Musculoskeletal Flashcards
What prompts osteoprogenitor cells to become osteoclasts?
RANKL binding to RANK
What in inhibits RANK
OPG (Osteoprotegerin)
List the key features of rheumatoid arthritis
Chronic autoimmune disease characterised by pain, stiffness and SYMMETRICAL SYNOVITIS of synovial joints
- Morning stiffness in and around joints
- Symmetrical polyarthritis typically involving the small joints of the hand and/or wrists
- Subcutaneous nodules
- Rheumatoid factor
- The synovial membrane becomes thickened and chronically inflamed. Joint erosions of adjacent cartilage and bone (seen on radiographs)
Define rheumatoid factor
Antibodies that recognize the Fc portion of IgG as their target antigen typically IgM antibodies i.e. IgM anti-IgG antibody
What substance makes synovial fluid viscous?
Hyaluronic acid a non-sulphated glycosaminoglycan
Define Reactive Arthritis
Sterile inflammatory synovitis following an infection whose extra-articular manifestations may include:
- Enthesopathy
- Skin inflammation (circinate balanitis, keratoderma blennorrhagicum)
- Eye inflammation (conjunctivitis)
- HLA-B27 association
List two infections associated with Reactive Arthritis
Classically Gut and urogenitary
Urogenital infections
•E.g. Chlamydia trachomatis
Enterogenic infections
•E.g. Salmonella, Shigella, Campylobacter infections
(Reactive arthritis may be first manifestation of HIV or hepatitis C infection)
Define and give two examples of an enthesopathy
Inflammation where a ligament, tendon, fascia or capsule insert into bone. Examples include:
- Achilles tendonitis (painful heel)•
- Plantar fasciitis (painful feet)
- Spondylitis (spinal inflammation) in Ankylosing Spondylitis
- inflammation where the outer part (annulus fibrosis) of the inter-vertebral disc inserts into the vertebral body
What is the HLA association of Rehumatoid arthritis
HLA-DR4
What is the HLA association of Reactive arthritis
HLA-B27
Summarise osteoarthritis
Irreversible loss of articular cartilage, Mechanical in aetiology, mainly in the ageing population
Define (i) proteoglycan and (ii) glycosaminoglycan and give one example of each
Proteoglycan: glycoproteins containing sulphated glycosaminoglycan chains e.g.
•Aggrecan
Glycosaminoglycan repeating polymers of disaccharides e.g.
•Chondroitin sulphate
•Keratan sulphate
•Hyaluronic acid (= hyaluronate)
What is the major collagen found in articular cartilage?
Type II collagen
What is the major proteoglycan found in articular cartilage?
(i)Aggrecan
What is an osteophyte and name a condition in which they may be seen
Osteophytes, commonly referred to as bone spurs[1] are bony projections that form along joint margins.
Osteoarthritis (eg Heberden’s nodes)
What is the major HLA association for SLE?
HLA- DR3
Summarise the composition of bone
Bone is comprised of protein matrix (osteoid) and mineral (hydroxyapatite)
Define osteoporosis
Predisposition to skeletal fractures resulting from reduction in regional or total bone mass.
Bone chemistry is normal (serum calcium, phosphate, PTH, alkaline phosphatase)
What does a T-score calculate?
How many standard deviations the patient’s score is above/below the mean for a young, normal subject’s, representing ‘peak bone mass’
What are the paramenters for the following conditions?
Define osteomalacia
Osteomalacia literally means ‘soft bones’ and is defined as impaired mineralisation in mature bones. Rickets is impaired mineralisation in immature bones
What are the causes of osteomalacia ?
Due to inadequate phosphate and/or calcium
Caused by:
- Vitamin D deficiency
- Abnormal vitamin D metabolism e.g. liver or kidney disease
- Hypophosphataemia (may be due to renal phosphate loss which can be determined by measuring urinary phosphate levels)
What are the biochemical features of osteomalacia
- Low or normal serum calcium
- Low phosphate (PTH drives out phosphate throught the kidneys)
- Secondary hyperparathyroidism i.e. high PTH and high serum alkaline phosphatase