Large Birth Weight Baby With Slower Arm and Leg Movement on One Side of Body

Annu Proc Assoc Adv Automot Med. 1998; 42: 93–113.

An Overview of Anatomical Considerations of Infants and Children in the Adult World of Car Rubber Design^§

Abstruse

The baby and child differ structurally from the adult in a number of ways which are disquisitional to the design for protection against impact forces and for adequate occupant restraint systems. The purpose of this paper is to bring together a contour of the anatomy, anthropometry, growth and development of the babe and kid. Age differences related to the proper design of child restraint systems are emphasized. Bug discussed include child--adult structural differences, center of gravity of the torso, the head mass in relation to the neck and general body proportions, positions of central organs, and biomechanical properties of tissues.

Introduction

Infants and children are not miniature adults. Trunk size proportions, muscle bone and ligamentrus strengths are unlike and thus occupant packaging for crash protection need special consideration. This newspaper is an overview of pediatric size and proportional differences with considerations of some child injuries in car crashes along with a review of some biomechanical data.

GROWTH OF THE INFANT Body AS A WHOLE

Growth and development of the human body occurs continuously from nascence through senesence (quondam age). Such development is desultory and non-uniform, nevertheless it does non occur haphazardly. For the about role, incremental growth of whatever dimension or part of the body occurs co-ordinate to predictable trends. Most body dimensions follow trends which involve rapid growth separated past a menses of relatively slower or uniform growth. There are notable differences in the timing of these incremental growth spurts, for well-nigh tissues and organs of the trunk collectively reflect the general trunk growth. As an example, the brain grows rapidly during the menstruum before birth and then slows considerably during the per-school years. At nativity the brain is typically 25% of its adult size, although the torso weight of the newborn is only about 5% of adult weight (Stuart and Stevenson, 1950). Importantly, nearly half of the postnatal growth of the brain book occurs during the kickoff year of life, and attains about 75% of its developed size by the end of the second year. By contrast, genital organs develop very slowly during this period but, instead, attain their adult size during the second decade of life.

Subcutaneous tissue (body fat) is a body component infrequently considered equally a cistron in the proper pattern of protective devices for the infant body. This tissue tends to increase rapidly in thickness during the first nine months post-obit birth, which growth of the trunk as a whole is much slower. Later this period of high incremental alter there is a menstruum of less rapid growth, so that by v years of age the thickness of the subcutaneous layer is about one-half the thickness of the ix calendar month old infant.

Loading of the torso by strap-type restraints must occur in areas where the body is strongest, i.eastward., on solid skeletal elements. In some, the fatty subcutaneous tissue tin can produce bulges or 'rolls' of flesh in the areas of placement on such restraint straps. Thus, proper positioning of restraint straps on the chubby 1–3 yr old may be hard to maintain considering of the abundance of this fatty tissue.

Changes in body weight similarly follow characteristic age group trends (Krogman, 1960; Krogman and Johnston, 1965; Martin and Thieme, 1954; and Meredith, 1963). From the 10th day after birth, when the post-nascence weight loss is usually regained, in that location is a steady increase in weight then that during the first three months an average baby gains most two pounds per month, or nearly one ounce per day (Krogman 1941). At v months the nativity weight has doubled. Beginning at six months, there is but a i pound gain per month in weight so that the nascence weight is tripled at the cease of the first year and quadrupled at the end of the 2nd. From this time on, the rate of increment in trunk weight gradually decreases during the second year co-ordinate to a factor of one-half pound per month (Krogman and Johnston, 1965). After the 2nd year proceeds in weight may go irregular and less anticipated on a monthly basis. As a general pattern, after the 2nd year and until the 9th yr there is a five pound annual increment. Thus, at 5 years the trunk weight is 6 times the birth weight and in the 10th year the weight of the body is ten times the birth weight (Krogman, 1960).

Changes in trunk peak and trunk proportions too have specific age trends (Figs. 1–three). The newborn child is approximately 20 inches in total torso length. During the first yr this height is increased by approximately ten inches. Until about the 7th twelvemonth, total torso length should be doubled by the fourth year and tripled by the 13th year. The height of an adult is about twice the superlative of a two-year-old child. From the 2nd to the 14th year, total body peak increases (in inches) co-ordinate to the formula: Height=age in years × 2.5 + 30 (Weech, 1954).

Per centum distribution of body segments as related to pre- and postnatal evolution. (Modified from Salzmann, "Principles of Orthodontics.")

Developmental change in trunk proportions equally seen in direct comparison between the adult and the newborn, kid and boyish. (Modified from Chenoweth and Selrick, "School Wellness Issues.")

