DOI: 10.1148/rg.234035030
(Radiographics. 2003;23:811-845.)
From the Archives of the AFIP
Child Abuse: Radiologic-Pathologic Correlation1
Gael J. Lonergan, Lt Col, USAF MC,
Andrew M. Baker, MD,
Mitchel K. Morey, MD and
Steven C. Boos, Lt Col, USAF MC
1 From the Department of Radiologic Pathology, Armed Forces Institute of Pathology, 14th and Alaska Sts NW, Bldg 54, Rm M-121, Washington, DC 20306-6000 (G.J.L.); Department of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, Md (G.J.L.); Hennepin County Medical Examiner’s Office, Minneapolis, Minn (A.M.B., M.K.M.); and Armed Forces Center for Child Protection, National Naval Medical Center, Bethesda, Md (S.C.B.). Received February 10, 2003; revision requested March 24 and received March 31; accepted April 4. Address correspondence to G.J.L. (e-mail: glonergan@mac.com).
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Abstract
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In the United States, roughly one of every 100 children is subjected to some form of neglect or abuse; inflicted injury is responsible for approximately 1,200 deaths per year. Child physical abuse may manifest as virtually any injury pattern known to medicine. Some of the injuries observed in battered children are relatively unique to this population (especially when observed in infants) and therefore are highly suggestive of nonaccidental, or inflicted, injury. Worrisome injuries include rib fracture, metaphyseal fracture, interhemispheric extraaxial hemorrhage, shear-type brain injury, vertebral compression fracture, and small bowel hematoma and laceration. As noted, however, virtually any injury may be inflicted; therefore, careful consideration of the nature of the injury, the developmental capabilities of the child, and the given history are crucial to determine the likelihood that an injury was inflicted. The majority of these injuries are readily detectable at imaging, and radiologic examination forms the mainstay of evaluation of child physical abuse. Detection of metaphyseal fracture (regarded as the most specific radiographically detectable injury in abuse) depends on high-quality, small field-of-view radiographs. The injury manifests radiographically as a lucent area within the subphyseal metaphysis, extending completely or partially across the metaphysis, roughly perpendicular to the long axis of the bone. Acute rib fractures (which in infants are strongly correlated with abuse) appear as linear lucent areas. They may be difficult to discern when acute; thus, follow-up radiography increases detection of these fractures. For skull injuries, radiography is best for detecting fractures, but computed tomography and magnetic resonance imaging best depict intracranial injury.
Index Terms: Abdomen, injuries, 70.419 • Children, injuries • Extremities, injuries, 40.4195 • Infants, injuries • Head, injuries, 10.419, 10.433 • Ribs, fractures, 471.4195
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LEARNING OBJECTIVES FOR TEST 1
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After reading this article and taking the test, the reader will be able to:
- Describe the common injury patterns in abused children.
- Recognize the imaging features of inflicted metaphyseal and rib fracture, interhemispheric hemorrhage, and hollow organ abdominal injury in children.
- Discuss the biomechanical basis of common abusive injuries.
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Introduction
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The intentional infliction of pain and suffering, both physical and emotional, on children is a distressingly common occurrence. Harm by caretakers may be categorized as neglect (63% of cases), physical abuse (19%), sexual abuse (10%), and psychologic abuse (8%). In the United States in the year 2000, approximately 1,200 children died as a result of inflicted trauma or neglect, representing a rate of 1.7 per 100,000 children. The youngest children are the most vulnerable: Children less than 1 year of age account for 44% of all abuse-related fatalities. Three million cases of suspected abuse were reported in 2000; 879,000 of these cases were substantiated, representing 1.22% of U.S. children. Parents accounted for 77% of perpetrators (1).
The rate of victimization decreases as age increases: From birth to 3 years of age, 15.7 per 1,000 children are abused or neglected, compared with 5.7 per 1,000 for the 16–17-year-old group. Girls are abused slightly more often than boys when all forms of abuse are considered together (12.8 vs 11.2 for girls and boys, respectively, per 1,000 children). However, in the subcategory of child sexual abuse, girls are more than four times as likely to be victims than boys (1.7 vs 0.4, respectively, per 1,000 children) (1). Physicians and other allied health professionals are mandated by law in all 50 states and the District of Columbia to report suspected abuse within 48 hours to Children’s Protective Services (2).
The first description of child physical abuse was by the French forensic physician Ambrose Tardieu (3) in 1860. The next mention in the medical literature was not until 1946, when the American pediatric radiologist John Caffey (4) described six infants with long bone fractures and subdural hematomas. He postulated that these injuries were inflicted and later (1957) described the metaphyseal fracture, which remains to this day the most specific injury in child abuse (5). Kempe et al (6) in 1962 coined the term battered child syndrome to describe metaphyseal fracture and other injuries typical of abuse. In 1971, Guthkelch (7) was the first to invoke shaking as the causative mechanism in abusive head injury. Paul Kleinman and colleagues (8–17), beginning in the 1980s and continuing today, have contributed extensively to our understanding of the pathophysiology and mechanisms of injury in child physical abuse. This article reviews the injuries commonly observed in child physical abuse, with special emphasis on those injuries that are highly specific or suggestive of abuse (Fig 1). We discuss the radiologic injury patterns commonly discovered in physically abused children, with special emphasis on the biomechanical forces that produce the injuries, their pathologic and radiologic appearances, and forensic implications of certain features (such as evidence of fracture healing) of the injuries.
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Figure 1. Violent shaking and squeezing of an infant may result in subdural hemorrhage (top right diagram) and shear-type brain injury, rib fracture (middle right diagram), and metaphyseal fracture (lower right diagram). These injuries are fully described and illustrated in subsequent sections.
