Textbook of Radiology: Musculoskeletal Radiology Hariqbal Singh, Shrikant Nagare
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Congenital Skeletal Anomalies and Dysplasia1

 
Preaxial and Postaxial Polydactyly
Polydactyly may be preaxial (radial) or postaxial (ulnar). It may range from an ossicle to complete duplication of fingers or toes. On occasion the hand may be duplicated. When present, should search for an associated syndrome. Syndactyly may be associated with polydactyly. Postaxial polydactyly is more frequent congenital often seen as fifth digit duplications in hands or feet (Figs 1.1A to D).
 
Ectrodactyly Ectodermal Dysplasia Cleft lip syndrome
Ectrodactyly ectodermal dysplasia cleft lip (EEC) syndrome is a uncommon condition with multiple congenital anomalies with normal intelligence characterized by ectodermal dysplasia, clefting of hands, feet, lip and palate. It is an autosomal dominant syndrome. Management of the cases requires a multidisciplinary approach. Early diagnosis allows precise counseling of parents with reassurance of normal intelligence.
Examination of that baby revealed ectrodactyly (splitting of hands and feet), ectodermal dysplasia, cleft lip and palate, sparse scalp hairs and eyebrows and absence of eyelashes (Figs 1.2A to E). These abnormalities constitute the EEC syndrome.
 
Madelung’s Deformity
Madelung’s deformity is commoner in girls and is generally bilateral and presents during adolescence. The defective development of the inner third of the epiphysis of the lower end the radius result in bowing of radial shaft thus increasing the interosseous space.
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Figs 1.1A to D: (A) AP radiograph of hand shows pre-axial (radial) polydactyly in a 6-year-old female; (B) Oblique radiograph of foot shows pre-axial polydactyly in 14-year-old male; (C) shows post-axial (ulnar) polydactyly; (D) is magnified view of C
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The lower end of ulna is subluxed backward. The hand project forward at the wrist joint to produce a bayonet-like appearance in a lateral projection (Fig. 1.3).
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Figs 1.2A to E: Both hands have claw like appearance due to cone shaped defect (arrow). Soft tissue fusion of the middle and ring finger of the right hand and index and middle finger of the left hand is seen (A). Both feet show claw like appearance due to soft tissue fusion of the 3rd, 4th and 5th toes (B). Surgery has been performed for cleft lip (C). X-ray hands (D) show a cone shaped defect. There is absence of middle and distal phalanges of middle finger on the left side. X-ray feet (E) show cone shaped defect due to absence of 2nd toe on either side. Syndactyly of the metatarsals of the left foot is seen. There is absence of middle and distal phalanges of 3rd, 4th and 5th toes on either side
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Fig. 1.3: Madelung deformity of right wrist in a 13-year-old female
 
Congenital Hip Dislocation
Congenital hip dislocation is a very important condition as treatment depends upon early recognition. Females are more commonly affected (F>M, 5:1). Dislocation is usually unilateral (L>R, 11:1), both hips may be involved. Ultrasound is now the accepted method of primary investigation of suspected developmental dysplasia of the hip (Figs 1.4A and B).
 
Osteopetrosis
Osteopetrosis or Albers-Schönberg disease or marble bone disease is a rare disorder in which due to deficiency of carbonic anhydrase in osteoclasts resulting defective bone resorption by osteoclasts, when resorption fails and formation persists leads to excessive bone formation. Hence all the bones become hard dense and brittle. Radiological hallmark is generalized markedly increased bone density giving rise to a bone-in-bone appearance, Erlenmeyer flask type deformity of the tubular bones and sandwich vertebrae seen as dense bands of sclerosis parallel to the endplates (Figs 1.5A to D).3
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Figs 1.4A and B: AP and frog pelvis radiographs shows congenital hip dislocation in a 3-year-old male
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Figs 1.5A to D: CT scout images of pelvis with both hips, left thigh and both hands show generalized markedly increased bone density indicative of osteopetrosis
 
Sprengel deformity
Sprengel described 4 cases of upward displacement of the scapula in 1891 and named the entity as Sprengel deformity. It is also known as high scapula or congenital high scapula. It is a rare congenital skeletal abnormality where one shoulder blade sits higher on the back than the other. It is failure of descent of scapula secondary to fibrous or osseous omovertebral connection; it may be associated with Klippel-Feil syndrome, renal anomalies, and webbed neck. It results in elevation and medial rotation of scapula. It may be associated with Gorlin basal cell nevus syndrome (Figs 1.6A and B).
The deformity is due to a failure in early fetal development where the shoulder fails to descend properly from the neck to its final position. Treatment includes surgery in early childhood and physiotherapy.
 
