Definition of osteoarthritis
Is a non inflammatory disorder of movable joints which affected any synovial joints and affected both bone and cartilage and characterized by deterioration of articular cartilage and formation of new bone at the joint surfaces and margins this disorder is also known as degenerative joint disease

There are two types of osteoarthritis primary and secondary osteoarthritis

There is no obvious underlying causes but the frequency of osteoarthritis increase with age and it is associated with genetic and hereditary predisposition as the siblings of individuals undergoing large joints replacement due to primary osteoarthritis are themselves three times more likely than members of the general population of the same age
also there are many factors which are important in the aetiology of degenerative joint disease such as
  • Obesity
  • Genetic and heredity
  • Occupatuinal eg.,intraphalangeal joint degeneration in the fingers of cotton mill workers
  • Multiple endocrine disorders such as diabetes mellitus and acromegaly
  • Multiple metabolic disorders including paget,s disease gout and calcium pyrophosphate deposition (CPPD)  disease

Secondary osteoarthritis causes
Can be divided into

Traumatic causes like either acute or chronic trauma
  • Intraarticular joint fractures osteochondral fractures
  • Joint instability as cruciate ligament injury , joint hyper-mobility syndrome
  • Post meniscetomy injury as osteochondritis dissecans
  • Neuropathic joint charcot joint
  • Mechanical causes include leg length discrepancy instability and occupational or repetitive works
  • Avascular necrosis
Genetic or developmental causes
Metabolic and endocrine causes
Inflammatory disorders causes
Bone disease
Blood disease
Neuropathic joints
  • Syringimyelia
  • Deep dorsal horn disorders
Connective tissue  causes
  • Hypermobility
Others causes
  • Overuse of intraarticular steroid injections
  • Frostbite
Clinical patterns in osteoarthritis
Primary osteoarthritis
  • Affect men common in middle age
  • Affect women common in old age
  • affect commonly many joints polyarthropathy
  • Common joint affection weight  or load bearing joints common knee hip hand carpometacarpal joint of the thumb and spine
  •  Common in female more than male
Secondary osteoarthritis
  • Affect any age
  • Monoarticular or polyarticular affection
  • Affect both bone and cartilage
  • Disruption of the surface collagen (fibrillation) and softening of the cartilage
  • Cartilage loss or erosion lead to narrowing or loss of joint space
  • Osteophytes formation by proliferation of osteoblasts in subchondral bone leads to new bone formation and the growth of marginals osteophytes and also due to stimulation of synovial membrane
  • Subchonderal sclerosis these are radiagraphic signs and ut us dur to microfractures in subarticular bone
  • Bone eburnation or polishing  appearance due to increased cellularity and bone deposition of subchondral bone
  • Subchondral cyst due to synovial fluid intrusion into bone
  • Bone collapse due to compression of weakened bone may lead to deformity and malalignment
  • Loose body formation inside joint due to fragmentation of osteochondral surface
  • Destruction and distortion of capsular ligaments lead to also deformity and malalignment
Degeneration of the cartilage can be graded as
Grade 1 softening of articular cartilage
Grade 2 fibrillation and fissuring
Grade 3 partial thickness loss clefts and chondal flaps
Grade 4 full thickness loss with bone exposed
Pain in osteoarthritis is due to
Inflamed and thickened synovium
muscle spasm
irregular exposed joint surfaces

Symptoms signs  complications investigations and treatment of osteoarthritis see here

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