Age changes in the ratio between sitting (trunk) summit and total trunk tiptop cannot be overlooked when considering the dynamics of changing body proportions. (Fig. 4). Sitting height represents about lxx% of the total height at birth, just falls rapidly to well-nigh 57% in the third year. At xiii-years of age in girls, and two years after in boys, the ratio of sitting summit to total body height is about fifty%.

Changes in sitting height from birth to adulthood.

Longitudinal growth of limb basic occurs equally long as the epiphyseal cartilage prolificates; growth ceases when the cartilage ossifies and fuses to the os segments surrounding information technology. Since the fusion of epiphyses in the lower extremities occurs earlier in girls than in boys, girls tend to have a lower 'sitting height-total torso height' ratio than boys, between 8 and 12 years, and a higher one between the 14th and 18th year.

Thus, particularly in the early on years of life, the infant is markedly elongating in stature. Also, the postural changes of the infant, from a recumbent one to that of a slouched, upright position, is completed within a relatively brusque period of time.

In general, children of either sex are of the same height, weight, and full general body proportions upwards to 10 or 11 years of historic period; yet, not infrequently one sees girls slightly taller than their male counterparts even at ages vi–10. Girls tend to have an earlier pubertal growth spurt between 11 and 14 years and, in general, are taller than boys of this historic period. In the early on to mid-teens, the boys grab upward, and and then surpass the girls in stature (Watson and Lowrey, 1967). These variations in full height at the 10–14 year age span reflect the differences in sitting height between boys and girls.

At nascence the head is ane-4th the total trunk length, whereas in the adult information technology is one-seventh (Fig. five). Also the trunk is long with the upper limbs being longer than the lower limbs. From the second one-half of the first twelvemonth to puberty the extremities grow more rapidly than the head. At puberty the growth rates of the trunk and limbs are about equal, but the trunk continues to grow in length later on limb elongation has declined in the adolescent period. The mid-point of the trunk is slightly above the umbilicus (navel) in the newborn, and a two years the mid-betoken of the body is slightly beneath the navel; at almost 16 years, this mid-point is nigh the pubic symphysis.

The proportional changes in torso segments with historic period.

The middle of gravity of the child varies according to historic period, child size, weight, and torso form as well as sitting posture. A study by Swearingen and Young (1965), of individuals at ages 5, 10, 12, and 18 years, indicated that the center of gravity (CG) cannot exist located accurately and precisely in groups of seated children. They found that a plot of the CG would fall within an asymmetrically ellipsoidal area. In these children it was establish that the CG was located vertically on the trunk well above the lap chugalug level. This high CG in children must be considered when developed lap belts are used to restrain children, since the greater body mass above the belt may cause the child to whip forward more than in the instance of an adult. In a subsequent study of infants anile 8 weeks–3 years, it was constitute that the CG is located even higher on the body (Young, 1968).

THE Caput

In automotive collisions, the child's head is the torso area near frequently and most seriously involved. In a study of children'southward injury patterns in 14,520 rural automobile accidents involving 31,925 occupants, it was found that children (birth through 11 years) had a frequency of 77% head injuries (Moore et al, 1959). This was a much greater frequency than either adolescents (69%) or adults (lxx%) in this report, although it was constitute that child caput injuries were of a more than minor variety than either adolescents or adults. Agran and Winn (1987) identified caput injuries in 50% of children, either lap-shoulder belted or unrestrained. Contributing to specific head impact issues are the big head of the child, the relatively soft, pliable, and elastic basic of the cranial vault, and the fontanelles. As compared with the adult, these features make the head of the child less resistant to impact trauma. In a collision, for example, the unrestrained kid, because of his big head and high CG, would 'lead with his head'. Crash data covering infants and children up to four years of age indicate that 77% of those who were injured in automobile accidents had head injuries (Kihlberg and Gensler, 1967). The vulnerability to injury of an babe'due south head occurs even prior to nascence, as has recently been shown in a study of fetal deaths involving restrained and unrestrained significant women in auto accidents (Crosby et al, 1968). The reasons for this greater frequency of head injury in children tin can be demonstrated both anatomically and biomechanically. The child's caput is proportionately larger than in the adult (Immature, 1966). (Fig. 5). This heavier head mass and resulting higher seated CG in young children, coupled with weaker neck supporting structures, may exist, in part, the basis for this higher frequency of head injury.

