McCance 46: Alterations of Musculoskeletal Function in Children (PDF)

CHAPTER 46 Alterations of Musculoskeletal Function in Children Marcella R. Woiczik, McCall G. McDaniel, Russel J. Butterfield http://evolve.elsevier.com/McCance/ Content Updates Chapter Summary Review Review Questions Case Studies Animations CHAPTER OUTLINE Musculoskeletal Development...

CHAPTER 46 Alterations of Musculoskeletal Function in Children Marcella R. Woiczik, McCall G. McDaniel, Russel J. Butterfield http://evolve.elsevier.com/McCance/ Content Updates Chapter Summary Review Review Questions Case Studies Animations CHAPTER OUTLINE Musculoskeletal Development in Children, 1472 Bone Infection: Osteomyelitis, 1482 Bone Formation, 1472 Rheumatologic Disorders, 1484 Bone Growth, 1473 Avascular Diseases of the Bone: Osteochondrosis, 1484 Skeletal Development, 1473 Cerebral Palsy, 1486 Muscle Growth, 1474 Neuromuscular Disorders, 1486 Musculoskeletal Alterations in Children, 1474 Musculoskeletal Tumors in Children, 1489 Congenital Defects, 1474 Nonaccidental Trauma, 1492 Abnormal Density or Modeling of the Skeleton, 1478 Musculoskeletal alterations in children are very common. They may be Cellular aggregation and maturation occur in two types of fetal congenital, such as clubfoot; hereditary, such as muscular dystrophy; tissue, depending on which bones are being formed. The cranium, facial or acquired, such as Legg-Calvé-Perthes disease. Some of these disorders bones, clavicles, and parts of the jawbone (classically called flatbones) are acute, and the child will recover completely; other disorders are arise from a fetal membrane termed the mesenchyme. Bones that develop chronic or, in some cases, terminal. An understanding of the pathophysiol- on or within the mesenchyme grow by the process of intramembranous ogy of these alterations will aid in providing the best care possible for formation of bone. As the mesenchyme becomes vascularized, the these children. immature bone cells aggregate and mature into osteoblasts, which form the centers of ossification and create solid bone or osteoid. MUSCULOSKELETAL DEVELOPMENT Endochondral formation of bone is the development of new bone IN CHILDREN from cartilage (Fig. 46.1). First, mesenchymal tissue forms a cartilage anlage, which defines the shape of the bone. This is usually found by Bone Formation 6 weeks’ gestation. Blood vessel invasion to inside the anlage brings Bone formation, which begins at about the sixth week of gestation, osteoprogenitor cells leading to primary centers of calcification by 8 involves two phases: (1) the delivery of bone cell precursors to sites of weeks. Endochondral bone formation begins in the outer layer of the bone formation and (2) the aggregation of these cells at primary centers cartilage model, which consists of a layer of dense connective tissue of ossification, where they mature and begin to secrete osteoid (see called perichondrium. The perichondrium contains cells that develop Chapter 44). Some of the bone cell precursors are present in fetal into osteoblasts, forming a collar of bone, termed the periosteal collar, connective tissues, whereas others migrate in blood to sites of bone around the cartilage model. Cartilage enclosed within the periosteal formation after blood vessels have grown into the tissue. collar degenerates, and capillaries from outside the perichondrium 1472  CHAPTER 46 Alterations of Musculoskeletal Function in Children 1473 Secondary ossification Epiphyseal center cartilage Calcified Primary cartilage ossification center Compact bone Marrow Perichondrium Primary cavity marrow cavity (nutrient artery) (blood vessels) Spongy bone Cartilage Periosteum Bone collar Articular cartilage FIGURE 46.1 Stages of Endochondral Bone Formation and Centers of Ossification in Long Bone. invade the degenerating cartilage cells, carrying with them osteoblast the distal radius, which contributes 80% of overall radial length, is a precursors from the inner layer of the perichondrium and osteoclast flat, smooth physis that is far more resistant to traumatic injury. precursors from the blood itself. Growth in the diameter of bone occurs by deposition of new bone Endochondral bone formation progresses at the primary center of on an existing bone surface. Bone matrix is laid down by osteoblasts ossification in the middle of the cartilage model and extends toward on the periosteal surface and subsequently becomes calcified. At the either end of the developing bone. At the same time, the periosteal same time, bone resorption occurs on the endosteal surface. Endosteal collar thickens and becomes wider toward the epiphyses. By the end of resorption increases the diameter of the medullary cavity, which contains gestation secondary centers of ossification (i.e., the epiphyseal centers) marrow and spongy bone. begin to lay down bone at both ends of the cartilage model. Here, too, Many factors affect the development, physiology, and rate of growth cartilage within the periosteal collar degenerates, and blood vessels grow of the epiphyseal plate. Growth hormone must be secreted by the pituitary inward, delivering bone cell precursors. Once the osteoblasts begin to gland at a constant rate to stimulate the growth plate consistently. Other secrete osteoid, ossification spreads from the secondary centers in all known factors affecting growth include peptide regulatory factors (e.g., directions until all the cartilage within the model is replaced by bone. fibroblast growth factor [FGF]); changes in cell-to-cell interactions Two regions of cartilage remain at the ends of long bones: (1) articular through cell adhesion molecules (CAMs) and cell junctions; and complex cartilage over the free ends of the bone, and (2) the physeal plate, a interactions or changes in the extracellular matrix (ECM), nutrition, layer of cartilage between the metaphysis and epiphysis. (These structures general health, and other hormones (e.g., thyroid hormone, adrenal are described and illustrated in Chapter 44; see Fig. 44.3). The physeal and gonadal androgens, estrogens). When these factors are poorly plate retains the ability to form and calcify new cartilage and deposit controlled, skeletal dysplasias, such as achondroplasia, can occur. bone until the skeleton matures approximately 1 year after sexual maturity Even after physeal closure at skeletal maturity, bone is constantly (11 to 15 years of age in females, 15 to 18 in males). being destroyed and re-formed (see Chapter 44). This is a rapid process in young children, allowing them to heal bone injury more quickly Bone Growth than adults. By adulthood, however, bone turnover, or remodeling, Until adult stature is reached, growth in the length of long bones occurs occurs at a relatively slow rate. Peak bone mass is achieved by the middle at the physeal plate through endochondral ossification. Cartilage cells to late twenties and slowly decreases throughout life; therefore ensuring at the epiphyseal side of the physeal plate multiply and enlarge. As appropriate intake of calcium and phosphorus, performing weightbearing rapidly as new cartilage cells form, cartilage cells at the metaphyseal exercises, and minimizing caffeine intake are especially important for side of the plate are destroyed and replaced by bone. a young female if she is to avoid osteoporosis in later life. Recently, the In the shaft of new bone, where growth is relatively slow, the bone importance of vitamin D levels also has been emphasized. In one study, produced by accretion is compact and dense. The compact bone is nearly 70% of American children had low levels of vitamin D.1 The thickest where it has to withstand the maximal stresses, which generally actual percentages of children and adults with low levels of vitamin is occur in the middle of the shaft. debated. Children with vitamin D insufficiency have a higher incidence The two physes of the long bone often have varying activity rates. of fracture2 and also may be at greater risk for sustaining more severe For example, the distal physis in the femur contributes 80% of the fractures.3 overall length, whereas the proximal physis at the hip contributes only 20%. The more active of the two has more power to remodel deformity Skeletal Development but also can be more sensitive to injury. The architecture of the physis The axial skeleton changes shape with growth. (The axial skeleton and also dictates its sensitivity to injury. The distal femur, for example, has appendicular skeleton are described and illustrated in Chapter 44; see an undulating pattern that increases its resistance to sheer force; when Fig. 44.5.) In a newborn the entire spine is concave anteriorly, or injured, however, growth disturbance is highly likely. On the other hand, kyphosed. In the first 3 months of life, with the infant’s ability to control 1474 UNIT XIII The Musculoskeletal System the head, the upper (cervical) spine begins to arch, or become lordotic. and facial muscles are well developed at birth so that the infant can The normal lordotic curve of the lower (lumbar) spine begins to develop perform the vital functions of breathing and sucking. Other muscle with sitting. groups, such as the pelvic muscles, take several years to develop fully. The appendicular skeleton (the extremities) grows faster during Throughout life the weight of the skeletal muscles can be increased by childhood than does the axial skeleton. The newborn has a relatively exercise. large head and long