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Radiographs
Symposium on Common Orthopedic Problems
Radiographs
Robert H. Wilkinson, MD.*
Increasing concern exists regarding the medical use of ionizing radiation because of possible genetic damage. Radiographic examinations serve a vital role in medical care, but physicians should always evaluate carefully the need for such examinations and avoid their routine use. Radiographs should be performed when there is a likelihood of abnormality, the detection of which will have a bearing on treatment. Before elaborating on specific skeletal abnormalities, the technical aspects of radiologic examinations should be considered.
Technical Aspects The trend toward better tissue detail with a smaller radiation dose to the patient is evident as new films, screens, radiographic tubes, and generators are developed. Use of nonscreen or cardboard cassettes in children are now made obsolete by par speed or high speed screens which permit considerable reduction of radiation dose and radiographic images of excellent quality. Rare earth screens have some limitations in the evaluation of the skeleton and soft tissues, but are useful in other areas. No fluoroscopy of children should be done today in this country without image amplification. Shielding of the gonads, an important consideration to reduce radiation exposure, is easier in boys; however, ovarian shielding is possible except in examinations of the bony pelvis and its contents. Collimation of the primary beam is an effective method of reducing the radiation dose by diminishing scatter and by eliminating unessential primary radiation. In the examination of the extremities of smaller children, table top techniques produce radiographs of high quality at a considerable lower dose than with grid or Bucky methods. Short exposure times are vital in the children so that motion can be eliminated. Elaborate immobilizing devices are available commercially, but the judicious use of tape, sand bags, and foam blocks usually suffice if a friendly and gentle but firm attitude is used by the examiner.
':'Radiologist, Children's Hospital Medical Center, Boston; Associate Professor of Radiology. Harvard School of Medicine, Boston, Massachusetts Pediatric Clinics of North America- Vol. 24, No.4, November 1977
685
686
ROBERT
H.
WILKINSON
Radiographic Views and Methods Generally two views at 90° to each other are required for adequate delineation. More views may be desirable; for example, oblique views of the hand and wrist and foot and ankle are commonly used. Standard views are described in numerous textbooks and these should be used. 5 , 11, 12 If a radiographic examination is indicated, a proper one should be performed. Fluoroscopy as a screening procedure prior to the inspection of good quality preliminary radiographs is hazardous and frequently unrewarding, especially when dealing with the skeleton. The resolution of bony detail is inferior and the use of fluoroscopy for more than quickly positioning for spot films or tomography or for brief evaluation of motion is to be condemned. Fluoroscopy for dynaInic events should always be used in conjunction with videotape recording. Tomography or body section radiographs are indicated in definition of bony defects or deformitie!i in obscure areas or in bones of complex contours. Thus the finer structures of the skull such as the middle ear, lesions of the spine, or lesions in close proximity to joints are frequent!y best evaluated by this technique. Stereoscopic radiographs permit three dimensional display which can be particularly useful in evaluation of the skull, spine, shoulders, pelvis, and hips. For example, in dislocations of the shoulder, no manipulation of the patient is required to take two stereoscopic frontal projections which will show the position of the dislocation and rule out the presence of a fracture. The complex contours of the vertebra, pelvis, and skull are well studied by this technique, and the increase in dose is minimal. Radionuclide scanning is discussed elsewhere in this volume, but it is such an important tool in evaluation of the young skeleton, that brief mention is made here. It is valuable in the early detection of osteomyelitis, stress or other occult fractures, and in searching for skeletal metastases. Xeroradiography is helpful in localization of nonradiopaque foreign bodies, but the relatively high radiation dose currently involved makes this technique suitable in children primarily in the extremities only. Ultrasound is still of limited use in examinations of the skeleton and is utilized primarily for evaluation of soft tissues. Total body computerized tomography will likely be of increasing value, particularly in the evaluation of spinal injuries, for example, localizing bony fragments in the neural canal and visualization of nonossified diastematomyelia.
Comparison Views This subject deserves special discussion. Many competent authors insist that comparison views of the extremities in children always be exposed. If an experienced radiologist is at hand, I believe this is an unnecessary expenditure of radiation and money. Good quality radiographs of the area in question should be examined first. If the soft tissues and bones are normal, comparison views will add nothing
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useful. Skeletal trauma and infection almost always are accompanied by soft tissue deformity. Of course, if an abnormality is detected, such as a displaced epiphysis, then comparison views are essential to evaluate the amount of displacement (Fig. 1). There are important exceptions. Both hips should always be examined (Fig. 2). The deformity of juxtaarticular soft tissues may be subtle, and comparison views are required. In addition, hip disease in children (congenital dislocation, Legg-Perthes disease, and slipped femoral epiphysis) is not uncommonly bilateral. Comparison views for evaluation of acromioclavicular separation are essential, and there are other exceptions. In general, however, routine comparison views are unnecessary.
Indications for Radiographic Examinations It is beyond the scope of this discussion to describe all the indications for radiographic examination of the child's skeleton. Rather, a brief mention of some general principles is made and a few specific illustrations are used.
