Physical child abuse (ie, nonaccidental injury that a child sustains at the hands of his or her caregiver) can result in skeletal injury, burns, bruising (see the first image below), and central nervous system injury from head trauma (see the second image below). To determine whether a child's injury was likely to have been inflicted rather than accidental, the clinician must establish the full extent of the injury and must understand the child's developmental level and abilities.
See Pediatric Concussion and Other Traumatic Brain Injuries, a Critical Images slideshow, to help identify the signs and symptoms of TBI, determine the type and severity of injury, and initiate appropriate treatment.
Also see the 12 Can't-Miss Findings on Pediatric Imaging Studies slideshow to help correctly evaluate abnormal findings in imaging studies for pediatric patients.
Signs and symptoms
Physical indicators that should raise suspicion for maltreatment include the following:
Injury pattern inconsistent with the history provided
Multiple injuries/multiple types of injuries
Injuries at various stages of healing
Presence of pathognomonic injuries, including loop marks; forced immersion burn pattern; and classic abusive head trauma findings of subdural hematoma, retina hemorrhage, and skeletal injuries
Bruising over bony prominences is common in childhood, but patterns of bruising that raise the concern of possible abuse include the following:
Involvement of multiple areas of the body beyond bony prominences
Bruising of ears, facial cheeks, buttocks, palms, soles, neck, genitals
Bruises at many stages of healing
Bruises in nonambulatory child
Patterned markings resembling objects, grab marks, slap marks, human bites, and loop marks
Oral injury, lingular or labial frenula tears
Skeletal injuries in children younger than 2 years may not be obvious; therefore, a skeletal survey screening is recommended. Many fracture types can be accidental or inflicted. Fractures that raise a high degree of suspicion for inflicted injury include the following:
Any fracture in a nonambulatory infant without clear accidental and consistent mechanism
Multiple, bilateral, differently aged posterior rib fractures
Multiple and complex skull fractures if only simple impact history
Spinous process fractures
Burn patterns that may suggest physical maltreatment include the following:
Patterned contact burns in clear shape of hot object (eg, fork, clothing iron, curling iron, cigarette lighter)
Classic forced immersion burn pattern with sharp stocking-and-glove demarcation and sparing of flexed protected areas
Splash/spill burn patterns not consistent with history or developmental level
Bilateral or mirror image burns
Localized burns to genitals, buttocks, and perineum (especially at toilet-training stage)
Evidence for excessive delay in seeking treatment, and the presence of other forms of injury
See Clinical Presentation for more detail.
History and the physical examination findings determine which laboratory and diagnostic imaging studies are performed.  Screening tools for suspected disorders or injuries are as follows:
Bleeding problem: A basic bleeding evaluation (platelets, prothrombin time [PT], activated partial thromboplastin time [aPTT])
Genetic bone disease or mineralization defect: Calcium, magnesium, phosphorus, and vitamin D levels; review of radiographs with a pediatric radiologist; genetic consultation, if available, may be warranted
Toxin or drug ingestion: toxicology screening 
Screening for abdominal injury is recommended in children younger than 5 years in whom abuse is suspected, even in the absence of clear external evidence of abdominal injury or symptoms such as pain or vomiting. Screening includes the following markers [3, 4] :
Liver injury: Aspartate aminotransferase (AST) and alanine aminotransferase (ALT)
Pancreatic injury: Amylase and lipase levels
Urinary tract injury: Urine analysis for red blood
Intestinal injury: Stool guaiac
Photodocumentation of cutaneous injuries, such as burns, bite marks, bruising, or other injuries, is very helpful in cases of child abuse.
See Workup for more detail.
Treatment for physical abuse is a complex endeavor involving an interdisciplinary team approach. The nature of the injury determines the form of medical therapy, as follows:
Skeletal fractures of the long bones may require casting; orthopedics should be consulted
Burns vary in severity, and treatments range from cleansing the area to skin grafting; plastic surgery should be consulted for more serious burns; transfer to a burn unit may be indicated
The most severely injured children, such as those with CNS injury, may require resuscitation and will need intensive care; a multitude of specialists may need to be involved
Whenever abusive head trauma is suspected, ophthalmology should be consulted for a formal evaluation, including examination of the eyes for retinal hemorrhages.
