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METABOLIC BONE DISORDERS
Systemic skeletal disease characterized by low
bone mass and micro architectural
deterioration of bone tissue , with a consequent
increase in bone fragility and susceptibility to
• Osteoporosis is one of the most devastating disorders
associated with aging.
• Osteoporosis-related fractures result in significant morbidity
• Characterized by qualitatively normal but quantitatively
• Generalized decrease in bone mass is seen.
• Bone is normal structurally as determined by histological
and chemical analysis
• Radiographs in patients with osteoporosis reveal increased
radiolucency of bone (Osteopenia)
• Osteopenia occurs when bone resorption exceeds bone
"Microarchitectural deterioration" refers to the
thinning of the trabeculae and the loss of
intertrabecular connections in bone
Major risk factors Minor risk factors
-Age > 65 years
-Systemic glucocorticoid therapy of >3
-Primary hyper parathyroidism
-Propensity to fall
-Osteopenia apparent on X-ray film
-Early menopause (before age 45)
-Family history of osteoporotic fracture
(especially maternal hip fracture)
- Rheumatoid arthritis
- Past history of clinical
- Chronic anticonvulsant therapy
- Low dietary calcium intake
- Excessive alcohol intake
- Excessive caffeine intake
- Weight <57 kg
- Weight loss >10% of weight at
- Chronic heparin therapy
PROXIMAL PORTION OF THE FEMUR:
Analysis of the trabecular pattern of the upper end of the femur has
been used as an index of osteoporosis.
In this region, five anatomic groups of trabeculae can be identified.
1. Principal compressive group.
2. Secondary compressive group.
3. Greater trochanter group.
4. Principal tensile group.
5 .Secondary tensile group.
Patterns of trabecular loss may correlate with increasing severity of
osteoporosis. This trabecular analysis is termed as SINGH INDEX.
ANATOMIC GROUPS OF TRABECULA
• Principle compressive group
• Principal tensile group
• Secondary compressive group
• Secondary tensile group
• Greater trochanter group
• Wards triangle
NORMAL TRABECULAR PATTERNS. Proximal Femur. A. Three major patterns exist: principal
compressive group (1), secondary compressive group (2), and principal tensile group (3). The
confluence of these trabeculae leaves an area relatively void of structure, Ward’s triangle (W).
B. Specimen Radiograph- the arrangement of the trabecular bundles can be discerned,
defining Ward’s triangle, which is relatively devoid of bony struts.
C. Specimen Radiograph. The corresponding plain film confirms the trabecular orientation and
arrangement within the proximal femur and Ward’s triangle.
OSTEOPOROSIS IS CLASSIFIED AS:
(involving the major portion of the skeleton, particularly its
(involving one segment of the skeleton)
(single multiple focal areas of osteoporosis)
1. Primary osteoporosis
• Involutional (most common) - osteoporosis in
which no underlying cause can be identified.
oType I (postmenopausal)
oType II (aging related)
2. Secondary osteoporosis - osteoporosis in which
there is an underlying cause.
OSTEOPOROSIS CAN ALSO BE CLASSIFIED AS
• Postmenopausal osteoporosis occurs in women within
15-20 years after menopause.
• Age-related, or senile, osteoporosis describes the disease
in the elderly.
• Juvenile osteoporosis affects prepubescent boys and
• Idiopathic osteoporosis describes the condition in young
adults when the cause is not related to another disease.
Note the diminished density of the vertebral bodies and the thinned but relatively prominent
cortical endplates. No fracture deformities are seen.
Postmenopausal (Type I)
Senile (Type 2) Osteoporosis:
• Most common cause of generalized
• Peak bone mass occurs in the second decade of
• Then gradual loss of skeletal mass occurs,
beginning in the
fifth or sixth decade of life in men
fourth decade in women
Patients may be
• entirely asymptomatic,
• significant loss of bone mass accompanied by
various clinical signs
– Bone pain, particularly in the back,
– Loss of height owing to vertebral compression.
– Increase thoracic kyphosis is apparent (dowagers hump).
– Neurologic complications are unusual.
• Laboratory analysis
elevated urinary hydroxyproline levels.
Type I (PM) Type 2 (Senile)
Age 51-75 yrs > 70 yrs
Sex ratio (F:M) 6:1 2:1
Type of bone loss Mainly trabecular Cortical and trabecular
Fracture types Vertebral (crush), distal
wedge), hip, proximal
humerus and tibia
Rate of bone loss Accelerated Not accelerated
Parathyroid function Decreased Increased
Main causes Estrogen deficiency Aging, calcium
IDIOPATHIC JUVENILE OSTEOPOROSIS
• uncommon, self-limited disease of childhood.
• clinically evident disease present about 2 years before puberty with
• spinal symptoms.
• extra spinal symptoms.
• On radiographic examination,
• osteoporosis of the spine may be combined with vertebral collapse.
• Kyphosis represents the characteristic spinal complication.
• transverse and oblique fractures occur in the peripheral skeleton,
• typical feature appears to be metaphyseal injury, especially about the knees and
• Metaphyseal lucent lesions may lead to complete fractures with subsequent
• D/D: Osteogenesis imperfecta
ADULT IDIOPATHIC OSTEOPOROSIS
middle aged or young men.
• Vertebral compression fractures are a prominent feature.
