Musculoskeletal System

Movement is so much a part of a child’s activities that it is important to screen for disorders that can affect a child’s socialization, exercise patterns, participation in sports, and ability to engage in self-care. Early diagnosis and intervention in disorders such as developmental dysplasia of the hip can possibly prevent more exhaustive treatment as the child grows.

The musculoskeletal system provides support for the body and enables movement. The musculoskeletal system is composed of bones, muscles, tendons, ligaments, cartilage, and joints.

The skeleton arises from mesoderm. At birth the epiphyses of most bones are made of hyaline cartilage. Shortly after birth, secondary ossification centers appear in the epiphyses. The epiphyses ossify, except for the epiphyseal plate, which separates the epiphyses and the diaphyses. The epiphyseal plate is replaced by bone until only the epiphyseal line remains. When the epiphyses are completely ossified, no further bone lengthening occurs.

Muscle fibers are developed by the fourth or fifth month of gestation. The number of muscle fibers remains constant throughout life. Muscle growth is accomplished by increase in the size of the fibers. Muscle mass decreases from one fourth of total body weight at birth to one sixth of total body weight at adolescence. Transient increases in nonlean mass (subcutaneous fat) occur just before the growth spurt, especially in boys, accompanied by decreases 1 to 2 years later. Lean body mass increases, chiefly muscle, occur after the growth spurt, with the increase greater in males than in females.

Inquire whether the infant sustained trauma or injury at birth. Inquire whether there is a family history of bone or joint disorders and whether the child has experienced delays in gross or fine motor development, trauma, joint stiffness and swelling, fever, or pain. If the child has or has had pain, it is important to determine the location, type, intensity, and time of occurrence of the pain. Sharp pain that lessens during rest can indicate injury. Constant dull pain that awakens the child might indicate tumor or infection. Inquire about participation in sports activities (type of sport, level of training involved, amount of contact, previous injuries) and diet. Minimal clothing assists with assessment of the spine.

Assessment

Findings

If the child is able to walk, observe the gait. Note the presence of casts and braces.

Infants and toddlers tend to walk bowlegged. A wide-based gait is normal in the infant and toddler. Clinical Alert Limping can indicate developmental dysplasia of one hip (especially in toddlers). If both hips are involved, the child has a waddling gait. (Table 20-1 lists further indications of developmental dysplasia of the hip.) Table 20-1 Assessment for Presence of Developmental Dysplasia of the Hip Test/Sign Assessment Abnormal Findings Galeazzi or Allis’sign Place the infant supine with the hips and knees flexed so that heels are as close to the buttocks as possible. The knees are unequal in height. (Finding might not be apparent in the infant younger than 6 weeks.) Unequal thigh folds Place the infant or child prone. Observe symmetry of the thigh folds. Unequal thigh folds. Ortolani’s test Place the infant supine. With your thumbs on the inside of both thighs and your fingertips resting over the trochanter muscles, flex (do not force) both hips and knees. Slowly abduct each knee until the lateral aspect of each knee touches the examining table. This test is the most reliable in the infant from birth to 3 months. A click or clunk is heard on abduction. Affected hip will not fully abduct. Barlow’s test Place the infant supine. Flex and slightly adduct both hips while lifting the femur and applying downward pressure to the trochanter. This test is reliable from birth to 2 or 3 months of age. Instability of hip joints. Trendelenburg gait Observe the gait of the child. When the child bears weight on the affected side, the unaffected side of the pelvis drops (Figure 20-3). Asymmetric inguinal folds and limited hip abduction. Place the child supine and flex the hips. Gently abduct the hips while hips are in flexion (hip abduction is the most sensitive indicator of developmental dysplasia past 2 or 3 months). Asymmetry of folds. Limited abduction on the affected side. Figure 20-3Trendelenburg gait. Limping also indicates scoliosis, Legg-Calvé-Perthes disease, infection of the joints of the lower extremities, a slipped capital femoral epiphysis, or stress fractures of the metatarsals. Weight bearing on the toes (pes equines) and short heel cords indicate muscular disease or cerebral palsy.