<B>Osteoarthritis </B>

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Osteoarthritis

Etiology:

• Generally regarded as a degenerative disease.

Pathogenesis:

• Chondrocytes are believed to play an important role in the development of osteoarthritis.
• Aging chondrocytes are believed to release numerous cytokines, including TNF alpha, TGF beta and prostaglandins that can cause breakdown of the chondroid matrix of the articular cartilage.

Epidemiology:

• It is the most commonly encountered disease of joints; most individuals above the age of 65 have some evidence of osteoarthritis.
• The disease can occasionally occur in younger individuals with some predisposing conditions, such as trauma to a joint, developmental deformities or occupational reasons.
• Thus, athletes offer exhibit osteoarthritis of selected joints, depending on the sport.

General Gross Description:

• Osteoarthritis is also know as degenerative joint disease.
• Grossly, early stages of osteoarthritis can be detected by an increase in the granularity of the articular cartilage.
• Subsequently, cracks and fissures can be detected in the superficial layers of the cartilage.
• Eventually, full or partial thickness segments of cartilage slough off the articular surface and fall into the joint space.
• The bone lying under the cartilage becomes highly burnished and thickened.

General Microscopic Description:

• Microscopically, evidence of horizontal and vertical fissures and fibrilary changes in the cartilage can be detected early.
• Late in osteoarthritis, joint fluid gets forced into the bone resulting in the formation of cysts.

Clinical Correlations:

• Osteoarthritis is characterized by pain, morning stiffness and limitation of the range of movement of the affected joint.
• Joints frequently affected by the degenerative process include the large joints of the lower limbs (hips and knees); inter-vertebral joints; and the interphalangeal joints.
• The course of osteoarthritis is unpredictable; some patients stabilize at some level of discomfort, while in others, it can progress to be disabling.

References:
•Robbins "Pathologic Basis of Disease". (Cotran, Kumar and Robbins, Eds.) 5th Edition. pp 1247.