Congenital A multitude of anomalies of the skeleton requires examination with a variable degree of urgency. Myelomeningocele, club feet, various forms of dwarfism, and limb deformities are but a few where radiographic evaluation is required. The physician should be aware that anomalies commonly are multiple and may occur in predictable combinations. Thus examination of genitourinary and gastrointestinal tracts is undertaken early in the management of a child with major spinal anomalies such as absent sacrum, congenital scoliosis, and myelomeningocele (Fig. 3). Extra digits may be present as an isolated lesion or may represent a more complex constellation of deformities such as the Ellis-van Creveld syndrome. The association of limb anomalies such as absent or hypoplastic thumbs and/or absent radii should raise the possibility of the Fanconi syndrome or congenital aplastic pancytopenia. The hematologic abnormality may not appear for several years. Likewise, the limb anomalies may be associated with cardiac anomalies, the Holt-Oram syndrome. Fortunately, there are several texts available today enumerating these various syndromes, for few physicians can remember all of them and their variable manifestations. 13, 15, 16. 18. 19 Prompt and accurate recognition of the entities is vital for genetic counseling and expectant care of the child. Congenital dislocation of the hip may be discovered at birth, but is more commonly discovered later. Radiographic examination in congenital dislocation of the hip may not be abnormal, but failure to demonstrate a radiographic abnormality should not be taken as documentation of normal hips. The hip joint in the newborn is still cartilaginous, and is thus invisible radiographically. Documentation of abnormal alignment of the femurs and of lateral displacement of the ossified proximal metaphysis in the ossified portion of the pelvis should suggest the likelihood of at least malposition of the hip. Occasionally, one will
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Figure 1. A child sustained a blow to the point of the elbow. The frontal projection was normal; the lateral projection (A) shows the soft tissue swelling over the olecranon together with evidence of ajoint effusion with displacement of both the anterior and posterior humeral fat pads. No fracture was noted, but because of the presence of effusion and the question of a subtle fracture through the growth plate of the olecranon, the comparison view (B) was exposed. This is identical except for the soft tissue changes.
Figure 2. Anteroposterior projection of both hips shows diminutive capital femoral epiphyses. Seeing one hip alone might raise the possibility of Legg-Calve-Perthes disease, but symmetrical bilateral deformity should suggest systemic generalized disease such as hypothyroidism or epiphyseal dysplasia. Other epiphyses were small and deformed, consistent with epiphyseal dysplasia.
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encounter definite acetabular deformity even in the newborn. Generally, however, physical examination is the most sensitive way to document this deformity. In later stages when ossification of the capital femoral epiphyses develops, generally after five months, asymmetric ossification or actual delay increases the accuracy of radiographic evaluation. As in so many other instances, it is never too early to begin looking, but one should hesitate to exclude the disease on the basis of a normal radiograph in the newborn.
Infections Acute osteomyelitis and septic arthritis are generally considered to be emergencies, but clinical presentation may be atypical and the diagnosis difficult. Early recognition of the disease is essential so that therapy may be instituted early, thus avoiding damage to bones and joints. By the time bones show radiographic evidence of destruction and periosteal new bone, the infection is well established and at least 10 to 14 days of age. One would hope to make the diagnosis before this by identifying the soft tissue deformity which almost always occurs early in the course of the disease and which antedates bone deformity.4 It is essential that the child suspected of bone or joint sepsis undergo careful radiographic examination for deep edema (Fig. 4). Radionuclide scanning is also helpful, particularly in the very early stages and also in those children whose infections are multi-focal. 17 Chronic osteomyelitis in children is becoming much less common, likely due to earlier diagnosis and more vigorous medical and surgical therapy. Now it is possible to treat and arrest the disease in its very earliest stages before the usual radiographic evidence of destruction has an opportunity to develop.
Trauma To recognize the abnormal, one must first know well the normal anatomy and its variations because the latter may mimic traumatic changes. There are several good atlases available showing most of the common variations. 3 , 8, 9 Points at which muscles and ligaments insert may be irregular in contour (Fig. 5)1 and may be mistaken for trauma or neoplasm, for example, the soleal line of the tibia. 1o Secondary centers of ossification may have unusual contours or may be multiple rather than single (Figs. 6-8). Frequently these variations are bilaterally symmetrical, but not always (Fig. 9). Acute trauma sufficient to damage the skeleton is generally associated with hemorrhage and edema. Therefore meticulous radiographic examination of the soft tissues is as important as examination of the bones. The weakest part of the immature skeleton is the growth plate or physis. Acute fractures through this unca1cified cartilage can be recognized by the presence of overlying soft tissue swelling. The secondary center of ossification may return to its normal position and alignment due to the stabilizing effect of the tough periosteal membrane of the child. An erroneous diagnosis of a sprain may be made. Epiphyseal fractures are
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Fig. 5
Figure 3. Scoliosis due to spinal anomalies led to this excretory urogram showing an associated anomaly, a large solitary right kidney. Figure 4. Note the increased thickness of the pretibial muscle shadow over the lower one-third of this leg consistent with deep edema. This 1 year old had signs and symptoms of a septic process. A radionuclide bone scan showed increased uptake in the distal one-half of the tibia. Blood cultures grew staphylococci; the child was successfully treated for osteomyelitis. Figure 5. This knee is slightly externally rotated. The irregularity of cortical contour and density of the posteromedial femur is benign and secondary to pull of adductor magnus along the medial supracondylar ridge and should not be mistaken for neoplasm or infection. Figure 6. Two views of an ankle show an extra ossification center in the medial malleolus. It is smooth and well corticated. Comparison views might be asymmetrical. The absence of overlying soft tissue swelling suggests that this is a normal variant, not a fracture. Figure 7. Secondary centers of ossification are present throughout the skeleton and some are infrequently seen. This one at the inferior tip of the scapula may mimic a fracture, or, when projected through the lung, a pulmonary density.
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Figure 8. A close-up of an anteroposterior film of the pelvis shows asymmetry of the ischiopubic synchondrosis in the process of ossifying. The left side appears expanded but both are normal.
Figure 9. Considerable irregularity of contour may be observed in the immature distal femoral epiphyses. This is normal and should not be mistaken for a pathologic condition.