Psychosocial management that requires a significant amount of coordination among various services providers, including the physician and other health care providers, complements the medical management. The details of the caregiving environment determine the psychosocial supports needed to keep the child safe.
Physical abuse, a subset of child abuse, is defined in various ways by different states. However, common to all definitions is the presence of an injury that the child sustains at the hands of his or her caregiver. These injuries are also referred to as inflicted or nonaccidental injuries. Some states use broad definitions that encompass a wide range of injuries; other states use more narrow definitions that include specific signs and symptoms. Physical abuse can produce various injuries and injury patterns in children. This article focuses on several common examples of inflicted injury dealing with the skeleton (eg, fractures), skin (eg, burns, bruises), and CNS (eg, subdural hematoma [SDH], abusive head trauma [AHT], shaken baby syndrome [SBS]/shaking-impact syndrome).
Definitions of physical abuse
The federally funded Fourth National Incidence Study (NIS-4) is a congressionally mandated effort of the United States Department of Health and Human Services to provide updated estimates of the incidence of child abuse and neglect in the United States and measure changes in incidence from the earlier studies.  NIS defines physical abuse as a form of maltreatment in which an injury is inflicted on the child by a caregiver via various nonaccidental means, including hitting with a hand, stick, strap, or other object; punching; kicking; shaking; throwing; burning; stabbing; or choking to the extent that demonstrable harm results. 
The advantage to a narrow definition is that it objectively states what is and is not physical abuse; however, such a clear delineation of circumstances likely fails to identify all possible cases of physical abuse (eg, pulling the child's hair, biting the child's skin). Definitions may also attempt to characterize the seriousness of injury; however, characterization is difficult because injuries vary greatly from mild redness on the buttocks that fades over several hours to injuries so severe that the child dies. Recent medical definitions focus more on the effect of the injury on the child and less on the perceived intention of the caregiver.
Additionally, newer definitions also consider the sociocultural context in which the injury occurs; folk healing practices may cause the appearance of nonaccidental injury to the child. Finally, the effect of the physical abuse may not be limited to just the immediate injury findings. The National Center on Child Abuse and Neglect (NCCAN) estimated that 37% of children with maltreatment injuries developed a disability or special need, directly from the abusive actions or omissions of the child's caregivers.  Furthermore, NCCAN estimated that incidence of disabilities caused by or likely to have been caused by maltreatment was 147 per 1000 maltreated children.
Multifactorial nature of physical abuse
No one single cause has been identified that explains the occurrence of all cases of physical abuse. The multifactorial nature of physical abuse requires a more comprehensive amalgam of models and conceptual frameworks to account for the heterogeneous set of cases classified as physical abuse.
Circumstances that may give rise to the occurrence of a child's injury via physically abusive actions have been organized into a typology having the following 5 subtypes:
Caregiver's angry and uncontrolled disciplinary response to actual or perceived misconduct of the child
Caregiver's psychological impairment, which causes resentment and rejection of the child by the caregiver and a perception of the child as different and provocative
Child left in care of a babysitter who is abusive
Caregiver's use of substances that disinhibit behavior
Caregiver's entanglement in a domestic violence situation
This typology describes commonly observed circumstances that may result in nonaccidental injury to children; however, it does not shed light on why the circumstance leads to a child's injury.
Ecological model of human development and interaction
It is impossible and inadvisable to consider physical abuse of a child as an isolated incident with one cause and one effect. The ecological model of human development and interaction is generally regarded as an ideal conceptual framework from which to approach the complex interactions among the caregiver, child, family, social situation, and cultural values leading to the nonaccidental injury or physical abuse of the child. Note the image below.
The ecological model sees a child functioning within a family (microsystem), the family functioning within a community (exosystem), the various communities linked together by a set of sociocultural values that influence them (macrosystem), and all of these systems operating over time (chronosystem). Each of these system components is interactional in nature and affects one another. Similar events have different effects that depend on the period and circumstances in which the event occurs (eg, the child interacts and has an impact on the family, the family influences the child).
Environmental stress and caregiver frustration
Helfer builds on this ecological viewpoint and states that physical maltreatment arises when a caregiver and child interact around an event, in a given environment, with the end result being injury to the child.  Viewing maltreatment in this way allows consideration of the factors that the caregiver, child, and environment contribute to placing the child at risk for injury. The caregiver is viewed as having a personal developmental history, personality style, psychological functioning, and coping strategies. The caregiver often possesses expectations of the child, and a level of ability to nurture the child's development that meets the child's developmental and caregiving needs.
