Porth's Essentials of Pathophysiology, 4e

1106

Musculoskeletal Function

U N I T 1 2

meaning that the femur is rotated externally from under the epiphysis. It is considered the most common hip dis- order of adolescence with an increased prevalence among males, most often between 11 and 16 years of age. 72 The cause of slipped capital femoral epiphysis is obscure, but it may be related to the child’s susceptibil- ity to stress on the femoral neck as a result of genetics or structural abnormalities. Affected children often are overweight with poorly developed secondary sex char- acteristics, or, in some instances, are extremely tall and thin. In many cases, there is a history of rapid skeletal growth preceding displacement of the epiphysis. The condition also may be affected by nutritional deficien- cies or endocrine disorders such as hypothyroidism, hypopituitarism, and hypogonadism. Children with the condition often complain of referred knee pain accompanied by difficulty in walking, fatigue, and stiffness. The diagnosis is confirmed by radiographic studies in which the degree of slipping is determined and graded according to severity. 72 Early treatment is impera- tive to prevent further slippage and permanent deformity. Avoidance of weight bearing on the femur and bed rest are essential parts of the treatment. Traction or gentle manipulation under anesthesia is used to reduce the slip. Surgical insertion of pins to keep the femoral neck and head of the femur aligned is a common method of treat- ment for children with moderate or severe slips. Crutches are used for several months after surgical correction to prevent full weight bearing until the growth plate closes. Children with the disorder must be followed closely until the epiphyseal plate closes. Long-term prognosis depends on the amount of displacement that occurs. Complications include avascular necrosis, leg shorten- ing, malunion, and problems with internal fixation. Degenerative arthritis may develop, requiring joint replacement later in life. Scoliosis Scoliosis is a lateral curvature of the spine in the upright position. Scoliosis is classified as postural or structural. With postural scoliosis, there is a small curve that cor- rects with bending. It can be corrected with passive and active exercises. Structural scoliosis does not correct with bending. It is a fixed deformity classified according to the cause: congenital, neuromuscular, or idiopathic. 75–79 Types of Scoliosis Congenital scoliosis is caused by disturbances in verte- bral development during the sixth to eighth weeks of embryologic development. 75–79 It may involve failures of formation or failures of segmentation. Failures of for- mation indicate the absence of a portion of the vertebra, such as hemivertebra (absence of a whole side of the vertebra) and wedge vertebra (missing only a portion of the vertebra). Failure of segmentation is the absence of the normal separation between the vertebrae. The child may have other anomalies and neurologic com- plications if the spine is involved. Early diagnosis and treatment of progressive curves are essential for children

with congenital scoliosis. Surgical intervention is the treatment of choice for progressive congenital scoliosis. In neuromuscular scoliosis, there is often a long, C-shaped curve from the cervical to the sacral region. It is seen in children with cerebral palsy, in whom severe deformity may make treatment difficult. It also develops in children with Duchenne muscular dystrophy and usu- ally is not severe. Idiopathic scoliosis is a structural spinal curvature for which no cause has been established. It occurs in healthy, neurologically normal children. Although the incidence is only slightly greater in girls than boys, it is more likely to progress and require treatment in girls. 8,77–79 It seems likely that heredity is involved because mother–daugh- ter pairings are common, but identical twins are not uniformly affected, and the magnitude of the curvature in an affected individual is not related to magnitude of curvature in relatives. A recent study of the melatonin receptor 1B (MTNR1B) gene in persons with adolescent idiopathic scoliosis suggests that the MTNR1B gene may serve as a susceptibility gene. 81 Idiopathic scoliosis usually appears clinically between the age of 10 and skeletal maturity, but may be seen at any age. By definition, the curve must be greater than 10 degrees—this has historically been used because 10 degrees is the limit that can be detected by physical exami- nation. 8 Although the curve may be present in any area of the spine, the most common curve is a right thoracic curve. Manifestations Scoliosis usually is first noticed because of the deformity it causes. A high shoulder, prominent hip, or projecting scapula may be noticed by a parent or in a school-based screening program (Fig. 43-24). Idiopathic scoliosis

Elevated shoulder

Right rib hump

Prominent hip

Left lumbar hump

FIGURE 43-24. Scoliosis: Abnormalities to be determined at initial screening examination.