Arthritis Flashcards
Synovial Joint
Anatomy
Synovial Fluid
Analysis
Acute Arthritis
Pathogenesis
-
Acute inflammation
- Peaks in about 3 hours
- Cyclooxygenase products produced ⇒ innate immunity mech.
- T_hree main processes occur:_
- Increased blood flow
- Increased permeability of the capillaries
- Migration of neutrophils
- Chronic inflammation takes at least 6 weeks ⇒ acquired immunity mech.
Acute Arthritis
Differential Diagnosis
-
Infection – Always need to consider this dx in acute mono-articular arthritis
- Disseminated Gonococcal Infection
- Non-gonococcal bacterial infection
- Fungal, Mycobacterial, Viral
- Lyme Disease
-
Inflammation
- Crystalline arthropathies (Gout, Pseudogout)
- Systemic Inflammatory Arthritis (at onset)
- RA, spondyloarthropathy, SLE, sarcoidosis, etc.
- “Exacerbations” of Osteoarthritis
-
Trauma
- Tears of meniscus/ligaments, hemarthroses
-
Cancers
- Can present as acute arthritis
Gonococcal
Septic Arthritis
- Gonorrhea tends to infects joints
- Can result in less inflammation than non-gonoccal infections e.g. S. aureus
-
± Skin pustules w/ disseminated gonorrhea
- Usually a few lesions
- Usually found on extremities
Non-Gonococcal
Septic Arthritis
- Most dangerous/destructive form of arthritis
- Cartilage and joint can be destroyed rapidly if not drained and tx with abx
- 30% have residual pain/⇓ ROM post treatment
- 5-15% mortality; up to 50% in polyarticular disease
- 80-90% monoarticular presentation
- Polyarticular can be seen in patient with preexisting polyarticular arthritis, IVDU
Bursitis
- Swelling of the bursa
- See erythema and tenderness
- Septic Olecranon bursitis and septic prepatellar bursitis common
- If it looks ugly, tap it
- Tx w/ aspiration, steroids, and ± abx
Septic Arthritis
Diagnosis
-
Purulent synovial fluid
- 50 to 100K WBC/mm3
- > 90% PMNs
- May see lower fluid WBC if peripheral WBC is low (Oncologic patient)
-
Send fluid for:
- Cell count and diff
- Gram stain (60-80% positive)
- Culture (>90% positive)
- Crystal analysis
- Blood Cultures (50% are positive)
- X-rays to establish baseline; r/o adjacent osteomyelitis
Septic Arthritis
Treatment
-
Parenteral antibiotics for at least 2 weeks or longer
(depending on the organism/clinical situation)- 4 to 6 weeks for S. aureus, GNR
- For Gram Positives:
- Vancomycin initially
- Narrow coverage when sensitivities return
- Serial Drainage (repeat arthrocentesis) may be necessary
- Follow WBC, culture results
- Surgery if persistent infection, poor access, prosthetic joint
Hyperuricemia
Elevated uric acid in the blood
Uric acid (and/or sodium urate) is the end product of the breakdown of nucleoproteins
Uric Acid Synthesis
-
First step is rate limiting:
-
5-phosphoribosyl -1- pyrophosphate (PRPP) plus glutamine
- By PRPP amidotransferase
-
5-phosphoribosyl -1- pyrophosphate (PRPP) plus glutamine
- Nucleotides recycling back into synthetic pathway requires hypoxanthine guanine phosphoribosyl transferase (HGPRT)
- Humans w/ 1° disorders of ↑ uric acid in blood and urine
-
Humans & great apes excrete uric acid in the urine
- Other mammals degrade it to allantoin
- ↑ Levels of uric acid ⇒ ± Gout
Hyperuricemia
Causes
-
Overproduction
- Secondary:
- Myeloproliferative disorders, drugs, enzyme defects
- Idiopathic (primary?): Defect unknown
- Secondary:
-
Under-excretion
- Secondary: Renal defect or failure
- Idiopathic: Defect unknown
Gout and Uric Acid Levels
- Above 7 mg% in men over 6 mg% in females usually lower
- Minute to minute blood level of uric acid does NOT reflect TOTAL BODY POOL
- Complications are associated with an increase in TOTAL BODY POOL
- Gout is a disease caused by the precipitation of urate crystals
Gout
Clinical Manifestations
-
Acute Gouty arthritis
- Podagra = gout of the big toe
- Urate urolithiasis
- Tophi
- (Intercritical gout)
Tophi
- Appear rather late in gout
- Aspirate tophus and visualize on a slide
- Multiple birefringent crystals will be seen on polarized microscopy
Gout
Diagnosis
-
History:
- Gouty arthritis ⇒ acute inflammatory reaction
- Peaks in three hours
- Lasts 2 to 3 weeks
- Tophi are not inflamed
- Kidney stones should be analyzed
- Gouty arthritis ⇒ acute inflammatory reaction
-
Physical examination:
- Acute inflammation (infection is the same)
- Hip a problem to evaluate
-
Laboratory Diagnosis:
- Monosodium urate crystals in synovial fluid during an acute attack
-
Needle-shaped, strongly ⊖ birefringent crystals under polarized light microscopy
- Finding of urate crystals is virtually diagnostic BUT there may also be an infection
- You should look for and find urate crystals at least one time ⇒ “crystal proven”
- Looking at a tophus is just as good
- Typical picture with response to therapy?
