Degenerative Joint Disease Flashcards
What is osteonecrosis and what is it characterised by?
Osteonecrosis is death of bone in the absence of infection.
Characterised by loss of osteocytes from lacunae and marrow.
What is the most common cause of osteonecrosis?
AVN - Avascular necrosis
Caused by loss of blood flow to area of the bone
What are some anatomically vulnerable sites to AVN?
Head of femur, tibia and scaphoid bone.
How can AVN occur in the context of fracture?
AVN can be traumatic - displaced fracture or non-union resulting in AVN
What are the different methods in which types of bone heal necrosis?
Trabecular bone heals by creeping substitution - necrotic marrow is replaced by invading neovascular tissue, bone remodelling
Cortical bone heals by cutting cones - osteoclasts bore holes into the necrotic cortex via vascular channels with osteoblasts trailing behind and forming new bone
What are the two less common forms of osteonecrosis?
Osteonecrosis of the mandible - following dental extraction
Osteoradionecrosis - following radiotherapy. Difficult to heal due to combined vascular damage and radiation damage to osteoblasts/clasts
Define arthritis
Arthritis is a general term referring to joint pain leading to loss of function.
Inflammation is usually, but not always the cause.
Symptoms and signs of arthritis?
Symptoms - pain, stiffness, lsos of function
Signs - heat, swelling, redness, reduced ROM. deformity, tenderness
Describe degenerative joint disease
Most common joint disorder in the developed world.
Pathogenesis and predominantly degenerative - inflammation is secondary or absent.
What occurs in DJD ?
Joint space narrowing
Formation of osteophytes (bone spurs)
Fibrillation (damage) and loss of articular cartilage and wear and tear of underlying bones (eburnation)
What joints are most affected by DJD?
Weight bearing synovial joints - knee, hip
Fingers
