Block 9 - L16, 17 Flashcards
What percent of US adults are diagnosed with arthritis?
20%
What is the most common form of arthritis?
Osteoarthritis
Compare the frequency of arthritis in men and women.
More common in women
What happens in osteoarthritis (aka degenerative arthritis)?
Degeneration of articular cartilage (chondrocytes respond to stress in a way that results in breakdown of the matrix)
List some causes of secondary osteoarthritis.
- Trauma
- Inflammatory arthritis (RA, infectious, seronegative spondyloarthropathies)
- Dysplastic and hereditary conditions
- Kashin-Beck disease (joint hypermobility)
- Bone disorders
- Metabolic and endocrine disorders
What age group is osteoarthritis most commonly seen in?
> 65 y/o
In OA, ___ changes can be seen beginning at 45 years of age, but these are fairly unsymptomatic.
Radiographic (37% - knee, 27% - hip, >90% - hands)
What are the risk factors for OA? What is the strongest risk factor?
- Age (strongest)
- Obesity (leptin may influence chondrocytes)
- Chronic repetitive impact loading (long term weight bearing sports)
- Genetics (family history)
- Joint dysplasia (increases risk for hip OA)
List the components of normal morphology in this connective tissue.
- Collagen
- Proteoglycans
- Water
- Chondrocytes
What type of collagen is most prominent in this connective tissue and what is its role?
Type II collagen; distributes compressive forces, tethers cartilage to subchondral bone, dissipates weight bearing force
What type of proteoglycans are seen in this connective tissue and what is its role?
Aggrecans - high fixed negative charge allows for retention of water
What is the role of chondrocytes here?
Mediate turnover of matrix components
Discuss the morphologic changes seen in OA.
The articular cartilage loses homogeneity, becomes disrupted, and the surface fragments.
Deeper layers of cartilage are invaded by capillaries from calcified cartilage.
Chondrocytes (normally isolated) proliferate and cluster.
Osteophytes form.
Water content increases.
Increase in both anabolic and catabolic activity. Eventually, catabolic > anabolic.
Chondrocytes release degradative enzymes.
List the clinical characteristics of OA.
- Localized joint pain
- Stiffness (but very little morning stiffness)
- Worse with weight bearing
- Better with rest
- Involved areas: DIP, PIP joints, knees, hips, cervical/lumbar spine
- Joint crepitus
- Swelling NOT common
- Bony enlargement
What is seen on X-ray in OA?
Decreased joint space
Subchondral sclerosis and cysts
Osteophytes (spurs)
What lab tests are useful in OA?
None
How is OA managed?
- No cure
- Manage risk factors (PT, exercise, weight loss, dietary measures)
- Pharmacologic (acetaminophen, NSAIDs, intra-articular steroid injections in selected cases)
- Joint replacement surgery
What is rheumatoid arthritis?
Systemic, chronic, inflammatory, autoimmune disease primarily involving joints
What extra-articular organs may be involved in RA?
- Lungs (interstitial lung disease, pleural effusion)
- Anemia of chronic disease
- Eyes (episcleritis, scleritis)
- Skin (vasculitis), soft tissue (rheumatoid nodules)
- Heart (pericarditis)
- CNS rarely, peripheral neuropathy
Discuss the prevalence of RA, particularly in F vs. M.
Overall - 1%
F>M (5:1)
What is the peak incidence age range of RA?
20-50 y/o
What are environmental risk factors for RA?
- Infectious triggers (P. gingivalis)
2. Smoking (anti-CCP Ab)
Compare RA and OA.
RA: inflammatory (swelling), prolonged morning stiffness, systemic manifestations, joints involved = PIPs, MCPs, wrists, NO lumbar spine
OA: degenerative (no swelling), limited morning stiffness, localized symptoms, joints involved = DIPs, PIPs, CMC, lumbar spine
Compare the morphology of RA vs. OA.
RA - more inflammation, forms a panus that erodes into bone
OA - general wear and tear, more symmetrical
Discuss the pathogenesis of RA.
- Activation of CD4+ helper T cells
- T and B cells respond to self-antigens, leading to an inflamed synovium and increased inflammatory cytokines
- Fibroblasts, chondrocytes, synovial cells respond to the pro-inflammatory milieu, release destructive enzymes
- Osteoclasts are activated, leading to bone erosions
What cytokines are common in RA?
IL-1, IL-6, TNF-alpha
Describe the morphology of RA.
- Chronic papillary synovitis
- Synovial cell hyperplasia and proliferation (thickening) - pannus formation
- Perivascular inflammatory cell infiltrates (dense)
- Angiogenesis
- Neutrophils and organizing fibrin on synovial surface (layered)
- Increased osteoclast activity (erosion)
What is a pannus?
Thickening of the synovium
How is RA diagnosed clinically?