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Skeletal Injury
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Skeletal injury is the most common abuse-related injury (excluding pure soft-tissue injuries such as bruising). Virtually every type and location of fracture has been documented in abused children. The prevalence of fracture varies with report and the population studied. Fracture is documented in 11%–55% of physically abused children (18–20). In one large series of abuse-related fractures (429 fractures), when all pediatric age groups were considered together, 76% of fractures were in the long bones (Fig 2); 8%, the skull; and 8%, the rib cage (21).
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Figure 2. Femoral shaft fracture in an abused 5-year-old boy. Frontal radiograph shows a transverse fracture of the diaphysis in femoral pin traction. The mother’s boyfriend confessed to pushing a television cabinet on top of the boy.
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Children less than 18 months of age sustain some unusual injuries because of their immature skeletons and unique mechanisms of injury (such as violent shaking). Metaphyseal and rib fractures, in particular, are rarely found in older children with abuse-related injury, but when discovered in infants, these fractures are highly specific for abuse. Thus, the low frequency of these lesions in large fracture series belies their common occurrence in infants. In studies of fracture patterns in infants, rib fractures constitute 35%– 60% of fractures (9,22). Although long bone shaft fractures are often seen in abused infants, metaphyseal fractures are the most common long bone fracture in this population. Postmortem specimen radiographic studies of infants yield significantly increased detection of rib fracture; in this population, rib fractures are more common than long bone fractures of any type (9).
Metaphyseal Fracture
Of all the injuries observed in child physical abuse, none is more specific than the metaphyseal fracture. First described in 1957 by the eminent pediatric radiologist John Caffey (5), metaphyseal fracture is virtually pathognomonic of abuse (8). Kleinman et al (9,12–15) coined the term classic metaphyseal lesion (CML) to describe the injury. CMLs are relatively common in abused infants and are discovered in 39%–50% of abused children less than 18 months of age (9,22). Thus, CMLs are highly specific for abuse, although they are observed in half or fewer of cases. Overall, CMLs most often occur in the distal femur, proximal tibia, distal tibia, and proximal humerus (8,12–15,22). They are seen almost exclusively in children less than 2 years of age for reasons detailed in the following biomechanical discussion.
The CML is a series of microfractures across the metaphysis; the fracture line is oriented essentially parallel to the physis, although it may not travel the entire width of the bone (8). Its orientation perpendicular to the long axis of the bone reveals that the precipitating force is a shearing injury across the bone end. Shearing in this manner is a peculiar force for a long bone to sustain, since it is the result of differential horizontal motion across the metaphysis and is therefore not a feature of falls or blunt trauma (23,24). The force is generated by manual to-and-fro manipulation of the extremities (eg, holding and shaking an infant by the feet or hands or shaking the infant while he is held around the chest, with the limbs whiplashing back and forth and sustaining horizontal shear forces) (8). Therefore, CML is seen almost exclusively in children less than 2 years of age—those children who are small enough to be shaken violently and who are unable to protect their extremities (24,25). Fortunately, the long-term sequelae of CML appear to be minimal (26).
Pathologic Characteristics.—
The elegant work of Kleinman and colleagues in the 1980s established the histologic definition of the CML as a series of microfractures in the subepiphyseal region of bone. This region is the primary spongiosa, and it is the most immature area of the mineralized matrix in the growing metaphysis. Interestingly, it is this immature mineralized bone, and not the adjacent cartilaginous physis, that is disrupted by shearing forces. Microfractures extend variably across the metaphysis and may completely or partially traverse it. When complete, the fracture fragment may be conceptualized as a wafer or disk of bone (primary spongiosa), separated from the shaft by the series of metaphyseal microfractures (Fig 3). The edge (rim) of the CML tends to be thicker than its center, since at the periphery the microfractures usually angle obliquely toward the diaphysis, thus creating a rim of relatively thicker bone at the periphery of the disk-shaped fracture fragment. The more central microfractures are closer to the physis, resulting in a considerably thinner central region of the fracture fragment. The CML, when complete, is a disk with a broad, thin center and a thick circumferential rim (8).
Acute CML manifests as disruption of the bony trabeculae in the primary spongiosa (Fig 4). The columns of calcified cartilage extending into the metaphysis are also disrupted. Periosteal disruption and extension into the physis are relatively rare (8). When the acute CML heals, there is an increase in the number of regional osteoblasts and osteoclasts, as well as fibrin deposition. There is typically no periosteal disruption, and little or no callus is formed. However, changes at the physis subjacent to a CML may indicate a subacute CML.
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Figure 4a. Acute CML in a fatally abused 2-month-old child. (a) Specimen radiograph of the proximal left humerus shows the subtle lucency of the CML (arrows). (b) Photomicrograph (unmagnified, hematoxylin-eosin stain) shows disruption of the calcified cartilage cores of the primary spongiosa (arrows). (Case courtesy of Paul K. Kleinman, MD, The Children’s Hospital, Boston, Mass.)
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Figure 4b. Acute CML in a fatally abused 2-month-old child. (a) Specimen radiograph of the proximal left humerus shows the subtle lucency of the CML (arrows). (b) Photomicrograph (unmagnified, hematoxylin-eosin stain) shows disruption of the calcified cartilage cores of the primary spongiosa (arrows). (Case courtesy of Paul K. Kleinman, MD, The Children’s Hospital, Boston, Mass.)
