Which one of the following best describes the etiology of a womanwith osteoarthritis ? (AIIMS Nov 2014)
|A||“Wear and tear” destruction of articular cartilage|
|B||Anti- IgG autoantibodies|
|C||Deficient enzyme in the metabolic pathway involving tyrosine|
|D||Deposition of needle-shaped negatively birefringent crystals|
a. Osteoarthritis (degenerative joint disease), the single most common form of joint disease, is a “wear and tear” disorder that destroys the articular cartilage, resulting in smooth subchondral bone (eburnated, “ivory-like”).
b. This loss of cartilage results in formations of new bone, called osteophytes, at the edges of the bone.
c. Osteophytes located over the distal interphalangeal (DIP) joints are called Heberden’s nodes, while osteophytes located at the proximal interphalangeal (PIP) joints are called Bouchard’s nodes.
d. Fragments of cartilage may also break free into affected joint spaces, producing loose bodies called “joint mice.”
e. Patients develop pain, stiffness, and swelling of the affected joints without acute inflammation.
f. A characteristic clinical appearance is the presence of crepitus, a grating sound produced by friction between adjacent areas of exposed subchondral bone.
g. In contrast, anti-IgG autoantibodies (rheumatoid factor) are seen with rheumatoid arthritis, deficient enzyme in the metabolic pathway involving tyrosine (homogentisic acid oxidase) is seen with alkaptonuria, deposition of needle-shaped negatively birefringent crystals (uric acid) is seen with gout, and deposition of short, stubby rhomboid-shaped positively birefringent crystals (calcium pyrophosphate) is seen with pseudogout.