spine with disproportionately shorter limbs than an adult. By 1 year of age, 50% of the total growth of the spine has occurred and is more than 70% complete by age 8.4 Therefore failure MUSCULOSKELETAL ALTERATIONS of the spine to grow (e.g., spinal fusion) does not limit eventual height IN CHILDREN as much as the premature fusion of the growth plates of the lower extremities. In children with congenital curvature of the spine, growth Congenital Defects tends to worsen the deformity rather than to increase the length of Syndactyly the spine. The most common congenital defect of the upper extremity is syndactyly, Besides getting longer, growing bones of the extremities undergo or webbing of the fingers (Fig. 46.2). Simple webbing involves the soft changes in rotation and alignment. In the newborn the proximal femur tissue envelope alone and is best released surgically when the child is is rotated forward up to 40 degrees and the tibia is rotated inward. With 6 months to 1 year of age. Complex syndactyly involves fusion of the growth the femur assumes its normal alignment (by 12 years of age) bones and nails as well as the soft tissues; it may be associated with and tibial rotation neutralizes at 8 years of age.5 Bowlegs and knock absence or anomaly of bony or neurovascular units. The primary goal in knees can be normal at certain stages of growth. At birth the newborn’s surgical correction of these defects is to achieve maximal function and legs are bowed because of stresses in utero. Genu varum (bowleg) appearance. Ideally, corrective surgery is deferred until the child is 1 to reaches a peak by 30 months of age, whereas genu valgum (knock 2 years old and completed before the child enters school. Vestigial tabs, knee) maximizes by 5 to 6 years of age. If genu varum or genu valgum such as an extra digit, however, are best removed during the immediate persists past these ages, a pathologic process rather than a physiologic neonatal period. Anomalies on the radial aspect of the arm, such as a phase may be present. Pathologic causes of genu varum are Blount foreshortened or absent radius, are often associated with abnormalities disease, rickets, skeletal dysplasias (such as achondroplastic dwarfism), of blood, heart, or kidneys. Lateral or ulnar-sided defects are less often traumatic injury, and musculoskeletal infection. Genu valgum also may associated with systemic anomalies and are extremely rare. persist in children with a skeletal dysplasia, benign musculoskeletal tumors (multiple hereditary exostoses), osteogenesis imperfecta, or Developmental Dysplasia of the Hip following a traumatic injury or infection. A genetic predisposition to Developmental dysplasia of the hip (DDH), formerly known as genu valgum also may be evident. congenital dislocation of the hip, is an abnormality in the development of the proximal femur, acetabulum, or both (Fig. 46.3). Although Muscle Growth most often present at birth, it may occur at any time in the newborn The composition and size of muscles vary with age. In the fetus, muscle or infant period. tissue contains a large amount of water and much intercellular matrix. The incidence of true dislocation of the hip or a dislocatable hip is After birth, both are reduced considerably as the muscle fibers (cells) 1 in 1000 live births. Some degree of instability of the hip is present in enlarge by accumulating cytoplasm. Little information is available about approximately 10 per 1000 live births. The left hip is affected in 60% the numbers of fibers in a given muscle at various ages, but the total of cases, whereas the right hip alone is affected only 20% of the time. mass of muscle in the body can be estimated from the amount of Bilateral DDH occurs 20% of the time. creatinine excreted in the urine, because the conversion of creatine to Risk factors for DDH include family history, female gender (6:1), creatinine takes place only in muscle (see Chapter 44). Between birth metatarsus adductus (20%), torticollis (10%), oligohydramnios, first and maturity the number of muscle nuclei in the body increases 14 pregnancy, and breech presentation. First pregnancies and oligohydram- times in boys and 10 times in girls. Muscle fibers reach their maximal nios (deficient volume of amniotic fluid) are thought to limit fetal size in girls at approximately 10 years of age and in boys by 14 years. movement, and breech presentation not only limits movement but also Growth in length occurs at the ends of muscles, and the increase in places the hips in a position of flexion and adduction, which creates a length is accompanied by an increase in number of nuclei in the fibers. Muscle fibers increase in diameter as the fibrils become more numerous. The fibrils themselves do not increase in diameter. Connective tissue components of muscle grow where the tendon and muscle meet. A potent stimulus to the growth of a muscle is the separation of its attachments as the skeleton grows. The length of a muscle fiber is the direct consequence of its intended range of movement. The stimulus for the formation of a tendon is probably the pull of the muscle rudiment on undifferentiated connective tissue. If the normal opponents of a muscle are paralyzed, the muscle fails to grow properly and can result in contracture of a joint. Muscle growth during adolescence is a major factor in weight gain. Gender differences in muscle size and weight are minor in childhood but become considerable with the onset of puberty. In the infant, muscle accounts for approximately 25% of total body weight, compared with 40% in the adult. In the adult, approximately 55% of muscle weight is in the lower limb muscles, whereas in the infant the majority of the weight is axial musculature. The respiratory FIGURE 46.2 Syndactyly with Polydactyly.  CHAPTER 46 Alterations of Musculoskeletal Function in Children 1475 more shallow socket, or acetabulum. Although only 2% of births have subluxated hip maintains contact with the acetabulum but is not well breech history, as many as 40% of infants with DDH had a breech birth. seated within the hip joint. The acetabulum is often dysplastic (or Maternal hormones that reportedly increase joint laxity also have an shallow) although the femur is often normal. The dislocatable hip is effect on DDH, although the exact mechanism is unknown. DDH also sometimes located but can be dislocated easily. The dislocated hip has is more common in whites and those cultures that swaddle infants with no contact between the femoral head and the acetabulum. Some degree the hips in extension and adduction. It is almost unknown in African of acetabular dysplasia is present in almost all cases. Typically, the cultures where infants are carried, with legs abducted, on the back. acetabulum is shallow or sloping rather than cup shaped. PATHOPHYSIOLOGY. The hip can be described as subluxated (partial By approximately 10 weeks’ gestation, the femur, acetabulum, and contact only), dislocated (no contact between femoral head and acetabu- hip joint capsule are well developed. It appears that most hip dysplasia lum), and acetabular dysplasia (the femoral head is located properly develops within the second and third trimesters and is often the result but the acetabulum is shallow or underdeveloped) (Fig. 46.4). The of positioning factors (i.e., breech positioning). There also can be a genetic component, although this is still poorly understood. In addition, 2% of DDH cases are teratologic or caused by a systemic syndrome, such as arthrogryposis or spina bifida, in which muscle contracture or imbalance leads to DDH. If DDH is left untreated in the growing child, secondary changes occur. If the hip remains subluxated or dislocated, the acetabulum becomes increasingly shallow and the soft tissues shorten around the proximal femur. Subluxation leads to early osteoarthritis (OA), and it is now estimated that at least 60% of all OA of the hip is related to DDH. If the hip is dislocated, the bone acetabulum fills with soft tissue and a false acetabulum forms where the femoral head contacts the iliac crest. An apparent limb length inequity and hip muscle weakness occur, leading to a waddling gait. Back pain and hip pain develop in adulthood. Adult reconstruction of a dislocated hip, even with an artificial hip, is very difficult.6 CLINICAL MANIFESTATIONS. The clinical manifestations of DDH vary with the severity of the condition and the age of the child. Signs and symptoms that should be noted include the following: 1. Asymmetry of gluteal or thigh folds 2. Limb length discrepancy (Galeazzi sign) 3. Limitation of hip abduction 4. Positive Barlow maneuver (hip reduced, but dislocatable) (Fig. 46.5, A) 5. Positive Ortolani sign (hip dislocated, but reducible) (Fig. 46.5, B) 6. Positive Trendelenburg gait (waddling) 7. Pain (very late) The child also should be examined for other anomalies, such as torticollis or metatarsus adductus, which can be associated with DDH. FIGURE 46.3 Hip Dysplasia in Children. Developmental dysplasia of the hip EVALUATION AND TREATMENT. In the newborn period clinical (DDH) with residual acetabular dysplasia (red arrows). Radiographs at birth, 3, 10, examination is the most important diagnostic tool. Real-time ultrasound, and 19 years (top to bottom) show persisting dysplasia. in which the hip is examined while the ultrasound is performed, also Normal Dysplasia Subluxation Dislocation FIGURE 46.4 Configuration and Relationship of Structures in Developmental Dysplasia of the Hip. (From Hockenberry MJ, Wilson D: Wong’s nursing care of infants and children, ed 10, St Louis, 2015, Mosby.) 