Orthopedics ,BMD test , osteopenia , osteoporosis

1. Bone Mineral Density
(BMD) test
-Dr.Apoorva.E
PG,DCMS

2. STRUCTURE OF A NORMAL BONE
• The majority of bone is made of the matrix.
• Difference between matrix of bone and that of
other cells is that the matrix of bone is hard.
• It has inorganic and organic parts.
MOLECULAR STRUCTURE :
MATRIX
INORGANIC
ORGANIC

3. • The inorganic part/bone mineral consists of
calcium hydroxyapatite (Ca10(PO4)6(OH)2).
• The organic part of matrix is mainly composed of
Type I collagen.
It is also composed of various growth factors
like glycosaminoglycans,osteocalcin, osteonectin,
osteopontin and Cell Attachment Factor.

4. CELLULAR STRUCTURE :
• There are several types of cells constituting the bone :
-Osteoblasts are bone-forming cells.They are the
immature bone cells which lay down the matrix as
unmineralised osteoid.They produce alkaline
phosphatase which helps in mineralisation of bone.
-Osteocytes originate from osteoblasts.Their functions
incude matrix maintenance and
calcium homeostasis.They are mature bone cells.
-Osteoclasts are the cells responsible for bone
resorption,thus they break down bone. New bone is
then formed by the osteoblasts.

5. ELECTRON
MICROGRAPHIC PICTURE
OF BONE MINERAL
STRUCTURE OF BONE

6. • In osteopenia and osteoporosis,there is an
imbalance between osteoblastic and osteoclastic
activity.Existing bone is reabsorbed faster than
new bone is made.
• As this occurs,the bones lose minerals,
heaviness(mass) and structure,making them less
dense,weaker and increasing the risk of fractures.
PATHOGENESIS OF OSTEOPENIA AND
OSTEOPOROSIS

7. What is a Bone Mineral Density
(BMD) test?
• A bone mineral density test is an easy,reliable
test that measures the density or thickness of
bones.
• It measures the amount of mineral (calcium)
in a specific area of the bone.
• The more mineral in the bone measured, the
greater is the bone density or bone mass.

8. • A BMD test can:
-Measure the density of bones
-Detect osteoporosis before a fracture occurs
-Help to predict chances of fracturing in the future
-Monitor the effectiveness of treatments for osteoporosis
and osteopenia.
• There are several different ways to measure BMD
1.Dual-energy X-ray absorptiometry (DEXA)
2.Peripheral dual-energy X-ray absorptiometry (P-DEXA).
3.Dual photon absorptiometry (DPA)
4.Quantitative computed tomography (QCT)
5.Quantitative ultrasound

9. • This is the most accurate and standardized
way to measure BMD.
• It uses two different X-ray beams to estimate
bone density in the spine and hip.
• It is a quick,easy and painless test where
nothing is injected or swallowed.
• A low-dose x-ray is taken which is is only 10%
of the radiation exposure of a chest x-ray.
Dual-energy X-ray absorptiometry
(DEXA)

10. DEXA SCANNER

11. Peripheral dual energy X-ray
absorptiometry (P-DEXA)
• P-DEXA is a type of DEXA test.
• It measures the density of bones in the arms
or legs,such as the wrist.
• P-DEXA machines are portable units.
• The results are quicker than standard DEXA
measurements.
• P-DEXA has a disadvantage of not being able
to monitor the treatment of osteoporosis.

12. Four Informative Skeletal Sites
1.Radius -The distal one-third of the radius
(wrist) is efficacious in predicting fracture risk.
2.Phalanx-The proximal phalanx.
3.Metatarsus-The 5th metatarsus.Measurement
at this site is particularly important because
weight-bearing bone may lose strength at a
different rate than non-weight-bearing bone.
4.Tibia-The mid-shaft of the tibia.It is useful in
the monitoring of treatment for osteoporosis.

13. INDICATIONS FOR BMD TEST
BMD is done in :
• All women aged 65 or older and men over 70
years of age regardless of risk factors
• Postmenopausal women under age 65 and
men in the age group of 50 – 70 years who
have one or more risk factors

14. RISK FACTORS FOR OSTEOPOROSIS
1.Having a current or previous fracture
2.On steroid medications for more than three months
3. Chronic anticonvulsant therapy
3.Men with low testosterone,alcoholism or any other secondary
cause of osteoporosis
4.Chronic rheumatoid arthritis
5.Chronic kidney disease
6.Early menopause
5.History of hormone treatment for prostate cancer or breast
cancer
6.Smoking
7.Strong family history of osteoporosis
8. Significant loss of height (vertebral compression fractures)

15. CONTRAINDICATIONS FOR BMD TEST
• Pregnancy
• Recent gastrointestinal contrast
studies(recommend waiting for at least 72 hours
before central DEXA Scan)
• Body weight exceeding limit for DEXA
scanners(>120-130kgs)
• Bilateral hip replacements or bilateral hip pins or
screws would prevent the hip sites from being
scanned.Metallic rods or spinal fusion devices in the
lumbar spine prevent scanning at this site.