The child may have certain characteristics that make providing care more complex; however, caution must be used in considering the child's contribution to the abusive interactions. A "difficult" child does not justify abusive treatment by a caregiver. Specific factors that may place the child at higher risk for physical maltreatment include prematurity, poor bonding with caregiver, medical fragility, various special needs (attention deficit hyperactivity disorder), and the child being perceived as different (owing to physical, developmental, and/or behavioral/emotional abnormalities) or difficult, based on temperament style.
Finally, the environment may contain stressors that may make the caregiving less than ideal and may overextend the coping abilities of the caregiver. While exploring the role of environmental stress and caregiver frustration in the occurrence of child abuse, Straus and Kantor found a complex interaction between the amount of stress present in the family setting and the response of the caregivers.  Not all stressed caregivers responded by inflicting harm on the children in the environment.
Straus and Kantor concluded that human beings have a capacity for acting violently both in and outside the family setting. Physical abuse can result if a specific home situation arises that has a relatively high degree of stress and a baseline amount of violence within it (eg, spanking the children, pushing or slapping a spouse). Thus, risk of child abuse is related to the response of caregivers whose caregiving environment has a certain amount of overall risk for violent behavior. The caregivers' level of social connectedness to nonrelatives seems to have a role to play in the children's risk for maltreatment. Caregivers under high degrees of stress who did not participate in clubs, unions, and other organizations (ie, socially isolated) had higher rates of abusing children than those who were not as socially isolated. However, children whose caregivers had many family members living nearby did not achieve the same protective effect, as did the nonfamilial social connectedness group.
Domestic violence, intimate partner violence, corporal punishment, and child maltreatment
The relationship of domestic violence or intimate partner violence (IPV) and child maltreatment is receiving increasing attention. Each year, between 3.3 and 10 million children witness episodes of family violence; 30-59% of mothers of abused children are victims of domestic violence or intimate partner violence. Additionally, children whose mothers are victims of domestic violence or intimate partner violence are 6-15 times more likely to be maltreated compared to children living in families in which their mothers are not being battered. The American Academy of Pediatrics (AAP) recommends that pediatricians assess for the presence of domestic violence and intimate partner violence in the child's family and observes that intervening on behalf of the victimized parent (typically the child's mother) may be an effective child-abuse prevention strategy.  Note the image below.
The relationship between the application of corporal punishment and risk for maltreatment remains an area of concern. Corporal punishment is defined as a discipline method that uses physical force as a behavioral modifier. Corporal punishment is nearly universal; 90% of US families report having used spanking as a means of discipline at some time. Corporal punishment has its roots in personal, cultural, religious, and societal views of children and how they are to be disciplined. Corporal punishment includes pinching, spanking, paddling, shoving, slapping, shaking, hair pulling, choking, excessive exercise, confinement in closed spaces, and denial of access to a toilet.
No credible evidence in medical literature supports the continued use of corporal punishment; spanking is less effective than "time out" or removal of privileges for decreasing undesired behavior in children. Discipline, however, is a necessary component for child rearing, and appropriate discipline aims for limit setting, teaching right from wrong, assisting in decision making, and helping the child develop a sense of self-control.
When physical force is used as a discipline technique (as in corporal punishment), the concern arises that if the misconduct continues even after corporal punishment is applied, the caregiver then may become angry and frustrated and reapply the physical force. As the physical force is reapplied while the caregiver is becoming increasingly angry, the potential emerges for the caregiver to lose control and injure the child. Regardless of whether injuring the child was the intended outcome of the corporal punishment, the end result experienced by the injured child is that he or she has been hurt.
Caregivers who use corporal punishment are often angry, irritable, depressed, fatigued, and stressed. They apply the punishment at a time that they "have lost it," and caregivers frequently express remorse and agitation while punishing their children. To avoid this risk of harming the child and in order to model nonviolent behavior for children, many healthcare professionals advocate child discipline via consistent, nonphysical force based approaches such as "time out," loss of privileges, expressions of parental disappointment, and grounding. Approximately one half of US pediatricians report being opposed generally to the use of corporal punishment; about one third are completely opposed to its use (about three fourths of the pediatricians reported having been spanked when they were children).