1476 UNIT XIII The Musculoskeletal System A B FIGURE 46.5 Congenital Dislocation of the Hip. A, Barlow maneuver. With one hand pressing the symphysis in front and the sacral spine in back, lateral pressure is applied to the thigh with the thumb of the other hand while pressure is applied with the palm to the knee on the side being examined. The hip that has been flexed to 90 degrees is then adducted. A positive sign is a sensation of abnormal movement, indicating dislocation of the femoral head from the acetabulum. The hands are reversed for examining the other hip. This sign and Ortolani sign may be found only in the first weeks of life. B, Ortolani maneuver. Sign of jerking into correct position. After the Barlow maneuver (A), the hip should be abducted to about 80 degrees while the femur is lifted anteriorly with the fingers along the thigh. A positive sign is a sensation of a jerk or snap with reduction into the joint socket. (Adapted from Specht EE: Am Fam Physician 9:88–96, 1974.) is extremely valuable in the newborn period, especially in high-risk infants. The use of ultrasound allows visualization of the cartilaginous structures of the hip (the femoral head and the outer lip of the acetabu- FIGURE 46.6 Pavlik Harness for Bilateral Hip Dislocation. (From Wheaton lum), which are not seen on plain roentgenogram. Radiographs are Brace Co.) used after age 6 months when the ossific nucleus of the femoral head appears.7 Treatment depends on the age of the child, severity of dysplasia, Metatarsus adductus is usually classified by two criteria: flexibility and duration of dysplasia. The earlier that treatment is begun, the better (passively correctable vs. rigid) and degree of deformity. The degree of the result. In children less than 4 to 6 months of age, a Pavlik harness deformity (mild, moderate, severe) is ascertained by the heel bisection can brace the hip in abduction and flexion, and the acetabulum will line. A mild deformity is one in which the heel bisection line passes remodel as the femoral head rests centered in the socket (Fig. 46.6). medial to the third toe; moderate, through the third or fourth toes; With this treatment, up to 98% of children will have an excellent result. and severe, lateral to the fourth toe. Serial casts during the first 6 months A “closed” reduction (without opening the joint) followed by spica or of life are suggested for moderate to severe deformities and those body casting for up to 3 months can be done in children up to 12 deformities that appear less flexible. By 6 years of age, 87% of children months of age. After 12 months, surgical intervention—including opening usually correct spontaneously, and 95% by 15 years of age. Even in those the joint and cutting and realigning the femur and/or acetabulum—may children with some residual deformity, functional symptoms are rare. be required. The percentage of good outcomes decreases as the child Clubfoot: Equinovarus Deformity. Clubfoot describes a range ages. Up to 70% of children treated surgically for DDH after age 3 of foot deformities in which the foot turns inward and downward. develop early osteoarthritis.8 Early intervention before age 1 is critical Technically called equinovarus, the heel is positioned varus (inwardly for a good outcome; therefore vigilance for this problem within the deviated) and equinus (plantar flexed) (Figs. 46.7 and 46.8). The clubfoot first year is essential. Moderate evidence supports performing an imaging deformity can be positional (correctable passively), idiopathic, or tera- study (ultrasound) before 6 months of age in infants with one or more tologic equinovarus (as a result of another syndrome, such as spina of the following risk factors: breech presentation, family history, or bifida). These three types are discussed in the following sections. Overall, history of clinical instability.9 the positional equinovarus deformity lends itself to rapid correction by conservative stretching exercises or by application of a few serial Deformities of the Foot casts. The idiopathic variety is treated by weekly cast correction/ Congenital Deformity. Congenital foot deformity is found in manipulation, followed by Achilles tenotomy and abduction bracing. approximately 4% of all newborns, and metatarsus adductus accounts Teratologic equinovarus deformities more often require surgical cor- for 75% of these deformities (Table 46.1). Metatarsus adductus is a rection or muscle-balancing procedures, or both; however, initial serial forefoot adduction deformity associated with a normal, plantigrade casting may achieve correction of the foot deformity albeit with a higher hindfoot and is believed to be secondary to intrauterine positioning. risk of recurrence. It is associated with developmental dysplasia of the hip in 20% of cases; Positional Equinovarus. Positional equinovarus is a deformity consequently, the hips of these infants must be carefully evaluated. in which an infant’s foot is in equinovarus position but does have  CHAPTER 46 Alterations of Musculoskeletal Function in Children 1477 TABLE 46.1 TERMS USED TO DESCRIBE FOOT ABNORMALITIES TERM DEFINITION Position Abduction Lateral deviation away from the midline of the body Adduction Lateral deviation toward the midline of the body Eversion Twisting of the foot outward along its long axis Inversion Twisting of the foot inward along its long axis Dorsiflexion Bending the foot upward and backward Plantar flexion Bending the foot downward and forward Abnormality A Talipes Congenital abnormality of the foot (clubfoot) Pes Acquired deformity of the foot Varus Inversion and adduction of the heel and forefoot Valgus Eversion and abduction of the heel and forefoot Equinus Plantar flexion of the foot in which the heel is lower than the toes Calcaneus Dorsiflexion of the foot in which the heel is lower than the toes Planus Flattening of the medial longitudinal arch of the foot (flatfoot) Cavus Elevation of the medial longitudinal arch of the foot (high arch) Equinovarus Coexistent equinus and varus deformities Calcaneovarus Coexistent calcaneus and varus deformities Equinovalgus Coexistent equinus and valgus deformities Calcaneovalgus Coexistent calcaneus and valgus deformities B FIGURE 46.7 Bilateral Clubfoot. A, Infant with bilateral congenital talipes equinovarus. B, Ponseti casting. (A courtesy Dr. A.E. Chudley, Section of Genetics and Metabolism, Department of Pediatrics and Child Health, Children’s Hospital and University of Manitoba, Winnipeg, Manitoba, Canada. In Moore KL et al: The developing human, ed 10, Philadelphia, 2016, Saunders.) flexibility without deep creases at the posterior ankle or midfoot. The Achilles tendon is still flexible. The foot can be passively brought to a plantigrade position and is amenable to stretching and casting. In general, conservative therapy corrects this foot without the need for surgical intervention or lengthy bracing. Idiopathic Congenital Equinovarus. The etiology of idiopathic equinovarus (clubfoot) is unknown. In one human fetal study, all clubfeet were associated with identifiable anterior horn cell changes in L5 and S1. Muscle biopsies of both the anterior tibialis long flexors and the peroneus brevis muscles in clubfoot reveal that at least 50% of cases show a decreased number of muscle fibers and/or abnormal fiber histol- ogy. The soleus often has an increase in type 1 fibers, whereas the peroneus brevis has a fiber type disproportion. The more abnormal the histopathol- FIGURE 46.8 Idiopathic Clubfoot. Idiopathic clubfoot displaying forefoot ogy, the more severe the deformity, and the greater the chance of recurrent adduction (toward midline of body) and supination (upturning) and hindfoot equinus deformity after treatment. The genetic component is unclear and studies (pointed downward). Note skin creases along arch and back of heal. are ongoing. Idiopathic equinovarus occurs in approximately 0.3 to 7.8 per 1000 newborns, with males being affected twice as often as females. Historically, technique involves six to eight above-knee casts, left on for 5 to 7 days these deformities were treated by posteromedial release, a surgical each, followed by a percutaneous tendo achilles lengthening procedure procedure that lengthened all tight structures and opened the capsule performed with local anesthesia. The child then uses special braces at of all tight joints in the foot. However, since 1998 the casting technique night until 3 to 4 years of age. Noncompliance with braces leads to developed by Ignacio Ponseti (see Fig. 46.7, B) has been used; the increased recurrence and need for additional casting or surgery. Nearly 1478 UNIT XIII The Musculoskeletal System BOX 46.1 PONSETI CASTING Abnormal Density or Modeling of the Skeleton Ponseti casting implements toe-to-groin casts changed weekly for 6 weeks. Osteogenesis Imperfecta Casting begins as early as possible after birth and culminates in a percutaneous Osteogenesis imperfecta (OI) (brittle bone disease) is a collagen-related tendo achilles lengthening in the clinic, followed by a final cast worn for 3 bone dysplasia. Collagen is the main component of bone and blood weeks. In recalcitrant cases, a full surgical posteromedial release (PMR) still vessels. The disorder was first described in 1840 as a syndrome in may be required. The need for PMR in idiopathic clubfoot has