OSTEOARTHRITIS

 It is chronic joint disorder in which there is progressive softening and disintegration of articular cartilage accompanied by new growth of cartilage and bone at joint margin (osteophytes) and capsular fibrosis, it is not inflammatory disorder

Etiology:

1. Age cartilage //dose ageing showing decrease of cellularity and reduce proteoglycan, loss of elasticity lead to weak cartilage, so OA common at old age.

2. Inflammatory //any inflammatory processes may lead to enzyme release by synovial cell and leucocytes which causes, decrease in proteoglycan syntheses

3. Mechanical// in majority of cases the mechanical stress is the most cause of OA, this may lead to increase load (deformity) or alteration of articular surface

4. Genetic// primary changes in cartilage matrix might weaken the structure which lead to cartilage break down

Types:

A. Primary/secondary: Primary when there is no cause and 2nd, which usually

follow deformity, primary at old age group and 2nd at younger age group.

B. Progressive and non-progressive: Progressive seen in the maximal load bearing at the hip joint in the superior part and articular cartilage rapidly destruction, non progressive type commonly seen at inferior medial edge of

femoral head.

Pathogenesis:

Early changes is increase water content lead to increase extractability of proteoglycogen matrix (failure internal net work) ----------------------------damage of proteoglycogen--------------decrease cartilage stiffness--------------------------damage chondrocyte-------------enzyme release----------further damage to cartilage --------loss of shock absorption of cartilage ---------increase force to subchondral bone Pathology:

1. Cartilage destruction.

2. Cystic formation.

3. Sclerotic of surrounded bone. 4. Osteophyte.

5. Capsular fibrosis.

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 Risk factor:

1. Abnormal joint like CDH

2. Trauma And intraarticular fracture 3. Occupation, excessive stress

4. Obesity

5. Family history