1. BONE PATHOLOGY

2. The Skeletal System Parts of the skeletal system
Bones (skeleton)
Joints
Cartilages
Ligaments (bone to bone)(tendon=bone to muscle)
Divided into two divisions
Axial skeleton
Appendicular skeleton – limbs and girdle
The skeleton has 206 bones

3. Functions of Bones Support of the body Protection of soft organs
Movement due to attached skeletal muscles
Storage of minerals and fats
Blood cell formation

4. Normal bone

6. Types of Bone Cells Osteocytes Osteoblasts Osteoclasts
Mature bone cells
Osteoblasts
Bone-forming cells
Osteoclasts
Bone-destroying cells
Break down bone matrix for remodeling and release of calcium
Bone remodeling is a process in which both osteoblasts and osteoclasts participate

8. Bone Fractures A break in a bone Types of bone fractures
Closed (simple) fracture – break that does not penetrate the skin
Open (compound) fracture – broken bone penetrates through the skin
Bone fractures are treated by reduction and immobilization
Realignment of the bone

9. Stages in the Healing of a Bone Fracture
Slide 5.19

10. Stages in the Healing of a Bone Fracture
1-Haematoma formation
2-Fibrocartilage callus formation
3-Boney callus formation
4-Bone remodelling
Slide 5.19

11. Classification of Bone Pathology:
Infectious Diseases of Bone
Developmental Disorders of Bone
Metabolic Disorders of Bone
Avascular Bone Necrosis (Osteonecrosis)
Paget’s Disease of Bone
Tumors of Bone

12. Infectious Diseases of Bone
Osteomyelitis
Pott’s Disease

13. OSTEOMYELITIS Classification:
Definition:
This is inflammation of bone and bone marrow
Classification:
Non- bacterial osteomyelitis:
Viral osteomyelitis
Sarcoidosis
Radiation osteomyelitis

14. Bacterial osteomyelitis:
Acute suppurative osteomyelitis
Acute haematogenous osteomyelitis
Acute non-haematogenous osteomyelitis
Chronic osteomyelitis:
Chronic non-specific osteomyelitis
Chronic specific osteomyelitis ( TB & Syphilis)

15. ACUTE HAEMATOGENIUS OSTEOMYELITIS
Definition: Acute osteomyelitis is an acute inflammation of bone caused by an infecting organism
Haematogenous osteomyelitis is predominantly seen in children and involves the highly vascular long bones especially those of the lower limbs.
In adults, haematogenous spread is more common to the lumbar vertebral bodies than elsewhere.

16. Pathogenesis The spread of infection is usually haematogenous.
1-Among children: the metaphysis of the long bones is the most common site, where blood flow slows in the sinusoids, allowing bacteria to adhere to the vascular membranes.
2-Local trauma with skin penetration and seeding of organisms is another pathway.
3-Localized trauma without skin penetration to the bone causing haematoma, vascular obstruction in the metaphyseal region and bacteraemia at around the same time result in infection.

18. Metapheseal blood sinsoids

19. Stages of disease
1-Inflammation: Initial inflammation with vascular congestion and increased intra-osseous pressure. 2-Suppuration: Pus within the bones forces its way through the Haversian system and forms a subperiosteal abscess in 2-3 days.

20. 3-Sequestrum: Vascular obstruction and infective thrombus decrease or obstruct the periosteal and endosteal blood supply, causing bone necrosis and sequestrum formation in approximately 7 days.
4-Involucrum: This is new bone formation from the stripped surface of periosteum.
5-Resolution or progression to complications: With antibiotics and surgical treatment early in the course of disease, osteomyelitis resolves without any complications.

21. MP of acute osteomyelitis
Inflammation of bone

22. Acute osteomyelitis

23. Complications of osteomyelitis:
Pathological fracture
Spread of infection: eg. Arthritis (joint inflammation), myositis (muscle inflammation) or neuritis (nerve inflammation)
Blood spread: causing toxaemia & septicaemia
Chronic suppurative osteomyelitis: including sequestrum formation and skin sinus formation
Damage to the growth plate causing subsequent growth deformity

24. Pott's disease
Pott's disease is a presentation of extra pulmonary tuberculosis that affects the spine, a kind of tuberculous arthritis of the intervertebral joints.
The lower thoracic and upper lumbar vertebrae are the areas of the spine most often affected.