decreased from newborns that consisted of osteoporosis with fractures and skeletal 90% to less than 20% of infants when this casting technique is used. Long-term deformities. The Sillence classification is based on both models of results, presumably because of less scarring and more long-term flexibility, inheritance and clinical findings (Table 46.2), and has been useful to are better with Ponseti casting than with the PMR method. describe the most common types of OI. Newer classifications also exist and are based on the mode of inheritance, identifying the defective gene, protein, or mechanism12 (Table 46.3). In the most severe form of this disorder, the child is usually stillborn 30% of children may need an anterior tibialis transfer around age 3.10 or dies soon after birth, although some survive into childhood. OI in Studies comparing operative posteromedial release with Ponseti tech- its more severe forms is evident at birth because fractures and deformity niques show better long-term results with the less invasive Ponseti have occurred in utero. The less severe forms may not become evident method11 (Box 46.1). until the child begins to walk. Some children with this milder form Teratologic Equinovarus. The most common cause of teratologic then experience numerous fractures that can be mistaken for nonac- equinovarus is either neuromuscular (such as spina bifida) or syndromic cidental trauma until the diagnosis is made. The prevalence rate of the (such as arthrogryposis or osteochondrodysplasia [e.g., diastrophic most common form is about 1 in 30,000. Inheritance is usually autosomal dwarfism]). The teratologic clubfoot, unlike the idiopathic type, more dominant but can be autosomal recessive. At least four syndromes have often fails to be corrected with Ponseti casting and may require operative been identified that have various clinical manifestations and prognoses intervention. The surgery is often more extensive than that for an (see Table 46.2). idiopathic clubfoot, and revision surgery is also more common (see PATHOPHYSIOLOGY. The major errors in OI lie in the synthesis Box 46.1). of collagen, a triple helix with two matching α chains and one β chain. Pes Planus (Flatfoot) Deformity. Pes planus (flatfoot) commonly Collagen is present in bone, cartilage, eye tissue, skin, and the vascular raises parental concern. Despite medical evidence to the contrary, it system. The severity of the OI phenotype and the related anomalies of can be very difficult to convince families that a flexible flatfoot is often the eye, dentition, or vascular system are all dependent on the severity as functional as one with a “normal” arch. The majority of babies are of the genetic anomaly and the part of the triple helix that is affected.13 born with flat (or “fat”) feet, with the arch becoming more apparent (Genes are discussed in Chapter 4.) with age. The relatively benign natural history, however, should not A number of metabolic abnormalities are associated with OI. Some overshadow the importance of accurate diagnosis. Significant ankle individuals have increased serum thyroxine levels, suggesting hyper- valgus, vertical talus, tarsal coalition, and skewfoot must be accurately thyroidism. This is consistent with the findings of increased sweating, differentiated from flexible pes planus. heat intolerance, increased body temperature, a resting tachycardia, and Flexible flatfoot deformity appears to be familial, with occasional tachypnea. Studies of leukocyte metabolism suggest an uncoupling of association of generalized ligamentous laxity. Careful evaluation of oxidative phosphorylation. Reports of alterations of platelet function possible occult Achilles contracture is done by holding the hindfoot in with defects in adhesion and clot retraction also exist. varus position and dorsiflexing the ankle. Achilles contracture can signify CLINICAL MANIFESTATIONS. The classic clinical manifestations of a more severe flatfoot variant. The flexibility of the hindfoot is evaluated OI are osteoporosis and increased rate of fractures, possible bony by having the child stand on his or her toes facing away from the deformation, triangular facies, possible vascular weakness (i.e., aortic examiner. In flexible pes planus, the hindfoot swings into a varus position aneurysm), possible blue sclerae, and poor dentition. The Sillence as the planter fascia tightens in toe raise. In rigid pes planus, the hindfoot classification designated types I through IV on the basis of severity. stays in valgus and the child has more difficulty going up onto tip-toe. The most severe, types II and III, are comparable to osteogenesis imperfecta Surgical or orthotic treatment of asymptomatic flexible pes planus congenita. These two types are characterized by autosomal recessive is unnecessary. Custom orthotics, Helfet heel cups, and corrective inheritance and early onset of manifestations. Both can cause stillbirth orthopedic shoes have no influence over the natural history (clinically or severe neonatal deformity and a short life expectancy. Less severe or radiographically) of flat feet. Adult studies on army recruits have are types I and IV, which are comparable to osteogenesis imperfecta shown that soldiers with flat feet perform just as well as their counterparts tarda. Type I is slightly more common than types II and III, and type without “fallen” arches. IV is quite rare. Types I and IV are inherited as autosomal dominant There is a small subset of children with painful, flexible flat feet. traits and vary in age of onset from birth to adulthood. Type IV, especially For these children careful attention to the possibility of Achilles con- when the sclerae are white, is the least deforming type and is often tracture or tarsal coalition (congenital union of the hindfoot bones) confused with nonaccidental trauma (child abuse). must be made. This group of children is best treated with inexpensive EVALUATION AND TREATMENT. Evaluation of OI is based primarily shoe inserts and then expectantly watched. If pain continues into on clinical manifestations. Serum alkaline phosphatase level is elevated adolescence, requiring more aggressive treatment, calcaneal lengthening in all forms of the disease. OI can be diagnosed prenatally by ultrasound will correct the pes planus without decreasing hindfoot motion. In or chorionic villi sampling. Quantitative analysis of cultured skin rigid flat feet, a computed tomographic (CT) scan often will reveal a fibroblast collagen by electrophoresis shows a decreased quantity of coalition, a bony or cartilaginous connection between the bones—if collagen in 95% of individuals. painful, this can be resected. Heel cord contractures can be surgically Type II OI is often terminal in the perinatal period, and therefore lengthened if stretching alone is inadequate. All surgery carries risk; if little is known about appropriate treatment for the few children who a foot is flat but nonpainful, treatment is not required. The painless survive. For other types of OI, careful positioning and handling of the flatfoot should be viewed as a variation of normal feet. newborn help prevent fractures. Beyond the neonatal period, various  CHAPTER 46 Alterations of Musculoskeletal Function in Children 1479 TABLE 46.2 SILLENCE CLASSIFICATION OF OSTEOGENESIS IMPERFECTA SYNDROMES TYPE TRANSMISSION MAIN BIOCHEMICAL DEFECT ORTHOPEDIC MISCELLANEOUS IA AD Decreased production of type I Mild to moderate bone fragility, Blue sclera, hearing loss, easy bruising, collagen osteoporosis, normal stature dentinogenesis imperfecta absent IB AD Short stature More severe in IA with dentinogenesis imperfecta II AD, AR, and mosaic Substitutions of glycyl residue in X1 Multiple intrauterine fractures, extreme Usually lethal in perinatal period, or X2 chains in triple helix bone fragility delayed ossification of skull, intrauterine growth restriction IIA Long bones broad, crumpled; ribs broad with continuous beading IIB Long bones broad, crumpled; ribs discontinuous or beading IIC Long bones thin, fractured; ribs thin, beaded IID Severely osteoporotic with generally well-formed skeleton; normal-shaped vertebrae and pelvis III AD and AR Abnormal type I collagen Progressive deforming phenotype, severe Hearing loss, short stature, blue sclerae bone fragility with fractures becoming less blue with age, shortened life expectancy, dentinogenesis imperfecta, relative macrocephaly with triangular facies IVA AD Shortened pro-α (I) chains Mild to moderate bone fragility, Light sclerae, normal hearing, normal osteoporosis, bowing of long bones, dentition, dentinogenesis imperfecta scoliosis absent IVB AD Dentinogenesis imperfecta present AD, Autosomal dominant; AR, autosomal recessive. Reproduced with permission from Vaccaro AR, editor: Orthopaedic knowledge update 8, Rosemont, IL, 2005, American Academy of Orthopaedic Surgeons, p 248. TABLE 46.3 OSTEOGENESIS IMPERFECTA (OI) TYPES CAUSED BY DEFECTS IN GENES AND THE COLLAGEN-RELATED PROTEINS THAT THEY ENCODE OI TYPE DEFECTIVE GENE DEFECTIVE PROTEIN DEFECTIVE MECHANISM Autosomal dominant I COL1A1 α1(I) collagen Collagen quantity 85%–90% of OI case types II COL1A1 or COL1A2 α1(I)/ α2(I) collagen Collagen structure I–IV III COL1A1 or COL1A2 α1(I)/ α2(I) collagen IV COL1A1 or COL1A2 α1(I)/ α2(I) collagen V IFITM5 BRIL Matrix mineralization 10%–15% of OI cases Autosomal recessive VI SERPINF1 PEDF Collagen 3-hydroxylation 10%–15% of OI case types VI VII CRTAP CRTAP to unclassified VIII LEPRE1 P3H1 IX PPIB CyPB X SERPINH1 HSP47 Collagen chaperoning XI FKBP10 FKBP65 Telopeptide hydroxylation XII BMP1 BMP1/mTLD Collagen processing Unclassified SP7/OSX SP7/OSTERIX Osteoblast development WNT1 WNT1 TMEM38B TRIC-B CREB3L1 OASIS Data from Marini J et al: Curr Opin Pediatr 26(4):500–506, 2014. 