• The disorder is often severe, progressive, and refractory to
Is diagnosed when an identifiable cause other than age or
menopause is present.
• Deficiency state
SECONDARY OSTEOPOROSIS CAUSES
Genetic Osteogenesis imperfecta, Gonadal dysgenesis, Turner syndrome,
Klinefelter syndrome, Hypophosphatasia, Homocystinuria,
Mucopolysaccharidosis, Gaucher disease, Sickle-cell anemia,
Deficiency Scurvy, Malnutrition, Anorexia nervosa, Protein deficiency,
Alcoholism, Vitamin D deficiency, Calcium deficiency
Medications Corticosteroids, Antiepileptics, Phenobarbital, phenytoin,
Cytotoxics: methotrexate, cyclosporin A,
Thyroid hormone, Lithium, Heparin, warfarin
Endocrine Hyperthyroidism, Hyperparathyroidism, Cushing syndrome,
Acromegaly, Estrogen deficiency, Hypogonadism, Diabetes mellitus,
Neoplastic Myeloma, leukemia, lymphoma, metastatic disease
Iatrogenic Heparin induced, steroid induced, dilantin (phenytoin) induced
Miscellaneous Amyloidosis, ochronosis, immobility, weightlessness
EVALUATION OF SECONDARY OSTEOPOROSIS
• Increased creatinine level : Renal disease
• Increased hepatic transaminase levels: Hepatic disease
• Increased calcium level :Primary hyperparathyroidism or malignancy
• Decreased calcium level: Malabsorption, vitamin D deficiency
• Decreased phosphorus level: Osteomalacia
• Increased alkaline phosphatase level: Liver disease, Paget's disease, fracture, other bone
• Decreased albumin level :Malnutrition
• Decreased TSH level : Hyperthyroidism
• Increased ESR: Myeloma
• Anemia: Myeloma
• Decreased 24-hour calcium excretion level: Malabsorption, vitamin D deficiency
• Generalized osteoporosis is most prominent in the axial
skeleton, particularly the
• vertebral column,
• less extensive changes may become evident in the tubular
General radiological features of osteoporosis:
• Increased radiolucency
• Cortical thinning
• Altered trabecular patterns
• Fracture deformity
A. AP Shoulder. B. AP Knee. Observe the decreased density, trabecular enhancement,
and thin cortices.
PELVIS AND FEMORA. AP Pelvis. Observe the thin cortices and relative
accentuation of those remaining trabeculae. Within the femoral necks, the principal
compressive trabeculae (arrows) are enhanced. Of incidental notation are calcified
abdominal mesenteric lymph nodes (crossed arrows) and a supra-acetabular bone
Spinal Manifestations of Osteoporosis
DECREASED BONE DENSITY
Accentuation of primary trabeculae
CHANGES IN VERTEBRAL SHAPE
Vertebra plana (pancake vertebra or silver dollar vertebra)
Biconcave deformities (fish vertebra)
Localized endplate deformities
Spinal manifestations are distinctive and pronounced.
Increased kyphosis is common due to
• compression fractures,
• anterior vertebral body remodeling
• loss of disc height
Decreased bone density: Especially density, of the vertebral body,
diminishes in parallel with loss of bone mass.
SEVERE SENILE KYPHOSIS.
Lateral Thoracic Spine.
The severe postural alteration, which is
a complication owing to loss of disc
height and anterior wedging of the
This underlies the physical appearance
of the buffalo or dowager’s hump
“EMPTY BOX” APPEARANCE
“Empty box” appearance
Initially there is relative
increase in the density of
vertebral end plates due
to resorption of spongy
bone causing what is
called as “empty box”
• Within the vertebral bodies the vertical trabeculae appear
to become increasingly accentuated. This is largely due to
preferential resorption of the horizontal trabeculae,
allowing easier delineation of those remaining.
• In certain individuals this may simulate the vertical radio
dense striations of hemangioma
• Osteoporosis can be differentiated, since it involves a
number of contiguous segments, while hemangioma is
usually a solitary lesion. In some instances no internal
trabeculae may be visible
• It is the vertical trabecular accentuation that produces the
so-called pseudo-hemangiomatous appearance of
moderately advanced osteoporosis.
A. Lateral Lumbar Spine
The vertical struts appear more
B. Lateral Thoracic Spine
vertical trabeculae distinctively conspicuous. A
minimal wedged anterior compression
deformity is also present
PSEUDO-HEMANGIOMATOUS APPEARANCE. A. Lateral Lumbar Spine Pseudo-
Hemangioma. Observe the accentuated vertical trabecular patterns of multiple segments,
producing a pseudo-hemangiomatous appearance. This is a manifestation of early to moderate
osteoporosis, the appearance being lost in advanced cases. There is loss of the horizontal supports
with thickening of the vertical struts. B. Lateral Thoracolumbar Spine Hemangioma. Note that
this most common benign tumor of the spine presents with strikingly similar accentuated vertical
trabecular markings (corduroy cloth appearance) but is localized to only one level (arrow)
The cortical outlines of the vertebral body and neural
arch are usually notably thinned. This is best depicted at
the vertebral body end plates, which are normally
Changes in shapes:
A number of altered vertebral configurations seen.