25. Pott’s Disease

26. Tuberculosis of the spine in an Egyptian mummy

27. Clinical presentation:
Back pain
Fever
Night sweating
Anorexia
Weight loss
Spinal mass, sometimes associated with numbness, paraesthesia or muscle weakness of the legs

28. Diagnosis Blood tests – elevated erythrocyte sedimentation rate (ESR)
Tuberculin skin test
Radiographs of the spine
Bone scan
CT of the spine
Bone biopsy
MRI

29. Pott’s Disease; X-ray
Pott’s Disease; MRI

30. Complications Vertebral collapse resulting in kyphosis
Spinal cord compression
Sinus formation
Paraplegia (called Pott's paraplegia)

31. Tuberculous in long bones
Commonly around the knee, affects metaphysis and epiphysis, rarely diaphysis
Well-defined lytic area

32. Tuberculous arthritis
The hip and knee are the
most commonly affected
peripheral joints.
Characterized by joint space
narrowing and erosions which
may lead to extensive destruction
of the articular cortex.

33. HEREDITARY BONE DISORDERS
Achondroplasia
Osteogenesis imperfecta
osteopetrosis

34. Achondroplasia Clinically:
Long bones are short and thick  short extremities  dwarfism
Cranial and vertebral bone spared  relatively large head and trunk
Normal intelligence, life span and reproductive ability

35. Achondroplasia

36. Osteogenesis imperfecta
1-Generalized osteopenia: brittle
bones, resulting in recurrent
fractures and skeletal deformity
2-Most patients have an
abnormally thin sclera with
blue hue
Abnormally thin sclera with blue hue

37. Laxity of joint ligments leads to hypermobilty
Involvement of the bones of the inner and middle ear produces deafness
Some patients have dentinogenesis imperfecta: small, fragile and discolored teeth due to deficiency of dentin
The skin may be abnormally thin and the skin is susceptible to easy bruising

38. Osteogenesis imperfecta
Laxity of joint ligaments
Osteogenesis imperfecta
Brittle bones

39. Dentinogenesis imperfecta

40. Osteopetrosis Marble bone
Hereditary defect leading to thick sclerotic bones
Pathology:
-Increased bone density and thickening of bone cortex
-The thickened bones are brittle and fracture easily

41. X-ray findings: Symmetrically generalized osteosclerosis
Long bones may have broadened metaphyses, resulting in an "Erlenmeyer flask" deformity

42. Osteopetrosis X-ray findings
Symmetrically generalized
Osteosclerosis
Long bones may have broadened
metaphyses, resulting in an
"Erlenmeyer flask" deformity
Osteosclerosis
Erlenmeyer flask
shaped deformity

43. Metabolic Diseases of Bone

44. Osteoporosis Refers to increased porosity of skeleton.
Osteoporotic bones:
Thin and fragile and are susceptible to fracture.
Occurs due to:
Loss of organic bone matrix and minerals.
Resulting in :
Decreased bone mass and density.
Decreased thickness of cortical and trabecular bone.

45. Osteoporotic vertebral body Normal Vertebral body
Osteoporotic vertebral body (right) shortened by compression fractures, compared with a normal vertebral body.
Osteoporotic
vertebral body
Normal
Vertebral body

46. Fracture
Osteoporosis
Vertebrae, osteoporosis - Gross, cut surfaces  

47. Types of Osteoporosis Localized : e.g. disuse of a limb
Generalized: involves entire skeleton.
Primary:
Old age (Senile)
Estrogen deficiency (postmenopausal)
Secondary: (due to underlying disease)
Cushing’s disease (Hypercortisolism)
Drugs (Heparin and Steroids)

48. Postmenopausal Osteoporosis
Due to estrogen deficiency
Estrogen deficiency  increased resorption of bone by osteoclasts and decreased formation of bone by osteoblasts.