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Figure 10. A, The initial examination of this ankle after injury showed considerable soft tissue swelling. Obvious is the anteromedial displacement of the distal tibial epiphysis along a metaphyseal fragment. This is a Salter-Harris type II fracture. Less obvious is the fracture of the talus. B, 37 months later there is still growth of the distal tibial physis and normal alignment. However, there are ischemic changes in the talus and continued observation is indicated.
more common than sprains and dislocations since the ligaments are stronger than the growth plate. Failure to make the proper diagnosis may result in inadequate immobilization of the fracture and delayed recognition of a potential disturbance of growth, leading to incongruity of joint surfaces or discrepancy in the length of limbs (Fig. 10). Most fractures of the metaphysis or diaphysis of the bone are easily recognized. However, the immature skeleton is more plastic and may bend rather than break;2 when it breaks, it may crack or unwind rather than shatter as the mature skeleton tends to do (Figs. 11 to 13). A certain amount of stimulation or overgrowth of bone can be anticipated in diaphyseal fractures prior to age 10 years secondary to hyperemia. Therefore, especially in the femur, some overriding of the bone ends is acceptable, barring the deformities already mentioned. 14 Chronic trauma is not uncommon in children. This may be only an exaggeration of physiologic forces and may be free of pain, but deforming, nonetheless. For example, the obese child may flatten the medial aspect of the proximal tibial epiphysis. The crawling infant may develop calluses on the knees which may mimic edema of superficial infection (Fig. 14). Stress fractures are common in young athletes and are due to chronic trauma. 7 They may be associated with little pain. Deformity may be minimal and the bone repair may be mistaken for neoplasia
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Figure 11. The lateral view of a boy's forearm shows bowing of both bones without evidence of a fracture following a fall. He had pain and limitation of pronation and supination. Reduction is indicated to restore full motion.
Figure 12. Three views of a 10 year old boy's wrist show the typical wrinkle-type fracture of woven bones. Note the lucency visible on the lateral view of the right. This is fat squeezed out of the marrow space as the medullary canal is compressed (arrow).
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Figure 13. This toddler refused to walk or bear weight following a fall. Note in the lateral view (A) the deep edema in the distal pretibial area, overlying the undisplaced fracture best seen in B. A toddler's fracture may be very difficult to see, but the swelling should prompt careful search for it. One month later (C) there is periosteal new bone visible along the tibial shaft. The fracture is easier to see as dead trabeculae are resorbed.
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(Fig. 15). Usually callus formation is abundant because the causative activity is continued, such as the "march" fracture of the metatarsal. Occasionally the fractures are subtle and are associated with little or no edema. Multiple views, magnification views, tomography, and radionuclide scans 6 may be required to localize these fractures in the early stages.
Battered Child or Trauma X Inflicted trauma in children has been recognized in this country for about 25 years. The child may be struck, shaken, pushed, thrown, or burned by a parent or guardian, babysitter, or sibling; typically the assaults are repetitive. Usually the parent or custodian seeks medical attention for the child and denies the deliberate nature of the trauma or ascribes the injury to a real fall or true accident. This type of skeletal trauma can usually be suspected by several features. It is generally inappropriately more extensive and severe than the initial history would suggest. The fractures typically show different stages of healing, substantiating the repetitive nature of the trauma (Fig. 16). While any part of any bone may be fractured, damage to the epiphyses are almost universal (Fig. 17). There is a gamut of soft tissue injuries from superficial trauma to the skin to major contusions of solid organs including brain, liver, spleen, and kidneys; perforations and hematomas of the gastrointestinal tract also occur. A complete radiographic survey of the skeleton is indicated. Separate views of the extremities, skull, spine, and pelvis are more accurate than a "babygram," total-body examination on one large film. Sometimes several views of an area may be required to recognize older fractures, which remodel rapidly in the young child (Fig. 18). Differential diagnosis includes metabolic disorders associated with excessive fragility of abnormal bone such as in osteogenesis imperfecta. Copper deficiency in the premature infant and aberration of copper absorption in Menke's syndrome (kinky hair) are associated with fractures during normal care and handling of these infants. Metabolic Bone Disease The question is commonly raised, "What areas of the skeleton should be radiographed to rule out metabolic bone disease?" The answer should be obvious to most pediatricians: the area which is growing most rapidly. The more rapid the growth, the more pronounced will be the deformity. For this reason, a frontal view of a knee should suffice, especially in rickets, osteoporosis, or lead poisoning. A lateral projection is included if an estimation of maturity is also desired. One knee should suffice unless hemihypertrophy or atrophy is suspected. Commonly rickets is assumed to result in bowed legs, but knock knees also occur. Osteomalacic bones are soft and do bend. The direction of the bending depends on the direction of the deforming forces at the time of the onset of the disease. Toddlers tend to have bowed legs; older children commonly go through a stage of genu valgus. Most children with bowlegs or knock knees are normal, but a radiographic examina-
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Fig. 15
Fig. 14
Fig. 16 Figure 14. The normal sharp interface between subcutaneous fat and underlying muscle is obliterated anterior to the knee of this 7 month old. This could represent superficial cellulitis, but in actual fact is physiologic skin thickening in an infant who "ambulates" by crawling. Figure 15. There is well organized periosteal and endosteal new bone in the distal femur of this young athlete who complained of knee pain. The margins of the bony mass medially are sharply defined and the linear configuration of the intraosseous repair show this to be a healing stress fracture, not a bone tumor. Figure 16. An anteroposterior radiograph of the chest shows several rib fractures inferiorlyon the left, an uncommon injury in infants. Note the shoulders which show evidence of old injuries with epiphyseal displacement on the right and altered trabecular pattern in the humeral metaphyses. The appearance is typical of trauma X.
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Fig. 17
Fig. 18
Figure 17. This 11 month old girl was injured in an automobile accident. There is an acute traumatic slip of the proximal femoral epiphysis, but note the defOrmity of trabecular pattern in the distal femoral and proximal tibial metaphyses. These should suggest previous fractures and other evidence of inflicted trauma was discovered on further examination.