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A review of normal longitudinal bone growth at the physis will help clarify the discussion of the subacute CML. The normal physis (the cartilaginous growth plate situated between the epiphysis and metaphysis) is a disk of chondrocytes that extends in columns toward the metaphysis. With growth, the juxtametaphyseal chondrocytes (which form the hypertrophic zone of the physeal cartilage) die, and mineralization of the osteoid around the cartilage columns occurs. Thus, there is progressive mineralization of the hypertrophic (juxtametaphyseal) zone of the physis, such that longitudinal bone growth proceeds at the metaphysis. This pattern of metaphyseal growth depends in part on a normal vascular supply to the hypertrophic zone of physeal cartilage, which is derived from the metaphysis (27). Studies have shown that disruption of the vascular supply leads to an abnormally thick physis, representing diminished mineralization at the chondroosseous junction (28). Similar changes at the chondroosseous (physeal-metaphyseal) junction have been observed in the CML, occurring distal to, not within, the metaphyseal injury. It is believed that the CML disrupts blood supply to the more distal metaphyseal fragment and its neighboring hypertrophic zone, resulting in persistence of the hypertrophic zone and diminished matrix mineralization. Thus, unaffected regions of the metaphysis-physis complex grow and mineralize normally around the injured area; however, the area distal to the CML does not mineralize normally, and the chondrocytes persist abnormally. At histologic analysis, this pattern appears as an area of focal or diffuse (depending on the extent of the CML) hypertrophic chondrocyte columns in the primary spongiosa (Fig 5) (10). One study found this pattern in 15 of 15 healing CMLs; in the same study, only one of 25 fractures in which this finding was missing demonstrated evidence of healing. No acute fractures in this study showed physeal cartilage extension into the metaphysis (29). The extension of hypertrophic cartilage into the primary spongiosa is an excellent indicator of a subacute CML.
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Figure 5a. Subacute CML in a fatally abused 7-week-old boy. (a) Specimen radiograph of the distal femur (overlying soft tissue removed) shows irregular lucency of the medial femoral metaphysis (arrow). (b) Photograph of the fixed, bivalved femur shows physeal cartilage extension into the metaphysis (arrow). (c) High-power photomicrograph (original magnification, x100; hematoxylin-eosin stain) of the physis reveals hypertrophied chondrocytes (black arrow) growing into the metaphyseal fracture site (white arrows).
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Figure 5b. Subacute CML in a fatally abused 7-week-old boy. (a) Specimen radiograph of the distal femur (overlying soft tissue removed) shows irregular lucency of the medial femoral metaphysis (arrow). (b) Photograph of the fixed, bivalved femur shows physeal cartilage extension into the metaphysis (arrow). (c) High-power photomicrograph (original magnification, x100; hematoxylin-eosin stain) of the physis reveals hypertrophied chondrocytes (black arrow) growing into the metaphyseal fracture site (white arrows).
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Figure 5c. Subacute CML in a fatally abused 7-week-old boy. (a) Specimen radiograph of the distal femur (overlying soft tissue removed) shows irregular lucency of the medial femoral metaphysis (arrow). (b) Photograph of the fixed, bivalved femur shows physeal cartilage extension into the metaphysis (arrow). (c) High-power photomicrograph (original magnification, x100; hematoxylin-eosin stain) of the physis reveals hypertrophied chondrocytes (black arrow) growing into the metaphyseal fracture site (white arrows).
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Radiologic Appearance.—
The radiologic appearance of the CML correlates very closely with its histologic counterpart. It manifests as a lucent area within the subphyseal metaphysis, extending completely or partially across the metaphysis, roughly perpendicular to the long axis of bone. Because the wafer of bone that is the fracture fragment may have a very thin center, this region may be radiographically occult. The thicker peripheral rim is more readily visible and appears as a triangular fragment when viewed in profile (commonly referred to as a corner fracture). If the fragment is separated from the remainder of the long bone by a prominent fracture lucency, or if the fracture is viewed at a slightly oblique angle, the thick rim may be visible as a curvilinear structure resembling a bucket handle (Fig 6). Thus, the appearance varies with the length and width of the fracture fragment (ie, how far across with metaphysis the fracture extends), as well as its position at radiography (8). Healing of CML is often difficult to assess, because callus and subperiosteal new bone formation are both unusual. Focal or diffuse extension of the physeal cartilage into the metaphysis, manifested as metaphyseal lucency, is a highly specific indicator of healing, although exact estimation of fracture age cannot be determined from this finding alone (Fig 5) (29).
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Figure 6a. CML in an abused 2-month-old girl. (a) Frontal radiograph of the ankle shows a rim of bone (arrow) separated from the tibial shaft by the metaphyseal fracture lucency, giving the appearance of a bucket handle. A CML of the distal fibula is also faintly seen (arrowhead). (b) Lateral radiograph depicts the tibial and fibular fractures as corner fractures (arrows).
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Figure 6b. CML in an abused 2-month-old girl. (a) Frontal radiograph of the ankle shows a rim of bone (arrow) separated from the tibial shaft by the metaphyseal fracture lucency, giving the appearance of a bucket handle. A CML of the distal fibula is also faintly seen (arrowhead). (b) Lateral radiograph depicts the tibial and fibular fractures as corner fractures (arrows).
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Skeletal scintigraphy may demonstrate increased uptake of technetium-99m methylene diphosphonate (Tc-MDP) at the CML (Fig 7). However, this finding may be subtle, especially if the examination is not of technically excellent quality and the reader is not experienced in pediatric scintigraphic interpretation. Normal young children may exhibit intense uptake of Tc-MDP at the metaphyses, making it difficult to recognize abnormally increased uptake, especially if it is bilateral. Conway et al and others, in a report of two studies and review of the literature, conclude that skeletal scintigraphy is best conceived as complementary in the evaluation of suspected child abuse (24,30). The American Academy of Pediatrics Section on Radiology reached a similar conclusion in a recent recommendation (31). Scintigraphy is superior, however, to plain radiography for the detection of some injuries, particularly rib fracture.
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Figure 7a. Tibial CML in an abused 10-week-old girl. (a) Frontal radiograph demonstrates a CML, which has a corner fracture appearance (arrowhead). There is subtle periosteal new bone along the medial tibial shaft (arrow). (b) Tc-MDP scan of the lower extremities demonstrates increased uptake along the right tibial shaft (straight arrow) and metaphysis (curved arrow).