• rare in the cervical spine,
• less common in the upper thoracic spine,
• most common in the mid-thoracic & thoraco-lumbar
VERTEBRAL BODY CONFIGURATIONS:
B. Normal with Pencil-Thin Cortices.
C. Wedge Shape Owing to Anterior Loss of Height.
D. Plana with Both Anterior and Posterior Collapse.
E. Biconcave (Fish Vertebra) Owing to Gradual Endplate Depression.
F. Angular Endplate Depression from Acute Fracture.
Vertebra plana (“Pancake” Vertebra):
Pancake vertebra is a compression deformity of the vertebral
body characterized by a loss in both the anterior and posterior
vertical heights, often in multiple segments.
This is an unusual presentation for osteoporosis and, if seen,
must arouse the suspicion for these other malignant bone
diseases to be the underlying cause for these fractures.
When present, this configuration must be differentiated from a
more serious cause, especially metastatic carcinoma and
multiple myeloma, by pertinent laboratory investigations.
MRI does not reliably differentiate between pathologic and
VERTEBRAL BODY PATHOLOGIC
FRACTURE (VERTEBRA PLANA)
Isolated compression fracture at the T8
segment noted (arrow).
The loss of the posterior and anterior
height suggests an underlying
pathologic condition for which the
differential diagnosis includes
• multiple myeloma,
• metastatic carcinoma,
• other malignancy,
The diagnosis in this case was
Lateral lumbar spine
radiograph shows severe
crush fracture of L2
• Compression deformities that demonstrate loss of the anterior
vertebral body height with preservation of the posterior height are
termed wedged vertebrae.
• The resultant trapezoidal configuration is diagnostic of this type of
compression abnormality and may also be seen at multiple levels
• The same shape is also common in traumatic compression
fractures of the spine, even those that exhibit normal
• These are most common in the midthoracic and thoracolumbar
Lateral thoracic spine
Wedge compression fracture seen
in lateral thoracic vertebra
VERTEBRAL BODY SHAPE
In Lateral Thoracic Spine.
Note that several changes in
vertebral body shape can be
• wedge (W)
• plana (P)
• biconcave (B)
Also, the thoracic kyphosis has
increased, which is a frequent
Biconcave Deformities (Fish, Codfish, Fish mouth or Hourglass
Due to Central depression of the vertebral body endplates seen at multiple
contiguous levels, endplates show an exaggerated concavity
(this simulates the vertebral body appearance found in a normal fish)
This deformity is the direct mechanical sequelae of pressure on the weakened
bone from the nucleus pulposus.
Intervertebral disc spaces are usually of normal height.
The same endplate defects are frequently seen in diseases such as
BICONCAVE ENDPLATES (FISH VERTEBRAE). A. Lateral Lumbar Spine. Note that the endplates are
markedly concave in contour at multiple levels. Note the thin cortices and normal intervertebral disc
spaces. This configuration does not occur unless there is loss of vertebral body strength and a normally
hydrated nucleus pulposus to exert mechanical deformation of the endplate.
B. Alaskan King Salmon Spine. Note the profile of the endplates can be seen to be deeply depressed
centrally, creating an appearance of distinctly biconcave endplates (arrows). It is from this striking
similarity to the endplate deformities of the osteoporotic vertebral body that the term fish vertebra has
Isolated Endplate Deformities:
Frequently, isolated endplate fractures
occur peripherally or centrally. Central
endplate fractures are most frequent at
L1 and L4. These deformities are often
depicted only on a single view, such as
an oblique on which the endplate is
projected into a slightly different plane.
Radiographic manifestations consist of
an altered orientation of the endplate,
sharp offset in continuity, and increased
density adjacent to the fracture site.
A standard lateral standing radiograph of the lower
lumbar spine: Disk space narrowing at the level
L5/S1. Endplate irregularities of the fifth lumbar
vertebra and the first sacral vertebra.
Localized intrabody discal
herniations are frequently
superimposed on the
osteoporotic spinal column.
Most commonly, these
nuclear extrusions occur in
the thoracic and upper
RISK FACTORS FOR OSTEOPOROTIC FRACTURES
H/o fracture in a first degree relative
Personal history of fracture as an adult
POTENTIALLY MODIFIABLE FACTORS
• Current cigarette smoking
• Low body weight [<58kg]
• Estrogen deficiency
• Lifelong low calcium intake
• Recurrent falls
• Inadequate physical activity
• Poor health / fraility
• Impaired eyesight despite correction
SIGNS AND SYMPTOMS
• Symptoms of osteoporosis indicate advanced disease.
• Fractures of the hip, spine, and wrist are most common.
• Kyphosis (dowager's hump) results from collapse of
several vertebral bodies.
• Skeletal back pain may also be a symptom.
• Vertebral fracture (morphometric fractures].
• Back pain and decreased mobility.
• Disfiguring kyphosis (dowager's hump)
• Height loss
• Decreased pulmonary capacity
• Abdominal protrusion
• Insufficiency fractures occur when the elastic strength of the
bone is not sufficient to withstand normal physiological stress.
• In osteoporosis, the most common locations for complication
from insufficiency fractures are the spine, hip, and distal radius.
• When affecting the weight-bearing bones of the lower limb,
these fractures are frequently bilateral. Such fractures
characteristically affect the weight-bearing bones, including
metatarsal necks, posterior calcaneum, distal and proximal tibia
and fibula at their outer margins, medial neck of femur, and
• The fracture site may be marked by localized periosteal
response and transverse opaque zones of callus.