Each form of injury sustained by a child as a result of physical abuse has its own set of biomechanics and pathophysiology. This article looks specifically at the mechanisms of injury for skeletal injury, burns, bruising, and CNS injury observed in abusive head trauma.
Skeletal fractures are caused by the application of force to the bone. An essential step in the evaluation of injury in children is determining whether the injury being evaluated matches the history provided by the caregiver. This process requires understanding both the mechanisms and forces needed to cause specific types of fractures as well as specific characteristics of infant and childhood bone compared with adult bone.
The child's immature skeleton is characterized by more porous/trabecular bone than in the mature bone. The less-dense porous bone tolerates more deformity than adult bone and accounts for the childhood bending and buckling injuries observed with green stick and buckle injuries. The periosteum (the fibrous membrane that covers the bone) is thicker and more easily elevated off the bone in children. The child's joint capsule and ligaments are strong and relatively more resistant to stress than the bone and cartilage, which accounts for less joint dislocations and ligamentous tears in childhood. Finally, bone healing is more rapid in children than in adults, which makes dating of childhood fractures more complicated.
Types of fractures
While certain types of fractures (eg posterior rib, scapular, classic metaphyseal lesions) are more common in physical abuse than accidental injury, there is no fracture that is pathognomonic for child physical abuse. All fractures must be carefully evaluated and correlated with the child's medical history and with the history given by the caregivers. Fractures can be classified by location in the body (eg skull vs long bone) and then by location in the bone (eg diaphyseal vs metaphyseal, posterior vs anterior rib). Certain fracture types are only seen in developing, immature bone (eg, greenstick, classic metaphyseal lesions, Salter-Harris fractures).
Specifically in long bones, fractures are described based on location and type. Diaphyseal fractures are breaks in the mid shaft of the long bones. Transverse fractures typically occur if the force is applied perpendicular to the long axis of the bone. Spiral or oblique fractures occur if the force applied has a rotational component. Buckle or compression fractures occur commonly at the transition from diaphysis to metaphysis. Note the images below.
Metaphyseal fractures (also called corner fractures or bucket handle fractures) are microfractures through the immature part of the bone edge and often appear like chips or corner fractures on radiographs. The metaphysis is an area of rapid bone turnover in the growing infant and toddler. Metaphyseal fractures are specific to infants as they involve the immature physis; they are caused by shearing and tensile stress seen in rapid acceleration and deceleration forces to the extremity.
Skull bones may be fractured as a result of direct impact to the head with a solid surface or object. Skull fractures typically occur at the site of impact to the head, but owing to the oval shape of the head, a single point of impact may result in bilateral fractures remote from the site of impact. The skull bones differ from long bones in that they develop within a membrane and not from cartilage as do the long bones.
Rib fractures may be observed in physical abuse as well. Rib fractures occur as a result of direct blows to the chest and via anteroposterior compression. Most abusive rib fractures are posterior, adjacent to the vertebral body, with the rib levering over the transverse process of the vertebra.
Bone healing and dating of injuries
Dating of boney injuries is particularly important in the evaluation of physical abuse, because it may assist investigators in determining who had access to the child in the period the injury is estimated to have occurred. The body of medical literature evaluating the precision of dating of fractures has evolved over the last decade. The classic teaching has been that fractured long bones and ribs heal in a predictable manner, which is divided into the following 4 stages: initial healing, soft callus, hard callus, and remodeling. Orthopedic aspects of bone healing are described in Forearm Fractures.
This traditional description of bone healing included general timelines for the age of the injury based on the stage of healing seen at the time of injury identification. In young children, bone healing tends to occur more rapidly than in older children and adults. Newer studies of dating of fractures, however, emphasize that the classic descriptions (eg, soft callus, hard callus) are based on histiologic specimens rather than plain film readings, and significant inconsistencies exist among radiologic interpretation of healing phases.  The evaluation of the healing process on plain films permits some level of dating of injuries and allows the healthcare professional to distinguish new and relatively older fractures in the same child; providers should exercise caution in precisely dating fracture age based on x-ray findings alone.
