CONGENITAL AMPUTATIONS & LIMB DEFICIENCIES

Congenital amputations may be due to teratogens (eg, drugs or viruses), amniotic bands, or metabolic diseases (eg, maternal diabetes). Limb deficiencies are rare with an overall prevalence for all types of limb deficiencies of 0.79 per 1000. The most common cause of limb deficiencies is vascular disruption defects (prevalence of 0.22 per 1000). As a group, upper limb deficiencies occur more frequently than lower limb deficiencies, but the single most frequent form of limb deficiency is congenital longitudinal deficiency of the fibula. Children with congenital limb deficiencies, such as absence of the femur, tibia, or fibula, have a high incidence of other congenital anomalies, including genitourinary, cardiac, and palatal defects. Deficiencies usually consist of a partial absence of structures in the extremity along one side. For example, in radial club hand, the entire radius is absent, but the thumb may be either hypoplastic or completely absent. The effect on structures distal to the deficiency varies. Complex tissue defects are virtually always associated with longitudinal bone deficiency since associated nerves and muscles are not completely represented when a bone is absent.

Treatment

Limb lengthening and/or contralateral limb shortening can be used to treat less severe deficiencies. More severe deficiencies are treated with a prosthesis to compensate for the length discrepancy. For certain severe anomalies, operative treatment to remove a portion of the malformed extremity (eg, foot) is indicated to allow for early prosthetic fitting. In these instances, early prosthetic fitting allows for maximization of function.

Typically, a lower extremity prosthesis would be fit at about 1 year of age allowing the child to begin ambulation at an appropriate developmental age. The prosthesis is well accepted since it becomes necessary for balancing and walking. In unilateral upper extremity amputation, the child benefits from the use of a passive mitten type prosthesis starting as early as 6 months of age. Early fitting has the advantage of instilling an accustomed pattern of proper length and bimanual manipulation. Although myoelectric prostheses have a technologic appeal, the majority of patients find the simplest construct to be the most functional. Children quickly learn how to function with their prostheses and can lead active lives.

DEFORMITIES OF THE EXTREMITIES

Metatarsus Adductus

Metatarsus adductus, a common congenital foot deformity, is characterized by inward deviation of the forefoot. When the deformity is more rigid, it is characterized by a vertical crease in the medial aspect of the arch. Angulation occurs at the base of the fifth metatarsal causing prominence of this bone. Most flexible deformities are secondary to intrauterine positioning and usually resolve spontaneously. Several investigators have noticed that 10%–15% of children with metatarsus adductus have hip dysplasia; therefore, a careful hip examination is necessary. The etiology of rigid deformities is unknown. If the deformity is rigid and cannot be manipulated past the midline, it is worthwhile to perform serial casting, with cast changes in 1–2-week intervals, to correct the deformity. Corrective shoes do not live up to their name; however, they can be used to maintain the correction obtained by casting.

Clubfoot (Talipes Equinovarus)

Classic talipes equinovarus, or clubfoot, requires three features for diagnosis: (1) plantar flexion of the foot at the ankle joint (equinus), (2) inversion deformity of the heel (varus), and (3) medial deviation of the forefoot (adductus). Clubfoot occurs in approximately 1 per 1000 live births. The three major categories of clubfoot are idiopathic, neurogenic, and those associated with syndromes such as arthrogryposis and Larsen syndrome. Infants with a clubfoot should be examined carefully for associated anomalies, especially of the spine. Idiopathic club feet may be hereditary.

Treatment

Manipulation of the foot to stretch the contracted tissues on the medial and posterior aspects, followed by casting to hold the correction is the preferred treatment. Serial castings are typically performed on a weekly basis for 6–8 weeks. When instituted shortly after birth, correction is rapid. If treatment is delayed, the foot tends to become more rigid within a matter of days. Casting treatment requires patience and experience, but fewer patients require surgery when attention is paid to details of the Ponseti technique. After full correction is obtained, a night brace is necessary for long-term maintenance of correction. Recent studies indicate that there is poor compliance with brace use following intervention with the Ponseti technique. If the foot is rigid and resistant to cast treatment, surgical release and correction are appropriate. Approximately 15%–50% of patients require a surgical release.

