Chapter Outline
Normal Growth and Development 3
Disorders of Normal Growth and Development 3
Evolution of Proportionate Body Size 5
Physical Growth 5
Developmental Milestones 6
This chapter on growth and development is presented first for several important reasons. One of the unique aspects of pediatric care is the dynamic evolution of each individual from neonate to adolescent. During this period, a remarkable process of growth and development takes place in gross and fine motor skills; intellectual, social, and verbal skills; body size; gait; and sexual characteristics.
Growth refers to an increase in an individual’s total body size or to an increase in the physical size of a particular organ or organ system. References to normal human growth parameters from the third trimester to adulthood are provided in Proceedings of the Greenwood Genetic Center: Growth References. This publication also provides parameters for growth patterns seen in specific diseases, such as achondroplasia, diastrophic dysplasia, Down syndrome, Marfan syndrome, and skeletal dysplasias (comparative curves). Growth standards are also available in Hensinger’s Standards in Pediatric Orthopedics.
Development refers to the physical changes of maturation that occur as a child ages. The developmental process encompasses other aspects of differentiation of form, but it primarily involves changes in function that transform humans into increasingly more complex beings. Development is influenced by many interrelated factors, including genetics, physical trauma, nutrition, and socioeconomic status.
The age at which children reach specific milestones of development depends on the maturation rate of their central nervous system (CNS), which varies from child to child. Ranges for variations in normal have been developed to assist in the assessment of the pediatric patient, and the most commonly used assessment tool is the revised Denver Developmental Screening Test (DDST) ( Fig. 1-1 ). It is important to know when a child should normally achieve expected milestones of growth and development so that potentially abnormal situations are evident to the physician who is taking a patient’s history and performing a physical examination.
The significance of various findings must be related to the child’s particular stage of growth and development. Although no one should expect a 4-month-old infant to be walking, it is distinctly abnormal for an 18-month-old child not to be doing so. Similarly, a 12-month-old child is likely to have some degree of genu varum, whereas the presence of genu varum in a 3-year-old child should be cause for concern and a focus of further investigation.
Normal Growth and Development
Neonates are primarily reflexive, but they do exhibit some cognitive traits. These traits include showing more curiosity about facelike figures than about other figures of comparable brightness, as well as a preference for black-and-white tones rather than gray. Neonates should turn their eyes toward sound and be able to distinguish their mothers from other people.
The normal neonate is born with a predominant flexor tone, and physiologic flexion contractures are typical ( Fig. 1-2 ). At birth the newborn’s limbs are maintained in flexion posture, and passive movement of the extremities and neck elicits strong flexor tone. A normal neonate’s limbs move in an alternating fashion when they are stimulated.
Normal development progresses cephalocaudad; infants acquire the ability to control their head and hands before they are able to control their legs. During the first few months, gaining head control predominates. Hand control, such as the ability to grasp objects, follows. As development continues, the infant gains more and more control of the legs.
To determine whether an infant’s growth and development are progressing normally, the examiner needs to find out from the parents what developmental milestones the child has attained and when and then compare them with the norms. If the child appears to have developmental delays, referral to a physician who specializes in growth and development problems is recommended.
Because of the wide variations in the times at which developmental milestones are achieved and the numerous reasons for delays, the diagnosis of developmental delay can be difficult to make in the very young child. In addition, a child may exhibit delay in acquiring certain skills and unusual rapidity in acquiring others. When a delay is evident, the physician must determine the cause, which may be a neuromuscular condition. Factors suggesting a neurologic cause include failure of normal developmental responses to appear, prolonged retention of primitive infant reflexes, or a delay in achieving gross motor milestones within normal limits.
Disorders of Normal Growth and Development
Many pediatric orthopaedic problems result from disorders or conditions that adversely affect normal growth and development. The four major failures of normal growth and development are malformations, deformations, disruptions, and dysplasias.
Malformations
Malformations are structural defects that result from interruption of normal organogenesis during the second month of gestation. Examples include myelomeningocele, syndactyly, preaxial polydactyly, Poland syndrome, and proximal focal femoral deficiency (congenital femoral deficiency).
Deformations
Deformations are defects in the form, shape, or site of body parts caused by mechanical stress. The mechanical stress, which may be intrinsic or extrinsic, alters or distorts tissues. Because the fetus grows considerably faster than the infant, fetuses are more vulnerable to deformations. Examples include supple metatarsus adductus, calcaneovalgus feet, congenital knee hyperextension, and physiologic bowing of the tibia.
Differentiating deformations from malformations is important. During a cursory examination, severe deformations may look like malformations. Careful assessment is essential if the child is to receive appropriate care for the condition. Malformations cannot be corrected directly, whereas deformations can often be reversed relatively easily either by eliminating the deforming force or by counteracting the force with stretching, casting, or bracing.
Disruptions
Disruptions are morphologic abnormalities that result from an extrinsic interference with or breakdown of the normal growth and development process. Disruptions can be caused by drugs or toxic materials. These structural defects may affect organs or systems that were normal during organogenesis. A congenital constriction band in the limb is an example of a disruption.
Dysplasias
Dysplasias are structural defects caused by abnormal tissue differentiation as cells organize into tissues. Examples include osteogenesis imperfecta, achondroplasia, and spondyloepiphyseal dysplasia.
Evolution of Proportionate Body Size
At birth, the neonate’s head is disproportionately large, comprising approximately one fourth of the body’s total length. During the first year of infancy, the head continues to grow rapidly, and the head circumference usually is greater than the circumference of the infant’s chest. The evolution of body proportions is indicated by a change in the child’s upper to lower segment ratio (the relation of the center of gravity to body segments). This ratio is measured as the distance from the top of the head to the symphysis pubis, divided by the distance from the symphysis pubis to the bottom of the feet ( Fig. 1-3 ). At birth, the ratio is approximately 1 : 7. At approximately 10 years of age, the upper and lower segments are almost equal in length (i.e., the ratio is ≈1.0). After 10 years of age, as individuals become adolescents and adults, the ratio normally becomes less than 1.0, as the upper segment becomes shorter than the lower segment.
Physical Growth
Head Circumference
During infancy it is essential to obtain individual or serial measurements of the patient’s head circumference to determine whether head growth is slower or faster than normal. Head circumference should be measured at every physical examination during the first 2 years and at least biennially thereafter. With the child supine, the examiner places a centimeter tape over the occipital, parietal, and frontal prominences of the head. The tape should be stretched and the reading noted at the point of greatest circumference. Possible conditions that can affect head circumference and growth include microcephaly, premature closure of the sutures, hydrocephalus, subdural hematoma, and brain tumor. Head circumference should be charted for age and percentile, as noted in Figure 1-4 .
Height and Weight
A child’s growth, as demonstrated by an increase in body height and weight within predetermined normal limits, is one of the best indicators of health during infancy and childhood. The child’s height and weight should be plotted on a standard growth chart to verify that normal progress is being made. Numerous tables, charts, and graphs depicting pediatric growth standards are available in Hensinger’s Standards in Pediatric Orthopedics and in Proceedings of the Greenwood Genetic Center: Growth References. The World Health Organization published an extensive study of child growth standards for length and height for age, weight for age, weight for length, weight for height, and body mass index for age. Height and weight should be charted for age and percentile, as noted in Figure 1-5 . If growth measurements are lower than the 3rd percentile or higher than the 97th percentile, or if a recent deviation from previously stable percentile rankings is noted, further investigation is warranted.