Metaphyseal fractures are generally harder to date because of the relative lack of disruption in the periosteum at the time of the fracture. Skull fractures heal differently than do long bones because of their intramembranous nature; they do not heal with a large amount of callus formation and are more difficult to date. The skills and advice of an experienced pediatric radiologist should be consulted if dating of injuries becomes central to the maltreatment investigation.
Burns arise from the application of heat energy to the child's skin. Various sources such as hot liquids (scalds), hot objects (contact or dry), flame (flash), chemicals, and electricity can generate heat. Three concentric zones of affected tissues have been identified. Coagulation is the most direct contact with the heat source in which the skin undergoes immediate coagulation necrosis as the proteins denature, and no cellular repair is possible. Stasis involves less heat energy exposure than with coagulation, and these cells, though injured, have some potential for repair. Hyperemia is the least direct injury, and these cells have the greatest potential for repair. All of these types and depth of burns can be encountered in both inflicted and accidental burns in children.
Human skin is composed of 3 layers: the epidermis, dermis, and subcutaneous tissue. Burns are classified clinically depending on the depth of the injury and the involvement of the various skin layers.
Superficial burns, which injure only the uppermost tissue of the epidermis, present as red, painful areas without blisters. Complete healing is expected from superficial burns. Deeper burns that extend through the epidermis into the upper levels of the dermis are referred to as partial thickness burns and present as painful blistering areas. Healing of partial-thickness burns varies, with various degrees of scarring depending on the level of tissue that is damaged. Finally, the deepest burns, full-thickness burns, extend past the epidermis and dermis and involve the subcutaneous tissue. These burns essentially have destroyed the overlying skin, blood vessels, and associated nerves and present as white, insensitive areas because of this destruction. A high degree of scarring and disfigurement result from full-thickness burns.
Evaluation of suspicious burns in children must include, as with any medical complaint, a detailed history from the caregiver and child, including a developmental history to ensure the child is capable of contributing to the injury (eg, "turned on the faucet"). Physical examination should include assessment of the burned area; critical assessment of the burned versus spared areas of skin can be helpful in determining the position of the child at the time of the burn. Note the image below.
Careful gathering of information about what the child was wearing at the time, the time elapsed since the burn, symptom progression, and any topical treatments to the area is important in the determination of cause. Many childhood burns involve hot water in bathtubs or heated liquids in a kitchen setting. Scene investigations by child protective services and/or law enforcement can gather crucial information for determining whether the burn was inflicted or accidental burn (eg, temperature of tap water, height of faucets from floor, ease of turning handles, food residue on clothing or at the scene). Note the image below.
Bruising occurs when blunt mechanical force is applied to the child's skin to such a degree that capillaries (and potentially larger vessels) become disrupted resulting in the leakage of blood into the subcutaneous tissue. The amount of blood and size and location of the involved area account for the appearance of the bruise. If force is applied via an object, the bruise may reflect the shape and geometry of the object.
In general, a bruise progresses through a series of colors beginning with deep red, blue, or purple, then changes to a deep blue, then greenish, and, finally, resolves with a yellowish brown color. The various colors emanate from the breakdown of the extravascular blood into the components of hemoglobin. As the extravascular blood organizes itself and is resorbed, certain patterns of color change are expected; however, caution is advised because no clearly predictable chronology can be relied on with absolute certainty. Physicians should be cautious in offering dating information and, at most, only should suggest broad time ranges based on the clinical appearance and stages of healing of the bruise. Similar to fractures, recent data on dating of bruises indicate that color is a poor predictor of bruise age. 
CNS trauma is among the most serious forms of injury that is observed in the context of physical abuse. CNS trauma may result in intracranial hemorrhage, including (1) epidural hemorrhage, which is bleeding into the space between inner skull bone surface and the dura, frequently due to a direct injury to the middle meningeal artery; (2) subdural hemorrhage, which is bleeding into the space between the inner surface of the dura and arachnoid membranes, typically caused by sheering of the bridging vessels that go from the brain surface to the dura; and (3) subarachnoid hemorrhage, which is bleeding into the space between the inner surface of the arachnoid and the brain surface.
Other CNS injuries may include contusions (ie, direct injury to the brain tissue) and intraparenchymal bleeding (ie, bleeding directly into substance of the brain). These primary injuries can be obscured or complicated by anoxic brain injuries and swelling, which are frequently seen in complex head injury, whether accidental or inflicted.