1480 UNIT XIII The Musculoskeletal System A B C FIGURE 46.9 Osteogenesis Imperfecta Treated with Osteotomies and Telescoping Medullary Rods. A, Severe deformity of both femurs. B, Same individual after multiple osteotomies with telescoping medullary rod fixation. C, Same individual 4 years later demonstrating growth of femurs, no recurrence of deformity, and elongation of rods. (Plaster casts are in place for immobilization of tibial osteotomies.) (From Crenshaw AH, editor: Campbell’s operative orthopaedics, ed 8, vol 3, St Louis, 1992, Mosby.) orthopedic measures are applied, such as prompt splinting of fractures and correction of deformities arising from the progressive bowing or bending of the skeleton by intramedullary rodding of the bones (Fig. 46.9). Newer, telescoping rods, which grow with the child, have been Impaired growth shown to reduce the reoperative rate by 30%.14 Scoliosis is present in Craniotabes up to 50% of Sillence III cases and often requires surgery. A multicenter study of a bisphosphonate therapy showed promising results in type Frontal bossing III OI, with marked improvements of bone density (up to 30%). Chronic Dental defects bone pain and fatigue also are thought to be lessened with routine bisphosphonate therapy. Despite these results, there is concern that the Chronic cough healing of fractures and surgical intervention can be more difficult. Tunnel chest More study is needed to address the efficacy and safety of these types of drugs. Genetic counseling for affected families should aim at primary Kyphosis prevention. Rachitic rosary Rickets Rickets is a disorder in which growing bone fails to become mineralized Harrison groove (ossified), resulting in “soft” bones and skeletal deformity (Fig. 46.10). Flaring of ribs Rickets results from either insufficient vitamin D, insensitivity to vitamin D, wasting of vitamin D by the kidney, or inability to absorb vitamin Enlarged ends D and calcium in the gut. The most common form is X-linked hypo- of long bones phosphatemic rickets in industrialized nations. In addition to the severe Enlarged abdomen form of metabolic rickets, dietary and lifestyle changes in the United States have led to widespread vitamin D deficiency in children.15 Although Coxa vara unprotected exposure to ultraviolet rays is not suggested, children still need 15 to 20 minutes per week of true sun exposure to activate vitamin Bowleg D, the mineral necessary for absorption and metabolism of calcium (genu varum) and phosphate. In one recent study, up to 90% of normal American children had a low vitamin D level, especially children of color. This can lead to early fracture or slow bone healing after fracture.16 Severe metabolic rickets in the immature skeleton leads to short stature and bowing of the limbs with broad, irregular growth plates. FIGURE 46.10 Rickets. The rows of cells in the growth plate that are intended to ossify fail to do so as they reach the metaphysis since calcification is impeded. attachments of the ribs become prominent, and the long bones of the Children with rickets are often listless and irritable. They have extremities (tibia, femur, radius, ulna) may be bowed. Growth is restricted, hypotonia and muscle weakness and may be unable to walk without and fractures are common. support. Abnormal parietal flattening and frontal bossing occur in the Like osteogenesis imperfecta, surgical treatment of bony deformity skull. The calvaria become soft, and the sutures may widen. Cartilaginous can be required. However, medical management of calcium, phosphorous,  CHAPTER 46 Alterations of Musculoskeletal Function in Children 1481 and vitamin D levels must be optimized before surgical intervention. In addition to medical management, children may benefit from guided growth techniques to correct persistent deformity (Fig. 46.11). Scoliosis Scoliosis is a rotational curvature of the spine most obvious in the anteroposterior plane (Fig. 46.12). It can be classified as nonstructural or structural. Nonstructural scoliosis results from a cause other than the spine itself, such as posture, leg length discrepancy, or pain. Structural scoliosis is curvature of the spine associated with vertebral rotation. Nonstructural scoliosis can become structural if the underlying cause is not found and treated. Structural scoliosis can be caused by a great variety of conditions. It can result from congenital skeletal abnormalities (15%), neuromuscular diseases (15%), trauma, extraspinal contractures, bone infections that involve the vertebrae, metabolic bone disorders (e.g., rickets, osteoporosis, osteogenesis imperfecta), joint disease, and tumors. Most cases of structural scoliosis, however, have no known cause, although genetic factors are suggested. Structural scoliosis with no known cause, termed idiopathic scoliosis, accounts for at least 70% of cases. Idiopathic scoliosis is classified as infantile, juvenile, or adolescent, depending on the child’s age at the time of onset. In infantile scoliosis, also known as early onset scoliosis, spinal curvature develops during the first 3 years of life; in juvenile scoliosis, curvature develops between the skeletal age of 4 years and the onset of adolescence; and in adolescent scoliosis, it develops after the skeletal age of 10. Adolescent idiopathic scoliosis is the most common. Scoliosis in its milder forms occurs equally in boys and girls; however, girls are 10 times more likely than boys to develop curves greater than 30 degrees. PATHOPHYSIOLOGY. It has been hypothesized that in individuals with adolescent scoliosis, there is an abnormality of the central nervous A B system involving the balance mechanism (reticular system) in the FIGURE 46.11 Guided Growth Technique. A, Right genu valgum and bilateral midbrain. A genetic component is also suggested because 30% occur ankle valgus deformity in a 10-year-old female with osteogenesis imperfecta. within families. B, Corrected left genu valgum and ankle valgus with guided growth technique. Experimentally it also has been shown that individuals with adolescent (Used with permission from M. Woiczik personal patient collection, images taken idiopathic scoliosis have an abnormality in the function of the posterior from 2012 and 2013.) columns of the spinal cord. This results in abnormal proprioception and is not evident clinically except in the presence of scoliosis. The exact cause of scoliosis, however, remains elusive.17 The earliest pathologic changes, which are probably secondary changes, occur in the soft tissues. The muscles, ligaments, and other D A B C FIGURE 46.12 Scoliosis in Children. Normal spinal alignment and abnormal spinal curvatures associated with scoliosis. A, Normal. B, Mild. C, Severe. D, Rotation and curvature of scoliosis. 1482 UNIT XIII The Musculoskeletal System soft tissues become shortened on the concave side of the curve. Vertebral deformity occurs as asymmetrical forces are applied to the epiphyseal center of the ossification by shortened and tight soft tissues on the concave side of the curve. True curves involve not only bending but also twisting of the torso, leading to the “rib hump” seen when the child bends forward. The curves increase most rapidly during periods of rapid skeletal growth. If the curve is less than 40 degrees at skeletal maturity, the risk of progression is quite small. In curves greater than 50 degrees, the spine is biomechanically unstable, and the curve usually progresses even after the cessation of growth. Curves in the thoracic spine greater than 80 degrees result in decreased pulmonary function, whereas the most common complication of large curves in the lumbar spine is back pain. CLINICAL MANIFESTATIONS. The clinical manifestations of A nonstructural scoliosis are mild spinal curvature with prominence of one hip or rounded shoulders. The curvature disappears with forward flexion of the spine, lying down, or traction of the head. Treatment for nonstructural scoliosis is correction of the underlying disorder. The clinical manifestations of structural scoliosis include asymmetry of hip height, asymmetry of shoulder height, shoulder and scapular (shoulder blade) prominence, and rib prominence. EVALUATION AND TREATMENT. Spinal curvature is usually visible or palpable, and muscles on one side of the lower back (the convex side) may be prominent or bulging. Most cases of idiopathic scoliosis are noticed during school screening programs. In girls the deformity may be noticed because clothing does not “hang” properly on the body. Diagnosis is made by roentgenographic examinations. Brace treatment is indicated for children with curves of 25 to 40 degrees who have at least 2 years of growth remaining.18 A rigid, low- profile thoracolumbar brace is used in most cases. Low-profile braces are worn for 18 to 23 hours per day until skeletal maturity. Bracing will only prevent progression of the curve; it will not correct the curvature. Bracing is not effective in large curves or in skeletally mature individuals; B the most effective time for bracing is in growing prepubescents with a FIGURE 46.13 Pathogenesis of Acute Osteomyelitis Differs with Age. small curve.19 Extensive