3. Introduction
Zones of bone growth
1. Zone of resting cartilage contains normal, resting hyaline cartilage.
2. Zone of proliferating cartilage chondrocytes undergo rapid mitosis, leading to
proliferation and form distinctive looking stacks.
3. Zone of maturation / hypertrophy – Chondrocytes enlarge and begin to secrete
alkaline phosphatase which triggers calcification
3
4. Cont’d…
4. Zone of calcification – Chondrocytes die as they do not receive
nutrition leaving cavities that will later become invaded by bone-forming
cells.
5. Zone of ossification - Osteoprogenitor cells invade the area and
differentiate into osteoblasts, which elaborate matrix that becomes
calcified on the surface of calcified cartilage.
4
7. Rickets
The term is derived from ancient English term “wricken” which
means “to bend”.
It is the interruption of orderly development and mineralization of
growth plate.
Found in children prior to closure of growth plate
The essential pathologic alteration involves deficiencies of vitamin
D, calcium, or phosphate.
7
8. VITAMIN D AND RICKETS
Vitamin D promotes differentiation of enterocytes and the intestinal
absorption of calcium and phosphorus.
This helps in bone mineralization.
In conditions of hypocalcemia or hypophosphatemia, vitamin D
stimulates bone resorption, thereby maintaining serum levels of
calcium and phosphorus.
vitamin D deficiency or resistance thus causes hypocalcemia and
hypophosphatemia.
8
9. Cont’d…
Hypocalcemia stimulates the release of PTH, which, through its actions
on bone and kidney, partially corrects the hypocalcemia but enhances
urinary phosphate excretion, leading to hypophosphatemia and
osteomalacia.
9
12. Hx & P/E
The classic vitamin D-deficient presentation develops 6-12 mths of age.
Sx: muscle tetany & pain (commonest syptm.), irritability, weakness, delayed
development, small stature, bone deformities and pain.
Soft tissue swellings occur around the growth plates
Multiple costochondral bumps at anterior rib cage (rachitic rosary).
Enlargement of the wrists and costocartilage are most suggestive of the disease, with a
specificity of 81% and 64%, respectively.
Lab: ALP, Ca++ & phosphorus may be normal to slightly diminished.
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15. Ex
The mineralization defects can be classified as
Calcipenic (hypocalcemic) rickets caused by calcium deficiency or more commonly
Vitamin D
Phosphopenic (hypophosphatemic) rickets caused by phosphate deficiency &
commonly caused by renal phosphate wasting
Deficiency of vitamin D is usually more common than either isolated
calcium or phosphorus deficiency
15
17. Pathology
Decrease in the quantity of calcified osteoid and an increase in uncalcified osteoid
(osteoid seams) generalized radiolucency
The cartilage cells at the physis grow normally but fail to calcify and degenerate.
the growth plate is occupied by enlarged masses of overgrown cartilage, (widening the
region-- x-ray)
Absent metaphyseal zone of provisional calcification (X-ray)
The first sign of healing is restitution of this opaque metaphyseal line.
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18. Terminology
widening and irregularity of the growth
plate ("fraying").
widening of the metaphyseal end of the
bone ("splaying").
concavity of the metaphysis ("cupping")
18
19. Radiologic Features
All bones will appear more radiolucent, with coarsened trabecular
patterns.
Widened growth plate (earliest radiographic mfn.)with irregular, frayed,
and cupped metaphyseal margins ( paintbrush metaphyses)
No distinct white line of the zone of provisional calcification.
Epiphyses also appear frayed at the borders.
19
20. Cont’d…
Bowing deformities, fractures, decreased bony length, scoliosis, and
pseudo-fractures are other notable findings.
Bulbous enlargement of the costochondral junctions (rachitic rosary)
can be seen adjacent to cupped anterior rib ends, which can indent the
pleural interface or even the thymic shadow.
20
26. Other Imaging manifestations of
Rickets
MRI Though MRI is clearly unnecessary for the diagnosis of rickets, it is
important that the typical features are not misinterpreted as other
pathology. Findings include T2:
wide physis of the secondary ossification center (SOC)
absent zpc
increased signal intensity of the physis
26
28. Radionuclide
Radionuclide bone scanning is a useful aid in suspected cases.
(preterm)
It offers advantages over conventional radiology in terms of
sensitivity, radiation dose and extent of examination.
Unsuspected fractures of clinical or medicolegal significance may be
detected.
28
29. DEXA
Reduced aBMD, which are more pronounced in the
diaphyseal than in the metaphyseal regions of the radius and
ulna.