• Only occasionally a fracture line may be visible.
• These usually are metaphyseal in location.
The fracture through the intertrochanteric
Fractures of the proximal femur are the most
common severe presentation of
osteoporosis. Such fractures can occur
elsewhere within the proximal femur,
including subcapital, midcervical,
basocervical, and subtrochanteric locations.
• The most common cause of fracture of the sacrum is senile and
postmenopausal osteoporosis with a history of a recent fall onto the buttocks.
• It is precipitated by the high shear forces through the sacral ala during
walking and may coincide with a recent increase in activity.
• Onset usually after age 65.
• F:M= 5:1
• Increased pelvic tilt is thought to be a predisposing factor.
• Pain severity is variable, from severely debilitating to relatively
• Up to 75% of patients have a co-existing insufficiency fracture within the
pelvic ring, most commonly of a pubic ramus.
The two symmetrically located insufficiency fractures in the lateral
sacrum (arrows). Note the characteristic cortical offset at the anterior
sacral margin (arrowhead)
The most sensitive method of detection is isotopic bone scan.
Three patterns of sacral insufficiency fractures occur based on bone
• H pattern (butterfly or “Honda” sign). Bilateral vertical fractures
through the sacral ala are connected by a transverse fracture
through the S2, S3, or S4 bodies.
• I pattern. A single vertical fracture passes through the sacral ala.
This is the most common form of sacral insufficiency fracture in
at least 70% of cases.
• Arc pattern. A linear or curvilinear transverse fracture passes
horizontally across the sacrum.
Frontal Technetium-99m Isotopic Bone Scan:
The dense uptake of the isotope within the lateral sacrum as two vertical components corresponding
to the sites of fracture (arrows). These two vertical fractures are joined centrally by a transverse
fracture through the S2 body, signified by the transverse linear uptake zone (arrowhead). The
combination of these three components produces an H-shaped lesion referred to as the Honda sign.
INSUFFICIENCY FRACTURE OF THE PUBIS: AP Pubes.
Initial Radiograph. Note that no abnormality is identified, with the
pubis bilaterally normal.
Follow-up Radiograph. Note that a fracture line extends vertically
through the body of the pubis immediately adjacent to the articular
margin of the symphysis pubis (arrows)
REFLEX SYMPATHETIC DYSTROPHY SYNDROME:
• Reflex sympathetic dystrophy syndrome is a unique clinical and radiographic
• Also called post-traumatic osteoporosis, Sudeck’s atrophy, acute bone
atrophy, and causalgia.
• Although the mechanism has not been delineated, the syndrome is
characterized by an acute onset of a painful regional osteoporosis, usually
following trivial antecedent trauma.
Bilateral PA Hands. Note the distinct loss of bone density in the
affected hand (arrow), especially in the periarticular regions of all
articulations. Compare this appearance with the normal other side. A
minor trauma had been incurred at the wrist 8 weeks previously.
• > 50 years of age.
• History of recent trauma that may have been trivial.
• Progressive pain, swelling, and atrophy distal to the trauma
• Neurovascular imbalance, promoting osseous hyperemia.
• Patchy, mottled osteoporosis.
• Metaphyseal localization.
• Later, more generalized osteoporosis.
Disuse and Immobilization Osteoporosis
• Traumatic injuries that are immobilized, motor paralysis, and inflammatory
lesions of bones and joints constitute the most common causes.
• Changes appear on plain film after 7-10 days, becoming most extreme by
• Four radiologic patterns of disuse atrophy:
• Uniform- All bones involved exhibit a similar degree of bone loss.
• Spotty- Localized circular lucencies predominate, especially within the
epiphyseal portions of the bones
• Bands- Linear transverse subchondral or metaphyseal lucent zones
• Cortical lamination or scalloping- Lamination or scalloping loss of
definition in the outer and inner cortical margins.
A. Lateral Elbow. Note that the
bones are demineralized in a
uniform manner following
immobilization owing to a
B. PA Wrist. Observe the spotty
form of disuse osteoporosis of
the wrist after immobilization
for an elbow fracture.
C. PA Foot. A similar spotty
type of deossification has
occurred after immobilization
for an ankle fracture.
TRANSIENT REGIONAL OSTEOPOROSIS
• No associated cause.
• Sudden and reversible; affects periarticular bone.
Transient Osteoporosis of the Hip:
• 20-40 years; males predominant.
• Associated with pregnancy in females, left hip exclusively.
• Marked osteoporosis of the femoral head; less severe in femoral neck and
Regional Migratory Osteoporosis:
• Males most commonly affected.
• Usually in lower extremities.
• Localized, regressing, migratory osteoporosis.
DISUSE OSTEOPOROSIS: POLIO. AP Pelvis.
Osteoporosis of hemi pelvis
Decreased joint space hip & SI joint
Under development of femur, pubis & ischium
TRANSIENT OSTEOPOROSIS OF THE HIP
Diffuse osteopenia of the right
femoral neck and head
Decreased marrow signal on T1
images of the right hip
TRANSIENT OSTEOPOROSIS OF THE
A. T1-Weighted MRI, Coronal Hip.
B. T1-Weighted MRI, Axial Hip.
Note the diffuse loss of signal intensity in
the right femoral head and neck (arrows).