Macrodystrophia Lipomatosa
Macrodystrophia lipomatosa is a congenital local gigantism of the hand and foot characterized by proliferation of all mesenchymal components, particularly fibroadipose tissue. Macrodystrophia lipomatosa comes to clinical attention because of cosmetic reasons, mechanical problems secondary to degenerative joint disease or development of neurovascular compression (Figs 1.7 and 1.8).
 
Multiple Epiphyseal Dysplasia
It is characterized by an abnormality of mucopoly­saccharide and glycoprotein metabolism and develops in early childhood. Radiographs show delayed ossification and delayed mineralization of the epiphysis of long bones which are fragmented small and flattened, loose bodies may also occur in joints. Metaphyseal irregularity is seen in tubular bones, when spine is involved there is irregularity of vertebral end plates (Fig. 1.9).
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Figs 1.6A and B: Chest X-ray PA view and photograph shows sprengel deformity of left scapula
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Figs 1.7A to C: Clinical photograph of right hand shows enlarged, fused ring and middle finger. Plain radiograph (B) and coronal reformatted CT (C) shows soft tissue swelling and proliferation of fat on palmar aspect of the ring and middle fingers, along with dorsal angulation and syndactyly
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Figs 1.8A and B: T1 coronal MRI (A) reveals proliferation of fatty tissue on plantar aspect of the second and third toes of right foot with signal intensity similar to that of subcutaneous fat as seen by fat suppressed STIR coronal image (B)
 
Cleidocranial Dysostosis
Cleidocranial dysostosis, also called cleidocranial dysplasia is an autosomal dominant disorder resulting in delayed or failed ossification of midline bones, especially membranous bones but endochondral bones are also affected.
Patient usually present with large head, dispro­portionate small facial bones, narrow chest, sagging shoulders and may be with dwarfism or defective or delayed dentition.
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Fig. 1.9: A 5-year-old male with multiple epiphyseal dysplasia showing bilateral involvement long bones of lower limbs
 
Skull and Head
Radiographs of the skull show large head, large unossified areas, and failure of fusion at the fontanelles and sutures, and the presence of multiple wormian bones. Metopic suture is persistent. The bones of the base of the skull and face are small with small. Paranasal sinuses are hypoplastic. The jaws are often prognathous. Delayed eruption of the permanent teeth which may have faulty implantation and enamel defects. There may be an absence of some of the permanent teeth, or development of supernumerary teeth.
 
Chest
Defective formation of one or both clavicles is the most common finding from roentgen examinations. A variety of changes in the clavicles, from a simple transverse defect of the middle third, to complete absence of both clavicles. In the majority of cases the defects are found at the sternal ends. Thorax may be narrow or bell shaped. Sometimes super­numerary ribs are present.
 
Spine
Kyphosis, lordosis, and scoliosis may occur. Cervical ribs are common.
 
Pelvis
The pelvic bones frequently are abnormal in develop­ment. The pelvic canal is narrowed and the joint spaces are considerably widened, including the spaces between the ischium, ilium, and pubis at each acetabulum. The mature pelvis has broad, squat appearance associated with malformed, defective joints. Sacrum, iliac bones may be underdeveloped.
 
Extremities
There may be partial or complete absence of the radius. The distal phalanges are short and conical in shape. The middle phalanges are much shorter than normal and their lateral borders are concave, almost resulting in a dumb-bell shape. The metacarpal bones are expanded at their extremities and narrowed in the middle thirds, with some increase in the compact tissue at this level. Epiphyses frequently are seen at both ends of the basal phalanges and metacarpal bones. Femoral neck may be deformed, absent resulting in coxa vara.
 