Figure 18. Anteroposterior radiographs of this knee were exposed at one month intervals, left to right. Note on the left the displaced distal femoral epiphysis and the metaphyseal fractures. Only two months later (right), remodeling is almost complete.
tion should quickly exclude the presence of osteomalacia or other metabolic abnormality. In the diagnosis of hyper1>arathyroidism, roentgen examination of the hands and wrists may best show the subperiosteal bone resorption. This is a good region to check initially. Additional areas frequently show changes if further confirmation is desired. These may be useful in following the course of the disease and include shoulders, hips, and knees since trabecular resorption and repair proceed at different rates in different areas. The spine takes part in metabolic disease as do all the bones, but changes there may be subtle. An exception is the presence of compression fracture, commonly multiple, in osteoporosis. The presence of more than one compression fracture in the spine of a child strongly suggests an underlying disease such as acute leukemia or idiopathic osteoporosis. Benign and Malignant Bone Tumors Both benign and malignant lesions of bone may be painful. Primary malignancies tend to be more insidious in onset, the pain is more constant, and fractures· through these lesions tend to occur late in the disease. Benign simple cysts, in contrast, may be asymptomatic until a pathologic fracture occurs. Benign lesions, especially conversion growth defects such as benign cortical defects, are discovered by
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Figure 19. A close-up of the right calvicle shows a defect on the inferior margin of the clavicle. The margins are irregular and not very sclerotic. especially laterally. The appearance has some features of aggressive invasion, but this is a normal rhomboid fossa, the site of attachment of the rhomboid ligament which helps to stabilize the medial end of the clavicle.
serendipity and are usually asymptomatic. These are generally self-limited and should not be mistaken for malignant lesions. The radiographic appearance is the gross pathology of bone tumors. The more sclerotic the margins, the more likely the tumor is benign. Benign lesions usually are easily differentiated from adjacent normal bone, whereas malignant tumors are more aggressive and infiltrative with poorly defined margins (Fig. 19). Malignant lesions tend to grow faster, destroying bone and displacing periosteum, allowing less tirne for bone repair. Soft tissue masses develop beyond the bone and increase rapidly in size in association with malignant tumors of bone. It is difficult to describe and classify all the roentgen criteria for differentiating benign and malignant bone tumors. A surgical biopsy may be required since there may be an equivocal appearance on the radiographs. Clinical presentation is extremely important; persistent or severe bone pain warrants careful physical examination and evaluation. Usually radiographic examination follows. One area of bone pain not to be taken lightly in children is the spine. Functional back pain is uncommon at this age. Careful search for tumors, trauma, or infection in or about the spine should be undertaken. Idiopathic scoliosis is rarely painful in childhood. Scoliosis may be secondary to spinous or paraspinous disease.
Summary Physicians performing radiology for children should utilize modern equipment, expose children to the least amount of radiation possible, and avoid unnecessary examinations. Those interpreting radiographs must be familiar with the wide range of normal variations of the skeleton and/or be prepared to refer to texts and atlases dealing with
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these. Careful examination of soft tissues greatly increases the accuracy of diagnostic radiology in the search for trauma and infection.
REFERENCES 1. Barnes, G. R., Jr., and Gwinn, J. L.: Distal irregularities of femur stimulating malignancy. Am. J. Roentgenol. Radium Ther. Nucl. Med., 122:180-185, 1974. 2. Borden, S.: Traumatic bowing of the forearm in children. J. Bone Joint Surg., 56A:611, 1974. 3. Caffey, J.: Pediatric X-ray Diagnosis. Edition 6. Chicago, Year Book Medical Publishers, Inc., 1972. 4. Capitanio, M. A., and Kirkpatrick, J. A.: Early roentgenographic observations in acute osteomyelitis. Am. J. Roentgenol. Radium Ther. Nucl. Med., 108:488, 1970. 5. Darling, D.: Radiology of Infants and Children. Edition 2. Springfield, Illinois, Charles C Thomas, 1971. 6. Geslien, G. E., et al.: Early detection of stress fractures using 99mTc-polyphosphate. Radiology 121 :683-689, 1976. 7. Harris, J. H., Jr., and Harris, W. H.: The Radiology of Emergency Medicine. Baltimore, Williams and Wilkins Co., 1975. 8. Keats, T. E.: An Atlas of Normal Roentgen Variants. Chicago, Year Book Medical Publishers, Inc., 1973. 9. Kohler, A.: The Borderlands of the Normal and the Early Pathologic in Skeletal Radiology. Edition 11. New York, Grune and Stratton, 1968. 10. Levine, A. H., et al.: The soleal line. A cause of tibial pseudoperiostitis. Radiology, 119:79-81, 1976. 11. McInnes, J.: Clark's Positioning in Radiography. Edition 9. London, William Heineman Medical Books, Ltd. Distributed by Year Book Medical Publishers, Inc., Chicago, 1974. 12. Merrill, V.: Atlas of Roentgenographic Positions and Standard Radiologic Procedures. Edition 4. St. Louis, C. V. Mosby Co., 1975. 13. Poznanski, A. K.: The Hand in Radiologic Diagnosis. Philadelphia, W. B. Saunders Co., 1974. 14. Rang, M.: Children's Fractures. Philadelphia, J. B. Lippincott Co., 1974. 15. Spranger, J. W., Langer, L. 0., Jr., and Wiedemann, H. R.: Bone Dysplasias: An Atlas of Constitutional Disorders of Skeletal Development. Philadelphia, W. B. Saunders Co., 1974. 16. Taybi, J.: Radiology of Syndromes. Chicago, Year Book Medical Publishers, Inc., 1975. , 17. Treves, S., Khettry, J., Broker, F. H., et al.: Osteomyelitis: Early scintigraphic detection in children. Pediatrics, 57:173-186,1976. 18. Vaughan, V. C., III, and McKay, R. J. (eds.): Nelson Textbook of Pediatrics. Philadelphia, W. B. Saunders Co., 1975. 19. Wynn-Davies, R., and Fairbanks, T. J.: Fairbank's Atlas of General Affections of the Skeleton. Edition 2. London, Churchill-Livingstone, 1976. Department of Radiology Children's Hospital Medical Center 300 Longwood Avenue Boston, Massachusetts 02115
•
Radiographs
Robert H. Wilkinson, MD.*
Increasing concern exists regarding the medical use of ionizing radiation because of possible genetic damage. Radiographic examinations serve a vital role in medical care, but physicians should always evaluate carefully the need for such examinations and avoid their routine use. Radiographs should be performed when there is a likelihood of abnormality, the detection of which will have a bearing on treatment. Before elaborating on specific skeletal abnormalities, the technical aspects of radiologic examinations should be considered.