On T2-weighted images (not shown) this
low signal intensity area became
hyperintense, consistent with transient
The clinical presentation is variable.
MRI plays an important role in
establishing the differential diagnosis and
excluding other pathology such as
• Risk factors and Simple Calculated Osteoporosis Risk
• Clinical features
• Laboratory tests
• Radiologic techniques to assess bone
• Measurement of bone mineral density (BMD) by
• Dual X-ray absorptiometry (DXA)
• Dual-photon absorptiometry (DPA)
• Single X-ray absorptiometry (SXA)
• Single-photon absorptiometry (SPA)
• Quantitative computed tomography (QCT)
• Quantitative ultrasound (QUS).
Changes in bone mass are detectable on X-ray only when 30-
50% of bone has already been lost.
• Increased radiolucency of bones.
• Decreased number and increased thickness of trabeculae.
• Cortical thinning.
• Juxta-articular osteopenia with trabecular prominence.
• Bone bars (reinforcement lines).
• Insufficiency fractures.
• Vertebral wedge fractures, fish vertebrae, Schmorl nodes and
decreased heights of vertebrae and accentuation of the
ab +cd= combined cortical
ab +cd = INDEX OF BONE MASS
(the sum of cortices
approximates one half of the
In patients with chronic
osteopenia, radiographs of the
tubular bones commonly reveal
strands of trabeculae of variable
thickness, extending partially or
completely across the marrow
The precise pathogenesis of
bone bars is not clear.
• Studies have shown large (5%-20%) annual losses in spinal
trabecular BMD in women undergoing surgical or natural
• BMD assessment techniques have progressed from simple
radiography to more sensitive methods,
• early detection of osteoporosis
• monitor response to therapy
• assess bone strength reliably
• predict fracture risk.
PATIENTS RECOMMENDED FOR BMD MEASUREMENTS
• Women over age 65 and women under 65 with risk factors
• Amenorrhea, early menopause
• Bilateral oophorectomy before normal menopause
• Women not receiving hormone replacement therapy for at
least 5 years after menopause
• All men age 70 and older and Men with hypogonadism.
• Strong family history of osteoporosis.
• Patients undergoing prolonged Rx with glucocorticosteroids.
• Post chemotherapy (esp. breast and hematologic CA).
• Adults with a disease or condition associated with low bone
Basic Principles of BMD
• Bone attenuates or absorbs ionizing radiation. More bone present,
the more radiation the bone absorbs.
• Unabsorbed radiation passes through the bone and is measured
in a radiation detector.
• BMD refers to grams of bone mineral — specifically
hydroxyapatite — per square centimeter of bone cross-section
and is expressed in units of g/cm2.
• Total Proximal Femur
• Femoral Neck
• Forearm (33% Radius)
• If hip or spine cannot be
• Very obese
WHICH SKELETAL SITES SHOULD BE MEASURED?
Thickness of the cortices of bone is measured with a caliper on fine
detail radiograph to provide an index for bone density and bone
2nd, 3rd and 4th metacarpals, radius and clavicle.
positioning and measuring errors.
low dose of radiation,
Single photon Absorptiometry
This couples a monoenergetic photon source such as iodine-125 with a
sodium iodide scintillation counter
A single-photon source emits a photon beam that is attenuated as it passes
through bone, usually the radius or calcaneus. The density of bone is
calculated by the measured transmission count rate.
The calcaneus, distal radius and radial shaft all have about an equal degree of
association with vertebral osteoporosis but have high false-negative rates,
which makes the technique unreliable.
The radiation dose is 2-5 mrad.
DUAL PHOTON ABSORPTIOMETRY
• uses gadolinium-153
• This allows scanning of the spine and femur, as it is independent
of variation in soft tissue thickness
• the technique cannot measure absolute bone mineral content
• Aside from bone density analysis, modern advances of this
technique that can deliver high-resolution images have made this
modality a useful alternative for the clinical diagnosis and
evaluation of vertebral fractures.
• The major advantage is the relatively low radiation dose. The
radiation dose is 5-15 mrad.
• useful in quantitative mineral content changes
Single X-ray Absorptiometry
• SXA has succeeded single-photon absorptiometry
• Used for quantitative BMD assessment of the
• SXA has been used successfully in the diagnosis of
osteoporosis with reasonable precision and low
Dual X-ray Absorptiometry
Because single-energy measurements cannot be
obtained at sites with variable soft-tissue thickness and
composition (e.g., axial skeleton, hip), dual-energy
techniques were introduced.
Two xray beams of different energy levels are aimed at
the patient bones. When soft tissue absorption is
subtracted out, BMD can be determined from the
absorption of each beam by bone.
the most widely available BMD test
Low radiation dose : 5 mrad
high degree of accuracy
bone tissue per unit area ( g/cm2 )
• Central BMD measures the axial and appendicular
skeleton, which are the most commonly measured sites.
• Peripheral BMD measures the most peripheral areas of
the appendicular skeleton — namely, the forearm,
phalanges, and calcaneus.
• This can - Predict fracture risk
• But cannot diagnose osteoporosis and monitor therapy
LIMITATIONS OF DXA:
• Presence of barium or recent administration of radionuclides
(within 10 half-lives of the injected tracer) may yield
inaccurate BMD measurements.