16. WHAT DOES THE TEST DO?
• A DEXA test measures the bone mineral density
and compares it to that of an established standard .
• The results of the test are usually reported as a "T
score" and "Z score."
• In either score, a negative number means you have
thinner bones than the standard.
• The more negative the number, the higher your risk
of a bone fracture.

17. T-SCORE
• The T score compares your bone density with that
of healthy young adult.
• A score of 0 means your BMD is equal to the
standard for a healthy young adult.
• Differences between your BMD and that of the
healthy young adult standard are measured in units
called standard deviations (SDs). The more standard
deviations below 0, indicated as negative numbers,
the lower your BMD and the higher your risk of
fracture.

18. • As shown in the table below, a T-score between
+1 and −1 is considered normal or healthy.
• A T-score between −1 and −2.5 indicates that you
have low bone mass.
• A T-score of −2.5 or lower indicates that you
have osteoporosis.
• The greater the negative number, the more
severe the osteoporosis.

20. Z-SCORE
• The Z score compares your bone density with that
of other people of same age and gender.
• A low Z-score (below —2.0) is a warning sign that
you have less bone mass or that you are losing bone
more rapidly than expected for someone of your
age.
• Z-score = T-score - Reference T-score

23. How is a "Bone Scan" different
from a BMD test?
• Unlike a BMD test, a bone scan is an invasive test.
• The patient is injected with a dye that allows a
scanner to look at the condition of bone tissue.
• A bone scan can diagnose inflammation, fractures,
bone lesions and cancer.
• It cannot predict the risk of osteoporosis or
diagnose the condition.

24. Osteopenia
• Osteopenia refers to bone mineral density that is
lower than normal peak BMD (i.e,between -1.0 and
-2.5) but not low enough to be classified as
osteoporosis.
• It is a sign of normal ageing,in contrast
to osteoporosis which is a sign of pathologic ageing.
• It occurs more frequently in post-menopausal
women,can be exacerbated by lifestyle factors such
as lack of exercise,alcoholism,smoking or prolonged
use of glucocorticoid medications for asthma.

25. • Osteopenia has no symptoms.There is no pain as
the bone becomes thinner but the risk of fracture
increases as the bone becomes less dense.
• Diagnosis is by a bone mineral density test. A
standard X-ray is not useful in diagnosing because it
is not sensitive enough to detect small amounts of
bone loss or minor changes in bone density

27. • Osteopenia is treated by taking steps to prevent it
from progressing to osteoporosis like –
1.Lifestyle changes
2.Dietary modifications : Foods rich in
calcium(milk,dairy products,green leafy
vegetables) and vitamin D(eggs,fish,fish oils)
3.Vitamin D and calcium supplements

28. Osteoporosis
• Osteoporosis = "porous bones."
• Osteoporosis is defined by the WHO as a bone
mineral density that is 2.5 standard deviations or
more below the mean bone mass (average of
young,healthy adults).
• The underlying mechanism in osteoporosis is an
imbalance between bone resorption and bone
formation.

30. • Osteoporosis is classified as
1. primary type 1 - postmenopausal osteoporosis
2. primary type 2 - senile osteoporosis occuring after
age 75
3. secondary - resulting from chronic predisposing
medical conditions or prolonged use of
glucocorticoids,when the disease is called steroid-
or glucocorticoid-induced osteoporosis.
• The risk factors are same as that of osteopenia.

31. • Osteoporosis has no symptoms but its main
consequence is the increased risk of bone
fractures.
• Osteoporotic fractures are those that occur in
situations where healthy people would not
normally break a bone;they are therefore called
fragility fractures.

32. • Bones involved are the vertebral column,ribs,hip
and wrist.
• Acute and chronic pain in the elderly is often due to
osteoporotic fractures .
• The symptoms of a vertebral collapse (compression
fracture) are sudden back pain,shooting pain due to
nerve root compression.
• Multiple vertebral fractures lead to a stooped
posture, loss of height, and chronic pain with
resultant reduction in mobility.
• Hip fractures require immediate surgery as there
are risks of having a deep vein
thrombosis and pulmonary embolism.

33. stooped posture

34. • The diagnosis of osteoporosis can be made by using
conventional radiography and by measuring the
BMD using DEXA which is the gold standard for
diagnosis.
• It also requires blood tests to find out the
underlying cause.
• The main radiographic features of generalized
osteoporosis are cortical thinning and increased
radiolucency.

35. X-RAY SHOWING CURVED
SPINE DUE TO OSTEOPOROSIS

36. BMD TEST :
NORMAL OSTEOPOROSIS

37. • Prevention of osteoporosis-related complications is
by lifestyle changes,taking calcium and vitamin D
rich foods and supplements.
• Bisphosphonates can be prescribed in cases of very
high risk. Other medicines include raloxifene,
a selective estrogen receptor modulator(SERM).

38. • Teriparatide (a recombinant parathyroid
hormone) can be given for postmenopausal
osteoporosis.Strontium ranelate is effective in
decreasing the risk of fractures.
• Estrogen replacement therapy after
menopause can be started if indicated.
• In hypogonadal men,testosterone has been
shown to improve bone quantity and quality.