CT data not available
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30. Imaging differentials
The differential for leg bowing
Developmental or congenital bowing
Blount disease
osteogenesis imperfecta
30
33. The differential for widening of the growth plate
Schmid-type metaphyseal chondrodysplasia
Hypovitaminosis C (scurvy)
Delayed maturation due to illness
Endocrine disturbances
Growth hormone excess
Hyperparathyroidism
Hypothyroidism
33
36. The differential for flaring of the
metaphysis
anaemia(s)
fibrous dysplasia
storage diseases
chronic lead poisoning
bone dysplasias
36
37. Mnemonic “RICKETS”
Reaction of the periosteum (may occur)
Indistinct cortex
Coarse trabeculation
Knees, wrists, and ankles affected predominantly
Epiphyseal plates, widened and irregular
Tremendous metaphysis (cupping, fraying, splaying)
Spur (metaphyseal)
37
38. Osteomalacia
Metabolic disorder that alters the quality of bone
characterized by a lack of calcium salts being deposited
in osteoid tissue. “soft bones.”
s a condition that usually is overlooked and neglected
B/C of
wide spectrum of nonspecific clinical, radiographic, and
biochemical manifestations
38
40. Clinical Features
Often masked by its varied causes
Asymptomatic
Bone pain/tenderness
Muscular weakness
Lab: Inc. ALP, PTH, hydroxyproline
Ca++ & P marginally diminished
40
41. Pathology
Abnormal relative increase in uncalcified osteoid that coats the
surfaces of trabeculae and linings of the Haversian canals
(osteoid seams).
Pseudo-fractures linear regions of unmineralized osteoid
Occur bilaterally and symmetrically
Either insufficiency fractures or vascular pulsations acting on the softened bone
41
42. Radiologic Features
Decreased bone density may show
characteristic “erased” or “fuzzy” type of
demineralization.
Coarse trabecular pattern
Loss of cortical definition cortex reveals it to be
thinner and altered in structure.
42
43. Cont’d…
The only reliable sign for the diagnosis of osteomalacia is the
presence of the Looser zone
It is a radiolucency that runs perpendicular to the cortex of the bone
and may have a sclerotic margin and be indistinguishable from the
now frequently encountered stress fracture.
43
44. Pseudo-fractures
linear radiolucencies that usually occur bilaterally and
symmetrically
The most common sites for them to occur are the femoral necks,
pubic and ischial rami, ribs, and axillary margins of the scapulae.
44
45. Other causes of pseudo fractures
Paget’s disease
Fibrous dysplasia
Rickets
45
46. Deformities
In the pelvis, inferior displacement of the
sacrum produces a triradiate shape to the
pelvic canal
Medial acetabular migration forms a protrusio
acetabuli deformity
Bowing of the femur and tibia also are seen
Bellshaped thoracic cage
46
53. CT
Multidetector CT is well suited to demonstrate the intraspinal
ossification, which is a rare, but recognized, complication of the
enthesopathy associated with XLH osteomalacia
53
54. MRI
MRI has been widely used for the evaluation of various
disease processes, such as
Pelvic insufficiency fractures and
Oncogenic OM to detect the causative neoplasm
Metastasis of the pelvic skeleton
54
55. Insufficiency fractures on MR
The insufficiency fractures appeared
as hypointense lines or fissures in
both T1 & T2
Hyperintensity on T2WI adjacent to
these hypointense fissures suggest
acute insufficiency fracture
55
56. DEXA
Low BMD in 70% of cases
Bone scintigraphy
May benefit to aid the location of
pseudo fracture.
56
The matrix makes up about 30% of the bone and the other 70% is of salts that give strength to it.
Matrix= collagen(90-95%) + other salts like CaPO
Bone=matrix + cells
Bone matrix consists of organic and inorganic components. Organic(Osteoid)= collagen type I (95%) + amorphous material, including glycosaminoglycans that are associated with proteins. Inorganic matter represents about 50% of the dry weight of bone matrix, composed of abundant calcium and phosphorus, as well as smaller amounts of bicarbonate, citrate, magnesium, potassium, and sodium. Calcium forms hydroxyapatite crystals with phosphorus but is also present in an amorphous form.
4. (zone of provisional calcification)
Normal pattern of the left knee on a frontal plain radiograph (a) and a drawing (b). Routine radiograph of a healthy 9-year-old boy. The physis (arrows) appears as a radiolucent flat disc between the epiphysis and the metaphysis. The normal zone of provisional calcification (ZPC) (arrowheads) is a continuous, regular, thin (<1 mm thick) radiodense band.
25(OH)D also plays an important role in extraskeletal health.
vitamin D deficiency may be associated with certain immunological conditions such as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, inflammatory bowel disease, mood disorders, and cancers such as breast, prostate, and colon cancer.
