This document discusses three bone diseases: osteoporosis, rickets, and osteomalacia. It provides details on the causes, risk factors, symptoms, diagnosis, and treatment of osteoporosis. It explains that osteoporosis is a disease where loss of bone density leads to fragile bones that fracture easily. Rickets causes weak, soft bones in children due to vitamin D deficiency and inadequate mineralization. Osteomalacia is the same disease as rickets but occurs in adults.

1. Bones
(Applied Physiology)
DANISH HASSAN
LECTURER, UNIVERSITY OF SARGODHA

2. Diseases of Bone
1. Osteoporosis
2. Rickets
3. Osteomlacia

3. Osteoporosis
 Bone disease characterized by the loss of bone
matrix and minerals.
 Osteoporosis means‘porous bones’.
 It involves a reduction in total bone mass, with an
equal loss of both bone mineral and organic
matrix.

4.  It is responsible for more than 1.5 million fractures
annually, including 300,000 hip fractures, 700,000
vertebral fractures, 250,000 wrist fractures, and
300,000 fractures at other sites.
 Nearly one third of people who have hip fractures
end up in nursing homes within a year; nearly 20%
die within a year.

5. A normal bone (Left) and an Osteoporotic bone (Right)

7.  Causes of Osteoporosis
1. Occurs due to excessive bone resorption and
decreased bone formation.
2. Long-term dietary calcium deficiency can lead to
osteoporosis because bone mineral is mobilized to
maintain plasma calcium levels.
3. Vitamin C deficiency can also result in a net loss of
bone because vitamin C is required for normal
collagen synthesis to occur.

8. 4. A defect in matrix production and the inability to
produce new bone eventually result in a net loss of
bones.
5. A reduction in the mechanical stress placed on
bone can lead to bone loss.
6. Immobilization or disuse of a limb, such as with a
cast or paralysis, can result in localized osteoporosis
of the affected limb.

9. 7. Space flight can produce a type of disuse
osteoporosis resulting from the condition of
weightlessness.

10.  Risk Factors
1. Sedentary life
2. Genetic factor
3. Excessive smoking
4. Excessive alcohol or caffeine intake
5. Endocrine disorders like hypothyroidism, Cushing
syndrome, acromegaly and hypogonadism.

11. 6. Being a woman (especially a postmenopausal
woman)
7. Being of advanced age
8. Having a family history of the disease
9. Having low testosterone levels (in men)

13. Loss of bone Mass with Age

15.  Manifestations of Osteoporosis
 Loss of bone matrix and minerals leads to loss of
bone strength, associated with architectural
deterioration of bone tissue.
 Ultimately, the bones become fragile with high risk
of fracture.
 Commonly affected bones are vertebrae and hip.

16.  People may not know that they have osteoporosis
until they break a bone
 Vertebral (spinal) fractures may initially be felt or
seen in the form of
1. Persistent, unexplained back pain
2. Loss of height
3. Spinal deformities such as kyphosis or stooped
posture

19.  Diagnosis of Osteoporosis:
 Bone density determines the degree of osteoporosis
and the fracture risk.
 The most common test for measuring bone density is
dual-energy x-ray absorptiometry (DEXA) scanning.
 DEXA uses x-rays to measure bone density and
provides two measures of how dense bone is
 T score
 Z score.

20.  The T score compares the person’s bone density
with the average bone density of young healthy
adults of the same sex, a time when bone density is
at its peak.
 The Z score compares a person’s bone density with
that of people of the same age, sex, and weight,
and is less valuable in making predictions of risk of
fracture or in making decisions about treatment.

21.  Dual-energy X-ray Absorptiometry (DXA) Scan
Classification T-score
Normal -1 or greater
Osteopenia Between -1 and -2.5
Osteoporosis -2.5 or less
Severe Osteoporosis
-2.5 or less
and fragility fracture

22.  Prevention of Osteoporosis
 The principal current approaches include:
1. Estrogen replacement therapy
 Estrogen decreases bone loss in postmenopausal
women by inhibiting bone resorption, resulting in a
5–10% increase in BMD over 1–3 years.
 Calcium supplements enhance the effect of
estrogen on BMD.

23. 2. Bisphosphonates
 Bisphosphonates have a strong affinity for bone
apatite and are potent inhibitors of bone resorption.
 These agents reduce the recruitment and activity of
osteoclasts and increase their apoptosis.

24. 3. Calcitonin
 Calcitonin reduces bone resorption by direct
inhibition of osteoclast activity.
 Intranasal calcitonin produces significant effects on
BMD.
 Calcitonin is less effective in prevention of cortical
bone loss than cancellous bone loss in
postmenopausal women.

25. 4. Parath-hormone:
 Intermittent administration of human recombinant
PTH restores bone strength by stimulating new bone
formation at the periosteal (outer) and endosteal
(inner) bone surfaces, thickening the cortices and
existing trabeculae of the skeleton, and perhaps
increasing trabecular numbers and their
connectivity.

