View source for Joint Response to Injury

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|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Pathology
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|subtext1=JOINTS
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===Causes of injury ===

*Trauma
*Instability
*Lubrication failure
*Infectious organisms
*Immune-mediated disease

===Reaction to injury===

*[[Joints - Anatomy & Physiology#Articular cartilage|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 [[General Pathology - Disorders of Cell Growth#Metaplasia|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
*Synovial membranes respond by:
**Villous hypertrophy
***+/- [[Joints Inflammatory - Pathology|synovitis]]
**Hyperplasia