At birth the facial portion of the head is smaller than the cranium having a face-to-cranium ratio of i:8 (cf. adult ratio of one:two.v). Relative to the facial profile, the newborn forehead is high and quite bulged, due to the massive size of the frontal lobe of the brain (Fig. 6). Thus, in the newborn and infant the face up is tucked below the massive brain case (Fig. 7). The large head-pocket-size face pattern is noticeable in children fifty-fifty up to ages 7 and 8, Vertical growth of the baby face up occurs in spurts as related to both respiratory needs and tooth eruption. These growth spurts occur during the kickoff half dozen months afterwards nascency, during the 3rd and 4th yr, from the seventh to 11th year, and again betwixt the 16th and the 19th twelvemonth. The first growth spurt is chiefly olfactory as associated with the vertical growth of the upper portion of the olfactory organ and nasal crenel. The final spurt is related to boyish sexual development.

Soft tissue profile changes of the head and face.

Sequential changes of diverse caput and face regions.

Babe head shape also differs significantly from that of the adult (Fig 8). In the babe the cranium is much more elongate and bulbous, with big frontal and parietal (side) prominences (Fig. 8). At birth the circumference of the caput is nigh xiii–14 inches. Information technology increases by 17% during the first 3 months of life, and by 25% at 6 months of age. Information technology increases by nigh ane inch during the 2nd year, and during the 3rd through the 5th year head circumference increases past virtually half inch per year. There is only a 4 inch increase in herd circumference from the end of the 1st year to the 20th twelvemonth (Fig ix).

A comparison of face up-braincase proportions in the kid and adult. The horizontal line passes through the same anatomical landmarks on both skulls.

Skull profiles showing changes in size and shape. (Modified from Morris' "Human being Anatomy.")

Head circumference increases markedly during the first postnatal twelvemonth due to the progressive and rapid growth of the brain as a whole. The important relation of brain size and cranium size can exist demonstrated on a per centum footing, which shows that 70% of the developed encephalon weight is accomplished at 18 months, eighty% at 3 years, 90% at five–8 years and approximately 95% at the 10th yr. In the adult the boilerplate brain weight is 1350 k.

Infant and child skulls are considerably pliable, due to the segmental development and arrangement of the skull bones, plus the flexibility of individual bones which are extremely thin. The skull develops as a loosely joined arrangement of bones formed in the soft tissue matrix surrounding the encephalon. Junctions between basic are relatively broad and large, leaving areas of brain covered by a thin fibrous sheath and somewhat exposed to the external environment. These 'soft spots' (fontanelles) are several in number and are most obvious in the frontal and posterior skull regions (Fig. 10). The mastoid fontanelle, between the occipital and parietal basic, closed about vi–8 weeks after birth. However, a much larger midline junction between the frontal and parietal bones, i.e., frontal fontanelle, is not closed past bone growth until approximately the 17th month.

Size and location of the fontanelles. Arrows signal direction of fontanelle closure.

At birth all of the potential structures for the development of teeth are nowadays. The early on teeth first erupt at bout 6 months of age and go on to erupt progressively. The kid begins to lose his deciduous teeth nigh 5–half dozen years of age after which they are replaced past the permanent teeth.

Trauma to the jaws of infants or small children, peculiarly in the area where the unerupted teeth are found can atomic number 82 to serious problems in molar eruption, tooth spacing, tooth organisation and alignment. Traumatic injuries to the child'due south lower jaw (mandible) may be related to abnormal facial profiles with increasing age. The normal changes in size and position of the lower jaw are dependent upon a growth site in the mandible located near its junction with the skull. If this important growth site is significantly traumatized, the normal changes in size and position of the mandible diminish resulting in a smaller mandible and a recessive chin.

THE Cervix

There are several unique aspects of the anatomy of the child'due south cervix. Cervix musculus forcefulness increases with age yet, with the greater head mass perched on a slender cervix, the neck muscles generally are non developed sufficiently to dampen violent head movement, especially in children. In a study of lap-shoulder belted children, ages 10–14 years in all types of motor vehicle crashes, about 21% had cervical strain (Agran & Winn, 1987). The neck vertebrae of children are immature models of the developed. These cervical vertebrae are mainly cartilaginous in the infant, with complete replacement of this cartilage by bone occurring slowly. Articular facets, the contact areas between the vertebrae, are shallow; neck ligaments, as elsewhere in the body, are weaker than in adults. The disproportionately large caput, the weak cervical spine musculature, and laxity, can field of study the infant to uncontrolled and passive cervical spine movements and mayhap to compressive or distraction forces in sure touch on deceleration environments. These all contribute to a high incidence of injury to the upper cervical spine every bit compared to the lower cervical spine area (Sumchi and Stemback, 1991).