• Presence of radiopaque implants in the measurement area.
• Inability to straighten the lumbar spine or internally rotate
• Marked obesity.
the anatomic sites where DXA is
T SCORE INTERPRETATION
BMD or bone mineral content
(BMC) within 1 SD of the young-
adult reference means
-1 to –2.5 SD Low bone mass
Below –2.5 SD Osteoporosis
Below –2.5 SD +
one or more fragility
Professor John Kanis says:
“Such a cutoff value identifies approximately 30% of
postmenopausal women as having osteoporosis using
measurements made at the spine, hip or forearm. This
is approximately equivalent to the lifetime risk of
fracture at these sites.”
Kanis JA et al. J Bone Miner Res. 1994;9:1137.
QUANTITATIVE COMPUTED TOMOGRAPHY
A software package allows the conversion of relative
determined in the center of a vertebral body,
to an absolute measurement of bone density of
calcium in milligrams per cubic centimeter.
• measures trabecular or cortical bone separately at any skeletal
site in three dimensions
• primarily to determine trabecular bone density in the vertebral
• As trabecular bone is important for vertebral strength, it is used
• assess vertebral fracture risk,
• measure age-related bone loss,
• follow up of osteoporosis and other metabolic bone diseases
Quantitative Computed Tomography
QCT determination of density in
vertebrae is compared to known
density readings of external phantoms
A computer program compares the density of the patient's spinal vertebrae
(outlined in turquoise) with a special reference device placed under the
patient during the exam.
PERIPHERAL QUANTITATIVE CT
• Peripheral quantitative CT is used to obtain
BMD measurements in the peripheral skeleton
(principally the distal radius).
• The measurement of multiple sections is
potentially more representative of changes in
the distal radius and therefore may reflect the
bone status of an individual more accurately.
Declination of cortical and central trabecular bone in the forearm.
(a) Peripheral cross-sectional quantitative CT scan obtained at the level that represents
4% of the ulnar length from the distal radial end plate shows the area of interest (box).
(b) Magnified view of the area of interest shows the bone declination to greater
• The attenuation and velocity of a sound wave passing
through bone are related to the biomechanical
properties, geometry, density of the bone;
• The more complex the structure, the greater the
attenuation and velocity.
• Normal bone demonstrates higher attenuation and is
associated with greater sound velocity than
• Quantification of bone density and structure can be
achieved by analyzing the attenuation or velocity of
US in bone.
• easy to use,
• No ionizing radiation.
• can be obtained at various easily accessible
• The data produced are machine specific and
subject to the use of dissimilar databases by
• Clinical features (eg, ankle edema) are
potential causes of error.
• Choice of right or left heel for measurement
can influence the result unduly.
MAGNETIC RESONANCE IMAGING
• Can provide more detailed images of the structure of
osteoporotic bone than DXA and may be used to diagnose
subtle osteoporotic fractures.
• MRI is based on the different magnetic properties of bone
and bone marrow, which cause a distinct loss of signal that
is proportional to the density and spatial architecture of each
• Major disadvantage of MRI is the high cost
T1-weighted fat-suppressed image
obtained after administration of
contrast agent shows enhancement
in T12 and L1 vertebrae but no
enhancement of L2 vertebra
T1-weighted image shows that
acutely fractured T12 and L1
vertebrae have lower signal
intensity than chronically fractured
Radionuclide bone scan of a
patient with TOH of the right hip
shows marked uptake in the right
femoral head and neck.
T1-weighted coronal MR of hips
of the same patient with TOH
shows a diffuse zone of low
signal intensity in e femoral head
and neck consistent with marrow
• In the past, the techniques used to assess BMD were
imprecise and inaccurate.
• Today, the most widely used techniques-SXA, DXA, and
quantitative CT have errors in precision of 0.5%-2%
• To achieve this degree of precision, strict quality control
measures and careful technical monitoring are necessary
• Of the three techniques, DXA and SXA are the most precise,
whereas quantitative CT is the most sensitive
QCT is the most accurate BMD test
Ultrasound is the least accurate of the
DEXA is the most widely available
Gaucher disease (GD) is the most common lysosomal
storage disease in humans arising from a deficiency of
accumulation of a glycolipid (gluco-cerebroside)
within the lysosomes of macrophages, particularity in
the bone marrow.
• Type I (non-neuropathic form or adult form):
• commoner type
• progressive hepatosplenomegaly, anaemia and
thrombocytopaenia, and marked skeletal
involvement; lungs and kidneys may also be involved
but the CNS is spared
• Type II (acute neuropathic form or infantile form): severe
progressive neurological involvement with death by 1 to 2
years of age; hepatosplenomegaly is also present (usually
evident by 6 months of age)
• Type III: type I with neurological involvement presenting
in late adolescence or early childhood
• Bone crisis
• Osteopenia, osteoporosis
• Erlenmeyer flask deformity
• Short stature, growth arrest lines
• Cortical bone ‘infarct’
• Medullary bone ‘infarct’
• Deficient bone formation
• Deficient bone remodelling
• Failed linear bone growth
PATHOLOGICAL EVENT RESULTING SIGN OR SYMPTOM
Thought to arise from marrow
canal expansion and impaired
and Collapse of the
Flared metaphyseal regions
Results from an impaired remodeling process
• Higher marrow attenuation values owing to increased
amounts of fibrotic and calcific replacement.
