiographic changes point to inflammation?
X-rays that show erosions of bone at joint margins
What levels of WBC correspond to non-inflammatory, inflammatory or septic fluid analysis?
What percentage of PMNs correspond to non-inflammatory, inflammatory or septic fluid analysis?
What causes gout?
Metabolic disorder resulting in elevation of uric acid (hyperuricemia) beyond the level of saturation Overproduction -- 10% Underexcretion -- 90%
Does gout affect males of females more?
Males 1.3 : Females 0.5 Increase in females after menopause because estrogen promotes urate renal excretion
What other factors contribute to the likelihood of developing gout?
Higher in some non-Caucasian groups BMI
About how many milligrams of irate do we excrete per day?
What are the two types of hyperuricemia that you can get?
Overproduction (10%) Underexcretion (90%)
What types of things can cause an overproduction of uric acid?
Enzymatic abnormalities Increased cell turnover Diet EtOH
What types of things can cause an under excretion of uric acid?
Metabolic syndrome Renal disease Drugs: diuretics, cyclosporine EtOH
How do they diagnoses MSU crystals?
With bifringence -- crystals that are yellow when parallel = gout Should have negative bifringence.
What is polyarticular gout?
Gout affecting multiple joints
What is tophaceous gout?
Chronic form of gout where crystals are deposited in soft tissue areas of the body -- especially in areas of decreased temperatures (ears).
How does elevated MSU lead to inflammation?
Monosodium urate is recognized by pattern recognition proteins, phagocytosed and the inflammasome is activated. Caspase-1 activates IL-1B which is an inflammatory cytokine that sets up the inflammation process (released pro-inflammatory mediators and recruits neutrophils).
How common is calcium pyrophosphate deposition disease?
It affects approximately 12% of the elderly -- increasing incidence with age
What causes calcium pyrophosphate deposition disease?
Unknown but in most cases there is a related overproduction of PPi -- PPi binds Ca well and precipitates to CPPD (calcium pyrophosphate dihydrate) May be found as "mixed crystals" with urate crystals
What is pseudogout?
Attacks of acute arthritis similar to gout, but usually in larger joints (knee, wrist, shoulder)
How is psuedogout diagnosed?
Rhombodial shaped, positively birefringent crystals in joint fluid X-ray: diagnosis may be suggested by "chondrocalcinosis" but not seen in all cases.
How can CPPD arthritis present?
1. Asymptomatic -- most common
3. Osteoarthritis (OA)
4. RA-like (MCP joint enlargement) -- may produce chronic low grade inflammation
CPPD is also called....