The articular facets of the infant and young children are oriented in an even more horizontal direction than in the adult (Kasai, et al, 1996) (lx deg. @ one year, 53 deg. @ 3 years and 47 deg. @ 6 years). The "cervicocranium", the base of the skull, C1, C2 and the C2/C3 disc is a singled-out unit in infants and modest children, and should be considered as a specialized area of the cervical spine because of its anatomical difference from the lower and more than uniformly shaped cervical vertebrae (Huelke, et al, 1992). Using dynamic cervical spine radiographs information technology has been shown that the fulcrum for flexion is at C2-C3 in infants and young children, at C3-C4 at about age 5 or 6 and at C5-C6 in adults (Baker and Berdon, 1966).

In that the skull base, C1 and C2 motion as a unit of measurement in flexion and extension, and in some rotation, it is non surprising that inductive deportation of the entire cervicocranial unit can occur after traumatic disruption of the posterior portions of C2, causing separation of the neural arch ossification centers, stretching of the rubberband ligaments, or bilateral fractures of the pedicles without evidence of dislocation (Sumchi, and Stembacck, 1991). A distraction forcefulness on the cervical spine tin can pull apart the cervical cartilagenous-osseous structures and associated ligaments and, if in a forward direction, can cause spinal cord harm (Finnegen and McDonald, 1982; Tingvall, 1987).

Information technology has been reported that pseudosubluxation or physiological inductive deportation of C2 on C3 of more than than three millimeters occurs in approximately 24–33% of children less than eight years of age (Dunlap, et al, 1958; Fuchs, et al, 1989; Papavasilou, 1978). In dissection specimens the elastic infantile vertebral bodies and ligaments allows for column elongation of upwardly to ii inches, but the spinal cord ruptures if stretched more than ane/iv inch (Leventhal, 1960). Thus information technology is difficult to differentiate physiological displacement from pathological dislocation of C2 on C3 in childhood, especially when an 10-ray is taken with the kid'south head in flexion (Swishuck, 1977). Occasionally in young infants, in that location is a reversal of the normal anterior curve, seen in lateral C-spine ten-rays, probably due to the weak, immature cervical musculature (Harris and Edeiken-Monroe, 1987).

If neck motion exceeds tolerable limits, dislocation of vertebrae and possibly injury to the spinal cord can occur. This combination of anatomical features results in lowered protection of the neck in rapid deceleration and if the head is rotated or snapped to the side or to the rear, serious damage might occur to the frail system of critical arteries or veins of the brain, to nerves, to the vertebrae, and/or the spinal cord itself. The mechanism of pediatric cervical injury is relatively straight forwards---head flexion with either a tension or pinch component and a relatively restrained trunk. Basically, in the frontal-type crash the head continues forwards beyond the belted body. The construction of the child'south neck certainly plays a role in the injury. Fuchs, et al (1989) best summarized the reasons for this, including (1) A heavy head on a small body results in high torques beingness applied to the neck and consequently, high susceptibility to flexion-extension injuries, (ii) The lax ligaments that allows a significant degree of spinal mobility (anterior subluxation of up to 4.0 mm at C2-3 or C3-4 may occur every bit a normal variant), (three) The cervical musculature is not fully developed in the babe assuasive for unchecked distracting and deportation forces, (4) The facet joints at C1 and C3 are about horizontal for the commencement several years of life assuasive for subluxations at relatively picayune strength, (5) Young uncovertebral joints of the C2 to C4 levels may not withstand flexion-rotation forces (6) The fulcrum of cervical move is located higher in young children (C2-3 level than in adults (C5-6).

THE Chest

Thoracic injuries in children subjected to impact commonly occur to the internal organs. The thoracic walls are thinner and the ribs more elastic in infants and young children than in the adults. Therefore, impact to the thorax of an infant or a small kid will produce larger amounts of chest wall deflection onto the vital thoracic organs, eastward.thou. heart, lungs. As clinicians well know, closed cardiac massage in infants can be performed by using only one or two fingers which well demonstrates the highly elastic nature of the chest wall.

At birth the babe middle lies midway between the summit of the head and the buttocks. The long axis of the heart is directed horizontally in the fourth intercostal space with its apex lateral to the midclavicular line. These relationships are maintained until the 4th year, and later the center gradually moves downwardly, due to the elongation of the thorax, until information technology comes to lie at the fifth intercostal space with its apex within the midclavicular line. Until the first year, the width (or length) of the eye is no more than 55% of the breast width taken at the xyphoid line. After the first year, middle width is slightly less than 50% of the breast width (Fig. xi).

Schematic diagram of the position al changes of the center within the breast at various ages. (Redrawn from Watson and Lowrey, "Growth and Development of Children.")

At birth the chest is circular, but as the infant grows the transverse diameter becomes larger than the anterior-posterior dimension, giving the chest an elliptical appearance. At nascence the chest circumference is about one-half inch smaller than the head. At 1 year the chest is equal to or exceeds head circumference slightly; after i twelvemonth the chest becomes progressively larger in diameter than the head.