49. Osteoporosis Genetic factors Physical activity Peak bone mass
Nutrition
Menopause
↓ estrogen
↑ osteoclast activity
Aging
↓ activity of osteoblasts
↓ physical activity
Pathophysiology of postmenopausal and senile osteoporosis
Osteoporosis

50. Clinical findings: Bone pain Weight bearing bones predisposed to
Compression of vertebral bodies (most common)
Colles’ fracture of distal radius.
Fracture femoral neck.
Loss of height and kyphosis

52. Diagnosis:
Dual energy X ray absorptiometry (DEXA) to evaluate bone density.

53. Osteonecrosis (Avascular Necrosis)

54. Osteonecrosis (Avascular necrosis)
Ischemic infarction of bone & bone marrow.
Causes of ischemia:
Vascular interruption (fracture)
Corticosteroids (most common)
Sickle cell disease
Common sites include
Femoral head
Scaphoid bone.

55. Osteonecrosis
Femoral head with a subchondral, wedge-shaped pale yellow area of osteonecrosis

56. Osteonecrosis Osteonecrosis of the head of the femur.
A coronal section shows a circumscribed area of subchondral infarction with partial detachment of the overlying articular cartilage and subarticular bone.

57. PAGET’S DISEASE

58. Definition: Localized disorder of bone
Due to: Excessive bone resorption followed by disorganized bone replacement
Resulting in: Thickened but weak bone that is susceptible to deformity and fracture

59. Stages of paget disease
Osteolytic: osteoclastic activity predominates
Mixed ostelytic-osteoblastic
Osteosclerotic: osteoblastic activity predominates " burnout stage"

60. Diagrammatic representation of Paget disease of bone, demonstrating the three phases in the evolution of the disease.

61. Etiology: Possible slow virus infection
Possible genetic predisposition

62. Clinical features: Asymptomatic in most cases
Bone pain and deformities
Fractures
Warmth of overlying skin due to hypervascularity

63. Forms of involvement: Monosteotic (15%): involving one bone
Polyosteotic (85%) : involving multiple bones
Common sites include the skull, pelvis, femur and vertebrae

64. PATHOLOGY Microscopically :
Haphazard arrangement of cement lines, creating a mosaic pattern
Skull involvement:
Increase head size
Foramina narrowing causes impingement of cranial nerves, often leading to deafness
Involvement of facial bones may produce a lion-like facies

65. X-rays: Lab investigation: Complication:
Bone enlargement with lytic and sclerotic areas
Lab investigation:
Highly elevated serum alkaline phosphatase
Complication:
Osteosarcoma
Others sarcomas

67. Osteolytic changes of the skull

68. Mosaic pattern of lamellar bone

69. BONE TUMORS
BENIGN TUMORS OF BONE

70. Classification of benign tumors of bone:
Osteoma
Osteoid osteoma
Osteoblastoma
Osteochondroma
Osteochondromatosis
Enchondroma

71. Osteoma
Definition:
Benign neoplasm that frequently involves the skull and facial bones

72. Osteoid osteoma Definition: Clinically: X-ray:
Benign, painful growth of the diaphysis of a long bone, often the tibia or femur
Clinically:
Males> females
Age: 5-25 years
Pain that is worse at night and relieved by aspirin
X-ray:
Central radiolucency surrounded by sclerotic rim

73. Osteoid osteoma

74. Osteoblastoma
Similar to an osteoid osteoma but is larger (>2cm) and often involves vertebrae

75. Osteochondroma (Exostosis)
Definition:
Benign boney capped with cartilage that originates from epiphyseal growth plate
Clinical presentation:
Adolescent males
Firm solitary growths at the end of the long bones
They may be asymptomatic or it causes pain, deformity or it can undergo malignant transformation (rare)

76. Osteochondroma

77. Osteochondromatosis
Multiple hereditary exostosis in which there is multiple symmetric osteochondromas

78. Enchondroma Definition:
Benign cartilaginous growth within the medullary cavity of bone, usually involving the hands and feet
Typically solitary and asymptomatic and require no treatment

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