Bone Bone Disorders and Fractures

  1. Cells responsible for new bone formation
  2. Living elements of bone which regulate flow of minerals in and out of the bone
  3. Living tissue composed of cells, calcium, collagen, proteins, and water
  4. Examples are skull, sternum, and ribs
    Flat bones
  5. Type of bone for weight bearing
    Long bones
  6. Examples are carpals and tarsals
    Short bones
  7. Round and small bones which protect tendon
    Sesamoid bones
  8. Part of bone which forms the shaft
  9. Part of bone which forms the bone ends and supports the articular surface
  10. Part of bone found between diaphysis and epiphysis
  11. Part of bone between metaphysis and epiphysis
    Physis (epiphyseal growth plate)
  12. Cells responsible for bone resorption
  13. Primary ossification center of bone
    Medullary canal
  14. Sheaths surrounding the haversian/central canal
  15. Oblique channels connecting osteons/haversian systems
    Volkmann's canals
  16. Spaces within lamellar which serve as storage sites of osteocytes
  17. Functions of bone
    • Protects vital structures
    • Enhances leverage
    • Provides attachment
    • Stores minerals
    • Important during palpation (serves as landmark)
  18. Every change in the form and function of bone is followed by certain definite change in its internal architecture
    Wolff's Law
  19. Most widely used and validated tool to assess bone mineral density
    Dual energy x-ray absorptiometry (DEXA) scan
  20. Columns that are parallel to the long axis of bone
    Haversian systems (osteons)
  21. Microscopic canals between lacunae of ossified bone
  22. Normal BMD
    1 SD above or below the mean average of young adults
  23. 1-2.5 SD below the mean average of young adults
  24. Osteoporosis BMD
    >2.5 SD below the mean average of young adults
  25. MC bone disease in adults
  26. Racial characteristics associated with osteoporosis
    Asian, Caucasian, Hispanic
  27. Common sites of osteoporotic fractures
    • 1. Midthoracic
    • 2. Upper lumbar
    • 3. Hip
    • 4. Distal forearm
  28. Epidemiology of osteoporosis
    • F>M until 75 years old
    • F=M after 75 years old
  29. MC form of short-limb dwarfism
  30. Endochondral osteogenesis is retarded and ceased early
  31. Characteristics of achondroplasia
    • 1. Short arms and legs
    • 2. Height: 4 ft.
    • 3. Broad forehead
    • 4. Prominent jaw
    • 5. Small face
    • 6. Flat nose
    • 7. Brachycephalic (decreased AP diameter of head)
    • 8. Pudgy fingers
    • 9. Main en trident (gap between 3rd and 4th fingers)
    • 10. Bowing of femur and tibia
  32. Isolated fracture of the iliac wing secondary to direct blow to the ilium
    Duverney's fracture
  33. Very rare autosomal dominant genetic condition characterized by symmetric expansion of diaphysis resulting to leg pain, gait abnormalities, muscle weakness, and increased fatigability
    Engelmann's disease (progressive diaphyseal dysplasia)
  34. Fracture of base of fifth metatarsal
    Jones fracture
  35. Crushed fracture of cuboid and anterior calcaneus
    Nutcracker fracture
  36. Group of skeletal dysplasias primary characterized by punctate calcifications in cartilage (calcific stippling)
    Chondrodysplasia punctata
  37. Genetic disorder characterized by osteoclast dysfunction that leads to excessive osteoid tissue formation
  38. Acquired disease in which the osteoclast dysfunction initially causes excessive removal of bone and is later deposited at different rates during the different stages of the disease
    Paget's disease (osteitis deformans)
  39. Softening of bone due to poor and delayed calcification
  40. Bone disorder caused by mutation in fibroblast growth factor receptor 3

    B) Achondroplasia
  41. Osteoporosis is usually not visible on conventional radiographs until at least ___% of bone mineral has been lost

    C) 25-30
  42. Procedure of greatest clinical utility for measuring bone density
    Dual-energy x-ray absorptiometry (DXA) scan
  43. Senile and postmenopausal osteoporosis are examples of primary osteoporosis.

    Meanwhile, secondary osteoporosis occurs in association with other conditons (e.g. rheumatoid arthritis, vitamin D deficiency), medications (e.g. phenytoin, corticosteroids), or disuse with immobility.
  44. BMD is within 1 SD of a "young normal" adult

    B) Normal
  45. BMD is between 1 and 2.5 SDs below that of a "young normal" adult

    A) Osteopenia
  46. BMD is 2.5 SDs or more below that of a "young normal" adult

    C) Osteoporosis
  47. More fractures occur in persons with osteopenia compared to those with osteoporosis.

