Osteoarthritis

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Osteoarthritis

• Hoveda Mufti M.D.
• 9/6/06

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Definition

• Also known as degenerative joint disease or
  wear and tear arthritis.
• Progressive loss of cartilage with remodeling of
  subchondral bone and progressive deformity of the
  joint (s).
• Cartilage destruction may be a result of a
  variety of etiologies

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• Prevalence and epidemiology
• Over 20 million affected in U.S.
• About 60-90 of people over age 65
• Under 45 yrs it is equally common in men and
  women
• Over 55 yrs its more common in women
• Nodal OA involving DIP and PIP joints is more
  common in women and their first degree female
  relatives

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• Premature OA associated with gene mutations that
  encode collagen types 2, 9, 10
• OA of knee is more common in African American
  women
• Commonest cause of long-term disability
• Large economic impact as a result of medical
  costs
• OA cost the U.S. economy nearly 125 billion per
  year in direct expenses and lost wages and
  production.

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• It is not an inevitable part of aging, some
  people are more susceptible than others
• A combination of different factors are involved.
• Both mechanical and biologic destructive
  processes play a role in OA.

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• Risk factors
• Metabolic (hemachromatosis)
• Inflammatory (RA, infection)
• age
• gender
• genetic factors
• trauma
• weight

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Classification

• Primary
• Idopathic
• Localized or generalized
• Local knee, hip, spine, hands
• Generalized large joints and spine
• Small peripheral joints and spine
• Mixed and spine

• Secondary
• Post-traumataic
• Congenital or developmental
• Localized or generalized
• Calcium deposition disease
• Other
• Inflammatory
• Avascular necrosis

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Inflammatory OA

• OA is generally a non-inflammtory arthritis.
• Increasing evidence for inflammatory type
  caused by cytokines, metalloproteinase release.
• This erosive inflammatory type may have flares
  but later acts like typical OA.
• Primarily in women
• May be suspected from evidence of active
  synovitis, chondrocalcinosis on x-rays, morning
  stiffness greater than 30 mins, history of
  swelling and night pain.

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Overview of the process

• Articular cartilage gets disrupted
• Damage progresses deeper to subchondral bone

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• Fragments of cartilage released into joint
• Matrix degenerates
• Eventually there is complete loss of cartilage
• Bone is exposed

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• Normal knee anatomy

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• left Normal x-ray
• Right worn away cartilage reflected by decreased
  joint space

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The process at a cellular level

• Cartilage matrix has increased water content and
  decreased proteoglycan
• This is different from the changes that occur
  with aging ? cartilage dries up.
• Increased activity of proteinases compared to
  inhibitors of proteinases.
• Breakdown products of cartilage cause
  inflammatory reaction of synovium
• Cytokines cause matrix degeneration. Where do
  they come from?
• ? chondrocytes
• Cycle of destruction starts
• Compensatory bone overgrowth occurs - subchondral
  bone increases in density

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• Left View of normal elbow cartilage through an
  arthroscope - white, glistening, smooth
• Right severe elbow osteoarthritis - cartilage is
  lost and the bone underneath is exposed

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The process contd

• Bony proliferations at joint margins form, what
  are they called?
• ? osteophytes
• Thought to be new bone formation in response to
  degenerating cartilage
• They cause joint motion restriction

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What to look for in an x-ray

• Radiographic changes visible relatively late in
  the disease
• Subchondral sclerosis
• Joint space narrowing esp where there is stress
• Subchondral cysts
• Osteophytes
• Bone mineralization should be normal

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• Joint space narrowing where there is more stress
• Subchondral bone has thickened
• bony overgrowth

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• significant joint space narrowing as well as
  proliferative bone formation around the femoral
  neck (arrows)

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• Left normal hip
• Right There is some joint space medially but
  the superior portion is completely destroyed.
  Supralateral aspects affected most because the
  weight is transfered through the roof of the
  acetabulum.
• Note the sclerosis and oseophyte formation
  (arrow).

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• painful bone on bone contact at the CMC joint and
  the large bone spurs -- osteophytes.

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• X-ray shows lateral osteophytes, varus deformity,
  narrow joint space in a 70 yr old female with OA

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• Are crystals found in osteoarthritic joints?
• Yes
• Calcium pyrophosphate dihydrate and apatite.
• Are of unknown significance and asymptomatic

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Clinical features and diagnosis

• Pain
• Sources
• Joint effusion and stretching of the joint
  capsule
• Torn menisci
• Inflammation of periarticular bursae
• Periarticular muscle spasm
• Psychological factors
• Deep, aching localized to the joint
• Slow in onset
• Worsened with activity in initial stages
• Occurs at rest with advanced disease

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• May be referred eg hip pain referred to the
  thigh, groin, knee.
• Pain may be aggravated with weather changes

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Exam

• Joint line tenderness
• Bony enlargement of joint
• /- effusion
• Crepitus
• Decreased range of motion

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Joint exam

• Joint line pain can indicate tear of the lining
  of the capsule or the meniscus.
• Where is the patella?