Gout
Treatment
-
The Acute Attack
- Goal: Stop the acute Inflammation
-
The Hyperuricemia
- Goal: Keep urate blood level below 6 mg%
- Long-term causes tissue urate to mobilize ⇒ leave the body ⇒ ↓ total body pool
- Goal: Keep urate blood level below 6 mg%
Acute Gout Attack
Treatment
Essentially 2 choices:
NSAIDS vs Steroids (intra-articular, oral)
- Indomethacin 50 mg q4 hours for 3 days then 25 mg 4x/day for 2-3 days
- Prednisone 20 mg stat then 20 mg the next day, then evaluate daily for cont. tx
- Intra-articular steroids
Classic Colchicine 0.6 mg every hour x 8 is no longer used. Never give IV.
Hyperuricemia and Gout
Summary
- Hyperuricemia ⇒ urate level > 7 mg% in a male, 6 mg% in a female
- Blood level may not reflect total body pool
-
Gout is a disease with one or more of the following:
- Acute Gouty Arthritis
- Tophi
- Uric acid nephrolithiasis
- Acute attacks are treated with NSAIDs or steroids
-
Hyperuricemia is treated with Probenecid or Allopurinol
- Asymptomatic hyperuricemia is not treated
Pseudo-gout
(CPPD Arthropathy)
-
Calcium Pyrophosphate Dihydrate Crystal deposition in joints ⇒ acute arthritis
- Often mono- (knee, wrist) or oligo-articular arthritis that mimics gout
- Can be polyarticular and with less intense inflammation
- Pseudo-rheumatoid pattern
- Pseudo-osteoarthritis pattern
- Ass. with CPPD deposition in cartilage ⇒ chondrocalcinosis
- Typically affects elderly > 65
- Crystals are intracellular rod- or rhomboid-shaped w/ ⊕ birefringent under polarized light microscopy
Osteoarthritis (0A)
Overview
“Degenerative Joint Disease (DJD)”
- Most common type of arthritis
- 26.9 million Americans older than 25 y/o
- Prevalence increases with age
- Leading cause of long-term disability in U.S.
- Lower extremity OA is the most common cause of difficulty walking and stair-climbing
Osteoarthritis
Pattern of Disease
-
Weight-bearing joints are often affected:
- Spine, hips, knees
-
Hands (other UE joints rarely affected)
- DIP > PIP > MCP involved
- Symptomatic disease is more common in the knees
- Incidental e/o OA joint involvement more common than symptomatic disease
Osteoarthritis
Characteristics
- Wear and tear on synovials joint leading to joint failure
-
Can involve the entire joint including:
- Subchondral bone
- Ligaments
- Joint capsule
- Synovial membrane
- Periarticular muscles
- Articular cartilage
-
Non-inflammatory arthritis
- No persistent warmth or erythema of the joint
- No signs of systemic inflammation like fever or elevated inflammatory markers
Osteoarthritis
Pathophysiology
Initial trauma (micro or macro) ⇒ joint damage ⇒ failed repair ⇒ ∆ balance b/t synthesis and degradation of ECM ⇒ progressive loss of articular cartilage with subchondral bone remodeling ⇒ ∆ joint structure ⇒ OA
Osteoarthritis
Risk Factors
- ↑ risk with ↑ age
- Hand and knee OA are more common among women
-
Genetic predisposition
- Esp. in women with nodular disease in hands
- Strong family predilection
- Obesity ⇒ ↑ stress on weight-bearing joints
-
Diseases that alter cartilage
- Hemochromatosis, gout, pseudogout
- Joint instability from neuro problem or ligamentous laxity
- Prior infection of the joint
- Trauma (micro-trauma/macro-trauma)
-
Abnormal joint anatomy
- Congenital, Rheumatoid Arthritis, etc.