Developmental Dysplasia of the Hip Joint

Dysplasia is the term used to describe abnormal growth or development. Dysplasia of the hip encompasses a spectrum of conditions where an abnormal relationship exists between the proximal femur and the acetabulum. In the most severe condition, the femoral head is not in contact with the acetabulum and is classified as a dislocated hip. In a dislocatable hip, the femoral head is within the acetabulum but can be dislocated with a provocative maneuver. A subluxatable hip is one in which the femoral head comes partially out of the joint with a provocative maneuver. Acetabular dysplasia is used to denote insufficient acetabular development and is a radiographic diagnosis.

Congenital dislocation of the hip more commonly affects the left hip, occurring in approximately 1%–3% of newborns. At birth, both the acetabulum and femur are underdeveloped. Dysplasia is progressive with growth unless the instability is corrected. If the dislocation is corrected in the first few weeks of life, the dysplasia can be completely reversible and a normal hip will more likely develop. If the dislocation or subluxation persists with age, the deformity will worsen until it is not completely reversible, especially after the walking age. For this reason, it is important to diagnose the deformity and institute treatment early.

Clinical Findings

Clinical diagnosis of dislocations in newborns is dependent on demonstrating the instability of the joint by placing the infant on his or her back and obtaining complete relaxation. As these clinical signs can be subtle, with a crying or upset infant they can be easily missed. The examiner’s long finger is then placed over the greater trochanter and the thumb over the inner side of the thigh. Both hips are flexed 90 degrees and then slowly abducted from the midline, one hip at a time. With gentle pressure, an attempt is made to lift the greater trochanter forward. A feeling of slipping as the head relocates is a sign of instability (Ortolani sign). When the joint is more stable, the deformity must be provoked by applying slight pressure with the thumb on the medial side of the thigh as the thigh is adducted, thus slipping the hip posteriorly and eliciting a palpable clunk as the hip dislocates (Barlow sign). Limited hip abduction of less than 60 degrees while the knee is in 90 degrees of flexion is believed to be the most sensitive sign for detecting a dysplastic hip. Clinical signs of instability are more reliable than radiographs for diagnosing developmental dislocation of the hip in the newborn. Ultrasonography is most useful in newborns, and can be helpful for screening high-risk infants, such as those with breech presentation or positive family history. Asymmetrical skin folds are present in about 25% of normal newborns and therefore are not particularly helpful to diagnosing hip dislocation.

The signs of instability become less evident after the first month of life. Contractures begin to develop about the hip joint, limiting abduction to less than 90 degrees. It is important to hold the pelvis level to detect asymmetry of abduction. If the knees are at unequal heights when the hips and knees are flexed, the dislocated hip will be on the side with the lower knee. Radiological examination becomes more valuable after the first 6 weeks of life, with lateral displacement of the femoral head being the most reliable sign. An acetabular index or angle can be measured on pelvis radiographs by drawing one line horizontally through the triradiate cartilage and another line starting at the triradiate cartilage and extending to the outer edge of the acetabulum. A normal angle would be less than 30 degrees. In mild cases, increased steepness of acetabular alignment (acetabular angle > 35 degrees) may be the only abnormality.

If dysplasia of the hip has not been diagnosed before the child begins to walk, there will be a painless limp and/or a lurch to the affected side. When the child stands on the affected leg, a dip of the pelvis will be evident on the opposite side, due to weakness of the gluteus medius muscle. This is called the Trendelenburg sign and accounts for the unusual swaying gait. In children with bilateral dislocations, the loss of abduction is almost symmetrical and may be deceiving. In children with incomplete abduction during the first few months of life, a radiograph of the pelvis is indicated. As a child with bilateral dislocation of the hips begins to walk, the gait is waddling. The perineum is widened as a result of lateral displacement of the hips, and there is flexion contracture as a result of posterior displacement of the hips. This flexion contracture contributes to marked lumbar lordosis, causing the greater trochanters to be easily palpable in their elevated position. Treatment is still possible in the first 2 years of life, but the results are not as good as with early treatment. In patients older than 2 years, more aggressive procedures like osteotomies are often necessary to create a more normal orientation and shape of the hip joint.

