Bone Disease

Question 1

Osteoblasts

Answer 1

Form bone (collagen and mineralises (calcium and phosphorous delivered))
Release cytokines to stimulate
bone resorption by OCIs

Generally tell osteoclasts what to do

Question 2

Osteoclasts

Answer 2

Largest cell in body
Fused macrophages
Degrade bones (resorption) with enzymes
Interacts with the osteoblasts

Question 3

Osteomyelitis

Answer 3

• inflammation of bone marrow
• caused by bacteria (staph, haematogenous spread through blood stream), surgery, Ulcers on the skin
• caused by poor dental hygiene and infection of jaw, children and elderly hospitalised that have undergone surgery, diabetics

Question 4

Often occurrence in children

Answer 4

Bacteria enter blood stream through cut
Become caught in loops of capillaries near bones, develop thrombosis.
Ischaemia occurs- ischaemic necrosis
Bacteria thrive in hypoxic environment- proliferate
Formation of abscess
Forms sequestering- dead and dying bone
Involucres- new bone formation and resorption induced by infection- formed underneath periosteum - abnormal

Question 5

Osteomalacia and rickets

Answer 5

• abnormalities of vit D metabolism
• 1, 25(OH)2D3
• take in from small bowel. Travels from skin to liver, then delivered to kidney where it is transformed into active form. Here, acts on absorption of calcium from small intestine, deposit this on bone.
• lack of calcium in the collagen of bone
• due to decreased nutritional calcium intake, decreased oral vit D intake, decreased UV light, renal disease, small bowel disease etc.
• bowing of bones

Question 6

Osteopenia and osteoporosis

Answer 6

• decreased bone tissue: usually decreased formation and increased resorption.
• osteopenia - 1-2.5 standard deviations below young adult average - usually localised
• osteoporosis - 2.5 standard deviations below the average bone mineral density - prolonged immobilisation, astronauts, decreased muscle mass, increased corticosteroids stimulating osteoclasts to resorb bone, age

Question 7

Post menopausal op

Answer 7

• stop producing oestrogen, reduction in size of ovaries (atrophy). Approximately 48-50 years. Begins earlier in hysterectomy. Therefore, large increase in osteoclasts resorbtion causing a net loss of bone.
• most important aetiological factor is genetics, followed by oestrogen deficiency
• concordance rate >50%

Question 8

Risk factors for post menopausal OP

Answer 8

• late menarche (late onset of menstruation) and or early menopause- should be approaching 40 years.
• low calcium intake- cannot absorb calcium as well when we are older
• low vitamin D formation, intake or effect
• low weight bearing exercise
• excess alcohol and smoking
• being underweight
• low peak bone mass
• clinically
• back pain, decreased heigh (vertebral crush factor), dorsal kyphosis
• fracture

Clinically:

• back pain, decreased height (vertebral crush factors), dorsal kyphosis
• fracture