chiropractic manipulations and electrical A, In infants younger than 1 year the epiphysis is nourished by penetrating arteries stimulation have not been shown to change natural history. Surgical through the physis, allowing development of the condition within the epiphysis. treatment using spinal fusion with instrumentation is recommended B, In children up to 15 years of age the infection is restricted to below the physis for curves greater than 40 to 50 degrees. If surgery is indicated, it is because of interruption of the vessels. better performed during the adolescent years while there is greater flexibility of the curves and less risk of complications. BOX 46.2 CAUSATIVE Bone Infection: Osteomyelitis MICROORGANISMS OF Osteomyelitis is an infection of the bone. Occurring twice as often in OSTEOMYELITIS ACCORDING males as females, acute osteomyelitis may affect infants and children TO AGE of any age, but it occurs most often between 3 and 12 years of age. Bacteria enter the bone through the bloodstream and lodge in the Newborns Older Children medullary cavity, where a rich phagocytic mechanism often prevents Staphylococcus aureus Staphylococcus aureus most of the bacteria from establishing an infectious state. In some cases, Group B Streptococcus Pseudomonas however, the bacteria may lodge at the end of the venous loops beneath Gram-negative enteric rods Salmonella the epiphyseal plate, and infection then develops because there are no Neisseria gonorrhoeae phagocytic cells present to remove the bacteria20-22 (Fig. 46.13). Infants The microorganism responsible for osteomyelitis varies and is related S. aureus (MRSA 70, MRSA 30) Adolescents and Adults to the age of the child (Box 46.2). Osteomyelitis in the newborn is Haemophilus influenzae Pseudomonas caused primarily by Staphylococcus aureus. Group B streptococcus and Mycobacterium tuberculosis Escherichia coli infections are responsible for some cases, especially those of multiple bone involvement and in high-risk infants.22 S. aureus is the responsible microorganism in 80% to 90% of alarmingly in the past 5 years. Once an infrequent cause of childhood osteomyelitis cases in older children. Haemophilus influenzae, a previously osteomyelitis, MRSA now causes up to 30% of new cases.23 Gram-negative common cause of osteomyelitis in children less than 5 years of age, microorganisms account for an increasing number of infections of the has become rare with the improvements in immunization. However, vertebrae,24,25 whereas Salmonella infections are associated with sickle cases of methicillin-resistant Staphylococcus aureus (MRSA) have risen cell disease.  CHAPTER 46 Alterations of Musculoskeletal Function in Children 1483 Factors that predispose an individual to the development of osteo- myelitis include impetigo, furunculosis, infected lesions of varicella 1 2 (chickenpox), infected burns, cerebral abscesses, immunization with bacille Calmette-Guérin (BCG) vaccine, prolonged intravenous or central parenteral alimentation, drug addiction, and direct trauma to the area 3 adjacent to the site of osteomyelitis. PATHOPHYSIOLOGY. Osteomyelitis usually begins as a bloody abscess in the metaphysis of the bone. The abscess ruptures under the periosteum and spreads along the bone shaft or into the bone marrow 5 cavity if untreated. Infection rarely spreads down the medullary cavity of the bone but rather first gains entrance to the subperiosteal space in the metaphysis. The bone cortex in this area is porous, allowing easier entry for the bacteria than the shaft of the bone.26 Because of the accumulation of debris caused by the infection, the periosteum 4 may separate and form a shell of new bone around the infected portion of the shaft. Because the periosteum is separated from an adequate blood supply, sections of the bone die; these pieces of dead bone are FIGURE 46.14 Routes of Infection to the Joint. (1) The hematogenous route; called sequestra. The periosteum that maintains a blood supply generates (2) dissemination from osteomyelitis; (3) spread from an adjacent soft tissue infection; new bone and is responsible for the appearance of the periosteal new (4) diagnostic or therapeutic measures; (5) penetrating damage by puncture of bone, or involucrum. The presence of the sequestra and involucrum cutting. indicates that the disease is highly aggressive or established. In cases in which the infection in the metaphysis occurs near the joint, the accumulating pus (bacteria, white blood cells, fluid) creates increasing pressure that may cause a rupture into the joint cavity. If Osteomyelitis is much less common after the physeal plates are closed, rupture into the joint occurs, the pus causes inflammation and a condition except in the vertebral body. Infection may develop in any part of a called secondary septic arthritis.24 Studies show that up to 40% of bone, and abscesses spread slowly. Destruction of the cortex in a localized children will have adjacent joint involvement with osteomyelitis. The area may result in a pathologic fracture.24,25 most common joint to be affected is the knee. Osteomyelitis is most Spread of infection to contiguous joints is related to the child’s age. commonly caused by bacteria that reach the metaphysis through the Metaphyseal infection may spread to contiguous joints if the fibrous bloodstream but may occur through secondary inoculation of micro- joint capsule includes the metaphysis and epiphysis. This special situation organisms caused by trauma or contagious spread of infection from exists at the hip joint, distal femur, proximal humerus and radius, and cellulitis in adjacent soft tissue. lateral ankle. Careful clinical vigilance helps protect children with Osteomyelitis in infants is often associated with septic arthritis because osteomyelitis from suffering permanent joint injury. Unlike bone, the the infant’s bone has blood vessels that perforate the growth plate. articular cartilage of joints is unable to repair itself after injury from Because of the unique nature of the blood supply to an infant’s bones, infection.27 the occurrence of osteomyelitis and septic arthritis in combination is CLINICAL MANIFESTATIONS. The clinical manifestations of osteo- higher than 50%. Normal anatomic variations in infants allow infection myelitis are age dependent and are related to the differing vascular to spread directly to the epiphysis, which causes both joint disease and patterns found in the skeletal system at various ages. Three distinct permanent injury to the growth plate. Multiple sites of osteomyelitis groups may be identified: (1) infants younger than 1 year, (2) children are also common in children younger than 2 years of age. Other areas from 1 year of age to puberty, and (3) adolescents after cessation of of osteomyelitis and possibly septic arthritis must be evaluated through bone growth and adults. a bone scan of the entire skeleton.27 Children are susceptible to joint involvement for several reasons Infants (Fig. 46.14). In the immature infant, there is no epiphyseal plate or an Osteomyelitis may be an acute illness characterized by fever and failure ossific nucleus at the end of the bone and the cartilage precursor of to move the affected limb (pseudoparalysis). Infantile osteomyelitis is bone is penetrated by vascular channels. In these infants the infection characterized by involvement of multiple sites within the same bone begins in the vulnerable cartilage precursor of the end bone itself and or in multiple bones. If untreated, involvement of the adjacent growth results in rapid destruction of the joint and arrested growth of the plate can result in growth arrest. bone. For this reason early detection and treatment of osteomyelitis are crucial if the infant’s joint is to be saved from destruction. As the Children child matures and the epiphyseal, or growth, plate forms, a temporary Osteomyelitis in children between the ages of 1 year and puberty is barrier is established against infection because the arterioles end beneath characterized by fever and systemic signs of toxicity. The illness is the epiphyseal plate.26 sometimes subacute, with the child complaining of swelling, fever, In children older than 2 years, the epiphyseal plate prevents the tenderness, and decreasing ability to bear weight on or move the affected spread of a metaphyseal abscess into the epiphysis and the cortex of area. Onset can be abrupt. Osteomyelitis during childhood most often the metaphysis is thicker. These anatomic differences increase the affects the long bones but also may be found in the pelvis and spine. likelihood that the metaphyseal abscess will extend into the diaphysis, Clinical manifestations are usually accompanied by elevated white blood and the blood supply of the bone will be disrupted. The periosteum is cell counts and elevated erythrocyte sedimentation rates. When the also more difficult to perforate in older children; this may lead to a level of C-reactive protein (CRP) is elevated, it is a sensitive sign of larger subperiosteal abscess that could endanger the periosteal blood osteomyelitis and can rapidly decrease with appropriate treatment. supply as well. This process results in extensive sequestrum formation Evidence of infection using roentgenograms can be delayed but bone and chronic osteomyelitis.26 scan is positive within 48 hours. 