L23 - Bone and joint Flashcards
Subtypes of inflammatory bone and joint disease
- Degenerative
- Auto-immune
- Crystal deposition
- Infection
What are some pathogenesis of osteoarthritis?
- Increased unit load on joints
- Degradation of articular cartilage
- Biochemical abnormalities
Radiological features of OA
- Narrowing of the joint spaces
- Sclerosis
- Subchondral cyst
- Peripheral growths of bone and cartilage
Protective structure of the spine that help to withstand axial load
- Nucleus pulpolus
- Disc annulus
What is the orientation of collagen fibres in disc annulus?
Oblique
Complication of disc bulging or herniation
- Posterior bulge: spinal cord impingement –> myelopathy
- Lateral bulge: nerve roots impingement –> radiculopathy
What is rheumatoid arthritis?
Systemic, chronic inflammatory autoimmune disease, affecting many tissue, specifically the joints
What gene is rheumatoid arthritis is commnoly associated to?
HLA-DR4 gene
2 antibodies produced in RA, used for diagnostic purposes
- Rheumatoid factor
- Anti-citrullinated protein antibody
What are the key pathologic features of RA?
- Synovial inflammation –> swelling
- Formation of the pannus –> granulation tissue that develops into fibrosis, resulting in ankylosis
- Destruction of adjacent bone
- Formation of rheumatoid nodules
What characterised rheumatoid nodule from other granulomas?
Central zone of fibrinoid necrosis
What is gout characterized by?
- Crystal deposition
- Increased levels of uric acid
What is the difference between primary and secondary gout in terms of the cause?
Primary: Idiopathic, may be due to obesity, alcohol and fatty diet
Secondary: increased level of uric acid, may be due to medication, renal failure, familial juvenile nephropathy
What can you observe in the examination of synovial fluid of people with gout under polarized microscopy?
Strongly birefringent needle shaped crystal
What can you observe in the examination of synovial fluid of people with pseudogout under polarized microscopy?
Rhomboid shaped crystal that are weakly berefringent
What is the main causative agent in osteomyelitis?
Staph Aureus
How do infective agents enter the bone in osteomyelitis?
- Direct implantation
- Bloodborne spread
- Extension from contiguous site
Classification of OM
- Suppurative (acute on chronic)
- Non-suppurative (chronic)
How does the disease progress in suppurative OM?
- Introduction of bacteria through 3 ways
- Bacterial proliferation and spread (haversian system –> periosteum –> synovial cavity and fluid)
- Elevation of periosteum –> impaired blood supply and increase bone necrosis
- Rupture of the periosteum
What is involcrum and sequestrum?
Involcrum: new reactive woven bone formed beneath the elevated periosteum
Sequestrum: bone necrosis
What are the complications of tuberculous osteomyelitis
- Compression fractures
- Severe deformities
- Neurological deficits
What is osteoporosis?
Osteoporosis is an acquired condition characterized be reduced bone mass, leading to bone fragility and susceptibility to fractures
What is the difference between osteoporosis and osteomalacia and rickets?
Osteoporosis is the reduced mass of bone due to the reduction of bony traberculae. The bone calcification is normal
Osteomalacia is the condition where there is insufficient calcification in bone
Rickets is the same as osteomalacia but in children’s growth plate –> excessive cartilage formation
What is osteitis fibrosa cystica?
Excessive osteoclastic activity due to increased amount or activity of PTH, which is then replaced by fibrous tissue