Technical Aspects The trend toward better tissue detail with a smaller radiation dose to the patient is evident as new films, screens, radiographic tubes, and generators are developed. Use of nonscreen or cardboard cassettes in children are now made obsolete by par speed or high speed screens which permit considerable reduction of radiation dose and radiographic images of excellent quality. Rare earth screens have some limitations in the evaluation of the skeleton and soft tissues, but are useful in other areas. No fluoroscopy of children should be done today in this country without image amplification. Shielding of the gonads, an important consideration to reduce radiation exposure, is easier in boys; however, ovarian shielding is possible except in examinations of the bony pelvis and its contents. Collimation of the primary beam is an effective method of reducing the radiation dose by diminishing scatter and by eliminating unessential primary radiation. In the examination of the extremities of smaller children, table top techniques produce radiographs of high quality at a considerable lower dose than with grid or Bucky methods. Short exposure times are vital in the children so that motion can be eliminated. Elaborate immobilizing devices are available commercially, but the judicious use of tape, sand bags, and foam blocks usually suffice if a friendly and gentle but firm attitude is used by the examiner.
':'Radiologist, Children's Hospital Medical Center, Boston; Associate Professor of Radiology. Harvard School of Medicine, Boston, Massachusetts Pediatric Clinics of North America- Vol. 24, No.4, November 1977
685
686
ROBERT
H.
WILKINSON
Radiographic Views and Methods Generally two views at 90° to each other are required for adequate delineation. More views may be desirable; for example, oblique views of the hand and wrist and foot and ankle are commonly used. Standard views are described in numerous textbooks and these should be used. 5 , 11, 12 If a radiographic examination is indicated, a proper one should be performed. Fluoroscopy as a screening procedure prior to the inspection of good quality preliminary radiographs is hazardous and frequently unrewarding, especially when dealing with the skeleton. The resolution of bony detail is inferior and the use of fluoroscopy for more than quickly positioning for spot films or tomography or for brief evaluation of motion is to be condemned. Fluoroscopy for dynaInic events should always be used in conjunction with videotape recording. Tomography or body section radiographs are indicated in definition of bony defects or deformitie!i in obscure areas or in bones of complex contours. Thus the finer structures of the skull such as the middle ear, lesions of the spine, or lesions in close proximity to joints are frequent!y best evaluated by this technique. Stereoscopic radiographs permit three dimensional display which can be particularly useful in evaluation of the skull, spine, shoulders, pelvis, and hips. For example, in dislocations of the shoulder, no manipulation of the patient is required to take two stereoscopic frontal projections which will show the position of the dislocation and rule out the presence of a fracture. The complex contours of the vertebra, pelvis, and skull are well studied by this technique, and the increase in dose is minimal. Radionuclide scanning is discussed elsewhere in this volume, but it is such an important tool in evaluation of the young skeleton, that brief mention is made here. It is valuable in the early detection of osteomyelitis, stress or other occult fractures, and in searching for skeletal metastases. Xeroradiography is helpful in localization of nonradiopaque foreign bodies, but the relatively high radiation dose currently involved makes this technique suitable in children primarily in the extremities only. Ultrasound is still of limited use in examinations of the skeleton and is utilized primarily for evaluation of soft tissues. Total body computerized tomography will likely be of increasing value, particularly in the evaluation of spinal injuries, for example, localizing bony fragments in the neural canal and visualization of nonossified diastematomyelia.
Comparison Views This subject deserves special discussion. Many competent authors insist that comparison views of the extremities in children always be exposed. If an experienced radiologist is at hand, I believe this is an unnecessary expenditure of radiation and money. Good quality radiographs of the area in question should be examined first. If the soft tissues and bones are normal, comparison views will add nothing
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useful. Skeletal trauma and infection almost always are accompanied by soft tissue deformity. Of course, if an abnormality is detected, such as a displaced epiphysis, then comparison views are essential to evaluate the amount of displacement (Fig. 1). There are important exceptions. Both hips should always be examined (Fig. 2). The deformity of juxtaarticular soft tissues may be subtle, and comparison views are required. In addition, hip disease in children (congenital dislocation, Legg-Perthes disease, and slipped femoral epiphysis) is not uncommonly bilateral. Comparison views for evaluation of acromioclavicular separation are essential, and there are other exceptions. In general, however, routine comparison views are unnecessary.
Indications for Radiographic Examinations It is beyond the scope of this discussion to describe all the indications for radiographic examination of the child's skeleton. Rather, a brief mention of some general principles is made and a few specific illustrations are used.