- Chronic, symemtrical, inflammatory polyarthritis
2. +/- extra-articular manifestations (rheumatoid nodules, ILD)
How is RA diagnosed with blood tests?
- Rheumatoid factors (auto-Ab against Fc portion of normal polyclonal IgG)
- Anti-CCP Ab
- Elevated inflammatory markers
What is seen on x-ray in RA?
Erosions and peri-articular osteoporosis
What is seen in the synovial fluid in RA?
WBCs, low glucose (non-specific)
What is a rheumatoid nodules?
Area of fibrinoid necrosis surrounded by palisading histiocytes
How is RA treated?
- NSAIDs
- Corticosteroids (prednisone) - bridge, not monotherapy
- DMARDs (disease modifying anti-rheumatic drugs - mainstay of long-term treatment)
- Non-biologic DMARDs (methotrexate, leflunomide)
What is the first line biologic treatment for RA and what does it do?
Etanercept, Adalimumab, Infliximab - anti-TNF-alpha
What are seronegative spondyloarthropathies?
Group of inflammatory arthritides which primarily involve ankylosing of the spine
Describe the symptoms of seronegative spondyloarthropathies.
Inflammatory back pain that improves with exercise, not relieved by rest
Describe the pattern of joint involvement of seronegative spondyloarthropathy.
Oligoarticular, asymmetric, more large joints involved, axial involvement (sacroiliitis), bamboo spine (fusion of the vertebrae), enthesitis
What is enthesitis?
Inflammation of tendon insertions
What are the extra-articular manifestations of seronegative spondyloarthropathy?
Uveitis (not seen in RA), genitourinary tract (in reactive), skin (in psoriatic), GI tract (in IBD-associated)
List the types of spondyloarthropathies.
- Psoriatic arthritis
- Ankylosing sponylitis
- IBD-related
- Reactive arthritis
- Undifferentiated spondyloarthropathy
What is the typical age of onset for spondyloarthropathy?
16-30 y/o
Discuss the arithrogenic theory of spondyloarthropathy pathogenesis.
Molecular mimicry via infection with bacteria such as Yersinia, Shigella, Salmonella, Campylobacter, Chlamydia, body forms Ab against self because they look like the bacterial Ag
Discuss the theory of spondyloarthropathy pathogenesis related to dimerization.
Tendency to misfold and form dimers leads to inappropriate stimuli and inflammation. TNF-alpha is induced, NK, dendritic, and CD4 T cells are activated, IL-17 is produced.
Discuss the cytokines involved in sponyloarthropathy.
TNF-alpha (similar to RA), IL-17, IL-23 (Th17 cells)
What is the role of IL-17?
Important role in defense against extracellular bacteria; dysregulated expression leads to joint destruction
What is the role of IL-23 in spondyloarthropathy?
Strongly overexpressed int he gust of AS patients, promotes highly specific entheseal inflammation
What happens in sacroiliitis?
Granulation tissue erodes through the bone and cartilage into the joint cavity. Inflammation occurs. Bone may erode, cartilage may fuse, sclerosis may occur. Osteoblast activation eventually leads to replacement of cartilage by new bone, which causes anklyosis.
What happens in spinal ankylosis?
Inflammation at vertebral corners leads to development of syndesmophytes
What are syndesmophytes?
Sclerosis and squaring of vertebral corners; leads to complete bridging ossification
What are the features of spondyloarthropathy?
- Inflammatory back and/or buttock pain
- Chest wall pain
- Enthesitis
- Dactylitis (sausage shaped swelling of digit)
- Uveitis
- Sacroiliitis on imaging
What is the triad of symptoms in reactive arthritis?
- Non-gonococcal urethritis
- Conjunctivitis
- Arthritis
*Can have only arthritis
Follows certain enteric infections and sexually acquired infections
What is a mucocutaneous features sometimes seen in reactive arthritis?
Keratoderma blennorhagica
How is spondyloarthropathy treated?
- Education and PT
- NSAIDs
- Oral DMARDS
- Biologics (anti-TNF-alpha, anti-IL-23)
List the types of crystal-induced arthropathy.
- Gout
2. Pseudogout
What crystal causes gout?
Monosodium urate monohydrate
What crystal causes pseudogout?
Calcium pyrophosphate dihydrate
What happens in crystal-induced arthropathy?
Inflammatory arthritis (episodic and acute, but can be chronic)
What is the pathogenesis of crystal-induced arthropathy?
- Supersaturation of uric acid
- Cyrstal formation
- Crystals activate the immune system - complement cascade recruits neutrophils, monocyte phagocytosis activates the intracellular inflammasome.
- Inflammasome activation leads to increased IL-1b
Discuss the epidemiology of gout.