Treatment

Most unstable hips undergo spontaneous correction by 2–6 weeks of age. A Pavlik harness, which maintains reduction by placing the hip in a flexed and abducted position, can be easily used to treat dislocation or dysplasia diagnosed in the first few weeks or months of life. In order to be safely treated in a Pavlik harness, hips must be manually reducible with only gentle manipulation. Forced abduction, or reduction requiring extremes of motion for stability, can lead to avascular necrosis of the femoral head and is contraindicated. The use of double or triple diapers is ineffective. An orthopedic surgeon with experience managing the problem is best to supervise treatment.

In the first 4 months of life, reduction can be obtained by simply flexing and abducting the hip with a Pavlik harness; no other manipulation is usually necessary. In late cases, preoperative traction for 2–3 weeks may assist by relaxing soft tissues about the hip. Following traction, in which the femur is brought down opposite the acetabulum, reduction can typically be achieved, without force, under general anesthesia. A hip spica cast is used for 3 months after reduction. If the hip is not stable within a reasonable range of motion after closed reduction, open reduction is indicated. If reduction is done at an older age, operations to correct the deformities of the acetabulum and femur, as well as open reduction, may be necessary. Older children are more likely to experience complications from more extensive procedures.

Torticollis

Injury to the sternocleidomastoid muscle during delivery or disease affecting the cervical spine in infancy, such as congenital vertebral anomalies, may cause torticollis. When contracture of the sternocleidomastoid muscle causes torticollis, the chin is rotated to the side opposite of the affected muscle, causing the head to tilt toward the side of the contracture. A mass felt in the midportion of the sternocleidomastoid muscle in a newborn is likely a hematoma or developmental fibroma, rather than a true tumor.

If the deformity is left untreated, a striking facial asymmetry can persist. Passive stretching is an effective treatment in up to 97% of all cases. If the deformity does not correct with passive stretching during the first year of life, surgical release of the muscle origin and insertion can be an effective treatment option. Excising the “tumor” of the sternocleidomastoid muscle is unnecessary and creates an unsightly scar.

Torticollis is occasionally associated with congenital deformities of the cervical spine. Radiographs of the spine are indicated in most cases where such anomalies are suspected. In addition, there is a 15%–20% incidence of associated hip dysplasia.

Acute torticollis may follow upper respiratory infection or mild trauma in children. Upper respiratory infections may lead to swelling in the upper cervical spine, particularly at the C1-C2 region. This swelling renders the C1-C2 articulation susceptible to rotatory subluxation, which commonly presents as a clinical picture of torticollis. Rotatory subluxation of the upper cervical spine requires computed tomography for accurate assessment. Traction or a cervical collar usually results in resolution of the symptoms within 1 or 2 days. Other causes of torticollis include spinal cord and cerebellar tumors, syringomyelia, and rheumatoid arthritis.

GENERALIZED DISORDERS OF SKELETAL OR MESODERMAL TISSUES

Arthrogryposis Multiplex Congenita (Amyoplasia Congenita)

Clinical Findings & Diagnosis

Arthrogryposis multiplex congenita (AMC) consists of incomplete fibrous ankylosis (usually bilateral) of many or all joints of the body. AMC affects both genders equally and occurs in approximately 1 in 2–3000 live births. Upper extremity contractures usually consist of adduction of the shoulders; extension of the elbows; flexion of the wrists; and stiff, straight fingers with poor muscle control of the thumbs. Common deformities of the lower extremities include dislocation of the hips, extension contractures of the knees, and severe club feet. The joints are fusiform and the joint capsules decreased in volume due to lack of movement during fetal development. Muscle development is poor, and may be represented only by fibrous bands. Various investigations have attributed the basic defect to an abnormality of muscle or lower motor neurons.

It is possible to diagnose AMC during routine fetal ultrasound scanning. The fetus will be in an abnormal position or lack mobility. Early diagnosis helps the family and provider with delivery planning and counseling.

Treatment

Passive mobilization of joints is the early treatment. Prolonged casting results in further stiffness and is not indicated. Removable splints combined with vigorous therapy are the most effective conservative treatment; however, surgical release of the affected joints is often necessary. Clubfoot associated with arthrogryposis is very stiff and nearly always requires surgical correction. Knee surgery, including capsulotomy, osteotomy, and tendon lengthening, is used to correct deformities. In young children, a dislocated hip may be reduced operatively by a medial approach. Multiple operative hip procedures are contraindicated, as they may further stiffen the hip dislocation with consequent impairment of motion. Affected children are often able to walk if the dislocations and contractures are reduced surgically. The long-term prognosis for physical and vocational independence is guarded. These patients have normal intelligence, but they have such severe physical restrictions that gainful employment is hard to find.