Scientists are not entirely in agreement as to the master biomechanical causation of cardiac trauma during impact in the adult. Researchers such as Stapp (1965) and Taylor (1963) study that pressure is the major cistron. However, cardiac rupture has been produced experimentally in animals with the blood volume entirely removed, strongly suggesting that other factors are involved (Roberts et al, 1965). Lasky et al (1968), studying adult humans involved in steering-wheel impacts, believes that aortic laceration occurs at the weakest and narrowest point of the aortic arch, and that this anatomical fact is of biodynamic significance.

Introducing a new consideration, Life and Pince (1968) have demonstrated experimentally in animals that the contractile state of the ventricular myocardium at the instant of affect plays a critical role in whether or not cardiac rupture will occur. Clinical shock with abnormally irksome heart and pulse rates (bradycardia) occurs without structural failure in human adult impact tests, and constitutes a main limitation to the rate of onset (Taylor, 1963).

No thoracic impact data are available for children. Considering the differences between child and adult morphology, touch tolerances for the child are probably considerably less than those of the adult.

THE ABDOMEN

Although statistically meaningful studies on child abdominal injuries have non been conducted, the effect of blunt abdominal trauma to children, as compared to adults, has been suggested in the literature. Tank et al (1968), noted that but cerebral injuries and burns outrank injury to the abdominal organs as a form of serious adventitious injury to children. In adults, blunt injury to the intestinal viscera presents the near difficult diagnosis and treatment, and results in the highest mortality rate (Fonkalsrud, 1966; Orloff, 1966). Thus, any blunt abdominal injury can exist potentially serious, but such injuries to the baby and child are much more critical due to their developing and immature structure, large organ relationships, and almost consummate lack of overlying muscle or skeletal protection.

The bulge of the newborn abdomen is accentuated by the intestinal viscera pushing forward during respiration against the weak and atonic muscle wall of the belly. The right side of the baby and newborn abdomen is especially enlarged due to the low position of the liver which occupies two-fifths of the abdominal cavity. Along the midclavicular line the liver is approximately 2 cm below the costal margins in the newborn; one and half cm below the margin for the remainder of the get-go year; and one cm below from xviii months to 6 years. After nearly the 6th–7th year, the liver is seldom palpable except in abnormal cases. On a weight basis, the liver of the newborn comprises 4% of the total torso weight, and by puberty weighs x times as much (Watson and Lowery, 1967). The liver, although considered every bit an abdominal organ, lies almost entirely deep to the right lower ribs and the highly elastic ribs of the kid offer minimal protection for this organ from touch on.

Posteriorly, a like relative migration of the bony thorax downward occurs to provide some protection for the spleen, kidneys, and suprarenal glands as the infant ages. At birth, for example, the kidneys occupy a large portion of the posterior abdominal crenel owing to their relatively large size.

In the newborn, the urinary float lies close to the lower abdominal wall with only its lower portion located backside the pubic bones. During babyhood, much of the bladder descends into the pelvic area where information technology is more protected by the bony pelvis.

Once again, many of the child intestinal viscera are relatively unprotected by bone as compared to the developed. The bladder is located college, outside the pelvic area, the liver and kidneys are relatively exposed, all being more available to traumatic insult. The liver is an organ which is not well designed for withstanding traumatic insults even in the developed. Traumatic liver injuries produce the highest bloodshed rate of whatever intestinal organ (Di Vincenti et al, 1968). With the smaller breast and pelvis of the kid, less of the abdominal contents are protected by the rib muzzle and bony pelvis, and can be more easily injured.

Dimensions of the abdominal area likewise differ from that of the adult, both proportionately and in relation to position of body organs. Abdominal girth, in general, is about the same equally that of the chest during the first 2 years of life. After 2 years, increases in intestinal circumference at the umbilical level do not keep pace with the increases in thoracic girth. Pelvic latitude is another dimension which is less subject to variations in body posture and tonic activity of the muscular intestinal wall. The maximum distance between the external margins of the iliac crests is approximately 3 inches at birth, 5 inches at 1 year, vii inches at 5 years and 9 inches at ten years of historic period. More often than not, in the early on office of infancy at that place is little change in trunk form, merely after the supposition of erect posture there is a relative reduction in the inductive-posterior diameter of both of the thoracic and abdominal regions, accompanied by a subtract in the relative size of the umbilical region and a relative increase in the lumbar region. These changes go on throughout childhood and early adolescence.