AHT, SBS, and shaking-impact syndrome
Discussing CNS injury and physical abuse inevitably leads to a discussion of abusive head trauma (AHT), previously referred to as shaken baby syndrome (SBS) or shaking-impact syndrome.  The original description of AHT (originally referred to as whiplash syndrome) describes a clinical constellation of findings classically described as subdural hematoma, retinal hemorrhage (found in 65-95% of cases), and skeletal fractures, such as metaphyseal fractures and posterior rib fractures (found in 30-70% of cases) sustained when the child is shaken violently back and forth. AHT represents a significant injury pattern in the realm of child maltreatment; although it is associated with the findings listed above, the core injury is to the brain cells themselves, resulting from the application of forces to the child's delicate and developing brain tissue.
AHT has been extended to include cases where the child's head is impacted against a surface, either soft or hard, and may be called AHT. Diffuse, serious brain injuries result from external forces that cause the rotation of the brain about its center of gravity. Such forces exceed those generated in normal childcare activities and are different from the low velocity translational forces (straight-line movement) that commonly occur in household falls. Immense angular deceleration forces may be generated with sudden striking of the child's head against a surface; these forces act on the brain tissue and cerebral vessels and generate the deleterious effect, which is not specifically from the contact forces applied to the skull.
It is important to understand the sources of data on child maltreatment incidence. The National Incidence Study (NIS) methodology views maltreated children who are investigated by child protective services (CPS) agencies as representing only the "tip of the iceberg;" thus, children investigated by CPS are included along with maltreated children who are identified by professionals in a wide range of agencies in representative communities.
The Fourth National Incidence Study (NIS-4) uses data gathered from a nationally representative sample of 122 counties. CPS agencies in these counties provide data about all children in cases they accept for investigation during 1 of 2 reference periods (September 4, 2005 through December 3, 2005, or February 4, 2006 through May 3, 2006). Additionally, professionals in these same counties serve as NIS-4 sentinels and report data about maltreated children identified by the following organizations: elementary and secondary public schools; public health departments; public housing authorities; short-stay general and children's hospitals; state, county, and municipal police/sheriff departments; licensed daycare centers; juvenile probation departments; voluntary social services and mental health agencies; shelters for runaway and homeless youth; and shelters for victims of domestic violence.
In 2009, approximately 3.3 million reports involving 5.9 million children were made to CPS agencies. Of these, 60.7% were accepted as needing further investigation, and, once evaluated, the investigations concluded that child abuse and neglect had affected approximately 695,000 children included in 754,000 cases of abuse (ie, some children with more than one episode of substantiated abuse), with 17.6% of this total representing cases of substantiated physical abuse. The most common form of substantiated abuse in 2009 was child neglect (including medical neglect), which accounted for 80.7% of cases, followed by child sexual abuse (9.2% of cases) and emotional maltreatment (8.1% of cases). 
The NIS-4 reported that of the approximately 1.25 million estimated annual cases of child abuse, approximately 323,000 cases were identified as physical abuse.  The number of children who experienced physical abuse decreased from an estimated 381,700 at the time of the NIS–3 (1993) to an estimated 323,000 in the NIS–4 (a 15% decrease in number and a 23% decline in the rate).
It is important to recognize that these numbers reflect changes in the "Harm Standard" as defined by NIS, which is relatively stringent in that it generally requires that an act or omission result in demonstrable harm in order to be classified as abuse or neglect.
NIS-4 also reported on the Endangerment Standard, which includes all children who meet the Harm Standard but adds others as well. The central feature of the Endangerment Standard is that it counts children who were not yet harmed by abuse or neglect if thought that the maltreatment endangered the children or if a CPS investigation substantiated or indicated their maltreatment. In addition, the Endangerment Standard is slightly more lenient than the Harm Standard in allowing a broader array of perpetrators, including adult caretakers other than parents in certain maltreatment categories and teenage caretakers as perpetrators of sexual abuse.
Comparing the Endangerment Standard, the number of physically abused children decreased from an estimated 614,100 children in 1993 to 476,600 in 2006 (a 22% decrease in number, a 29% decline in the rate). The reasons behind this decrease are uncertain and may be a result of sample sizes in technique. These data should not be misinterpreted as an indication that physical abuse or endangerment of children has been "cured." NIS-4 data report that 1 child in every 58 in the United States was harmed under the Harm Standard definition, including physical abuse, sexual abuse, and neglect.