Marfan Syndrome

Marfan syndrome is a connective tissue disorder characterized by unusually long fingers and toes (arachnodactyly); hypermobility of the joints; subluxation of the ocular lenses; other eye abnormalities, including cataract, coloboma, megalocornea, strabismus, and nystagmus; a high-arched palate; a strong tendency to scoliosis (60% of all those diagnosed); pectus carinatum (an outward protrusion of the sternum); and thoracic aortic aneurysms due to weakness of the media of the vessels (see Chapter 37). Fibrillin-1 gene mutations are commonly associated with Marfan syndrome. Serum mucoproteins may be decreased, and urinary excretion of hydroxyproline increased. The condition is easily confused with homocystinuria, because the phenotypic presentation is nearly identical. The two diseases are differentiated by detecting homocystine in the urine of patients with homocystinuria.

Treatment is usually supportive and includes management of blood pressure and restriction of physical activity. Scoliosis may involve more vigorous treatment by bracing or spine fusion. The long-term prognosis has improved for patients since the development of better treatment of their aortic aneurysms.

Klippel-Feil Syndrome

Klippel-Feil syndrome is characterized by failure of segmentation of some or all of the cervical vertebrae. Multiple congenital spinal anomalies may be present, with hemivertebrae and scoliosis. The neck is short and stiff, the hairline is low, and the ears are low-set. Congenital scoliosis, cervical rib, spina bifida, torticollis, web neck, high scapula, renal anomalies, and deafness are commonly associated defects. Renal ultrasound as well as a hearing test are indicated if there is evidence of abnormal renal function. Surgical intervention is necessary to prevent neurologic injury in symptomatic patients who present with unstable spinal anomalies. If asymptomatic, a spine surgeon will determine if surgical intervention is warranted after review of patient’s age, history, and activity level. Spinal arthrodesis is indicated if progressive scoliotic deformities develop.

Sprengel Deformity

Sprengel deformity is a congenital condition where one or both scapulas are elevated and hypoplastic. The deformity prevents the arm from raising completely on the affected side, and torticollis may be an associated finding. The deformity occurs alone or in association with Klippel-Feil syndrome or scoliosis and rib abnormalities. If the deformity is functionally limiting, the scapula may be surgically relocated closer to the normal anatomic position. Surgical intervention improves cosmetic appearance and function.

Osteogenesis Imperfecta

Osteogenesis imperfecta is a rare genetic connective tissue disease characterized by multiple and recurrent fractures. The incidence is 1 in 15,000–20,000. Clinical features of the disease lead to diagnosis in the majority of cases. The severe fetal type (osteogenesis imperfecta congenita) is distinguished by multiple intrauterine or perinatal fractures. Moderately affected children have numerous fractures and exhibit dwarfism as a result of their acquired bone deformities and growth retardation. Fractures begin to occur at different times and in variable patterns after the perinatal period, resulting in fewer fractures and deformities relative to severe cases. Cortical thickness is reduced in the shafts of the long bones, and accessory skull bones that are completely surrounded by cranial sutures (wormian bones) are present in the skull. Blue sclerae, thin skin, hyperextensibility of ligaments, otosclerosis with significant hearing loss, and hypoplastic and deformed teeth are characteristic of osteogenesis imperfecta. Cardiovascular and respiratory problems are the most common causes of morbidity and mortality in adulthood. Intelligence is not affected. Affected patients are sometimes suspected of having suffered abuse. Osteogenesis imperfecta should be ruled out in any case of potential nonaccidental trauma.

Molecular genetic studies have identified more than 150 mutations of the COL1A1 and COL1A2 genes, which encode for type I procollagen. Ninety percent of cases occur as the result of a spontaneous mutation; in these families the likelihood of a second affected child is negligible. Among the other 10%, a recessive mode of inheritance has been identified in 2%–5%.