In adolescents, low serum vitamin D levels are associated with increased risk of hypertension, hyperglycemia, metabolic syndrome, and higher risk of upper respiratory infections. This chapter focuses on the skeletal manifestations of vitamin D deficiency
Diagram of the calcium homeostasis pathway. Ingested calcium is absorbed in the gastrointestinal tract, and vitamin D is either absorbed in the gastrointestinal tract or generated from 7-de-hydrocholesterol through exposure to UV light (UVB). Vitamin D is further processed in the liver and kidney, where it is converted to its fully active form, which promotes calcium absorption in the gut. Parathyroid hormone acts on the bones and the kidneys to increase serum calcium levels, and high serum calcium levels in turn suppress parathyroid hormone secretion. But it also promotes urinary phosphate excretion resulting hypophosphatemia. Parathyroid hormone, calcium, and phosphorous also modulate vitamin D metabolism in the kidney (21). 25(OH)D= 25-hydroxy-vitamin D, 1,25-(OH)2D= 1,25-dihydroxy-vitamin D.
Soft tissue swellings occur around the growth plates owing to hypertrophied cartilage.
As in osteomalacia, histopathologic examination of rachitic bone demonstrates a decrease in the quantity of calcified osteoid and an increase in uncalcified osteoid (osteoid seams).
(a)Anteroposterior radio-graph of the skull shows a partially patent frontal suture (arrow).
(b)Posteroanterior radiograph of the chest shows wide and rounded anterior rib ends (circles). This finding is often called a “rachitic rosary” because the chain of rounded rib ends resembles rosary beads at physical examination.
C. Anteroposterior radiograph of both lower extremities obtained 2 years later than a–d shows diffuse osteopenia, bowing of the tibiae and fibulae, flared metaphyses, and widening of the growth plates with sclerosis and irregularity on the metaphyseal side. Transverse sclerotic metaphyseal bands (arrows) parallel to the growth plate reflect periods of intermittent adequate mineralization followed by poor mineralization
A. Posteroanterior radiograph of both hands shows diffuse osteopenia, age-indeterminate fractures of several metacarpals (solid arrows), and cupped fragmented frayed metaphyses of the distal radii and ulnae (ovals). A peripheral rim of bone along the metaphysis (dashed arrow) occurs by membranous ossification.
B. Anteroposterior radiograph of both knees shows a fracture of the patient’s right distal femur (black arrow), as well as age-indeterminate fractures of her right tibia and both fibulae (dashed white arrows). The metaphyses are fragmented, frayed, and fractured (solid white arrow)
Radiographs of the knee of a 3.6-year-old girl with hypophosphatemia depict severe fraying of the metaphysis.
Radiograph in a 4-year-old girl with rickets depicts bowing of the legs caused by loading.
rachitic rosary
Observe the opaque, bulbous indentations of the lung adjacent to the enlarged costochondral junctions (arrows).
1: sagittal T2-weighted image with fat suppression(TR 4000/TE 110) of the femur shows a healing pathologic fracturewith periosteal reaction and marrow edema (curved arrow). Additionally, widening and increased T2 signal are seen in the main physis (large straight arrow) and the physis of the SOC (small straight arrow)
2: coronal T2-weighted image with fat suppression(TR 3200/TE 102) of the left hip reveals widening and increased signal of the physis of the SOC (open arrow) as well as loss of the zpc. There is no evidence of slippage of the femoral head
aBMD—area bone mineral density
B. Bilateral varus deformity (bowing). Medial spur from the tibial metaphysis evident on the right side Disturbed defective growth of the medial proximal tibial epiphysis.Irregularities of the physis on both sides.
Dfn: local disturbance of growth of the medial aspect of the proximal tibial metaphysis and/or epiphysis that results in tibia vara. The condition is commonly bilateral.
All bones are over-transparent suggesting osteopenia. Long bones are deformed due to muscles growth, which osteopenia cannot correct. Multiples fractures of different ages are seen
Dfn: a heterogeneous group of congenital, non-sex-linked, genetic disorders of collagen type I production, involving connective tissues and bones.
Radiographic findings: head, neck and spine
basilar invagination
wormian bones
kyphoscoliosis
vertebral compression fractures
codfish vertebrae
platyspondyly
chest
pectus excavatum or carinatum
pelvis
acetabular protrusio
coxa vara
general
severe osteoporosis
deformed, gracile (over-tubulated) bones
cortical thinning
hyperplastic callus formation
popcorn calcification: the metaphyses and epiphyses exhibit numerous scalloped radiolucent areas with sclerotic margins 1
zebra stripe sign: cyclic bisphosphonate treatment produces sclerotic growth recovery lines in the long bones
formation of pseudarthrosis at sites of healing fractures
AP radiograph of knees. Note irregularity, sclerosis and widening of the metaphyses with normal epiphyses
White line adjacent to epiphyseal plate. Wimberger's ring sign. Trummerfeld zone. Pelken spurs. Subperiosteal haemorrhage. Osteoporosis.
