1. Bone Pathology

2. Bone Pathology The cells Anatomy of bone Bone growth
Types of fractures
Fracture healing
Fat emboli
Osteoporosis
Osteomalacia/Rickets
Compartment syndrome

3. The Cells
Osteoblasts
Osteoclasts
Fibroblasts
Chondroblasts

6. Anatomy of Bone
Spongy bone
Compact bone

9. Spongy Bone
Trabeculae
Spaces filled with red marrow
Haematopoiesis

10. Compact Bone
Osteon
Central Haversian canal surrounded with lamellae of hard bone
Perforating (Volkmann) canals
Osteocytes
Lacunae
Canaliculi

12. Osteogenesis
Intramembranous
Endochondral

17. Bone Growth
Length
Appositional
Remodelling
Hormonal regulation

21. Types of Fractures

31. Fracture Healing 1 Haematoma 2 Fibrocartilaginous callous
3 Bony callous
4 Remodelling

32. Haematoma Local shock (minutes to 1/2 hour)
Static blood at fracture site
Bone cells lack oxygen and die

34. Fibrocartilaginous Callous
days
Capillaries grow into haematoma
Phagocytes clean up debris
Fibroblasts and osteoblasts migrate
Fibroblasts produce collagen
Osteoblasts form spongy bone
Chondroblasts secrete cartilage matrix
Bone is “splinted”

36. Bony Callous
weeks
Osteoblasts migrate inwards and multiply to form callous of spongy bone

38. Remodeling Months Excess callous shrinks Compact bone laid down
Final structure is a response to the mechanical stress experienced by the bone

40. Factors Affecting Healing
nature of injury
amount of bone loss
type of bone injured
degree of immobilization
infection
circulation

41. Fat Emboli may appear in lung or peripheral capillaries
Fat Embolism Syndrome
dyspnoea
confusion
tachycardia
fever
rash
fat globules in sputum and urine

42. Osteoarthritis Wearing out of the joint
Obesity, marathon runners, gymnasts
Health of chondrocytes determines joint integrity
Changes in both composition and mechanical properties of cartilage
Cracks appear in cartilage
Subchondral bone becomes exposed

43. Osteoarthritis
Fragments of cartilage and bone become free floating “joint mice”
Osteophytes or spurs form at joint margins
Non specific inflammation of the synovium

44. Mechanical injury
Chondrocyte response
Release of
Cytokines
(e.g. TNF, IL-1)
Production, release
of protease enzymes
Loss of smooth
cartilage surface
Development of
surface cracks
Destruction of
Subchondral bone
Destruction of
joint structures
Osteophyte
formation

46. Disc degeneration
Disc narrowing producing low back pain and disc degeneration are related to increasing BMI.

47. Osteoporosis A gradual decrease in bone mass risk of fractures
bone resorption is greater than bone formation
bone loss involves matrix and minerals
exercise and good nutrition may prevent or delay osteoporosis

48. Postmenopausal osteoporosis
due to decrease in oestrogen levels
oestrogen stimulates osteoblasts to form bone and inhibits osteoclasts
fractures tend to be in vertebrae & distal radius due to loss of trabeculae

49. Prevention
changes are reversed during oestrogen therapy (but what else?)
Calcium: RDA = 1000mg/day; RDA(post-menopause) = 1200mg/day
weight bearing exercise increases bone mass

50. Model for the Effects of Physical Activity on Bone Mass
Increased BMD
BMD
(g/cm2)
adulthood
menopause
growth
“Fracture Threshold”
AGE

51. Osteomalacia/Rickets
abnormal levels of minerals in bone
due to low levels of Vit D
caused by:
diet deficiency (Vit D or calcium)
low sun exposure
chronic renal failure
liver disease

52. Compartment Syndrome

54. Compartment Syndrome collagenous fascia doesn’t stretch
haemorrhage is contained
pressure may increase compromising blood flow and nervous function distally
fasciotomy may be required