osteoarthriths

Psoriatic arthritis

• fever: gout, Still dz, endocarditis
• Rash: SLE, psoriatic arthritis, Still dz
• Nodules: RA, gout
• Neuropahty: Polyarteritis nodosa, Wegener granulomatosis

•  lubricating fluid sack in between 2 bones that move against each other 
• located outside the joint capsule

• Clear, pale yellow liquid in small amounts
• lubricates the joint and provides nutrition
• Viscous: high [ ]s of hyaluronic acid
• does not clot
• Glucose: 10mg/dl lower than serum
  • RA: 30mg/dl lower 
  • Infectious arthritis: up to 70mg/dl lower 
• WBCs <200/mm3 (mostly mononuclear)
  • inflammation ↑ cell count and %age of PMNs
  • more than 90% PMNs strongly suggests septic (bacterial) arthritis, regardless of WBC
• RBCs suggests a traumatic tap

if you can send 1ml of fluid in each of 2 tubes:

1. Green top (heparin): crystals and CBC w/diff
2. Red top (plain): viscosity, mucin clot, complement, glucose, gram stain, culture

If you get nothing, send needle for C/S

1. Measure length of thread formed when spread between index finger and thumb: normal and OA string out 2.5-5cm before breaking. Inflammation: dilute/no stringing

2. Mucin clot test

3. Glucose

4. Gram stain: in septic arthritis (70% are gram+, and 30% are gram-)

5. Rh Factor: may be present in effusions of pts with RA when it is not (yet) present in blood

Acetic acid added to sample, the tougher the clot, the less hydrolyzed the hyaluronic acid 

"Good" clot: normal & OA (clear fluid, solid clot)

"Bad" clot: inflammation/infection: lupus, RA, Reiter's, gout, gonorrhea (cloudy fluid, solid clot → friable clot = inflammation; no clot = infection)

Gout: sodium urate crystals: needle-shaped, negatively bifringent (shine brightly) under polarized light

Pseudogout:calcium pyrophosphate crystal; rhomboid shaped and positively bilfringent

• most common type of Noninflammatory arthritis (DJD)
• cause unknown: highly correlated with age
• slow progressive clinical course
• Cartilage: becomes rough, irregular, no longer glistens → completely worn away, subchondral bone exposed → 2° synovitis → ostrophytic spur formation
• Characterized by degeneration of cartilage and hypertrophy of bone at articular margins 
• inflammation is minimal
• hereditary and mechanical factors contribute to cause

1°: either localized or generalized

2°: d/t trauma, metabolic conditions, and other forms of arthritis (RA, gouty)

Heberden's nodes: DIP joint

Bouchard's nodes: PIP joint

Varus (bowlegged) deformity of the knee

• Pain relief (analgesics and anti-inflammatories)
• Prevention of progression
• rest of involved joint (↓ inflammation and pain) 
  • wt loss, braces, cane or crutch
• Stretching exercises
• moist heat for pain
• low impact exercises: biking, swimming, cross country machines
• walking program and wt loss
• Surgery: hip/knee replacement

Drug therapies for osteoarthritis

• Mild dz: start with acetaminophen (2.6-4g/d; 650 mg q4h or 975 mg q6h). Aspirin as alternate (same dosage)
• NSAIDs if no response to acetaminophen
  • Celebrex (200mg qd, lower for elderly) 
  • Ibuprofen: 400-800 mg q6h (less GI toxicity)
  • Indomethacin: 25-50 mg bid-qid (↑ risk of GI and bone marrow effects)
  • Naproxen: 250-500 mg q6-8h (↓ for elderly) well tolerated
  • Toradol: 20mg IM or 30mg IV, then 30mg q6h IM or IV (↓ doses for elderly) (alt to opioid) short term use only (< 5days)
• May be able to eventually ↓ dosage or limit use to exacerbations 
• With effusion: intra-articular injection of triamcinolone (20-40 mg) may obviate need for above meds (can do up to 4x per year)
• Others: capsaicin cream 0.025-0.075% 3-4 x daily (good for knee pain)
• Doxycycline (off label) slows progression of knee O/A