In various clinical series, skeletal fractures are observed in approximately 30% of the children, burns are observed in 9-10%, bruises are quite common and are present in approximately 40% of child maltreatment cases, and inflicted CNS injury is observed in 24% of children treated for head injury.
Finkelhor, Jones, and Shattuck have analyzed trends in reporting and substantiation rates for child abuse and neglect from the 1990s through 2010 and have identified a decline in the number of substantiated cases of physical abuse.  According to their most recent analysis, the incidence of substantiated physical abuse cases declined 56% from 1992-2010. Cases of child sexual abuse have also declined substantially, with a 53% decrease in the number of substantiated cases of sexual abuse observed from 1992-2006. However, child neglect, the most common form of child maltreatment, declined but less so, with a 10% decline in substantiated cases from 1992-2010. Note the image below.
According to the NIS-4 study, an estimated 2400 children were known to have died as a result of maltreatment from 2005-2006. According to Prevent Child Abuse America's National Center on Child Abuse Prevention Research, in 2006 an estimated 1,530 were known to have died as a result of child maltreatment, which is an average of 4 children each day of the year.  Children aged 0-3 years accounted for 78% of the child abuse and neglect fatalities, with infants younger than 1 year accounting for 44.2% of these maltreatment-related fatalities. When looking at the types of maltreatment that accounted for the fatalities, the breakdown is as follows:
Child neglect - 43%
Multiple forms of maltreatment - 31.4%
Physical abuse - 22.4%
Psychological abuse - 2.9%
Child sexual abuse - 0.3%
The estimated death rate for child abuse and neglect in the United States is 3 per 100,000 children.
Different forms of injury have different risks. For example, CNS injury and occult abdominal injury in younger children are particularly serious. Bruises may be superficial or harbingers of more serious deeper injury. Burns observed in child maltreatment cases tend to be highly severe. Finally, skeletal injuries may be isolated or multiple in nature and may be associated with other injuries. DiScala and colleagues conducted a 10-year retrospective of medical records in the National Pediatric Trauma Registry (NPTR) from 1988-1997; it compared hospitalized, injured children younger than 5 years to determine differences between inflicted (n= 1,997) and accidental injuries (n= 16,831). 
DiScala's group found that compared with children who had accidental injury, children who were abused tended to be younger (12.8 mo vs 25.5 mo), were mainly injured by battering (53%) and shaking (10.3%), and were more likely to have a preinjury medical history of a medical problem or condition. The unintentionally injured children were mainly injured by falls (58.4%) and motor vehicles (37.1%). Note the image below.
In order to fully comprehend the morbidity of victims of child abuse victims, it is necessary to look beyond the immediate period of injury and recovery. Looking at potential long-term impacts on health and well being, Felitti et al explored the connection between exposure to childhood abuse and the connection between household dysfunction to subsequent health risks and the development of illness in adulthood in a series of studies referred to as the Adverse Childhood Experiences (ACE) studies.  Of 13,494 adults who completed a standard medical evaluation in 1995-1996, 9,508 completed a survey questionnaire that asked about their own childhood abuse and exposure to household dysfunction; the investigators then made correlations to risk factors and disease conditions.
In order to assess exposure to child abuse and neglect, the ACE questionnaire asked about categories of child maltreatment, specifically psychological, physical, and sexual maltreatment. When asking about physical abuse, the questionnaire asked the patients if a parent or other adult in the household had (1) often or very often pushed, grabbed, shoved, or slapped them or (2) often or very often hit them so hard that marks or other injuries resulted.
In order to assess exposure to household dysfunction, the ACE questionnaire asked questions by category of dysfunction, such as having a household member who had problems with substance abuse (eg, problem drinker, drug user), mental illness (eg, psychiatric problem), criminal behavior in household (eg, incarceration) or having a mother who was treated violently. In assessing if their mother was treated violently when the patient was a child, respondents were asked if their mother or step-mother was (1) sometimes or very often pushed, grabbed, slapped, bitten, hit with a fist, or hit with something hard or had something thrown at her or (2) was ever repeatedly hit for at least a few minutes or threatened with or hurt by a knife or gun.