Holt-Oram syndrome
Holt-Oram syndrome is an inherited disorder that causes abnormalities of the hands, arms, spine and heart. Occurs approximately one in every 100,000 and affects both sexes equally (Figs 1.10A to D).
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Figs 1.10A to D: (A and B) X-rays spine show multiple spinal anomalies; (C) shows congenital heart disease; (D) shows absence of radius. All these are features of Holt-Oram syndrome
6 It falls into two groups: (A) Defects in arm and hand bones involving one or both sides of the body. Most commonly the defects are in the carpal bones and thumb. The thumb may be malformed or missing. In severe cases the arms may be very short such that the hands are attached close to the body (phocomelia). (B) Heart abnormalities—Three forth of cases with Holt-Oram syndrome heart abnormality. It may be abnormal rhythms, atrial or ventricular septal defect.
 
Fibrous Dysplasia
Fibrous dysplasia is a developmental anomaly of the mesenchymal precursor of bone, an idiopathic lesion of the medullary portion of bone. There is replacement and distortion of the medullary bone by fibro-osseous tissue of woven bone. Bones affected with fibrous dysplasia rarely undergo malignant degeneration. The appearance of new lesions usually terminates after skeletal maturity. Its cause is unknown and is usually found in the proximal femur, tibia, humerus, ribs, and craniofacial bones in decreasing order of incidence. These resemble tumor hence the name pseudotumoral fibrous dysplasia is used to describe rapidly growing and expanding lesions, giving rise to facial deformity and asymmetry. Fibrous dysplasia can be monostotic or polyostotic. Only one bone is involved in monostotic fibrous dysplasia. Less often, multiple bones are involved (polyostotic fibrous dysplasia). The polyostotic form is generally more severe and is discovered earlier. This form can involve as few as two bones in the same limb or multiple bones throughout the skeleton. Males and females are equally affected by the disorder. Cases are usually diagnosed within the first three decades of life. It is usually asymptomatic, though pain and swelling may accompany the lesion.
Polyostotic fibrous dysplasia is known to have multiple associations with other disorders. The combination of polyostotic fibrous dysplasia, precocious puberty, and café au lait spots is called McCune Albright’s syndrome. The association of fibrous dysplasia and soft tissue tumors has been given the name Mazabraud’s syndrome. Other endocrine abnormalities including hyperthyroidism, Cushing’s disease, thyromegaly, hypo­phosphatemia, and hyperprolactinemia have been associated with fibrous dysplasia.
Radiologic appearance in fibrous dysplasia varies according to the degree of fibrous tissue present which is seen replacing the medullary bone. Bone texture varies from a ground glass appearance to inhomogeneous mixture of bone and fibrous tissue. It appears as a well circumscribed lesion in a long bone with a ground glass or hazy appearance of the matrix. There is a narrow zone of transition and no periosteal reaction or soft tissue mass. The lesions are normally located in the metaphysis or diaphysis with occasional focal thinning of the overlying cortex due to scalloping from within. The radiological appearance can also be cystic, pagetoid, or dense and sclerotic. Repeated fractures through lesions in the proximal femur can result in the formation of a shepherd’s crook deformity.
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Figs 1.11A to F: CT topogram (A) reveals diffuse thickening of calvarium. Axial CT (B) reveals diffuse thickening of calvarium, skull base with ground glass appearance. Sagittal, coronal and axial T2-weighted images (C to F) shows diffuse thickening of calvarium, skull base and maxillofacial bones
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Figs 1.12A to E: Fifteen-year-old female patient presented with complaint of left leg pain since seven months. X-ray of both hips and thigh AP (A) view shows expansile trabeculated lytic lesion in left femoral meta-diaphysis causing expansion of medullary cavity with thinning of cortex. X-ray left leg including knee joint, AP and lateral view (B) shows expansile lytic lesion seen in distal third shaft of tibia causing expansion of medullary cavity and thinning of cortex. T1W coronal image shows iso- to hypointense lesion in meta-diaphyseal region of left femur causing expansion of medullary cavity and thinning of cortex. Coronal STIR image (D) shows the lesion as hyperintense. STIR coronal (E) image of left thigh shows hyperintense lesion in distal third of left tibia causing expansion of medullary cavity and thinning of cortices. These findings suggest diagnosis of polyostotic fibrous dysplasia
MRI is helpful in delineating the extent of the lesion (Figs 1.11 and 1.12) and identifying possible pathological fractures and also sarcomatous change within the lesion. The lesions shows heterogeneous inter­mediate signal on T1W images and heterogeneously low signal on T2W images but may have regions of higher signal. Postcontrast T1W images show heterogeneous contrast enhancement. Bone scans demonstrate increased tracer uptake on Tc99 bone scans.
 