- Hemophilia
Osteoarthritis
Clinical Features
- Hallmark features are chronic joint pain and joint stiffness
- Pain worsens w/ activity and relieved w/ rest
- “Gelling” ⇒ joint stiffness brought on by rest and relieved rapidly with activity
- Frequently monoarticular but multiple joints can be involved
Osteoarthritis
General Exam Findings
- Bony enlargement
- Crepitus ⇒ creaking /cracking of the joint heard or felt when palpating the joint during ROM
- ↓ Range of motion (ROM)
- No signs of inflammation or thickened synovium
Osteoarthritis
Hip Findings
Decreased ROM with internal rotation occurs before external rotation.
Groin pain with rotation may also be seen.
Osteoarthritis
Knee Findings
- Crepitus
- Tenderness along joint line
- Varus or valgus deformity (due to asymmetric loss of cartilage)
Osteoarthritis
Hand Findings
- Tenderness / bony enlargement @ 1st carpometacarpal joint
- DIP > PIP > MCP involvement
- Osteophytes at DIP ⇒ Heberden’s nodes
- Osteophytes at PIP ⇒ Bouchard’s nodes
Osteoarthritis
Diagnosis
- Distinguish from inflammatory joint diseases by H&P
-
Characteristic radiographic features include:
- Subchondral sclerosis
- Subchondral cysts
- Narrowing of joint space
- Osteophytes
Osteoarthritis
Treatment
-
Non-pharmacologic:
- Weight loss
- Avoid excessive use of joint
- Physical therapy
- Assistive devices ⇒ ↓ weight on joint
- Knee brace and/or supportive footwear
-
Pharmacologic:
- Alters symptoms not course of disease
- Weigh pros and cons and potential issues with tx options
-
Potential options include:
- Acetaminophen
- NSAIDs ⇒ avoid in elderly and others with risk factors (kidney disease, CHF, etc)
- Topical NSAIDs and capsaicin ⇒ limit systemic toxicity issues
-
Glucosamine/chondroitin sulfate ⇒ no clear evidence from trials but seem to be safe
- Anecdotal reports of ↓ pain for some patients
- Intra-articular corticosteroid injection ⇒ short-term benefit
- Need to carefully consider narcotic/opioid use
-
Surgical options:
- Arthroscopic surgery ⇒ probably ineffective
-
Total joint replacement
- ↓ pain/disability and improves function
- Should be delayed as long as possible ⇒ ↓ need for future revisions
Osteoarthritis
Conclusions
- OA is the most common cause of arthritis
- Consider it early when a patient present with a non-inflammatory joint complaint
- Diagnosis is clinical, but can be confirmed with typical x-ray findings
Rheumatoid Arthritis
Definition
Systemic, symmetric inflammatory polyarthritis that leads to joint destruction, deformity and loss of function.
Rheumatoid Arthritis
Morphological Changes
Pathology of RA involves synovial membranes and periarticular structures of multiple joints.
Resulting in:
- Pain
- Swelling
- Uncontrolled inflammation ⇒ irreversible damage and deformity
- Stiffness
- Functional limitation
- Pannus formation
Rheumatoid Arthritis
Pathogenesis
- Interaction between APCs, T-cells, and B-cells
- ⊕ Helper T-cells ⇒ TNF-α and other soluble factors ⇒ ⊕ MΦ ⇒ secrete TNF-α, IL-1, and IL-6
- TNF-α plays a central role in the inflammation process
- Current therapies intervene at each one of these steps in the inflammation process
Rheumatoid Arthritis
Demographics
- Prevalence is 1% of adults worldwide
- Women affected 2-3x more than men
- Peak age of onset is 30-50 y/o
- Most pts are dx under 65 yrs of age
Rheumatoid Arthritis
Long-term Outcomes
- Joint destruction
- Functional and work disabilities
- Treatment side effects
- Psychosocial dysfunction
- Comorbidities
- ↓ quality of life
- ↓ life expectancy
- Total estimated annual cost in US ⇒ $9 billion
- Lifetime costs for RA rival those of CVD or CVA
Rheumatoid Arthritis
Etiology
- Etiology of RA is unknown
- May be multifactorial
-
Genetic susceptibility?
- HLA-DR4 and -DR1 Class II MHC leukocyte antigen types
- Enhanced T-cell responses to inflammatory stimuli
- Intrinsic abnormalities in synovial responses
-
Environmental factors?
- Unclear if either environmental and/or genetic effects account for ethnic differences in prevalence of RA
Rheumatoid Arthritis
Clinical Presentation
-
Onset is:
- Usually insidious ⇒ 70%
- Subacute onset ⇒ 20%
- Acute ⇒ 10%
- Rarely episodic course w/ migratory involvement
-
Peripheral joints of the hands and feet are involved in almost everyone
- Hands ⇒ MCPs, PIPs and wrists (DIPs are spared)
- Feet ⇒ MTPs and ankles
-
Axial and central joints
- C-spine (C1-2), hip, shoulder, TM