In addition to the questionnaire information, the standardized medical examination of the adults assessed risk factors and actual disease conditions. The risk factors included smoking, severe obesity, physical inactivity, depressed mood, suicide attempts, alcoholism, any drug abuse, a high lifetime number of sexual partners, and a history of sexually transmitted disease (STD). The disease conditions included ischemic heart disease, cancer, stroke, chronic bronchitis, emphysema, diabetes, hepatitis, and skeletal fractures.
Once all the data were collected and analyzed, Felitti et al found that the most prevalent ACE was substance abuse (25.6%), the least prevalent ACE was criminal behavior (3.4%), and the prevalence of physical abuse was 10.8% and the prevalence of the mother being treated violently was 12.5%.
Overall, 52% of the respondents had one or more ACEs and 6.2% had 4 or more ACEs. The following were findings in respondents who experienced 4 or more ACEs compared with those who had none:
Risk of alcoholism, drug abuse, depression, and suicide attempt increased 4-12 fold
Rates of smoking, poor self-rated health, and high number of sexual partners and STDs increased 2-4 fold
Physical inactivity and severe obesity increased 1.4-1.6 fold
The major finding of the ACE studies was a graded relationship between the number of exposures to maltreatment and household dysfunction during childhood to the presence in later life of multiple risk factors and several disease conditions associated with death in adulthood. Note the image below.
Bentley and Widom (2009) found that physical abuse during childhood is a risk factor for obesity in adulthood. In a prospective assessment comparing individuals with documented histories of childhood physical and sexual abuse and neglect with a matched cohort of children without such histories, 30-year follow-up showed that childhood physical abuse led to significantly higher body mass index (BMI) scores in adulthood (beta = 0.14, P < 0.05), even controlling for demographic characteristics, cigarette smoking, and alcohol consumption (beta = 0.16, P < 0.01). In contrast, childhood sexual abuse or neglect was not a significant predictor of adult BMI scores. 
No significant difference in incidence of physical abuse was noted based on race in both the 1993 NIS-3 and the 1986 NIS-2. In Child Maltreatment 2010, a specific breakdown for physical abuse was not provided; however, overall racial information for all cases of abuse is as follows: African American (1221.9%), American Indian/Alaskan Native (1.1%), Asian (0.9%), Pacific Islander (0.2%), white (44.8%), multiple racial affiliations (3.5%), Hispanic (21.4%), and unknown/missing information (6.3%). 
NIS-4 compared 3 major categories of white (non-Hispanic), black (non-Hispanic), and Hispanic and found that white and black children differed significantly in their rates of experiencing overall Harm Standard abuse during the 2005–2006 NIS-4 study year. An estimated 10.4 cases per 1,000 black children suffered Harm Standard abuse during the NIS-44 study year, compared with 6 cases per 1,000 white children and 6.7 cases per 1,000 Hispanic children. The abuse rate of black children is 1.7 times that of white children and 1.6 times that of Hispanic children.
NIS-4 found no significant difference between boys’ and girls’ rates of experiencing serious harm under the Harm Standard. Since the 1006 NIS-3 data, the incidence rates for both sexes declined, but the boys’ rate declined more than that of girls; the boys’ rate declined by 33%, whereas the girls’ rate declined by just 11%.
A specific sex-based breakdown is not provided in Child Maltreatment 2010; however, the overall incidence of child maltreatment was not markedly different in aggregate, with boys accounting for 48.5% and girls accounting for 51.2%.
The NIS-4 incidence of Harm Standard physical abuse is significantly lower for the youngest children (2.5 cases per 1,000 children aged 0-2 y) compared with children aged 6-14 years (4.6 cases per 1,000 or higher). The fairly low incidence rates for children younger than 2 years may reflect a detection problem; because children who are younger than school age are less observable to community professionals, their abuse may avoid detection.
In Child Maltreatment 2010, a specific breakdown was not provided for physical abuse; however, the overall unique count for substantiated cases by age was as follows: 1-3 years (34.0%), 4-7 years (23.4%), 8-11 years (18.7%), 12-15 years (17.3%), and 16-17 years (6.2%). Children younger than 1 year had the highest rate of victimization overall, at 20.6% per 1,000 children in the population of the same age.