26. 5. Vitamin D analogs:
 Vitamin D analogs induce a small increase in BMD
that seems to be limited to the spine.

27. 6. Exercise:
 Physical activity early in life contributes to high peak
bone mass.
 Walking, weight training, and high-impact exercises
induce a small (1–2%) increase in BMD at some
skeletal sites.
 Load-bearing exercise is more effective for
increasing bone mass than are other types of
exercise

28. Rickets
 Bone disease in children, characterized by
inadequate mineralization of bone matrix.
 It occurs due to vitamin D deficiency.
 Vitamin D deficiency develops due to
insufficiency in diet or due to inadequate
exposure to sunlight.

29.  Deficiency of vitamin D affects the reabsorption
of calcium and phosphorus from renal tubules,
resulting in calcium deficiency.
 It causes inadequate mineralization of epiphyseal
growth plate in growing bones.
 This defect produces various manifestations

30.  Causes of Rickets
1. Deficiency of vitamin D
2. Low dietary intake
3. Inadequate synthesis in skin
4. Reduced absorption from intestine
5. Renal diseases
6. Chronic renal failure
7. Dialysis-induced bone disease
8. Renal tubular acidosis

31. Features of Rickets
 Collapse of Chest wall
 It occurs due to the flattening of sides of thorax with
prominent sternum.
 This deformity of the chest with projecting sternum is
called pigeon chest/chicken chest/pectus
carinatum.

32. Funnel Chest (Left) and Pigeon Chest (Right)

33.  Rachitic Rosary
 A visible swelling where the ribs join their cartilages.
 It is because of the development of nodules at
sternal end of ribs, which forms the rachitic rosary.

35.  Kyphosis
 Extreme forward curvature of the upper back bone
(thoracic spine) with convexity backward (forward
bending).
 Severe kyphosis causes formation of a hump
(protuberance) which is called humpback,
hunchback or Pott curvature

36.  Lordosis
 Extreme forward curvature of back bone in lumbar
region: also called hollow back /saddle back
 Scoliosis
 Lateral curvature of spine

37.  Harrison Sulcus:
 A groove in rib cage due to pulling of diaphragm
inwards.
 It may also appear in rickets because the patients
lack the mineralized calcium in their bones
necessary to harden them.
 Thus the diaphragm, which is always in tension, pulls
the softened bone inward.
 It is due to the indentation of lower ribs at the point
of attachment of diaphragm.

39.  Frontal Bossing
 If rickets occurs at a later age, thickening of the skull
develops.
 This produces frontal bossing and delays the closure
of the anterior fontanelle

41.  Bowing of hands and legs
 It is due to inability of the limbs to bear body weight
(especially lower limbs)

43.  Enlargement of liver and spleen
 Tetany:
 In advanced stages, the patient may die because
of tetany, involving the respiratory muscles.

45. Decreases
in serum calcium, serum
phosphorus, calcidiol, calcitriol,
urinary calcium.
The most common laboratory findings in
nutritional rickets are:
Increased Parathyroid
hormone, alkaline
phosphatase,
urinary phosphorus
levels are elevated.

46.  Types of Rickets
1. Nutritional Rickets
 Nutritional rickets results from inadequate sunlight
exposure or inadequate intake of dietary vitamin D,
calcium, or phosphorus.

47. 2. Vitamin D Dependent Rickets
 Vitamin D-dependent rickets, type I is secondary to
a defect in the gene that codes for the production
of renal 25(OH)D3-1-alpha-hydroxylase
 Vitamin D-dependent rickets, type II is a rare
autosomal disorder caused by mutations in the
vitamin D receptor. Type II does not respond to
vitamin D treatment; elevated levels of circulating
calcitriol differentiate this type from type I

48. 3. Vitamin D Resistant Rickets
 Rickets refractory to vitamin D treatment may be
caused by the most common heritable form, known
as vitamin D-resistant rickets or familial
hypophosphatemic rickets.
 Because of mutations of the phosphate-regulating
gene on the X chromosome, renal wasting of
phosphorus at the proximal tubule level results in
hypophosphatemia. Normal levels of calcitriol are
found in this disorder.

49. Osteomalacia
 Bone disease in adults, characterized by
inadequate mineralization of bone matrix.
 Rickets in adults is called osteomalacia or adult
rickets.

50.  Causes of Osteomalacia
 Osteomalacia occurs because of deficiency of
vitamin D.
 It also occurs due to prolonged damage of kidney
(renal rickets).

51.  Features of osteomalacia
1. Vague pain
2. Tenderness in bones and muscles
3. Myopathy leading to waddling gait (gait means
the manner of walking).
4. Occasional hypoglycemic tetany.