Congenital A multitude of anomalies of the skeleton requires examination with a variable degree of urgency. Myelomeningocele, club feet, various forms of dwarfism, and limb deformities are but a few where radiographic evaluation is required. The physician should be aware that anomalies commonly are multiple and may occur in predictable combinations. Thus examination of genitourinary and gastrointestinal tracts is undertaken early in the management of a child with major spinal anomalies such as absent sacrum, congenital scoliosis, and myelomeningocele (Fig. 3). Extra digits may be present as an isolated lesion or may represent a more complex constellation of deformities such as the Ellis-van Creveld syndrome. The association of limb anomalies such as absent or hypoplastic thumbs and/or absent radii should raise the possibility of the Fanconi syndrome or congenital aplastic pancytopenia. The hematologic abnormality may not appear for several years. Likewise, the limb anomalies may be associated with cardiac anomalies, the Holt-Oram syndrome. Fortunately, there are several texts available today enumerating these various syndromes, for few physicians can remember all of them and their variable manifestations. 13, 15, 16. 18. 19 Prompt and accurate recognition of the entities is vital for genetic counseling and expectant care of the child. Congenital dislocation of the hip may be discovered at birth, but is more commonly discovered later. Radiographic examination in congenital dislocation of the hip may not be abnormal, but failure to demonstrate a radiographic abnormality should not be taken as documentation of normal hips. The hip joint in the newborn is still cartilaginous, and is thus invisible radiographically. Documentation of abnormal alignment of the femurs and of lateral displacement of the ossified proximal metaphysis in the ossified portion of the pelvis should suggest the likelihood of at least malposition of the hip. Occasionally, one will
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WILKINSON
Figure 1. A child sustained a blow to the point of the elbow. The frontal projection was normal; the lateral projection (A) shows the soft tissue swelling over the olecranon together with evidence of ajoint effusion with displacement of both the anterior and posterior humeral fat pads. No fracture was noted, but because of the presence of effusion and the question of a subtle fracture through the growth plate of the olecranon, the comparison view (B) was exposed. This is identical except for the soft tissue changes.
Figure 2. Anteroposterior projection of both hips shows diminutive capital femoral epiphyses. Seeing one hip alone might raise the possibility of Legg-Calve-Perthes disease, but symmetrical bilateral deformity should suggest systemic generalized disease such as hypothyroidism or epiphyseal dysplasia. Other epiphyses were small and deformed, consistent with epiphyseal dysplasia.
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encounter definite acetabular deformity even in the newborn. Generally, however, physical examination is the most sensitive way to document this deformity. In later stages when ossification of the capital femoral epiphyses develops, generally after five months, asymmetric ossification or actual delay increases the accuracy of radiographic evaluation. As in so many other instances, it is never too early to begin looking, but one should hesitate to exclude the disease on the basis of a normal radiograph in the newborn.
Infections Acute osteomyelitis and septic arthritis are generally considered to be emergencies, but clinical presentation may be atypical and the diagnosis difficult. Early recognition of the disease is essential so that therapy may be instituted early, thus avoiding damage to bones and joints. By the time bones show radiographic evidence of destruction and periosteal new bone, the infection is well established and at least 10 to 14 days of age. One would hope to make the diagnosis before this by identifying the soft tissue deformity which almost always occurs early in the course of the disease and which antedates bone deformity.4 It is essential that the child suspected of bone or joint sepsis undergo careful radiographic examination for deep edema (Fig. 4). Radionuclide scanning is also helpful, particularly in the very early stages and also in those children whose infections are multi-focal. 17 Chronic osteomyelitis in children is becoming much less common, likely due to earlier diagnosis and more vigorous medical and surgical therapy. Now it is possible to treat and arrest the disease in its very earliest stages before the usual radiographic evidence of destruction has an opportunity to develop.
Trauma To recognize the abnormal, one must first know well the normal anatomy and its variations because the latter may mimic traumatic changes. There are several good atlases available showing most of the common variations. 3 , 8, 9 Points at which muscles and ligaments insert may be irregular in contour (Fig. 5)1 and may be mistaken for trauma or neoplasm, for example, the soleal line of the tibia. 1o Secondary centers of ossification may have unusual contours or may be multiple rather than single (Figs. 6-8). Frequently these variations are bilaterally symmetrical, but not always (Fig. 9). Acute trauma sufficient to damage the skeleton is generally associated with hemorrhage and edema. Therefore meticulous radiographic examination of the soft tissues is as important as examination of the bones. The weakest part of the immature skeleton is the growth plate or physis. Acute fractures through this unca1cified cartilage can be recognized by the presence of overlying soft tissue swelling. The secondary center of ossification may return to its normal position and alignment due to the stabilizing effect of the tough periosteal membrane of the child. An erroneous diagnosis of a sprain may be made. Epiphyseal fractures are
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Figure 3. Scoliosis due to spinal anomalies led to this excretory urogram showing an associated anomaly, a large solitary right kidney. Figure 4. Note the increased thickness of the pretibial muscle shadow over the lower one-third of this leg consistent with deep edema. This 1 year old had signs and symptoms of a septic process. A radionuclide bone scan showed increased uptake in the distal one-half of the tibia. Blood cultures grew staphylococci; the child was successfully treated for osteomyelitis. Figure 5. This knee is slightly externally rotated. The irregularity of cortical contour and density of the posteromedial femur is benign and secondary to pull of adductor magnus along the medial supracondylar ridge and should not be mistaken for neoplasm or infection. Figure 6. Two views of an ankle show an extra ossification center in the medial malleolus. It is smooth and well corticated. Comparison views might be asymmetrical. The absence of overlying soft tissue swelling suggests that this is a normal variant, not a fracture. Figure 7. Secondary centers of ossification are present throughout the skeleton and some are infrequently seen. This one at the inferior tip of the scapula may mimic a fracture, or, when projected through the lung, a pulmonary density.
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Figure 8. A close-up of an anteroposterior film of the pelvis shows asymmetry of the ischiopubic synchondrosis in the process of ossifying. The left side appears expanded but both are normal.
Figure 9. Considerable irregularity of contour may be observed in the immature distal femoral epiphyses. This is normal and should not be mistaken for a pathologic condition.