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Figure 7b. Tibial CML in an abused 10-week-old girl. (a) Frontal radiograph demonstrates a CML, which has a corner fracture appearance (arrowhead). There is subtle periosteal new bone along the medial tibial shaft (arrow). (b) Tc-MDP scan of the lower extremities demonstrates increased uptake along the right tibial shaft (straight arrow) and metaphysis (curved arrow).
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Rib Fracture
Rib fractures occur in older children and adults as a result of trauma such as falls and motor vehicle accidents. In infants without metabolic bone disease, however, they are distinctly unusual injuries outside the setting of abuse (32–34). In part, this reflects the plasticity of the young child’s skeleton and rib cage, which allows the skeletal structures to deform (rather than break) until a threshold is met. Rib fractures in infants are strongly correlated with abuse because the mechanism that generates the fractures is relatively specific. A very tight hold around the infant chest by adult hands generates substantial squeezing force on the immature skeleton and may result in fractures of the anterior, lateral, and posterior aspects of the rib (35,36). Fractures of the first rib are considered virtually diagnostic of child abuse, since they require considerable force (37). In rare cases, rib fracture (including posterior rib fracture) may be produced by birth trauma (38,39). All reported birth-related rib fractures to date have been documented in large babies (>3,300 g), difficult deliveries, or both. Of note, one study of 34,946 live births found no rib fractures (40). Thus, birth-related rib fracture is a rare but reported event.
The rib cage is a roughly tubular structure, with 12 paired ribs attached posteriorly to the spine. When an infant is abusively squeezed around the chest, different mechanical forces are exerted on different parts of the rib cage (Fig 8). Posteriorly, the ribs are attached relatively tightly to the vertebral bodies and transverse processes; as the posterior rib arcs are squeezed, the posterior rib arc is levered over the transverse process, resulting in ventral (and sometimes complete) cortical disruption (41–44). This levering action is unusual; it is not a feature of most traumatic and iatrogenic (eg, cardiopulmonary resuscitation) forces. For this reason, posterior rib fracture in particular is highly specific for inflicted trauma. Laterally, squeezing creates both anterior and posterior compressive forces, resulting in buckling and impaction of the inner cortex and distraction of the outer cortical fracture margins (44). At the costochondral junction, sternal compression produces inward bending of the costochondral junction, also leading to fracture (44). Thus, tight squeezing of the infant’s chest results in a complex array of compressive and levering forces that leads to fractures of the posterior, lateral, and anterior rib. Because the forces are distributed in an area similar to the size of the perpetrator’s hands, fractures are typically seen in similar locations in multiple adjacent ribs and are often bilateral.
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Figure 8. Rib fracture mechanism in tight squeezing. Diagram of the midthorax during tight squeezing reveals anteroposterior compression, which causes compression and fracture of the ribs laterally (arrow). There is hyperextension of the posterior rib ends over the transverse process, with fracture of the ventral cortex (black arrowhead). Anteriorly, the chest wall compression leads to inward bending of the anterior ribs and fracture (white arrowhead).
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Pathologic Characteristics.—
Acute fractures of the rib are characterized by disruption of the cortex and subjacent bony trabeculae (Fig 9). Hemorrhage is often observed at the fracture site; the periosteum may be intact or disrupted. Fracture healing rapidly ensues and may be divided into four stages: inflammation, soft callus (also called reparative), hard callus, and remodeling. Initially, an intense inflammatory response is elicited by the necrotic bone ends at the fracture site. Cells delivered by blood vessels (predominantly in the periosteum) enter the hematoma, which serves mainly as a scaffold for the repair process (45). The invading cells produce fibrous tissue, cartilage, and finally immature (woven) bone (Fig 10). The soft callus phase of repair is heralded by the appearance of woven bone and cartilage. The woven bone will remodel into mature lamellar bone (hard callus); at this time, the fracture line is bridged by callus and solidly united (46,47). Over the following months (and even years), more trabecular bone will be laid down along stress lines and the marrow cavity will be reconstituted (48, 49). Within different parts of a given fracture, competing inflammatory and callus-forming activities may occur at the same time.
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Figure 9a. Acute posterior rib fracture in a fatally abused 7-month-old boy. (a) Autopsy photograph of the ventral surfaces of the right posterior ribs, after the pleura has been removed, clearly shows the acute rib fractures (arrows). (b) Axial specimen radiograph of one of the injured ribs with its vertebral articulations intact shows that the fracture (arrow) is limited to the ventral cortex. (The anomaly of the vertebral arch is an artifact incurred during autopsy resection.) (c) In an axial photomicrograph (unmagnified, hematoxylin-eosin stain) of one of the injured ribs with its vertebral articulations intact, the fracture is clearly visible (arrow), as is the cartilage of the rib head (*) and rib tubercle ( ).
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Figure 9b. Acute posterior rib fracture in a fatally abused 7-month-old boy. (a) Autopsy photograph of the ventral surfaces of the right posterior ribs, after the pleura has been removed, clearly shows the acute rib fractures (arrows). (b) Axial specimen radiograph of one of the injured ribs with its vertebral articulations intact shows that the fracture (arrow) is limited to the ventral cortex. (The anomaly of the vertebral arch is an artifact incurred during autopsy resection.) (c) In an axial photomicrograph (unmagnified, hematoxylin-eosin stain) of one of the injured ribs with its vertebral articulations intact, the fracture is clearly visible (arrow), as is the cartilage of the rib head (*) and rib tubercle ().
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Figure 9c. Acute posterior rib fracture in a fatally abused 7-month-old boy. (a) Autopsy photograph of the ventral surfaces of the right posterior ribs, after the pleura has been removed, clearly shows the acute rib fractures (arrows). (b) Axial specimen radiograph of one of the injured ribs with its vertebral articulations intact shows that the fracture (arrow) is limited to the ventral cortex. (The anomaly of the vertebral arch is an artifact incurred during autopsy resection.) (c) In an axial photomicrograph (unmagnified, hematoxylin-eosin stain) of one of the injured ribs with its vertebral articulations intact, the fracture is clearly visible (arrow), as is the cartilage of the rib head (*) and rib tubercle ().