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Joint exam

• In the evaluation of joint line pain, perform a
  varus or valgus stress test.
• Apply stress across the joint, place fingers
  directly over the joint line to assess for pain,
  a clunk may indicate a meniscal tear, or
  crepitus may indicate cartilage damage.

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• Have the patient to lie supine on the exam table
  with leg muscles relaxed
• Press the patella downward and quickly release
  it.
• the patella visibly rebounds.
• What does this mean?
• a large knee effusion
• Ballotable patella

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• Have the patient lie supine with leg muscles
  relaxed
• Compress the suprapatellar pouch with your
  thumb, palm, and index finger.
• "Milk" downward and laterally so that any excess
  fluid collects on the medial side.
• Tap gently over the collected fluid and observe
  the effect on the lateral side
• A fullness on the lateral side indicates the
  presence small knee effusion

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Involved joints

• DIP, PIP
• 1st carpometacarpal
• cervical/lumbar facet joints
• 1st metatarsophalangeal
• Hips
• Knees
• Uncommon
• Wrist, elbows, shoulders, ankles

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• 1st metatarso-phalangeal most commonly affected
  in OA of the foot.

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Typical findings

• Heberdens nodes
• Bouchards nodes

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• Rt varus deformity of the knee

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Treatment

• Non-pharmacokinetic
• No proven medication-based disease modifying
  intervention exists.
• Analgesics (acetominophen)
• NSAIDS
• Help pain symptoms but controversial for long
  term use in non-inflammatory OA because of risks
  vs benefits
• Narcotics
• Intra-articular steroids
• Chondroprotective agents
• Anti-depressants

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• Non-pharmacokinetic rx
• Reasonable evidence for efficacy
• Exercise prevent disuse atrophy of muscles
• Physical therapy Hydrotherapy/heat/cold,
  paraffin baths
• Weight loss
• Education
• Wedges shoe insoles/braces
• Refer to physiatrist for management plan.

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Analgesics

• Acetominophen at doses of upto 4g per day
• 2004 meta analysis of 10 trials showed that
  acetominophen superior to placebo but less
  efficacious in relieving pain than NSAIDS
• Do you worry about hepatotoxicity?
• Only seen in pts who are taking excessive amounts
  of alcohol, underlying disease.

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Opioid analgesics

• Generally should be avoided for long term use
• For short term rx they may be effective. A study
  showed oxycodone to be synergistic with NSAIDS.
• In older pts use caution because of side effects
  such as confusion, constipation, sedation.
• Can use tramadol with acetominophen, in addition
  to NSAID/COX-2 inhibitor

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• A controlled study showed codeine and
  acetominophen combination to be equivalent to to
  tramadol and acetominophen
• Consider opiates if pt is not a candidate for
  surgery, or is at high risk for side effects from
  NSAIDS

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NSAIDS

• Useful in non-inflammatory OA when pain is
  moderate to severe
• Topical preparations available
• PGE2 may contribute to local inflammation and so
  there is a role for NSAIDS in inflammatory OA

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• There is variability amongst patients in terms of
  side effects and efficacy of NSAIDS
• Non-acetylated salicylates have less renal
  toxicity
• Sulindac, salsalate
• Indomethacin has been associated with accelerated
  joint destruction, so avoid it for long term use
  in pts with hip OA

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Selective COX-2 inhibitors

• They have 200-300 times selectivity for COX-2
  over COX-1.
• Less gastroduodenal toxicity
• But if used with ASA pts may be at increased risk
  for GI bleeding.
• Use GI prophylaxis
• Avoid in pts with atherosclerotic CAD - use
  traditional NSAIDS with a PPI/sucralfate/misoprost
  ol

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Side effects

• Rash/hypersensitivity
• GI bleeding
• CNS dysfunction in elderly
• Impairment of renal/hepatic/platelet function.
  How can NSAIDS lead to renal dysfunction?
• By interfering with vasodilator renal PG and
  causing renal ischemia.

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Intra-articular corticosteroids

• May be used if NSAIDS are contraindicated,
  persistent pain despite use of other medications.
• (not gt 4 injections per year per joint)
• 2004 meta-analysis of controlled trials (w/
  placebo) showed short term improvement in knee
  pain, but efficacy in other joints is uncertain.
• saline vs steroid injection?
• A study comparing the two in knee OA showed no
  effect on joint space narrowing or significant
  difference in pain at the end of the study, but
  over a 2 yr period saline injections has less
  pain relief.

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Intra-articular hyaluronans

• Evidence shows they have a small advantage in
  terms of pain control, compared to
  intra-articular placebos or NSAIDS.
• No evidence for improvement in function
• Two studies comparing intra-articular steroids to
  hyaluronans have come to opposite
  conclusions-more trials are needed.

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Surgical arthroscopy

• arthroscopy is not recommended for nonspecific
  "cleaning of the knee.
• Used to fix specific structural damage on imaging
  (repairing meniscal tears, removing fragments of
  torn menisci that are producing symptoms).

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• Joint replacement
• If all other rx ineffective, and pain is severe
• Loss of joint function
• Joints last 8-15 years without complications

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The end