1484 UNIT XIII The Musculoskeletal System fewer than five joints (pauciarticular arthritis), arthritis in more than Adolescents and Adults five joints (polyarticular arthritis), and systemic or Still disease. JIA In addition to the sites previously mentioned, osteomyelitis in adolescents differs from the adult form in the following respects28,29: and adults may involve the vertebrae. Back pain, with a duration of 1. Predominantly the large joints are affected. several weeks, may be the only clinical complaint. This age group is 2. Subluxation and ankylosis of the cervical spine are common if less often affected than younger populations. the disease progresses. EVALUATION AND TREATMENT. White blood cell counts and 3. Joint pain may not be severe, as in the adult type. erythrocyte sedimentation rates are sometimes elevated, but this is not 4. Serologic tests often detect antinuclear antibody (ANA). a consistent finding. Monitoring of erythrocyte sedimentation rates is 5. Chronic uveitis is common, especially if ANA positive. an indication of response to management but can be delayed. CRP is 6. Serologic tests seldom detect rheumatoid factor. more quickly responsive to appropriate treatment. Blood cultures (positive 7. Rheumatoid nodules are not limited to subcutaneous tissue but in 30% to 40%) and aspiration of the soft tissue or bone, or both, are found in the heart, lungs, eyes, and other organs. should be done to identify the causative microorganism. Appropriate 8. Cyclic citrullinated peptide antibody is often positive. antibiotics should be prescribed after culture and sensitivity studies Many children with pauciarticular arthritis who are seronegative for have been completed. A tuberculin test also is administered because ANA will resolve their symptoms over time. However, with systemic Mycobacterium tuberculosis is sometimes responsible and has had a onset (Still disease) or seropositivity, JIA may progress to true adult RA. slight resurgence in incidence. Bone scans can be quite helpful with Treatment is supportive and aims to control inflammation and minimize diagnosis and in children younger than 1 year are absolutely required deformity. The emergence of new treatments, including use of biologics to define whether multiple sites are involved. and targeting of key cytokines and other inflammatory mediators, has Treatment includes intravenous (IV) antibiotics or, in highly reliable dramatically improved the prognosis for children with JIA.30 children and families, a combination of IV and oral antibiotics for 6 weeks. Drainage and margination of bone are required if changes are Avascular Diseases of the Bone: Osteochondrosis present on radiographs signifying abscess. Immobilization may help The avascular diseases of the bone, collectively termed osteochondroses, with pain control. If a joint is also infected (termed septic arthritis), the are caused by insufficient blood supply to growing bones. Disturbances situation becomes a surgical emergency; surgery on the affected joint of blood supply to primary and secondary centers of ossification during can help prevent damage to the articular cartilage by lysozymes released periods of rapid bone growth result in a variety of skeletal abnormalities. from the involved neutrophils. The cause of the osteochondroses remains obscure. In the past, Death is rare, but serious sequelae may occur. The course of the infection, nutritional deficiencies, and hormonal imbalances were disease and prognosis depend on the age of the child, the rapidity with blamed, but these causes have been largely disproved. Currently, vascular which the diagnosis is established, the initiation of early treatment, impairment and trauma, coupled with an underlying developmental or and maintenance of treatment for an adequate time. The most serious genetic predisposition, have been identified as probable causes of osteo- complications are growth arrest, osseous necrosis, and recurrence. chondroses. The most common osteochondroses are Osgood-Schlatter Recurrence with presently available antibiotic regimens is less than 10%. disease (tibial tubercle), Sinding-Larsen-Johansson syndrome (distal patellar pole), Panner disease (radial head), Kohler disease (the navicular Rheumatologic Disorders bone of the foot), and Sever disease (calcaneus). All are associated with The rheumatic diseases are a group of diverse conditions having in activity-related pain of the affected region that improves with rest. All are common the inflammation of connective tissues. They include juvenile more common in boys than girls and in athletes more than nonathletes. idiopathic arthritis (JIA, formerly known as juvenile rheumatoid arthritis), The osteochondroses involve areas of significant tensile or compressing systemic lupus erythematosus, dermatomyositis, and progressive systemic stress that undergo partial osseous necrosis, progressive bony weakness, sclerosis (formerly called scleroderma). The incidence of these disorders and then microfracture. Most of these are associated with trauma and in children is estimated in Table 46.4. overuse and improve with rest. Use of antiinlammatories, modiication Juvenile idiopathic arthritis (JIA) is the most common rheumatologic of activities, and even immobilization of the affected area are used disorder in childhood. Like adult-onset rheumatoid arthritis (RA), JIA during active stages of the disease. Reparative correction by revasculariza- is a syndrome that is often accompanied by systemic manifestations tion is the rule, although this may be a lengthy process. (see Chapter 45). Approximately 5% of all cases of RA begin in childhood. An estimated 250,000 children in the United States have JIA. Legg-Calvé-Perthes Disease The basic pathophysiology of JIA is the same as that of adult RA; Legg-Calvé-Perthes (LCP) disease, commonly called Perthes disease, however, the clinical manifestations of JIA may differ. Unlike adult RA, is classically thought to be an osteochondrosis like those previously which begins insidiously with systemic signs of inflammation and described. This self-limited disease of the hip is presumably produced generalized aches, JIA has three distinct modes of onset: arthritis in by recurrent interruption of the blood supply to the femoral head. The TABLE 46.4 INCIDENCE OF CONNECTIVE TISSUE DISEASES IN CHILDREN ANNUAL GENDER RATIO RACE RATIO PEAK AGE GROUP CHILDHOOD DISEASE RATE/105 (FEMALE/MALE) (WHITE/BLACK) AT RISK (yr) ONSET (%) Rheumatoid arthritis 40 3:1 Equal Increases with age (20–50) 5 Systemic lupus erythematosus 6 8:1 1:4 15–45 18 Dermatomyositis 0.8 2:1 1:3 45–65 20 Progressive systemic sclerosis 0.4 3:1 Equal Increases with age (30–50) 3 Polyarteritis 0.2 1:3 Equal Middle adulthood Rare Data from Hollingworth P. In Klippel JH, Dieppe PA, editors: Rheumatology, St Louis, 1994, Mosby.  CHAPTER 46 Alterations of Musculoskeletal Function in Children 1485 ossification center first becomes necrotic and collapses and then is LCP disease. Onset of symptoms is insidious unless trauma aggravates gradually remodeled by live bone. the disease process. The pain often is referred to the knee and can lead LCP disease is relatively common (1 in 5000 children), usually to misdiagnosis as a knee injury. The inner thigh and groin also can occurring in children between 3 and 10 years of age, with a peak incidence be painful. In some children, pain may be absent or minimal. If pain at 6 years. It is more common in boys than in girls by a ratio of about is present, it is usually aggravated by activity and relieved by rest. 5:1. The condition is bilateral in approximately 10% of affected children; The typical physical findings include spasm on inward rotation of however, bilateral cases are temporally separated. If LCP disease appears the hip and a limitation of internal rotation flexion and abduction. at identical stages and the femoral heads show matched radiographic If the child is walking, an abnormal gait, termed a Trendelenburg gait involvement, then another diagnosis, such as an epiphyseal dysplasia, or abductor lurch, is apparent. The child dips the trunk toward the should be considered. affected side with stance to compensate for weak abductor musculature. The cause of decreased blood supply to the head of the femur is If the hip pain or limp has been present for a prolonged period, muscles unknown. Several theories have been proposed, including trauma, of the hip and thigh atrophy. A limb length inequity may be present if infection, and protein C and S deficiencies, which cause a hypercoagulable the proximal femoral physis is involved. state or vascular anomalies.31 A plausible theory is that acute synovitis EVALUATION AND TREATMENT. Diagnosis is confirmed by radio- (infection of the synovial membrane) and increased hydrostatic pressure graphic examination. Principles of treatment are containment (keeping in the hip joint compress blood vessels that supply the femoral head. the ball completely in the socket) and motion to maintain the articular Constitutional factors definitely play a role. Skeletal maturation is cartilage. In the past, children were treated with bed rest and a variety delayed an average of 2 years in children with LCP disease, and affected of braces. Most children can be managed with antiinflammatory medica- children are between 2.5 and 7 cm shorter than unaffected children of tions and crutches for episodes of synovitis and with activity modification the same age. Familial occurrence is 30% to 40%. The disease is rare (avoidance of jumping activities that place increased stress on the hip) in blacks, and it