THE VERTEBRAL COLUMN

Normal evolution of erect posture involves a gradual transition from the early crawling stages involving interrelationships of the extremities, spine, and pelvis, to the well-counterbalanced weight- bearing relationships typical of the adult. When the baby first stands, the pelvis is tilted far forrard on the thighs and an erect posture is showtime attained in infancy concurrent with the development of the lumbar (low back) curve. As a issue of this lumbar curve, combined with increased tonic action of abdominal wall muscles the infant develops his characteristic sway-back and abdominal prominence which is maintained throughout pre-school years. The infant pelvis gradually rotates upward and forward beginning to constitute an adult-similar posture. The curvature of the sacrum every bit seen in the developed is already nowadays at nativity; nonetheless, in infants the vertebral column above the sacrum is usually straight (Fig. 12).

Curvature of vertebral column emphasizing the development of main curvatures (P) and secondary curvatures (S). Note: in the infant in that location are merely two primary curves, i.e. thoracic and sacral. In the adult there are secondary curves in the cervical and lumbar regions. In the aged only the principal curves persist. (Modified from Johnson and Kennedy, "Radiographic Anatomy of the Human Skeleton.")

Early in infancy the baby can heighten his caput while lying prone, and the cervical (neck) bend outset becomes well established as the head is held cock and cervical muscles get developed and increase their tone action. By the third or 4th month the infant can sit with support and past the seventh month can be expected to sit lone. At 8 or 9 months the babe can usually stand with support and so can stand without assistance by x–14 months.

In the adult, the prominent anterior superior iliac spines are used equally anatomical anchor points. But in children these spines are not well developed until about 10 years of age and basically practise not yet exist. Rather this anterior pelvic area is a broad gentle curve without a prominent spine as in the adult.

THE LIMBS

In considering the growth of the extremities it is necessary to examine factors of skeletal embryology and subsequent dimensional changes (Scammon and Calkins, 1929). Considering outset the trends in dimensional growth of the limbs, it is more often than not noted that the lower limbs increment in length more apace than do the upper limbs. At about 2 years of age, for case, their lengths are equal merely in the adult the lower limb is most on-sixth longer than the upper limb. The adult relations of the dissimilar limb segments are well established prenatally; however, there is some reduction in the relative length of the hand and of the foot afterwards birth. At nativity the lower limb forms about xv% of the body book and in the adult reaches about xxx%. In dissimilarity the upper limb constitutes near viii% of the trunk weight at birth and maintains this same proportionality thereafter.

As in the skull, the long bones of the extremities pass through successive developmental stages which, when compared to adult morphology, brand the limb bones less tolerable to trauma. In early development before birth, long bones are typically represented by a shaft of os which grows in diameter by addition of new bone on its surface with concomitant erosion within the shaft. This development of the shaft can best exist described as a tube that progressively increases in bore. Impact tolerances of children's bones are dependent upon the changing girth of the bone and relative proportions of the marrow crenel and bony walls, besides as the proportions of inorganic and organic materials that class bone tissue. In the early development of bone tissue, organic materials outweigh inorganic components. The degree of flexibility or torsional strength of the bone itself is directly related to the organic component of the bone construction. The preponderance of organic textile continues through adolescence after which in that location is a gradual buildup of inorganic bone substance.

Alter in length of long bones is a function of the connected growth of epiphyseal cartilage. In the early evolution of a long bone the shaft is capped on both ends by cartilage. From belatedly fetal life through puberty bond tissue appears in the cartilage at either end of the shaft just does not attach to the shaft. There is a remaining cartilaginous epiphyseal plate between the bony shaft and the bony epiphyseal ossification middle at each end. The surface of the epiphyseal cartilage in contact with the long bone shaft continues to grow which finer moves or pushes the epiphyseal bone cap away from the shaft. This activity of the epiphyseal cartilage accounts for increases in length of the long bone. Finally, when the adult length is attained for a specific bone as influenced past sex, race, nutrition and endocrine balance, the cartilage of the epiphyseal plate stops proliferation and begins to ossify. Thus, the bony epiphyseal cap is united to the shaft. In females the epiphyses unite sooner so that growth in length ceases before by most ii–3 years when compared to males of similar ages. Merely even in the male person almost of the fusions of long bone epiphyseal cartilages are completed at about the twentieth year. Patently, since bone length is a gene of epiphyseal cartilage growth, traumatic displacement of the cartilage out of line with the normal solitary axis of the bone can lead to gross limb distortion and malformations.

Conclusions

Infants and children are not miniature adults. Their anatomy differs from the developed in a number of means which should be considered in the proper design of occupant restraint systems specific to their age. Within the framework of car safety design it should exist emphasized that:

1. The frequency of head injuries in children involved in automobile accidents may exist due to the child's proportionately large head and higher center of gravity. As a event, infants and children restrained by a lap belt take a greater chance of existence projected over the restraining chugalug because the CG and body fulcrum is located above the belt location.