    Persons with osteopenia far outnumber those with osteoporosis; thus, more fractures occur in the osteopenic population.
  48. Recommended daily calcium intake for 19-50 years old

    D) 1000 mg/d
  49. Recommended daily calcium intake for >50 years old

    D) 1200 mg/d
  50. Which age range has the highest recommended daily calcium intake?

    A) 9-18 years

    • The recommended daily intake for the following age ranges are as follows:
    •  1. 0-6 months = 210 mg/d
    •  2. 4-8 years = 800 mg/d
    •  3. 9-18 years = 1300 mg/d
    •  4. > 50 years = 1200 mg/d
  51. Pregnant or lactating women who are 18 years or younger require higher daily calcium intake than their older counterparts.

    Pregnant or lactating women who are 18 years old or younger require 1300 mg of calcium per day; whereas those who are aged 19-50 years only require 1000 mg/d.
  52. At what age can a child begin to intake calcium via solid food?

    D) 7-12 months

    At 0-6 months of age, calcium intake only comes from human milk.
  53. For men and women aged 50 or older, the current recommendation for daily intake of vitamin D is 800-1000 IU/day.
  54. To aid in absorption of calcium and mineralization of bone, this is commonly prescribed as a supplement for patients who lack the 1-α-hydroxylase enzyme because of severe renal impairment

    A) 1,25-dihydroxycholecalciferol
  55. Vitamin D supplements can increase the risk for kidney stones, hypercalciuria, nephrolithias, or even nephrocalcinosis in patients at risk.

    Vitamin D supplements can cause such risks because they increase calcium absorption in the gut.
  56. For optimal bone health, an exercise program should include:

    A) Both of the above
  57. Most critical period of bone growth

    A) Puberty and adolescence
  58. What cell is responsible for the breakdown and resorbtion of the bone matrix?

    C) Osteoclasts

    Osteoclasts are the cells responsible for the breakdown and resorption of bone tissue for the purpose of remodelling in response to the stresses and pressures placed on it.

    Osteoblasts are the cells responsible for creating new bone tissue after osteoclasts have resorbed old bone tissue, they are also responsible for turning hyaline cartilage into bone tissue during new bone growth and turning the fibrocartilaginous callous into new bone during fracture repair.

    Osteocytes are the cells that make up healthy bone. These are found in the lacunae in the osteons of compact bone.

    Periosteum is the outer layer of the bone. It provides blood supply and protection to the bone, the inner layer contains the osteogenic cells required to make new bone during growth and repair.
  59. What is the pathogenesis of osteopetrosis (marble bone disease)?

    B) Poor osteoclast function due to a carbonic anhydrase II mutation

    An acidic environment is needed for osteoclasts to remove calcium from bone. A defect in maintaining this acidic environment leads to poor bone resorption by osteoclasts resulting in overgrowth and sclerosis of cortical bone. This abnormally thick bone fractures easily. Clinical features include bone fractures, anemia, thrombocytopenia (due to the bony replacement of marrow), and visual/ hearing loss due to cranial nerve compression. The patient can also develop renal tubular acidosis (defect in carbonic anhydrase leads to decreased reabsorption of bicarbonate) and hydrocephalus (due to narrowing of the foramen magnum).
  60. Which bone disorder is caused by an autosomal dominant mutation that impairs the synthesis of type 1 collagen?

    C) Osteogenesis imperfecta

    Osteogenesis imperfecta is also known as ‘brittle bone disease’. It is a congenital defect of bone formation. Clinical findings include multiple pathologic fractures, blue sclera, and deafness due to fractures of the bones in the middle ear.
  61. What is the pattern of inheritance of vitamin-D resistant rickets?

    B) X-linked dominant

    Other X-linked dominant conditions are fragile X syndrome and Alport syndrome.

    X-linked recessive conditions include red-green color blindness, hemophilia A and B, and Duchenne and Becker's muscular dystrophy.

    Autosomal dominant conditions include Huntington's disease, myotonic dystrophy, and Marfan's syndrome.

    Autosomal recessive conditions include cystic fibrosis.
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Bone Bone Disorders and Fractures