Fibrodysplasia Ossificans Progressiva
Fibrodysplasia ossificans progressiva (FOP) is a rare connective tissue disorder. A mutation of the body’s repair mechanism causes fibrous tissue (muscle, tendon, and ligament) to be ossified when damaged. In many cases, injuries can cause joints to become permanently frozen in place.
The gene that causes ossification is normally deactivated after a fetus’ bones are formed in the womb, but in patients with FOP, the gene keeps working. Aberrant bone formation in patients with FOP occurs in injured connective tissue or muscle cells at the sites of injury or growth (Figs 1.13A and B).
The bone that results occurs independently of the normal skeleton, forming its own discrete skeletal elements. These elements, however, can fuse with normal skeletal bone. The symptoms are often misdiagnosed as fibrosis or malignancy. This leads to biopsies, which can actually exacerbate the growth of the lesion. The diaphragm, tongue and extra-ocular muscles cardiac and smooth muscle are spared.
 
Mucopolysaccharidoses
Mucopolysaccharidoses (MPSs) are a group of lyso­somal storage diseases, due to an inherited deficiency of a lysosomal enzyme involved in the degradation of acid mucopolysaccharides leading to mental and motor retardation and bone changes. These diseases are autosomal recessive, except for type II, which is X-linked. The diagnosis is biochemical and based on assay of urinary excretion of the mucopolysaccharidoses. Seven distinct clinical types and numerous subtypes have been identified. Although each MPS differs clinically, most patients generally experience a period of normal development followed by a decline in physical and/or mental function.
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Figs 1.13A and B: Plain CT scan coronal reconstructed and axial images showing abnormal extensive ossification in soft tissues
 
MPS I H (Hurler Syndrome)
Hurler syndrome is caused by the enzyme deficiency alpha-L-iduronidase. There is excess urinary excretion of dermatan sulfate and heparan sulfate. Clinically, there is severe, progressive mental retardation. The children have a coarse facies, short stature, protuberant abdomen, hernias, joint contractures and a thoracolumbar gibbus (Figs 1.14A to F). There is also hepatosplenomegaly, cardiomyopathy and cardiac failure. Radiologically, there is a large skull with a J-shaped sella, shallow orbits, breaking and flattening of the anterior portion of the vertebral bodies at the thoracolumbar junction, wide, thick ribs, thick clavicles, generalized symmetric damage of the epiphysis, widening of the shafts of the long bones with flaring of relatively small iliac wings with acetabular roofs. All the mucopolysaccharidoses share in common pointing of the bases of the metacarpals.
 
MPS I S (Scheie Syndrome)
Scheie syndrome (earlier called MPS V) is caused by deficiency of the alpha-L-iduronidase. There is abnormal urinary excretion of dermatan sulfate and heparan sulfate. Children have normal intelligence, stiff joints and corneal clouding. Radiologically, the changes are similar to Hurler’s syndrome but with milder expression.
 
MPS II
Hunter syndrome is caused due to deficiency of alpha-iduronate sulfatase. Clinically, the physical appearances are similar to those of Hurler’s syndrome but milder in expression. Intelligence has a spectrum ranging from near normal intelligence to mental retardation. Hepatosplenomegaly, hirsutism, flexion joint contractures and dorsolumbar kyphosis occur. Radiologically, the changes are similar though milder than in Hurler’s syndrome.
 