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Figure 10a. Acute lateral and healing posterior rib fractures in a fatally smothered 7-week-old boy. (a) Frontal chest radiograph of the deceased infant reveals widening of the posterior right third through eighth ribs (arrows). (b) Magnified view of the lower lateral left chest wall reveals fractures of the lateral left seventh and eighth ribs, without callus (arrows). (c) Specimen radiograph of the anterolateral part of the left eighth rib reveals a fracture of the inner cortex (arrow). (d) Autopsy photograph of the resected chest cage shows the healing posterior rib fractures (arrows), which are subtle but distinctly larger and more bulbous than the contralateral normal posterior ribs. (e) Axial specimen radiograph of the right sixth posterior rib clearly shows the fracture callus (arrow). The vertebral articulations and the contralateral left sixth rib in the specimen are intact. (f) Axial photomicrograph (unmagnified, hematoxylin-eosin stain) of the rib fracture depicted in e shows mineralized callus (arrow).
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Figure 10b. Acute lateral and healing posterior rib fractures in a fatally smothered 7-week-old boy. (a) Frontal chest radiograph of the deceased infant reveals widening of the posterior right third through eighth ribs (arrows). (b) Magnified view of the lower lateral left chest wall reveals fractures of the lateral left seventh and eighth ribs, without callus (arrows). (c) Specimen radiograph of the anterolateral part of the left eighth rib reveals a fracture of the inner cortex (arrow). (d) Autopsy photograph of the resected chest cage shows the healing posterior rib fractures (arrows), which are subtle but distinctly larger and more bulbous than the contralateral normal posterior ribs. (e) Axial specimen radiograph of the right sixth posterior rib clearly shows the fracture callus (arrow). The vertebral articulations and the contralateral left sixth rib in the specimen are intact. (f) Axial photomicrograph (unmagnified, hematoxylin-eosin stain) of the rib fracture depicted in e shows mineralized callus (arrow).
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Figure 10c. Acute lateral and healing posterior rib fractures in a fatally smothered 7-week-old boy. (a) Frontal chest radiograph of the deceased infant reveals widening of the posterior right third through eighth ribs (arrows). (b) Magnified view of the lower lateral left chest wall reveals fractures of the lateral left seventh and eighth ribs, without callus (arrows). (c) Specimen radiograph of the anterolateral part of the left eighth rib reveals a fracture of the inner cortex (arrow). (d) Autopsy photograph of the resected chest cage shows the healing posterior rib fractures (arrows), which are subtle but distinctly larger and more bulbous than the contralateral normal posterior ribs. (e) Axial specimen radiograph of the right sixth posterior rib clearly shows the fracture callus (arrow). The vertebral articulations and the contralateral left sixth rib in the specimen are intact. (f) Axial photomicrograph (unmagnified, hematoxylin-eosin stain) of the rib fracture depicted in e shows mineralized callus (arrow).
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Figure 10d. Acute lateral and healing posterior rib fractures in a fatally smothered 7-week-old boy. (a) Frontal chest radiograph of the deceased infant reveals widening of the posterior right third through eighth ribs (arrows). (b) Magnified view of the lower lateral left chest wall reveals fractures of the lateral left seventh and eighth ribs, without callus (arrows). (c) Specimen radiograph of the anterolateral part of the left eighth rib reveals a fracture of the inner cortex (arrow). (d) Autopsy photograph of the resected chest cage shows the healing posterior rib fractures (arrows), which are subtle but distinctly larger and more bulbous than the contralateral normal posterior ribs. (e) Axial specimen radiograph of the right sixth posterior rib clearly shows the fracture callus (arrow). The vertebral articulations and the contralateral left sixth rib in the specimen are intact. (f) Axial photomicrograph (unmagnified, hematoxylin-eosin stain) of the rib fracture depicted in e shows mineralized callus (arrow).
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Figure 10e. Acute lateral and healing posterior rib fractures in a fatally smothered 7-week-old boy. (a) Frontal chest radiograph of the deceased infant reveals widening of the posterior right third through eighth ribs (arrows). (b) Magnified view of the lower lateral left chest wall reveals fractures of the lateral left seventh and eighth ribs, without callus (arrows). (c) Specimen radiograph of the anterolateral part of the left eighth rib reveals a fracture of the inner cortex (arrow). (d) Autopsy photograph of the resected chest cage shows the healing posterior rib fractures (arrows), which are subtle but distinctly larger and more bulbous than the contralateral normal posterior ribs. (e) Axial specimen radiograph of the right sixth posterior rib clearly shows the fracture callus (arrow). The vertebral articulations and the contralateral left sixth rib in the specimen are intact. (f) Axial photomicrograph (unmagnified, hematoxylin-eosin stain) of the rib fracture depicted in e shows mineralized callus (arrow).
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Figure 10f. Acute lateral and healing posterior rib fractures in a fatally smothered 7-week-old boy. (a) Frontal chest radiograph of the deceased infant reveals widening of the posterior right third through eighth ribs (arrows). (b) Magnified view of the lower lateral left chest wall reveals fractures of the lateral left seventh and eighth ribs, without callus (arrows). (c) Specimen radiograph of the anterolateral part of the left eighth rib reveals a fracture of the inner cortex (arrow). (d) Autopsy photograph of the resected chest cage shows the healing posterior rib fractures (arrows), which are subtle but distinctly larger and more bulbous than the contralateral normal posterior ribs. (e) Axial specimen radiograph of the right sixth posterior rib clearly shows the fracture callus (arrow). The vertebral articulations and the contralateral left sixth rib in the specimen are intact. (f) Axial photomicrograph (unmagnified, hematoxylin-eosin stain) of the rib fracture depicted in e shows mineralized callus (arrow).