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Figure 10. A, The initial examination of this ankle after injury showed considerable soft tissue swelling. Obvious is the anteromedial displacement of the distal tibial epiphysis along a metaphyseal fragment. This is a Salter-Harris type II fracture. Less obvious is the fracture of the talus. B, 37 months later there is still growth of the distal tibial physis and normal alignment. However, there are ischemic changes in the talus and continued observation is indicated.
more common than sprains and dislocations since the ligaments are stronger than the growth plate. Failure to make the proper diagnosis may result in inadequate immobilization of the fracture and delayed recognition of a potential disturbance of growth, leading to incongruity of joint surfaces or discrepancy in the length of limbs (Fig. 10). Most fractures of the metaphysis or diaphysis of the bone are easily recognized. However, the immature skeleton is more plastic and may bend rather than break;2 when it breaks, it may crack or unwind rather than shatter as the mature skeleton tends to do (Figs. 11 to 13). A certain amount of stimulation or overgrowth of bone can be anticipated in diaphyseal fractures prior to age 10 years secondary to hyperemia. Therefore, especially in the femur, some overriding of the bone ends is acceptable, barring the deformities already mentioned. 14 Chronic trauma is not uncommon in children. This may be only an exaggeration of physiologic forces and may be free of pain, but deforming, nonetheless. For example, the obese child may flatten the medial aspect of the proximal tibial epiphysis. The crawling infant may develop calluses on the knees which may mimic edema of superficial infection (Fig. 14). Stress fractures are common in young athletes and are due to chronic trauma. 7 They may be associated with little pain. Deformity may be minimal and the bone repair may be mistaken for neoplasia
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Figure 11. The lateral view of a boy's forearm shows bowing of both bones without evidence of a fracture following a fall. He had pain and limitation of pronation and supination. Reduction is indicated to restore full motion.
Figure 12. Three views of a 10 year old boy's wrist show the typical wrinkle-type fracture of woven bones. Note the lucency visible on the lateral view of the right. This is fat squeezed out of the marrow space as the medullary canal is compressed (arrow).
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Figure 13. This toddler refused to walk or bear weight following a fall. Note in the lateral view (A) the deep edema in the distal pretibial area, overlying the undisplaced fracture best seen in B. A toddler's fracture may be very difficult to see, but the swelling should prompt careful search for it. One month later (C) there is periosteal new bone visible along the tibial shaft. The fracture is easier to see as dead trabeculae are resorbed.
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(Fig. 15). Usually callus formation is abundant because the causative activity is continued, such as the "march" fracture of the metatarsal. Occasionally the fractures are subtle and are associated with little or no edema. Multiple views, magnification views, tomography, and radionuclide scans 6 may be required to localize these fractures in the early stages.
Battered Child or Trauma X Inflicted trauma in children has been recognized in this country for about 25 years. The child may be struck, shaken, pushed, thrown, or burned by a parent or guardian, babysitter, or sibling; typically the assaults are repetitive. Usually the parent or custodian seeks medical attention for the child and denies the deliberate nature of the trauma or ascribes the injury to a real fall or true accident. This type of skeletal trauma can usually be suspected by several features. It is generally inappropriately more extensive and severe than the initial history would suggest. The fractures typically show different stages of healing, substantiating the repetitive nature of the trauma (Fig. 16). While any part of any bone may be fractured, damage to the epiphyses are almost universal (Fig. 17). There is a gamut of soft tissue injuries from superficial trauma to the skin to major contusions of solid organs including brain, liver, spleen, and kidneys; perforations and hematomas of the gastrointestinal tract also occur. A complete radiographic survey of the skeleton is indicated. Separate views of the extremities, skull, spine, and pelvis are more accurate than a "babygram," total-body examination on one large film. Sometimes several views of an area may be required to recognize older fractures, which remodel rapidly in the young child (Fig. 18). Differential diagnosis includes metabolic disorders associated with excessive fragility of abnormal bone such as in osteogenesis imperfecta. Copper deficiency in the premature infant and aberration of copper absorption in Menke's syndrome (kinky hair) are associated with fractures during normal care and handling of these infants. Metabolic Bone Disease The question is commonly raised, "What areas of the skeleton should be radiographed to rule out metabolic bone disease?" The answer should be obvious to most pediatricians: the area which is growing most rapidly. The more rapid the growth, the more pronounced will be the deformity. For this reason, a frontal view of a knee should suffice, especially in rickets, osteoporosis, or lead poisoning. A lateral projection is included if an estimation of maturity is also desired. One knee should suffice unless hemihypertrophy or atrophy is suspected. Commonly rickets is assumed to result in bowed legs, but knock knees also occur. Osteomalacic bones are soft and do bend. The direction of the bending depends on the direction of the deforming forces at the time of the onset of the disease. Toddlers tend to have bowed legs; older children commonly go through a stage of genu valgus. Most children with bowlegs or knock knees are normal, but a radiographic examina-
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Fig. 16 Figure 14. The normal sharp interface between subcutaneous fat and underlying muscle is obliterated anterior to the knee of this 7 month old. This could represent superficial cellulitis, but in actual fact is physiologic skin thickening in an infant who "ambulates" by crawling. Figure 15. There is well organized periosteal and endosteal new bone in the distal femur of this young athlete who complained of knee pain. The margins of the bony mass medially are sharply defined and the linear configuration of the intraosseous repair show this to be a healing stress fracture, not a bone tumor. Figure 16. An anteroposterior radiograph of the chest shows several rib fractures inferiorlyon the left, an uncommon injury in infants. Note the shoulders which show evidence of old injuries with epiphyseal displacement on the right and altered trabecular pattern in the humeral metaphyses. The appearance is typical of trauma X.
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Figure 17. This 11 month old girl was injured in an automobile accident. There is an acute traumatic slip of the proximal femoral epiphysis, but note the defOrmity of trabecular pattern in the distal femoral and proximal tibial metaphyses. These should suggest previous fractures and other evidence of inflicted trauma was discovered on further examination.