M»F
Age 65 and older (can happen younger)
What is the crystallization point for uric acid?
6.3 mg/dL
Why are women at a lower risk of gout until menopause?
Estrogen has uricosuric effects (excreted in urine)
What are additional risk factors for gout?
Obesity, metabolic syndrome, high purine diet, fructose, medications
What medications put you at higher risk for gout?
Thiazide diuretics and low dose aspirin
What foods have the highest levels of purines?
Red meat, beer (hops), shellfish, beans
Gout may be caused by overproduction or underexcretion of urea - which is more common?
Underexcretion (90%)
What enzyme leads to the formation of uric acid?
Xanthine oxidase
What are the clinical features of gout?
- Acute inflammatory arthritis
- Usually monoarticular (can be oligo or poly)
- Podagra
- Resolves in days to weeks
- Repeated attacks (show characteristic erosions on x-ray)
- Tophi
What is podagra?
Acute involvement of the first MTP seen in gout
How is gout diagnosed definitively?
Demonstration of crystals on polarized microscopy
How do urate crystals appear?
Parallel, negative biorefringence - eyellow
Perpendicular, negative biofrefringence - blue
How is gout treated?
Acutely - NSAIDs, other pain control (IL-1 inibitor)
Anti-inflammatory prophylaxis
Reduction of urate burden (allopurinal)
What is calcium pyrophosphate deposition disease (CPPD, aka pseudogout)?
Caused by calcium pyrophosphate dihydrate crystals, acute presentation similar to gout - podagra not characteristic, knees and wrists most involved (also elbows, shoulders, ankles)
May see chondrocalcinosis on XR, but not sensitive or specific
What are the 4 presentations of CPPD?
- Asymptomatic (chondrocalcinosis on XR, no symptoms)
- Acute (pseudogout)
- OA + CPPD (pseudoOA)
- Chronic CCP cyrstal inflammatory arthritis (pseudoRA)
Discuss the epidemiology of CPPD.
More common in older individuals
What are some secondary causes of CPPD?
Hemochromatosis, hyperparathyroidism, hypophosphatasia, hypomagnesemia
What is chondrocalcinosis?
Calcium deposition
How do crystals of pseudogout appear?
Positive + parallel = blue
Positive + perpendicular = yellow
How is acute CPPD treated?
Similar to acute gout - NSAIDs, oral steroids, steroid injection, colcichicine, rarely anti-IL-1
Basic calcium phosphate crystals such as ___ may deposit in joints and soft tissues. One example is the Milwaukee shoulder - explain.
Hydroxyapatite
Destructive arthritis associated with hyroxyapatite; seen in elderly females, destruction of rotator cuff and glenohumeral joint, monoarticular (can be bilateral)
What is polymyalgia rheumatica?
AI disorder with pain and stiffness in the proximal joints and muscles - shoulders, hips, neck + constitutional symtpoms
Polymyalgia rheumatic may be seen in the setting of ___.
Giant cell arteritis
Discuss the epidemiology of polymyalgia rheumatica.
50+ y/o
2/3 F
Highest incidence rates in northern Europe, Scandinavian countries
The etiology of polymyalgia rheumatic is still unclear, but it may involve what cytokines?
IL-6
What lab findings are seen in polymyalgia rheumatica?
Increased ESR, CRP, IL-6, no serologies or Ab
How is polymyalgia rheumatica treated?
Corticosteroids
What is fibromyalgia?
Chronic widespread pain at 11+ tender points; must rule out organic and mechanical causes of pain; NOT AI or inflammatory
What are risk factors for fibromyalgia?
Female, worry or expectation of chronicity, lack of control of the stressor, intensity of the initial symptoms, inactivity following stressor
How is fibromyalgia managed?
Minimize chronic stressors, restorative sleep
What is the most common benign neoplasm of the synovium?
Tenosynovial giant cell tumor
What causes tenosynovial giant cell tumor?
Translocation fusing the promoter of the collagen 6A3 gene to the coding sequence of M-CSF
What are the two types of TSGCT?
- Diffuse
2. Localized
What happens in diffuse TSGCT?
Involves joint synovium, leads to monoarticular arthritis with recurrent swelling, erosions develop, knee, hip, ankle
Contorted mass of red brown folds, fingerlike projections, nodules
What happens in localized TSGCT?
Giant cell tumor of the tendon sheath, painless mass involving wrist and finger tendon sheaths; most common soft tissue tumor of the hand
Describe the histologic findings of TSGCT (both types).
Multiple hemosiderin-laden macrophages, osteoclast-like giant cells
What is synovial chondromatosis?
Multiple nodules of hyaline cartilage within subsynovial connective tissue that can undergo enchondral ossification; benign, does not metastasize; joint point, swelling, stiffness, crepitance, limited motion with locking, grating sensation
Knee most common