• Reduced T1 and T2 signal intensity from involved bone
marrow (due to infiltration with Gaucher cells)
• may give a "salt and pepper pattern" due to scattered
• features of superimposed osteonecrosis
Coronal STIR MR image shows a geographic area of low signal in the
left iliac bone, surrounded by a serpiginous high signal rim. This is a
characteristic appearance of a bone infarct
• Osteonecrosis in Gaucher disease. (a)
Plain radiograph of osteonecrosis
affecting both femoral heads
(particularly the right)
• (b) MR image of the same patient.
• (c) T1-weighted MR image showing
early stage osteonecrosis of the left
femoral head in another patient with
• MR images of bone marrow infiltration in Gaucher disease. (a) T1- and
(b) T2-weighted images of the spinal column illustrating the reduced
signal intensities; (c) T1-weighted image of the left and right femur
illustrating a heterogenous pattern of marrow infiltration
• Enzyme replacement with human placental, macrophage-
targeted glucocerebrosidase was shown to be safe and effective
in clinical trials and was introduced as a definitive therapy.
• MPS are a group of inherited metabolic disorders that result in
widespread skeletal, visceral, and mental abnormalities.
• A defect in metabolic degradation leads to storage of
mucopolysaccharide macromolecules in the nervous system and other
• MPS re classified in to various types
• MPS-I HURLER’S SYNDROME
• MPS-II HUNTER’S SYNDROME
• MPS-III SANFLIPPO’S SYNDROME
• MPS-IV MORQUIO’S SYNDROME
• MPS-VI MAROTEAUX-LAMY SYNDROME
• MPS-VII SLY’S SYNDROME
• Out of these hurler’s and morquios’s are commonly encountered where
as, others are very rare in incidence.
It carries an autosomal recessive inheritance manifesting in first
year of life.
It is clinically characterised by
• mental retardation,
• corneal clouding,
• cardiac disease,
• with death resulting in first decade often from cardiac
The estimated incidence is at ~ 1: 100,000
Skeletal features include
• concave articular surface of mandibular condyle
• J-shaped sella
• C1-C2 subluxation : atlanto-axial subluxation
• shortening and widening of long bones
• pointing of proximal metacarpals
• widening of anterior ribs (oar shaped / paddle ribs)
• hypoplastic vertebra at thoracolumbar junction
• inferior beaking of anterior vertebral margins
• thoracolumbar kyphosis
Widening of anterior ribs (oar
shaped / paddle ribs)
Lateral radiograph of the skull (magnified) showing ‘J’-shaped sella turcica (arrow)
Radiograph of both feet (AP
• short metatarsals (black
• bullet-shaped phalanges
• overlapping of the 3rd toe
over the 2nd.
Radiograph of the pelvis (AP View) showing
• shallow acetabulums,
• coxa valga (white arrows), and
• flaring of the iliac wings (black arrows)
Lateral radiograph of the
inferior beaks in the
lumbar vertebral bodies
Radiograph of the chest and upper limbs showing
• increase in the cardio–thoracic ratio,
• oar-shaped ribs (white arrows),
• short and deformed clavicles (black arrows),
• shallow glenoid cavities, and
• irregular upper humeral metaphyses, bilaterally
• The disease is progressive. Patients with Hurler's syndrome
appear normal at birth.
• They have accelerated growth during the first year of life, which
is followed by slowing of both mental and physical growth.
• The developmental delay appears between 12 and 28 months.
The radiological images are very characteristics of Hurler's
ENZYME REPLACEMENT THERAPIES ARE CURRENTLY IN USE
• It is an autosomal recessive condition with an estimated
incidence of ~ 1:40000
• It results from an excess of Keratan sulphate from a deficit in its
degradation pathway .
• Keratan sulphate accumlates in various tissues inclusive of
cartilage, the nucleus pulposus of the intervertabral disc and
• Many cases present at ~ 2 years of age and have normal intelligence
• severe dwarfism (< 4 ft)
• joint laxity
• corneal opacification / cloulding
• progressive deafness
• spinal kyphoscoliosis
• prominent mandible and lower face
• short neck
Plain film / CT
• Platyspondyly (refers to flattened vertebral bodies throughout the axial
• hypoplasia of odontoid peg
• atlanto axial subluxation
• os odontoideum (an uncommon craniovertebral junction (CVJ) abnormality
characterized by a separate ossicle superior to the dens).
• anterior central vertebral body beaking
• round vertebral bodies
X-ray of skull; AP and lateral view (1A and 1B) and cervical spine in flexion and
extension position (1C and 1D) showing a J-shaped sella and multi-level vertebra plana
Lateral view of the
cervical spine obtained
in flexion (right)
demonstrates a 9 mm
gap at the atlanto-axial
right), which is reduced
in extension (arrows,
subluxation is called if
the distance between
the dens and the
anterior arch of C1
exceeds 2.5 mm in
adults or 4.5 mm in
X-ray of dorso-lumbar spine in AP and lateral view (2A and 2B)
• kyphosis with multi-level vertebra plana
• Ribs show broadening of the anterior portion (tongue shape).