• total knee or hip replacement
• excellent and symptomatic improvement
• when walking is restricted or pain at night

Depends on disease stage

obj: terminate or prevent Acute attack

encourage tophi to move

reduce level of serum uric acid

• Arthritis is treated 1st (hyperruicemia wks-mths later if at all, sudden ↓ of serum uric acid can precipitate further episodes)
• NSAIDS are choice: traditionally Indomethacin 25-50mg q8h until sxs resolved (5-10 days)
  • Pts at high risk of upper GI bleed: COX2 inhibitor
•  Steroids: dramatic effects
  • monoarticular: Intraarticular triamcinolone 10-40 mg 
  • Poly:  IV Methylprednisolone 40mg/d or oral prednisone 40-60mg/d both tapered over 7 
  • Joint aspiration and gram stain before steroids are given b/c can coexist with septic arthritis
• High liquid intake (urinary output of >2L aids in urate excretion and minimizes urate precipitation)

• Thiazide and loop diuretics inhibit renal excretion of uric acid 
• low doses of aspirin or niacin aggravate hyperuricemia

1. Diet/lifestyle modification (treat obesity, moderate ETOH intake: 2 or< a day, limit beer especially, manage HTN (no diuretics) with single attack,  may only tmt needed if compliant

2. Colchicine: Used for mild hyperuricemia and occasional attacks, or when serum uric acid reducing agents are started, keeps uric acid levels from ↑ or ↓ too quickly, thereby preventing attacks. 

3. Urate lowering agents: indicated for frequent attacks not controlled by colchicine prophylaxis, and for those with tophaceous deposits or renal damage

Goal of medical tmt: keep serum urate levels at or below 5 mg/dl (to prevent crystallization)

• 2 classes: uricosuric drugs & allopurinol
• Neither of value in tmt of acute gout
• 24hr urine uric acid test to determine which class to use
  • Under 800 mg/dl: undersecretion of uric acid → uricosuric agents if renal fxn is preserved
  • Over 800 mg/dl: overproduction → allopurinol

• Block tubular reabsorption of filtered ruate
• prevent formation of new tophi and reduce size of those that are present
• When given with colchicine may lessen the frequency of recurrences 
• Ineffective in pts with renal insufficiency (serum creatine of more than 2 mg/dl)
• Probenecid: 0.5g po daily initially, with gradual increases to 1-2g qd
• Sulfinpyrazone: 50-100 mg orally bid initially, gradually increase to 200-400mg bid

• an xanthine oxidase inhibitor
• promptly lowers plasma and urinary [uric acid] and facilitates tophus mobilization
• special value in uric acid overproducers 
• also, gouty pts with uric acid renal stones
• initially 300 mg/d po for those with normal renal fxn and taking prophylactic colchicine 
• in absence of colchicine, start at 100 mg/d po
• increase in a week if needed to achieve desired serum uric acid level of 5.0 mg/dl, usually 300-400 mg/d
• Max dose is 800 mg/d
• dose must be reduced in renal dz

ampicillin: combination causes a drug rash in 20% of pts

Probenecid: if taking both pts may need to use slightly higher doses of allopurinol and lower doses of probenecid

• aka: Chondrocalcinosis or CPDD dz
• Crystal induced synovitis of unknown etiology
  • familial, associated with DM, renal dz
  • triggered by medical/surgical problems
• Deposits of calcium pyrophosphate dehydrate
• into joint hyaline and fibrocartilage
• age of onset 60-80, 20% of all people >80 yo
• most are asymptomatic
• similar to gout, but large joints are involved (1° knee) 
• Calcification of cartilage of knee (meniscus) common

Aspiration

cortisone injections

NSAIDs