Musc 9 - Revision

Question 1

List the key features of rheumatoid arthritis

F>M

Answer 1

1. Morning stiffness in and around joints
2. Symmetrical poly arthritis - typically involves small joints of the hand and/ wrist
3. Subcutaneous nodules
4. Rheumatoid factor
5. Joint erosions on radiographs

Question 2

Define rheumatoid factor

Answer 2

Antibodies that recognise Fc portion of IgG as their target antigen

Rheumatoid factor is typically IgM antibody (i.e. IgM anti-IgG antibody)

Question 3

What substance makes synovial fluid viscous?

Answer 3

Hyaluronic acid (a non sulphated GAG)

Question 4

Describe synovium

Answer 4

It is a 1-3 cell deep lining

Type A synoviocytes: macrophage like, phagocytic

Type B synoviocytes: fibroblast like, produce hyaluronate

Collagen is Type 1

Synovial fluid = hyaluronate rich viscous fluid

Question 5

Define reactive arthritis

M>F,

20-40 y/o, typically asymmetrical and oligoarticular. Large joints

HLA-B27

Answer 5

Sterile inflammatory synovitis - following an infection

Extra-articular manifestations may include:

• Enthesopathy
• Skin inflammation
• Eye inflammation

Question 6

List 2 infections associated with reactive arthritis

Answer 6

1. Urogenital infections - e.g. chlamydia trachomatis
2. Enterogenic infections - salmonella, shigella, campylobacter infections

Reactive arthritis may be the first manifestation of HIV or Hep C

Question 7

Define and give 2 examples of enthesopathy

Answer 7

Enthesopathy = inflammation where ligament/tendon/fascia/capsule insert into bone

e.g. Achilles tendonitis, plantar fasciitis, dactylitis, spondylitis in ankylosing spondylitis

Question 8

What is the key pathological finding in osteoarthritis?

Answer 8

Irreversible loss of articular cartilage

Question 9

What are the other pathological changes in OA

Answer 9

1. Focal areas of damage to articular cartilage
2. New bone formation at joint margins (osteophytosis)
3. Changes in subchondral bone (sclerosis)

Question 10

Define proteoglycan and give an example

Answer 10

Glycoproteins containing sulphated GAG chains - e.g. Aggrecan

Question 11

Define glycosaminoglycan and give an example

Answer 11

GAG = repeating polymers of disaccharides

e.g. chondroitin sulphate (glucuronic acid and N-acetyl galactosamine) / keratan sulphate (galactose and N-acetyl glucosamine) / hyaluronic acid (glucuronic acid and N-acetyl glucosamine)

Question 12

What is the major collagen found in articular cartilage?

What is the major proteoglycan found in articular cartilage?

Answer 12

Collagen type 2 (articular cartilage has 2 ts - type 2, bone has one in it so type 1)

Aggrecan

Articular cartilage is negatively charged so attracts a lot of water

Question 13

List the major HLA association for each of the following diseases:

Ankylosing spondylitis and reactive arthritis

SLE

Rheumatoid arthritis

Answer 13

Ankylosing spondylitis = HLA-B27

SLE = HLA-DR3

Rheumatoid arthritis = HLA-DR4

(SLE = 3 letters do DR3)

(2 words Ankylosing spondylitis, 7 syllables avg in ankylosing spondylitis and reactive arthritis - HLA-B27)

(U will remember that u is the 4th letter in rheumatoid so DR4)

Question 14

Summarise the composition of bone

Answer 14

Bone =composed of protein matrix (osteoid) and mineral (hydroxyapatite)

Question 15

Define osteporosis

Answer 15

Predisposition to skeletal fractures resulting from reduction in regional or total bone mass

Has normal bone chemistry (serum Ca, PO4, PTH, alkaline phosphatase)

Assessed by DEXA, T score. -1 - -2.5 = osteopenia. < -2.5 = osteoporosis

Question 16

Define osteomalacia

Answer 16

Osteomalacia = impaired mineralisation in mature bones. Ricket = impaired mineralisation in immature bones

Causes = Vit D deficiency, abnormal Vit D métabolism, hypophosphataemia.

Associated with low/normal serum Ca, low phosphate, secondary hyperparathyroidism (high PTH, high serum alkaline phosphatase)

Question 17

Define Pagets disease

Answer 17

Disorder of bone remodelling - unknown cause (increased bone resorption), then increased bone formation –> resulting in disorganised mosaic pattern of woven and lamellar bone

Bone chemistry = high alkaline phosphatase

Paget’s associated with increased cortical bone thickness on radiographs

Abnormal bone causes pain and bone deformity/fracture

Question 18

What are some radiological features of HPT

Answer 18

1. brown tumours
2. chondrocalcinosis
3. osteosclerosis
4. salt and pepper skull
5. rugger-jersey spine
6. sub-periosteal resorption

Question 19

What are the musculoskeletal disorders in chronic renal failure

Answer 19

1. Secondary and tertiary HPT
2. Osteomalacia
3. Soft tissue and vascular calcification