OA MSK

• • Osteoarthritis is a degenerative condition as a result of mechanical overload in a weightbearing joint (Abnormal load through normal joint or normal load through abnormal joint)
  • Hip osteoarthritis mainly affects the articular cartilage, as well as causing changes to the subchondral bone, synovium, ligaments and capsule
  • This degeneration leads to loss of joint space, which can potentially be symptomatic
  • Remodelling of adjacent bone and new bone formation (osteophytes) are at the joint margins
• In-depth Pathology:

  • Loss of proteoglycans leads to an increase in the water content of articular cartilage
  • Collagen fibres increase in diameter and become disorganized
  • This is then broken down leading to soft patches of thinning, fissuring which causes loss of integrity and continuity of cartilage
  • Fragmentation of cartilage may cause inflammation (synovitis)
• Attempts at repair

  • Osteoblastic activity increases in sub-chondral bone causing sclerosis (visible on Xray)
  • Increased Chondrocyte activity leads to weak cartilage being laid down
  • Osteophytes and chondrophytes form at joint margins with associated synovial hyperplasia