2. Observations that the child's head is relatively massive and supported poorly from beneath take been implicated in head snapping with rapid trunk deceleration. Such sudden snapping or rotation of the relatively unrestrained child's head tin can traumatize related nerves, blood vessels, and spinal cord segments.

3. Contributing to brain injuries of the young child is the relative lack of skull protection since, early in life, the skull is not an intact bony case for the brain but is a series of broadly spaced elastic bones.

4. Growth rates of different parts of the trunk vary with historic period. For example, the mid-point of the body is above the bellybutton at birth, slightly beneath information technology a 2 years of historic period and nearer the pubic bones at sixteen years.

5. Since growth of the kid is dependent upon the normal activity of growth centers, protection of these centers is vital. Abnormalities of body stature and limb mobility might result from injury to growth centers of the extremities. Similarly, in the head, the organisation of teeth as well as the facial profile tin exist affected by traumatic injuries to the facial growth centers.

6. Unlike the adult, the organs of the chest are housed in an elastic and highly compressible thoracic cage. Organs as the lungs and heart are extremely vulnerable to nonpenetrating impacts to the chest. The smaller rib muzzle likewise means less protection is offered to larger abdominal organs which would normally receive some protection class the larger stronger rib cage of the adult. The highly elastic structure of the thoracic cage is not acquiescent to direct trauma or loading of webbed restraints in children.

​

Increase in total stature at various ages as compared to the adult. (Modified from Chenoweth and Selrick, "School Health Problems.")

Footnotes

^§This paper is a modification and update of "Infants and Children in the Developed World of Automobile Safety Design: Pediatric and Anatomical Considerations for Design of Child Restraints", Burdi, AR, Huelke, DF, Snyder, RG, et al, J Biomech. 2:267-280,1969.

