Joint Response to Injury
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Causes of injury
- Trauma
- Instability
- Lubrication failure
- Infectious organisms
- Immune-mediated disease
Reaction to injury
- Articular cartilage has limited ability to regenerate
- Superficial defects are long standing
- Chondrocyte hyperplasia is ineffective at filling the defect
- Non-painful
- Defects reaching subchondral bone
- Filled with vascular fibroous tissue undergoing metaplasia into cartilage
- Painful
- Fibrillation - loss of proteoglycans -> condensation of collagen fibres -> fraying of surface
- Eburnation - loss of articular cartilage -> exposure of subchondral bone -> becomes dense and polished
- Superficial defects are long standing
- Synovial membranes respond by:
- Villous hypertrophy
- +/- synovitis
- Hyperplasia
- Villous hypertrophy