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Radiologic Appearance.—
Acute rib fractures appear as linear lucent areas (which may be complete or incomplete) across the rib (Fig 11). However, acute rib fractures may be quite difficult to discern, especially if the fracture is incomplete, nondisplaced, or viewed in an area with many superimposed structures or if the fracture line is oblique to the x-ray beam. Fractures of the rib head (at the costovertebral articulation) are particularly difficult to appreciate radiologically for all of these reasons, because they are often superimposed on the transverse process, are nondisplaced, and are oriented obliquely relative to the x-ray beam (41). In a series of 29 posterior rib fractures, only four were clearly visible at high-detail frontal radiography (42). With healing, most fractures become more visible, as subperiosteal new bone and callus become evident (Fig 12). Thus, follow-up radiography performed several weeks after the injury increases detection of rib fracture (50). Fractures involving the anterior and posterior ends of the ribs sometimes have an injury pattern very similar to that of the CML; indeed, the chondroosseous junction of the rib ends is analogous to that of long bones. Callus may not become evident when fractures of the rib occur in these locations, rendering them difficult to see even when healing. Oblique chest radiography (performed with high-detail systems and bone technique) and bone scintigraphy are especially helpful for the improved detection of rib fracture (50). In one study, scintigraphy demonstrated radiographically occult rib fractures in 10% of abused children (51). Other studies confirm that scintigraphy is sensitive for the detection of abuse-related fracture and is a useful adjunct to the radiographic skeletal survey (Fig 13) (30, 52,53). To increase detection of rib fracture, oblique chest radiography, bone scintigraphy, or follow-up chest radiography in 2 weeks is recommended (54). Computed tomography (CT) is a valuable adjunct, although no studies comparing CT with established imaging modalities for the detection of nonaccidental skeletal injury have been reported to date (Fig 14).
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Figure 11. Posterior rib fractures in an abused 3-month-old girl. Frontal chest radiograph reveals fractures without visible callus (white arrows) of the posterior eighth through tenth ribs. The posterior left fourth through seventh ribs are slightly thicker and more opaque than the opposite, normal right posterior ribs, indicating healing posterior rib fractures (black arrows).
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Figure 12a. Increased rib fracture conspicuity over time in an abused 5-month-old boy. (a) Frontal chest radiograph obtained at presentation with seizure reveals right lateral sixth rib fracture with callus (arrow) and possibly fractures of the right lateral fourth, fifth, and seventh ribs. (b) Frontal chest radiograph obtained 2 weeks later depicts healing right lateral fourth through seventh rib fractures (white arrows). New from comparison is callus of the posterior left seventh through tenth ribs (black arrows). Also noted are fractures of the anterior left fourth through sixth ribs (arrowheads).
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Figure 12b. Increased rib fracture conspicuity over time in an abused 5-month-old boy. (a) Frontal chest radiograph obtained at presentation with seizure reveals right lateral sixth rib fracture with callus (arrow) and possibly fractures of the right lateral fourth, fifth, and seventh ribs. (b) Frontal chest radiograph obtained 2 weeks later depicts healing right lateral fourth through seventh rib fractures (white arrows). New from comparison is callus of the posterior left seventh through tenth ribs (black arrows). Also noted are fractures of the anterior left fourth through sixth ribs (arrowheads).
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Figure 13a. Radiographically occult posterior rib fractures detected at bone scintigraphy in an abused 1-month-old boy. (a) Frontal chest radiograph reveals subtle increased width of the posterior sixth and seventh ribs (arrows). (b) Posterior Tc-99m MDP scan obtained the same day demonstrates increased uptake in multiple adjacent posterior left ribs. Incidentally noted is increased uptake of both proximal humeri, determined at skeletal survey to be secondary to a CML of the left proximal humerus (arrowhead) and periostitis of the right proximal humerus (*).
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Figure 13b. Radiographically occult posterior rib fractures detected at bone scintigraphy in an abused 1-month-old boy. (a) Frontal chest radiograph reveals subtle increased width of the posterior sixth and seventh ribs (arrows). (b) Posterior Tc-99m MDP scan obtained the same day demonstrates increased uptake in multiple adjacent posterior left ribs. Incidentally noted is increased uptake of both proximal humeri, determined at skeletal survey to be secondary to a CML of the left proximal humerus (arrowhead) and periostitis of the right proximal humerus (*).
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Figure 14a. Healing posterior rib fracture in an abused 2-month-old girl. (a) Frontal chest radiograph shows focal widening of the posterior left ninth rib (arrow). (b) Axial CT scan of the chest windowed for bone detail shows the posterior rib fracture with callus (arrow).
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Figure 14b. Healing posterior rib fracture in an abused 2-month-old girl. (a) Frontal chest radiograph shows focal widening of the posterior left ninth rib (arrow). (b) Axial CT scan of the chest windowed for bone detail shows the posterior rib fracture with callus (arrow).
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Cardiopulmonary Resuscitation and Rib Fracture in Children.—
Cardiopulmonary resuscitation (CPR) may result in rib fracture, although fracture is considerably more common in adults than in children receiving CPR (55). Numerous reports in the literature attest to the rarity of CPR-related rib fracture in children. Four series described a total of 446 children who underwent CPR, of whom three had CPR-related rib fracture. Notably, all of these fractures involved the anterior ribs (56–59). The highly specific posterior rib fracture has never been definitively documented to result from CPR. In an experimental study on CPR in rabbits, no posterior rib fractures could be induced, despite vigorous chest compression. Axial CT performed during chest compression helped confirm that levering of the posterior rib over the transverse process does not occur when the back is supported, as it is during CPR (back support limits excursion of the posterior rib arc relative to the spine, therefore limiting levering of the posterior rib head over the transverse process) (43). Thus, posterior rib fracture is highly specific for abuse and does not result from CPR. Not surprisingly, it has never been documented in the scientific literature.