MPS III
Sanfilippo’s disease is divided into four types dependent upon alteration of a different enzyme needed to completely break down the heparan sulfate sugar chain. Clinically, there are mildly coarse facial features, corneal clouding, mild joint stiffness and severe mental and motor retardation, which is progressive. There is hepatosplenomegaly and cardiomyopathy. There is storage of heparan sulfate in the tissues. Radiologically, changes are similar to those in Hurler’s syndrome.
 
MPS IV
Morquio’s disease has two subtypes. In subtype: (a) the defect is N-acetylgalactosamine-6-sulfatase. In subtype (b) the enzyme defect is b galactosidase. Clinically it becomes evident between the age of one and three as the children present with short trunk, short stature, abnormal posture with a lumbar kyphois, pectus deformity, knock knee deformity, abnormal hands and feet, hyperextensible joints but are of normal intelligence. Corneal clouding is seen in type (b). Radiologically, the skeletal changes are different to Hurler’s syndrome in that the skull shows only mild changes with underdevelopment of the mastoid air cells. There is platyspondyly, a small odontoid process of the axis with atlantoaxial subluxation, flaring of the ribs, pectus carinatum, constricted small iliac wings with steep acetabular roofs, coxa valga, secondary aseptic necrosis of the femoral head, often widening of the metaphyses and epiphyses at the knees with secondary degenerative changes. The hands show the typical appearance of the pointed bases to the metacarpals with, in addition, irregularity of the carpal bones.9
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Figs 1.14A to F: Spine shows thoracolumbar gibbus with breaking and flattening of the anterior portion of the vertebral bodies at the thoracolumbar junction (A), there is pointing (B and C) of the bases the metacarpals (feature shared by all the mucopolysaccharidoses), generalized symmetric damage of the epiphysis, widening of the shafts of the long bones (B and C), cardiomyopathy, thick clavicles with wide and thick ribs (D). Large skull with a J-shaped sella and shallow orbits (E and F)
 
MPS VI
Maroteaux-Lamy syndrome is caused by deficiency of the enzyme arylsulfatase B. Coarse facies, corneal opacity, and small stature are the dominant clinical features. There may also be hepatosplenomegaly, aortic and mitral valve disease. Intelligence is normal. Radiologically, there is a spectrum of severity of disease. In general, the skull vault is large and is often thick with premature closure of the cranial sutures, short mandibular rami, oval vertebral bodies with a lower thoracic or upper lumbar kyphosis with wedging anteriorly, hypoplasia of the odontoid, small scapulae with hypoplastic glenoid fossae, aseptic necrosis of the femoral capital epiphyses, poorly developed acetabular roofs and diaphyseal widening of the long bones and pointed bases of the metacarpals.
 
MPS VII
Sly syndrome is caused by deficiency of the enzyme beta-glucuronidase. In its rarest form, Sly syndrome causes children to be born with hydrops fetalis, in which extreme amounts of fluid are retained in the body. Survival is usually a few months or less. Most children with Sly syndrome are less severely affected. Neurological symptoms may include mild to moderate mental retardation by age 3, communicating hydrocephalus, nerve entrapment, corneal clouding, and some loss of peripheral and night vision. Other symptoms include short stature, some skeletal irregularities, joint stiffness and restricted movement, and umbilical and/or inguinal hernias. Some patients may have repeated bouts of pneumonia during their first years of life. Most children with Sly syndrome live into the teenage or young adult years.
 
MPS IX
Natowicz syndrome results from hyaluronidase deficiency. Symptoms included nodular soft-tissue masses located around joints, with episodes of painful swelling of the masses and pain that ended spontaneously within 3 days. Pelvic radiography showed multiple soft-tissue masses and some bone erosion. Other traits included mild facial changes, acquired short stature as seen in other MPS disorders, and normal joint movement and intelligence.
MRI is the primary imaging technique to detect CNS alterations. The presence of white matter alterations is significantly correlated with mental retardation. Other possible CNS alterations are perivascular, subarachnoid and ventricular space enlargement and abnormalities of the basal ganglia, the corpus callosum, and the atlantoaxial joint.10
 