• metaphyseal flaring in long bones
• multiple epiphyseal centres
• wide metacarpals with proximal pointing, irregular carpal bones
• short and wide tubular bones
• flattened femoral epiphyses ; risk of lateral subluxation and dislocation
• coxa valga
• goblet shaped flared iliac wings, increased acetabular angles
and constricted iliac bone base
Sternum and chest
• anterior sternal bowing, increased AP chest diameter, wide ribs
X-ray of the pelvis and both femurs in AP view shows
flared iliac bones laterally with inferior constriction (wine-glass shape).
Enlargement of both acetabular cavities is seen with rough margins, and poorly formed
femoral epiphyses and widened femoral necks with coxa valga.
X-ray of both knees in AP view (5A) and leg with foot in AP (5B) and lateral view (5C) showing
genu valgus, metaphyseal expansion of long bones, and tapering of the proximal phalanges
• Complications develop later and include breathing problems,
cardiac problems, spinal cord damage leading to possible
paralysis, vision problems, walking problems related to
abnormal curvature of the spine, and other bony problems.
• Treatment is currently only palliative.
• Possible future treatments include enzyme replacement, gene
therapy and allogenic bone marrow transplantation.
LANGERHANS CELL HISTIOCYTOSIS
• Langerhans cell histiocytosis (LCH) is a rare multi
system disease with a wide and heterogeneous clinical
spectrum and variable extent of involvement.
• The disease is more common in the paediatric
population, with a peak incidence between 1 and 3 years
of age . There is also a male predilection (M:F 1.2-2.1 :
Three clinical forms:
Acute disseminated langerhans cell histiocytosis
• Occurs most frequently in infants 2 years of age or
younger (and occasionally adults) Presents with multi
system organ involvement.
• Infiltration of bone marrow and other organs lead to
concurrent hepatosplenomegaly, lymphadenopathy,
pulmonary lesions, anemia, thrombocytopenia, recurrent
infections (otitis media)
• Eventually, there are destructive osteolytic bone lesions.If
untreated, this disease is rapidly fatal
• With chemotherapy, 5 year survival rate is approximately
Unifocal langerhans cell histiocytosis (Eosinophilic granuloma or
• Usually only affects the skeletal system of young adults.
• Typically presents as an osteolytic lesion involving the
• Bony lesions are usually asymptomatic In some cases, can cause pain
and even pathologic fractures.
• Skull (50%) Diploic space of parietal bone most often Round or ovoid
punched out lesions with beveled edge Sclerotic margin during healing
phase Beveled edge=hole-within-a-hole
• Button sequestrum- bony sequestrum within lytic lesion Axial skeleton
• "Vertebra plana"-"coin-on-edge"(Calve disease)=collapse of vertebral
body, mostly thoracic.Most common cause of vertebra plana in
• Skull Lesions
• Oval-shaped and well defined
• Look like punched out lytic
• Lytic lesions may contain a
fragment of intact bone referred
to as a button sequestrum
• Skull may take on “geographic”
• NO periosteal reaction or reactive
• Spinal Lesions
• Predilection for thoracic spine
• May lead to near collapse with
“vertebra plana” appearance
Lateral collimated radiograph of thoracolumbar spine shows multiple vertebra plana
Anteroposterior radiograph shows an
intramedullary osteolytic lesion of the tibial
diaphysis accompanied by a subtle lamellar
periosteal reaction (arrowhead).
b, c MR imaging reveals an oval lesion
(arrowheads) within the bone marrow of the
tibia with hypointense signal on b sagittal T1-
weighted SE image and hyperintense signal on
c sagittal STIR image, surrounded by a zone of
d Axial fat-suppressed T2-weighted FSE MR
image reveals circular periosteal and parosteal
edema, but absence of a soft tissue mass.
e Photomicrograph of histologic section
(hematoxylin and eosin stain) shows histocyte-
like cells (Langerhans' cells) and dense
infiltrates of eosinophils
LCH of the left femur in a 6-year old
boy with a 3-month history of left knee
pain and leg weakness.
(a) AP radiograph of the left femur
shows a well-defined area of lysis in
the middle of the femoral diaphysis
associated with thickly lamellated
peniosteal reaction bridging the
margins of uninvolved
(b) Whole-body scintigram shows
marked radiotracer uptake in the
middle of the left femoral diaphysis.
Multifocal langerhans cell histiocytosis (Hand-Schuller-Christian
Triad of Diabetes insipidus, Exophthalmos, Holes in the bone
Bone-Lytic skull lesions with overlying soft tissue nodules. Large
geographic skull lesions "Floating teeth" with mandibular involvement.
Diabetes insipidus is secondary to infiltration of the posterior pituitary
stalk by the Langerhans cell.
Similar to plain film findings with better demonstration of cortical erosion
and soft tissue involvement. Excellent for biopsy and surgical planning.
Signal characteristics include
T1 : typically low signal
T2 : isointense to hyperintense
C+ (Gd) : often shows contrast enhancement
Treatment and prognosis
The prognosis is excellent when disease is confined to the
skeleton, especially if it is a solitary lesion, with the majority
of such lesions spontaneously resolving by fibrosis within 1-2
However, where symptoms persist, other treatment options
may be considered.
• excision and curettage
• steroid therapy
• radiofrequency ablation
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