is frequent in children of Japanese and central European during the active phase of the disease. Serial roentgenograms monitor ancestry. the progress of the disease and ensure that the hip remains congruent. PATHOPHYSIOLOGY. LCP disease runs its natural course in 2 to Surgery may be necessary if the femoral head becomes subluxated or 5 years. In the initial stage the soft tissues of the hip (synovial membrane incongruent with the acetabulum before the reparative process. The and joint capsule) are swollen, edematous, and hyperemic, often with ball must be congruent to take on the shape of the socket as remodeling fluid present in the joint (Fig. 46.15). The joint space widens, and the occurs. Newer treatments, such as intraarticular injection of bisphos- joint capsule bulges. The first stage lasts only a few weeks. In the second phonates (that reduce the function of osteoclasts), are being studied.34 stage, called fragmentation, the entire epiphysis or the anterior half of Factors affecting the outcome of LCP disease are the age of the child the epiphysis of the femoral head loses blood supply and the metaphyseal at onset, the extent of necrosis, and the congruence of the joint at bone at the junction of the femoral neck and capital epiphyseal plate skeletal maturity. Recent studies have shown that girls, despite earlier is softened because of decalcification. Soon granulation tissue (procallus) skeletal maturity, do as well as boys. Outcome is 70% satisfactory with and blood vessels invade the dead bone. This stage lasts several months Herring stage A; for Herring stages B and C or age greater than 8 years, to 1 year. outcome is guarded. Present prospective studies are evaluating more The third (or regenerative healing) stage ordinarily lasts 2 to 3 years. aggressive early treatment (i.e., osteotomy of the femur or pelvis) on The dead femoral head is replaced by procallus, and new bone is laid the more involved hips to change long-term outcome. down. Collapse and flattening of the femoral head occur, and the femoral neck becomes short and wide (see Fig. 46.15). Osgood-Schlatter Disease In the fourth (or healed) stage, remodeling takes place and the newly Osgood-Schlatter disease consists of tendinitis of the anterior patellar formed bone is organized into a live spongy bone. Children less than tendon, within which the patella (kneecap) is embedded, and associated 6 years of age at onset have more time to remodel the damage LCP has osteochondrosis of the tubercle of the tibia. Osgood-Schlatter disease caused and have the best outcome. Recent multicenter studies, using occurs most often in preadolescents and adolescents who participate the Herring “lateral pillar” classification,32 have shown that hips younger in sports. The incidence is higher in boys than in girls, many of whom than 6 years with no involvement of the lateral femoral head (type A) have increased outward tibial torsion compared to controls.35 do better than those with involvement of the lateral femoral head. Those PATHOPHYSIOLOGY. The severity of the lesion varies from mild children with complete collapse of the lateral femoral head (type C) tendinitis to a complete separation of the anterior extension of the have the worst prognosis. Long-term studies of type C hips show that tibial epiphysis, which is the part of the epiphysis that contributes to 70% to 90% progress to osteoarthritis by 40 years of age.33 growth of the tibial tubercle. The underlying pathologic alterations also CLINICAL MANIFESTATIONS. Injury or trauma precedes the onset vary. The mildest form of Osgood-Schlatter disease causes ischemic of clinical manifestations in approximately one-third of children with (avascular) necrosis in the region of the bony tibial tubercle, with Joint space Femoral head Epiphyseal Necrotic Remodeled (black Procallus area) plate bone bone Metaphysis Cyst Femoral neck Normal hip joint Incipient stage Necrotic stage Regenerative stage Residual stage FIGURE 46.15 Stages of Legg-Calvé-Perthes Disease, a Form of Osteochondrosis. 1486 UNIT XIII The Musculoskeletal System hypertrophic cartilage formation during the stages of repair. In more EVALUATION AND TREATMENT. The diagnosis of CP is often made severe cases the abnormality involves a true epiphyseal separation of after failure to meet gross motor milestones at predicted ages. In some the tibial tubercle. infants, diagnosis is made at birth or in the first months of life because CLINICAL MANIFESTATIONS. The child experiences pain and swelling the child has an underlying diagnosis, such as a major brain malforma- in the region of the patellar tendon and tibial tubercle, which becomes tion, that is known to be associated with CP.38 Classic patterns of motor prominent and is tender to direct pressure. The pain is most severe after involvement include hemiplegia, involving only one side of the body; physical activity that involves vigorous quadriceps contraction or direct diplegia, involving only the lower extremities; and quadriplegia, involving local trauma to the tibial tubercle area. Often the child experiences sudden all four extremities. In addition to physical therapy, children with CP acute discomfort referable to the affected region. Sudden onset of pain should receive speech/language therapy with trials of augmentative can represent a pathologic fracture through an area of ischemic necrosis. communication devices so that underlying cognitive abilities, which EVALUATION AND TREATMENT. Diagnosis is confirmed by roent- may not be apparent because of motor problems, are given a chance genographic examination. The goal of treatment for Osgood-Schlatter to manifest. disease is to decrease the stress at the tubercle. Often a period of 4 to Treatment of CP is multifaceted and focused on maximizing 8 weeks of restriction from strenuous physical activity is sufficient. If functional abilities. Physical and occupational treatments, use of orthotics, pain relief is not achieved, a cast or brace is required to immobilize the spasticity reduction (by selected dorsal rhizotomy, oral, or intrathecal knee, a situation that is particularly difficult if the condition is bilateral. baclofen injections), botulinum-A (Botox) toxin injections, and surgery Gradual resumption of activity is permitted after 8 weeks, but return are commonly used approaches. In many centers, a multispecialty to unrestricted athletic participation requires an additional 8 weeks to approach at “CP clinics” occurs so that a family may, within one allow for revascularization, healing, and ossification of the tibial tubercle. clinic visit, see neurology, pediatrics, orthotics, orthopedic surgery, and All types of osteochondroses resolve once skeletal maturity is reached. rehabilitation clinicians. Children with CP should be carefully followed and given all possible Cerebral Palsy opportunities to flourish. Although CP is a static disorder, progressive Cerebral palsy (CP) is a general term that refers to nonprogressive deformity because of increased muscle tone can occur. Monitoring disorders of movement and posture resulting from injury or malforma- these children as they grow with a multispecialty approach is essential tion of the developing central nervous system. The resulting disability to their optimal outcome. may be mild, manifesting as a stiff (spastic) gait, or severe, in which the child is in a wheelchair and needs lifelong help eating, ambulating, Neuromuscular Disorders and communicating. Comorbid conditions, such as intellectual disability, The neuromuscular disorders are a group of inherited disorders seizures, scoliosis, and hearing or vision loss, are common, especially that cause progressive muscle fiber loss leading to weakness, mostly in children with more severe forms. The overall incidence is 3% to 5%; of the voluntary muscles. Duchenne muscular dystrophy (DMD) and this number has stayed approximately the same although changes in spinal muscular atrophy (SMA) are the most prevalent of the muscle prenatal and newborn care have been associated with shifts in the etiolo- diseases in childhood (Table 46.5). Neuromuscular disorders cause gies of CP.36,37 significant disability in affected children resulting in lifelong neurologic, TABLE 46.5 MAJOR NEUROMUSCULAR DISORDERS IN CHILDREN MODE OF AGE AT CLINICAL USUAL RATE OF INTELLECTUAL DISTINGUISHING DISEASE INHERITANCE ONSET DISTRIBUTION PROGRESSION DISABILITY FINDINGS Duchenne muscular X-linked recessive About 3 years Hips and shoulders, Rapid Frequent Elevated serum dystrophy (DMD) quadriceps femoris, enzymes (CPK, LDH, gastrocnemius SGOT, aldolase) (pseudohypertrophy) Spinal muscular Autosomal Variable depending on Proximal greater than Rapid Absent Tongue fasciculation, atrophy (SMA) recessive subtype (infant to distal, especially tremor childhood) involving hip and shoulder girdles Facioscapulohumeral Autosomal In first or second Shoulder girdle, Moderate Occasional Several distinct dystrophy dominant decade neck, face, pelvic muscle pathologic girdle (late) findings Limb girdle (LG) Poorly defined or Variable Pelvic and shoulder Variable Variable Collection of several dystrophy recessive girdles diseases Myotonic dystrophy Autosomal Variable—birth to fifth Distal extensor Slow, related to Frequent Percussion myotonia, (MyD) dominant decade muscle, eyelids, age at clinical cataracts, diabetic face, neck, hands, onset, faster with glucose tolerance pharynx younger patients test despite increased insulin, tes