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SOURCE

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Source: Buys LM, Wiedenfeld SA. Osteoarthritis. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey L, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=133893029. Accessed January 19, 2017.

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CONDITION/DISORDER SYNONYMS

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  • Degenerative joint disease.

  • Osteoarthrosis.

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DEFINITION

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  • Progressive joint disorder caused by gradual loss of cartilage, resulting in development of osteophytes and cysts at joint margins.

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ETIOLOGY

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  • Primary (idiopathic) osteoarthritis (OA) has no known cause.

  • Secondary OA may be associated with:

    • Rheumatoid arthritis.

    • Trauma.

    • Metabolic or endocrine disorders.

    • Congenital factors.

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PATHOPHYSIOLOGY

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  • Damage to articular cartilage increases metabolic activity of chondrocytes resulting in cartilage swelling, destruction, and loss.

  • Aggrecan destruction increases activity of matrix metalloproteinase (MMP) 13, which destroys collagen.

  • Subchondral bone releases vasoactive peptides and MMPs. Neovascularization and increased permeability of adjacent cartilage contribute to further cartilage loss.

  • Joint space narrowing leads to painful, deformed joints.

  • Remaining cartilage softens and develops fibrillations, splitting, and exposure of underlying bone.

  • Brittle, stiffer bone develops sclerosis and microfractures and has decreased weight-bearing ability.

  • New bone formations (osteophytes) appear at joint margins.

  • Inflammation in joint capsule and synovium result in effusions and synovial thickening.

  • OA pain results from distension of the synovial capsule by increased joint fluid, microfracture, periosteal irritation, or damage to ligaments, synovium, or the meniscus.

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EPIDEMIOLOGY

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  • Prevalence and severity increase with age.

  • Affects 22.7% of adults over age 18% and 49.7% of people age 65 and older.

  • Before age 50, men are more likely to have OA than women.

  • In older age groups, women have a higher prevalence of hip, knee, and hand OA than men.

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RISK FACTORS

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  • Advancing age.

  • Obesity.

  • Sex.

  • Repetitive use through work or leisure activities.

  • History of joint trauma or surgery.

  • Genetic predisposition.

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CLINICAL PRESENTATION

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  • Depends on duration and severity of disease and number of joints affected.

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SIGNS AND SYMPTOMS
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  • Localized deep, aching joint pain; limitation of motion, stiffness, crepitus, and deformities.

  • Limited motion with passive/active movement.

  • Upon arising, joint stiffness lasts <30 min and resolves with motion.

  • Joints most commonly affected:

    • Distal interphalangeal (DIP) joints (Heberden’s nodes) and proximal interphalangeal (PIP) joints (Bouchard’s nodes) of hands.

    • First carpometacarpal joints of wrist.

    • Knees.

    • Hips.

    • Lumbar spine.

    • First metatarsophalangeal joint of toes.

    • Shoulder, elbow, acromioclavicular, sternoclavicular and temporomandibular joints.

  • Patients with lower extremity involvement may report weakness or instability.

  • Physical examination reveals tenderness, crepitus, and possibly joint enlargement; presence of warm, red, tender joints suggests inflammatory synovitis.

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DIAGNOSIS

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MEANS OF CONFIRMATION AND DIAGNOSIS
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  • Patient history, examination of affected joint(s), radiologic findings, and laboratory testing.

  • Criteria for diagnosis of hip OA:

    • Presence of pain in the hip and at least two of the ...

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