Figure 18. Anteroposterior radiographs of this knee were exposed at one month intervals, left to right. Note on the left the displaced distal femoral epiphysis and the metaphyseal fractures. Only two months later (right), remodeling is almost complete.
tion should quickly exclude the presence of osteomalacia or other metabolic abnormality. In the diagnosis of hyper1>arathyroidism, roentgen examination of the hands and wrists may best show the subperiosteal bone resorption. This is a good region to check initially. Additional areas frequently show changes if further confirmation is desired. These may be useful in following the course of the disease and include shoulders, hips, and knees since trabecular resorption and repair proceed at different rates in different areas. The spine takes part in metabolic disease as do all the bones, but changes there may be subtle. An exception is the presence of compression fracture, commonly multiple, in osteoporosis. The presence of more than one compression fracture in the spine of a child strongly suggests an underlying disease such as acute leukemia or idiopathic osteoporosis. Benign and Malignant Bone Tumors Both benign and malignant lesions of bone may be painful. Primary malignancies tend to be more insidious in onset, the pain is more constant, and fractures· through these lesions tend to occur late in the disease. Benign simple cysts, in contrast, may be asymptomatic until a pathologic fracture occurs. Benign lesions, especially conversion growth defects such as benign cortical defects, are discovered by
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Figure 19. A close-up of the right calvicle shows a defect on the inferior margin of the clavicle. The margins are irregular and not very sclerotic. especially laterally. The appearance has some features of aggressive invasion, but this is a normal rhomboid fossa, the site of attachment of the rhomboid ligament which helps to stabilize the medial end of the clavicle.
serendipity and are usually asymptomatic. These are generally self-limited and should not be mistaken for malignant lesions. The radiographic appearance is the gross pathology of bone tumors. The more sclerotic the margins, the more likely the tumor is benign. Benign lesions usually are easily differentiated from adjacent normal bone, whereas malignant tumors are more aggressive and infiltrative with poorly defined margins (Fig. 19). Malignant lesions tend to grow faster, destroying bone and displacing periosteum, allowing less tirne for bone repair. Soft tissue masses develop beyond the bone and increase rapidly in size in association with malignant tumors of bone. It is difficult to describe and classify all the roentgen criteria for differentiating benign and malignant bone tumors. A surgical biopsy may be required since there may be an equivocal appearance on the radiographs. Clinical presentation is extremely important; persistent or severe bone pain warrants careful physical examination and evaluation. Usually radiographic examination follows. One area of bone pain not to be taken lightly in children is the spine. Functional back pain is uncommon at this age. Careful search for tumors, trauma, or infection in or about the spine should be undertaken. Idiopathic scoliosis is rarely painful in childhood. Scoliosis may be secondary to spinous or paraspinous disease.
Summary Physicians performing radiology for children should utilize modern equipment, expose children to the least amount of radiation possible, and avoid unnecessary examinations. Those interpreting radiographs must be familiar with the wide range of normal variations of the skeleton and/or be prepared to refer to texts and atlases dealing with
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these. Careful examination of soft tissues greatly increases the accuracy of diagnostic radiology in the search for trauma and infection.
REFERENCES 1. Barnes, G. R., Jr., and Gwinn, J. L.: Distal irregularities of femur stimulating malignancy. Am. J. Roentgenol. Radium Ther. Nucl. Med., 122:180-185, 1974. 2. Borden, S.: Traumatic bowing of the forearm in children. J. Bone Joint Surg., 56A:611, 1974. 3. Caffey, J.: Pediatric X-ray Diagnosis. Edition 6. Chicago, Year Book Medical Publishers, Inc., 1972. 4. Capitanio, M. A., and Kirkpatrick, J. A.: Early roentgenographic observations in acute osteomyelitis. Am. J. Roentgenol. Radium Ther. Nucl. Med., 108:488, 1970. 5. Darling, D.: Radiology of Infants and Children. Edition 2. Springfield, Illinois, Charles C Thomas, 1971. 6. Geslien, G. E., et al.: Early detection of stress fractures using 99mTc-polyphosphate. Radiology 121 :683-689, 1976. 7. Harris, J. H., Jr., and Harris, W. H.: The Radiology of Emergency Medicine. Baltimore, Williams and Wilkins Co., 1975. 8. Keats, T. E.: An Atlas of Normal Roentgen Variants. Chicago, Year Book Medical Publishers, Inc., 1973. 9. Kohler, A.: The Borderlands of the Normal and the Early Pathologic in Skeletal Radiology. Edition 11. New York, Grune and Stratton, 1968. 10. Levine, A. H., et al.: The soleal line. A cause of tibial pseudoperiostitis. Radiology, 119:79-81, 1976. 11. McInnes, J.: Clark's Positioning in Radiography. Edition 9. London, William Heineman Medical Books, Ltd. Distributed by Year Book Medical Publishers, Inc., Chicago, 1974. 12. Merrill, V.: Atlas of Roentgenographic Positions and Standard Radiologic Procedures. Edition 4. St. Louis, C. V. Mosby Co., 1975. 13. Poznanski, A. K.: The Hand in Radiologic Diagnosis. Philadelphia, W. B. Saunders Co., 1974. 14. Rang, M.: Children's Fractures. Philadelphia, J. B. Lippincott Co., 1974. 15. Spranger, J. W., Langer, L. 0., Jr., and Wiedemann, H. R.: Bone Dysplasias: An Atlas of Constitutional Disorders of Skeletal Development. Philadelphia, W. B. Saunders Co., 1974. 16. Taybi, J.: Radiology of Syndromes. Chicago, Year Book Medical Publishers, Inc., 1975. , 17. Treves, S., Khettry, J., Broker, F. H., et al.: Osteomyelitis: Early scintigraphic detection in children. Pediatrics, 57:173-186,1976. 18. Vaughan, V. C., III, and McKay, R. J. (eds.): Nelson Textbook of Pediatrics. Philadelphia, W. B. Saunders Co., 1975. 19. Wynn-Davies, R., and Fairbanks, T. J.: Fairbank's Atlas of General Affections of the Skeleton. Edition 2. London, Churchill-Livingstone, 1976. Department of Radiology Children's Hospital Medical Center 300 Longwood Avenue Boston, Massachusetts 02115
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