Wimberger sign: presence of a sclerotic rim around epiphysis
White line of frankel: dense zone of provisional calcification at the growing metaphysis
Trumerfeld zone: a lucent zone below white line due to lack of mineralisation
Pelkan spur:as the area is prone to fractures manifesting at cortical margin
Osteoporosis
Subperiosteal haemorrhage.
Loss of cortical definition: Close examination of the cortex reveals it to be thinner and altered in structure. Usually, the endosteal surface is blurred and indistinct.
Coarsened Trabecular Pattern. A decrease in the overall number of bony trabeculae within all bones enhances the contrast of those remaining. As a result, the texture of the spongiosa may appear coarse and mottled.
Fig: The trabecular pattern is fuzzy, coarse, and has a ground-glass appearance
Other name for Looser zone are:
pseudofractures
Increment fractures
Milkman’s syndrome
Umbau zonen
Pseudo-fractures occur in other bone-softening disorders, including Paget’s disease, fibrous dysplasia, rickets, and hyperphosphatasia.
Paget’s disease extensive bone remodeling expanded bone with coarse trabecular pattern.
Fibrous dysplasia localised defect in osteoblastic differentiation and maturation, with the replacement of normal bone with large fibrous stroma and islands of immature woven bone expansile ground glass appearing/ lytic bone lesion
Hyperphosphatasia
OSTEOMALACIA: PSEUDO-FRACTURES.
AP Pelvis. Note the true subtrochanteric fracture(arrowhead) and the pseudofractures (arrows) of the pubes. B. AP Pubis. Note that the bulbous appearance is caused by callus formation at the pseudo-fracture site
(arrows). Additional pseudo-fractures can be seen through the body of the pubis (arrowheads)
C and D. Scapular Axillary Borders. E. PA Forearm. Note the pseudofractures in the radius and ulna (arrows) These defects are recognized by their bilateral symmetry and perpendicular orientation to the cortex
OSTEOMALACIA: DEFORMITY. A. Lateral Thoracic Spine. Observe the increased biconcave endplate contours. The trabeculae are coarsened.
B. Acute Fracture Lateral Elbow. Note that after trivial trauma a fracture has occurred through the distal humerus. Note the pseudofracture in the proximal radius
Protrusion of acetabulum in case of osteomalacia
Dfn: Acetabular protrusio (also known as acetabular protrusion) is intrapelvic displacement of the acetabulum and femoral head, so that the femoral head projects medial to the ischioilial line.
Triradiate appearance of the pelvis with bilateral acetabula protrusio.
Osteopenic texture of the examined bones with coarse trabeculae.
Right superior and inferior pubic rami Looser's zones.
Subchondral bone absorption of acroiliac joints (more on the right).
Red arrows: represent stress fractures (looser's zones)
Yellow arrows: represent subchondral bony resorption at the sacroiliac joint.
X-linked hypophosphatemia (XLH), also called X-linked dominant hypophosphatemic rickets, X-linked vitamin d-resistant rickets, is an X-linked dominant form of rickets (or osteomalacia) that differs from most cases of rickets in that ingestion of vitamin D is relatively ineffective
Figure 2
53-year-old female woman who presented with chronic pelvic pain and history of decreased sun exposure (she was wearing long garments and veils). (a) Pelvic radiograph reveals insufficiency fractures at the superior and inferior pubic rami (white arrowheads). No pathological lesion was seen in the iliac and sacral bones. (b) Coronal T2-weighted MRI shows insufficiency fractures as hypointense fissures (arrows) without pathological signal intensity (sequel or healed fractures) at the pubic rami. (c) Coronal T1 and (d) T2-weighted MRI demonstrate a hypointense fissure line (white arrow) with pathological signal intensity (white arrowhead) at the right iliac bone (active type of insufficiency fracture). (e) Second-year follow-up coronal STIR MRI depicts the hypointense fissure and disappearance of the pathological signal intensity (white arrowhead). (f) Follow-up MR coronal STIR image also depicts a new hyperintense lesion at the left ramus pubis (arrowhead). Note the sequel or healed fracture lines at the pubic rami on this image (white arrows).
A whole-body 99m Tc- methylene diphosphonate bone scintigraphy showed increased uptake in the chest, both femoral heads, sacrum, left knee and left ankle, consistent with multiple pseudo-fractures