Fracture Healing in Children
The process of fracture healing described in the preceding sections occurs in children as in adults. Questions arise about the age of fractures in abused children, since there may be more than one fracture or the history given may be suspect. Unfortunately, there is little in the literature that aids us in precise dating of fractures in the very young child. One study in infants found that subperiosteal new bone (soft callus) is visible by 10 days after the injury (60). Another study evaluated the radiologic signs of healing of immobilized fractures in children 1–17 years old with known fracture ages. The earliest finding was blurring of the fracture margins, although this was observed in only 60% of fractures (the presence of casting material likely made this difficult to discern in many patients). Periosteal new bone was not observed before 2 weeks but was seen in all at 4 weeks. Visible (calcified) callus was observed in all fractures by 4 weeks and was seen as early as 2 weeks in some cases. Incomplete bridging of the fracture line was noted as early as 3 weeks after injury, and complete bridging (absence of a visible fracture lucency) was evident in almost half (40%) at 10 weeks (61). For a number of reasons, care must be taken when extrapolating these findings and conclusions to infants. Rib fractures are subject to continual motion as a result of breathing and handling; the effect of motion on the ra-diologic evolution of infant fracture healing is unknown. Infants appear to heal more quickly than do older children and adults (46,47).
Other Fractures
Virtually every type of fracture has been described in the setting of inflicted trauma. Therefore, any fracture is possibly abusive in origin. Particular attention should be paid to the age and developmental abilities of the injured child as well as to the injury and its mechanism. A 6-week-old child, who cannot yet crawl, is unable to arrive at the top of a flight of stairs and cause his own fall down the stairs. Once a child can walk, he is capable of causing himself considerable harm. The history given for the injury is also extremely important, since it reveals the degree of force and how likely the child was to cause his own injury. Household falls (eg, from a kitchen counter, changing table, sofa, crib, bed) are common accidents, but they are also frequently fabricated as a cause of injury by child abusers attempting to conceal their actions. Household falls infrequently result in fracture or other serious injury (Fig 15). In three separate studies, a total of 529 children sustained falls from heights up to 150 cm (283 of them were witnessed falling onto hard vinyl floors in the hospital). These falls resulted in a total of nine fractures: four skull, four clavicle, and one humerus (62–64). This represents a 1.7% incidence of fracture from household falls.
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Figure 15. Sacral fracture dislocation in an abused 2-month-old girl. Lateral radiograph depicts a fracture between the fourth and fifth vertebrae, through the intervertebral disk space. The fifth sacral vertebra and coccyx (arrows) are anteriorly displaced. The injury was originally explained as resulting from a changing table fall; the mother’s boyfriend later confessed to slamming the child down in a sitting position.
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A fall down stairs is often offered as an explanation for an inflicted injury. It is important to note that although a household staircase will typically traverse 8–10 vertical feet, falls down stairs are not comparable with free falls of that distance. Some have characterized a stairway fall as an initial moderate fall (the initial impact) followed by multiple short falls (subsequent tumbles down adjacent stairs) (65,66). Accordingly, epidemiologic studies of stairway falls demonstrate a limited injury pattern (65,67). Head injury from stairway falls is most commonly seen, followed by extremity injury, and much less often are trunk injuries observed (intestinal perforation has largely been excluded as a possible outcome of simple stairway falls) (68). The injuries are typically mild to moderate, including skull and ex-tremity fracture, concussion and brain contusion, and uncommonly a small subdural hematoma. The occurrence of more than one locus of injury (eg, a femur fracture and a skull fracture) is distinctly unusual. Certain factors can increase the severity of stairway falls, such as falling down stairs from the arms of an adult (which may significantly increase the vertical distance of the initial fall). Falling down stairs while in a walker, however, is considerably more injurious and may result in fatal head injury (69).
Spiral long bone and spine fractures deserve special mention because they are unusual injuries and imply mechanisms of force that are unusual, at least in infants. Spiral fractures wind around a long bone and are the result of torsional forces applied to the bone. Because of this unusual force, they are distinctly uncommon in infants, who typically sustain accidental injury from falls (Fig 16). Unless there is a good accidental explanation, spiral fractures in nonambulatory children are quite suggestive of inflicted injury (70,71). Once a child is walking, spiral fractures of the tibia ("toddler’s fracture") are quite common, often have no memorable traumatic antecedent, and by themselves are not suggestive of abuse.
Any spinal fracture without good accidental explanation, especially in an infant, is suggestive of abuse. Thoracolumbar compression fracture may be caused by shaking; when a baby is held around the chest and shaken, there is extension and flexion, centered at the thoracolumbar junction. Compression fracture of lower thoracic and upper lumbar vertebrae may result (with loss of vertebral body height or other compression deformity), as may avulsion of the posterior interspinous ligament at these levels (Fig 17) (17). Injury to the vertebral body is usually readily apparent at radiography irrespective of the age of the injury, because these deformities tend to persist. However, an interspinous ligament avulsion, with avulsion of the spinal apophysis, may be occult initially, since it is a cartilaginous and soft-tissue injury in infants. Over days to weeks, calcification may become evident (72,73).
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Figure 17. Vertebral body compression fracture in a shaken 3-month-old boy. Lateral radiograph of the lower thoracic and upper lumbar spine reveals anterior wedging of the second lumbar vertebra (arrow).