References

• Agran PF, Winn D. Traumatic Injuries Among Children Using Lap Belts and Lap/Shoulder Belts in Motor Vehicle Collisions. 31st Proc Am Assn for Machine Med. 1987:183–307. [Google Scholar]
• Chenoweth LB, Selkirk T. School Health Bug. Crofth; New York: 1937. [Google Scholar]
• Crosby WM, Snyder RG, Snowfall CC, et al. Touch on Injuries in Pregnancy--I. Experimental Studies. Am J Obstet Gynec. 1968;101:100–110. [PubMed] [Google Scholar]
• DiVincenti FC, Rives JD, Labordge EJ, et al. Edgeless Intestinal Trauma. J Trauma. 1968;eight:1004–1013. [PubMed] [Google Scholar]
• Dunlap J, Morris M, Thompson R. Cervical-Spine Injuries in Children. J Bone & Jt. Surg. 1958;40-A:681–686. [PubMed] [Google Scholar]
• Fonkalsrud EW. Acute Trauma in Infants and Children. In: Nahum A, editor. Early Manaaement of Astute Trauma. Mosby; St. Louis: 1966. pp. 180–192. [Google Scholar]
• Finnegen One thousand, McDonald H. Hangman's Fracture in an Infant. CMAJ. 1982;127:1001–1002. [PMC gratis article] [PubMed] [Google Scholar]
• Fuchs S, Barthel JJ, Flannery AM, et al. Cervical Spine Fractures Sustained by Young Children in Forward-Facing Machine Seats. Pediatrics. 1989;84:348–354. [PubMed] [Google Scholar]
• Harris J, Edeiken-Monroe B. The Radiology of Acute Cervical Spine Trauma. Williams and Wilkins; Baltimore, MD: 1987. pp. 1–10. [Google Scholar]
• Huelke DF, Mackay GM, Morris A, et al. Car Crashes and Non-Head Bear upon Cervical Spine Injuries in Infants and Children. Soc Auto Eng Intl Cong; Detroit, MI. 1992. Newspaper No. 920562. [Google Scholar]
• Johnson WH, Kennedy JA. Radiographic Beefcake of The Human Skeleton. Williams and Wilkins; Baltimore: 1961. [Google Scholar]
• Kasai T, Ikata T, Katoh S, et al. Growth of the Cervical Spine With Special Reference To Its Lorclosis and Mobility. Spine. 1996;21(18):2067–2073. [PubMed] [Google Scholar]
• Kihlberg JK, Gensler HR. Head Injuries in Automobile Accidents Related to Seat, Position and Age. Cornell Aeronautical Laboratory, Inc; 1967. [Google Scholar]
• Krogman WM. Philadelphia Center for Inquiry in Child Growth. Philadelphia, PA: 1960. Height, Weight and Trunk Growth of American White and American Negro Boys at Philadelphia, Aged vi–14 Years. [Google Scholar]
• Krogman WM, Johnston Iron. Philadelphia Center for Research in Child Growth. Philadelphia, PA: 1965. The Physical Growth of Philadelphia White Children, Age vii–17 Years. [Google Scholar]
• Krogman WM. Tabulate Biologicae. Vol. xx. Vitgerverij Dr. W. Junk; Den Haag: 1941. Growth of Man. [Google Scholar]
• Lasky I, Siegel AW, Nahum AM. Automotive Cardio-Thoracic Injuries: A Medico-Engineering Analysis. Soc Motorcar Eng; New York. 1968. SAE preprint No. 680052. [Google Scholar]
• Leventhal H. Birth Injuries of the Spinal Cord. J Ped. 1960;56:447–453. [PubMed] [Google Scholar]
• Life JS, Pince BW. Response of the Canine Heart to Thoracic Bear on During Ventricular Diastole and Systole. J Biomech. 1968;1:169– 173. [PubMed] [Google Scholar]
• Martin We, Thieme FP. A Joint Project of the United states Office of Education. The Academy of Michigan and the National School Service, Constitute; Chicago, IL: 1954. The Functional Body Measurements of School Age Children. [Google Scholar]
• Meredith HW. Advances in Child Evolution and Behavior. Vol. 1. Bookish Printing; New York: 1963. Change in the Stature and Trunk Weight of North American Boys During the Last 80 Years. [Google Scholar]
• Moore JO, Tourin B, Garrett JW, et al. Child Injuries in Automobile Accidents. Presented at 14th Intl Conf Pediatrics; Montreal Canada. Likewise in Traffic Safety Res Rev 4:16–21, 1959. [Google Scholar]
• Morris H. In: Morris' Human Anutomy. 12th Edn. Anson BJ, editor. Blakiston, NY: 1966. [Google Scholar]
• Orloff MJ. In: Abdominal Injuries. Early Management of Acute Trauma. Nahum A, editor. Mosby; St. Louis: 1966. pp. 148–161. [Google Scholar]
• Papavasiliou V. Traumatic Subluxation of the Cervical Spine During Childhood. Orthoped Clin N Amer. 1978;nine:945–954. [PubMed] [Google Scholar]
• Salzmann J. Principles of Orthodontics. Lippincott; Philadelphia, PA: 1943. [Google Scholar]
• Scammon RE, Calkins LA. The Evolution and Growth of the External Dimensions of the Human Body in the Fetal Period. Univ of Minnesota Printing; 1929. [Google Scholar]
• Stapp JP. Trauma Acquired by Impact and Boom. Clin Neurosurg. 1965;12:324–343. [PubMed] [Google Scholar]
• Stuart HC, Stevenson SS. In: Concrete Growth and Development. fifth Edn. Nelson, editor. Mitchell-Nelson Textbook of Pediatrics; Philadelphia: 1950. 1959. Reprinted in Documents-Geigy, Scientific Tables. [Google Scholar]
• Sumchi A, Sternback Thousand. Hangman'due south Fracture in a seven-Calendar week Old Infant. Ann Emerg Med. 1991;xx:86–89. [PubMed] [Google Scholar]
• Swearingen JJ, Young JW. Determination of Centers of Gravity of Children, Sitting and Standing. Ceremonious Aeromed Res Inst, Federal Aviation Agency; Oklahoma Metropolis, OK: 1965. Rep. No. AM 65-23 August. [Google Scholar]
• Swishuk 50. Anterior Deportation of C2 in Children: Physiologic or Pathologic? Ped Radiol. 1977;122:759–763. [PubMed] [Google Scholar]
• Tank ES, Eraklis AJ, Gross RE. Edgeless Intestinal Trauma in Infants and Childhood. J Trauma. 1968;8:439–448. [PubMed] [Google Scholar]
• Taylor ER. Biodyamics: Past, Present and Time to come. 657 1st Aero-medical Res Lab; Holloman AFB, New United mexican states: 1963. Rep. No. ARL- TDR-63-ten. [Google Scholar]
• Tingvall C. Injuries to Restrained Children in Cars Involved in Traffic Accidents. Acta Paedriatr Stand Suppl. 1987;339(Iii):1–15. [Google Scholar]
• Watson EH, Lowrey GH. Growth and Development of Children. 5th Edn. Year Book Publishers; Chicago, IL: 1967. [Google Scholar]
• Weech AA. Signposts on the Highway of Growth. AMA Am J Dis Child. 1954:881452. [PubMed] [Google Scholar]
• Young, JW: Personal communication. Unpublished Infant C.G. data, 1968.

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3400202/