Perthes Disease
Legg-Calvé-Perthes disease more frequently referred as Perthes disease (Figs 1.15A to E). It is idiopathic avascular necrosis (AVN) of the growing femoral epiphysis seen in children; it is seen between the 4–8 years of age. The most common presenting feature is pain with or without a limp. 10% of cases show bilateral involvement.
Plain X-rays show in early stage of the disease:
  • Smaller femoral epiphysis on affected side
  • Apparent increased density of the femoral head epiphysis
  • Widening of the medial joint space
  • Blurring of the physeal plate
  • Radiolucency of the proximal metaphysis
The late (stage 2) signs in the disease process include:
  1. The femoral head begins to fragment with sub­chondral lucency (crescent) and (b) redistri­bution of weight-bearing leading to thickening of few trabeculae which become more prominent.
Advanced burnt out (stage 4) of Perthes disease include:
  1. Femoral head deformity with widening and flattening
  2. Proximal femoral neck deformity
  3. Tongues of cartilage may extend inferolaterally into the femoral neck, creating lucencies
  4. The presence of metaphyseal involvement leads femoral neck deformity, and early physeal closure resulting in leg shortening.
 
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) provides early diagnosis (Figs 1.15A to E), before the onset of X-ray findings, and in assessing extent of cartilaginous involvement, important in prognosis and assessing joint congruency in a variety of joint positions.
Both arthrography and dynamic MRI access:
  • Deformity for the femoral head
  • Congruency to shows batching of femoral head contour to that of the acetabulum
  • Containment: To show the amount of lateral sub­luxation of the flattened femoral head out of the acetabulum.
Differential diagnosis include:
  • Slipped superior femoral epiphysis
  • Osteomyelitis
  • Secondary causes of avascular necrosis (AVN)
  • Dysplasia epiphysealis capitis femoris (Meyer dysplasia)
  • Tumors
  • Hemophilia
  • Juvenile rheumatoid arthritis.
Prognosis depends on the degree of primary deformity of the femoral head and the secondary osteoarthritic change. The treatment aims to maintain good femoroacetabular contact and a round femoral head. Finally hip replacements may be necessary.
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Figs 1.15A to E: A 10 years male presented with pain in right hip and difficulty in cross leg sitting. MR images (A to E) show partial collapse with irregular contour of right femoral head epiphysis, predominantly hypointense signals on all pulse sequences suggestive of sclerosis. Mild effusion seen in right hip joint (E). Flattening of right femoral head is seen. Small cyst is seen in medial aspect of right femoral neck. Left femoral head, femoral neck and bilateral proximal shafts show normal appearances and signal pattern. Findings are suggestive of Perthes disease of right hip with mild joint effusion
 
Congenital Bifid Sternum
Congenital sternal cleft or bifid sternum is an isolated developmental defect of multifactorial etiology (Fig. 1.16). It is the separation of the sternum with orthotopic normal heart and normal skin coverage. Sternal bands form in the sixth week of intrauterine life from the lateral plate mesoderm, and in the ninth week the fusion of these separate bands on either side of the anterior chest wall occurs in a craniocaudal direction.
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Fig. 1.16: Axial CT at mid-thorax shows broadly separated compo­nents of sternum in midline in a case of sternal cleft
The manubrium ossification centers on each side of the mid-sternum are fused at birth and fusion of ossification centers in the sternal body is completed by the sixth year. Failure of fusion of the sternal body results in congenital sternal clefts. The treatment is the closure of primary defect in neonatal age, when flexibility of the chest wall is maximal and compression of underlying structures is minimal.
 
Bone Island or Enostosis
Bone island or enostosis represents a focus of mature compact (cortical) bone within the cancellous bone (spongiosa). Typically asymptomatic, this benign lesion is usually an incidental finding, with a preference for the pelvis, femur, and other long bones. On radiography it is seen as a homogeneously dense, sclerotic focus in the cancellous bone and on CT scan, a bone island appears as a high attenuation focus (Figs 1.17A and B).
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Figs 1.17A and B: Scout image (A) and axial CT images (B) show two focal densely sclerotic compact bones in the spongiosa with thorny or brush borders. When the lesion is more than 20 mm it is known as giant bone island