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Postmortem Radiography
Children who die an unexplained or unexpected death normally undergo autopsy to determine the cause and manner of death. A complete forensic autopsy consists of external evaluation for bruises, burns, penetrating injuries, etc. For the internal evaluation, the cranium, thorax, and abdomen (and sometimes neck) are opened and thoroughly inspected. Radiographs may be obtained as part of the autopsy, although they are usually images of large areas of the body or even the whole body of a small child (a "babygram"). Although these images may be adequate to detect a foreign body such as a bullet, they are inadequate for the detection of subtle injuries of abuse such as CML and rib fracture. In addition, the metaphyses are not routinely evaluated at autopsy. Detection of CML (regarded as the most specific, radiographically detectable injury in abuse) depends on high-quality, small field of view radiographs (9,44,74). In the landmark study by Kleinman et al (9) of postmortem radiography, fully 93% of infants had evidence of older, highly abuse-specific injuries detected radiographically. Another study revealed that the findings at postmortem radiography influenced the determination of manner of death for six of eight fatally abused infants (74). For all these reasons, it is imperative that children dying under any suspicious circumstances undergo a skeletal radiographic survey as part of the postmortem evaluation. This survey is most easily accomplished while the child’s body is still in the hospital, before it is transported to the medical examiner’s office or morgue.
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Central Nervous System Injury
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Nonaccidental head injury (NAHI) occurs in approximately 12% of physically abused children and, in children under 2 years of age, accounts for 80% of deaths from head injury (75). In children less than 1 year old, 95% of all serious head injuries and 64% of all head injuries result from abuse (76). The outcome of infants suffering NAHI is considerably worse than for those of the same age who have sustained accidental brain injury (75). NAHI in infants is associated with 12.5%–40% mortality (77–80). Mental retardation and disability are common sequelae of abuse in those infants who survive. In one study of 14 surviving children of infant NAHI, seven (50%) were severely disabled or vegetative, two were moderately disabled, and five had a "good" outcome (although three from this last group repeated grades or needed tutoring) (81). NAHI is the leading cause of morbidity and mortality in abused children.
Skull Fracture
Skull fractures are relatively common in both accidental and abusive injury. In all cases and age groups of abused children, they represent approximately 8%–13% of fractures (21). However, in children less than 2 years of age, the percentage rises to 29%–33%. In abuse-related homicides in infants, skull fracture is discovered in up to 41% of cases (Fig 18) (9). Overall, there is generally poor correlation of skull fracture and underlying hemorrhage or brain injury, and skull fracture is found in children with brain injury in 23%–56% of cases (82–86). It is believed that deformation (inbending) of the infant skull injures the subjacent brain and meninges without fracture.
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Figure 18a. Linear parietal skull fracture secondary to abuse. (a) Frontal skull radiograph depicts a linear, right parietal skull fracture (arrow). (b) Lateral TC-MDP scan of the head appears normal.
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Figure 18b. Linear parietal skull fracture secondary to abuse. (a) Frontal skull radiograph depicts a linear, right parietal skull fracture (arrow). (b) Lateral TC-MDP scan of the head appears normal.
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Skull fractures result from contact injury. The velocity of the object striking the skull, or of the skull as it strikes a stationary object (as in a fall), dictates the magnitude of the contact force and thus the likelihood of fracture. The surface area and type of surface contacted influence whether a skull fracture will result: The larger and softer the surface area, the less likely a fracture will occur. A small contact area, given sufficient velocity, will result in a depressed skull fracture. The infant skull is relatively plastic (deformable) and thus tends to be more resistant to fracture. Not surprisingly, studies repeatedly show that skull fractures occur in only 1%–3% of children as a result of short (usually defined as 6 feet or less) falls (62–64,87,88). It is important to note that although skull fractures are not rare in household trauma, significant underlying brain injury (with the exception of epidural hematoma) is rare in household trauma. Only very rarely has severe brain injury and even death been reported from witnessed short falls (63,77,89). Cerebral contusions underlying direct trauma may result from more complex falls, such as stairway and bunk bed falls (67,90,91). Soft-tissue swelling may be absent, even in acute skull fracture; thus, lack of swelling should not be construed as evidence that the fracture is subacute (92–94).
Skull fracture patterns have been investigated to determine if any suggest an abusive cause, and none reliably do so. Studies have demonstrated, however, that multiple fractures, fractures that cross sutures, and bilateral fractures are more likely to be associated with abuse (Fig 19) (55,76,84,95,96). Reports vary as to the significance of diastasis; in one report, diastasis greater than 3 mm was associated with inflicted injury (96). Discovery of any fracture for which the history or developmental capabilities of the child are inconsistent should prompt a thorough evaluation, and skull fracture is no exception (95,96).
Radiologic Appearance.—
Radiography of the skull is preferred over CT, because fractures parallel or nearly parallel to the section orientation are missed at CT (97). Four views of the skull (anteroposterior, both lateral views, and a Towne view) constitute the standard skull radiographic series. Two views (anteroposterior and lateral) are recommended as part of the skeletal radiographic survey, with additional views taken as necessary, especially if head trauma is suspected (98). Fractures appear as linear or branching lucent areas with sharp margins. Diastasis (separation of 3 mm or more) may also be observed. Scintigraphy is not recommended, since it has been shown to be relatively insensitive for the detection of skull fracture (Fig 18) (30).
Interhemispheric Extraaxial Hemorrhage
Subdural hemorrhage (SDH) and subarachnoid hemorrhage (SAH) are common abusive injuries. Epidural hematoma is much more often accidental than inflicted and may result from relatively short falls. Thus, epidural hematoma is not a specific indicator of inflicted injury. In three studies of 177 children with intracranial injury, only four cases of inflicted epidural hematoma were discovered (77,84,99). SDH and SAH are much more common injuries in the abused child. In a series of 287 children aged 1 week to 6.5 years old with head injuries, SDH was found in 46% and SAH was discovered in 31% of children with NAHI (compared with 10% and 8%, respectively, in children with accidental head injury) (100). Another study of 99 children with head trauma who were less than 2 years old
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Abstract
LEARNING OBJECTIVES FOR TEST...