Bisphosphonates have been shown to decrease the incidence of fractures. Surgical treatment involves deformity correction of the long bones. Multiple intramedullary rods have been used to prevent deformity from fracture malunion. Patients are often confined to wheelchairs during adulthood.

Osteopetrosis (Osteitis Condensans Generalisata, Marble Bone Disease, Albers-Schönberg Disease)

Osteopetrosis is a rare disorder of osteoclastic resorption of bone, resulting in abnormally dense bones. The reduced marrow spaces result in anemia. There are two types: a milder autosomal dominant type and a more malignant autosomal recessive type. The findings may appear at any age. Radiologic examination shows increased bone density and transverse bands in the shafts, clubbing of ends, and vertical striations of long bones. Thickening about the cranial foramina is present, and heterotopic calcification of soft tissues is possible. Diminished life expectancy is seen in severe infantile forms.

Treatment is largely symptomatic. The most severe autosomal recessive forms of osteopetrosis can be treated successfully by hematopoietic stem cell transplantation.

Achondroplasia (Classic Chondrodystrophy)

Achondroplasia is the most common form of short-limbed dwarfism. The upper arms and thighs are proportionately shorter than the forearms and legs. Skeletal dysplasia is suspected based on abnormal stature, disproportion, dysmorphism, or deformity. Measurement of height is an excellent clinical screening tool. Findings frequently include bowing of the extremities, a waddling gait, limitation of motion of major joints, relaxation of the ligaments, short stubby fingers of almost equal length, frontal bossing, midface hypoplasia, otolaryngeal system dysfunction, moderate hydrocephalus, depressed nasal bridge, and lumbar lordosis. Intelligence and sexual function are normal. While this disorder has an autosomal dominant transmission pattern, 80% of cases result from a random mutation in the fibroblast growth factor receptor-3 (FGFR3) gene. Radiographs demonstrate short, thick tubular bones and irregular epiphysial plates. The ends of the bones are thick, with broadening and cupping. Epiphysial ossification may be delayed. Due to diminished growth in the spinal pedicles, the spinal canal is narrowed (congenital stenosis), and a herniated disk in adulthood may lead to acute paraplegia. Growth hormone is given to some children with bone dysplasia. Limb lengthening is possible, but controversial.

Osteochondrodystrophy (Morquio Disease)

Morquio disease is an autosomal recessive disorder affecting mucopolysaccharide storage. Skeletal abnormalities include shortening of the spine, kyphosis, scoliosis, shortened extremities, pectus carinatum, genu valgum or “knock knees,” and a hypoplastic odontoid with atlantoaxial instability. Appearance is generally normal at birth, with deformities developing between ages 1 and 4 years as a result of abnormal deposition of mucopolysaccharides. Increased urinary glycosaminoglycan levels are associated with increased severity.

Radiographs demonstrate wedge-shaped flattened vertebrae and irregular, malformed epiphyses. The ribs are broad and have been likened to canoe paddles. The lower extremities are more severely involved than the upper extremities. Progressive hip subluxation, genu valgum, and ankle valgus often require surgical intervention.

The major treatment issue revolves around prevention of cervical myelopathy. Bone marrow transplantation has been successful in alleviating some symptoms. Enzyme replacement therapy has emerged as another possible treatment option for afflicted patients. Prognosis depends on age of onset.

GROWTH DISTURBANCES OF THE MUSCULOSKELETAL SYSTEM

SCOLIOSIS

Scoliosis is characterized by lateral curvature of the spine associated with rotation of the involved vertebrae and classified by its anatomic location, in either the thoracic or lumbar spine, with rare involvement of the cervical spine. The convexity of the curve is designated right or left. A right thoracic scoliosis would denote a thoracic curve with convexity to the right. This is the most common type of idiopathic curve. Kyphosis or posterior curvature of the spine is normal in the thoracic area, although excessive curvature is pathologic. Anterior curvature of the spine, or lordosis, is normal in the lumbar and cervical spine regions.

Eighty percent of cases of scoliosis are idiopathic. Idiopathic scoliosis typically develops around age 8–10 years, with progression occurring during periods of rapid skeletal growth. In rare instances, infantile scoliosis may be seen in children age 3 years or younger; idiopathic infantile scoliosis is much more common in Great Britain than in the United States. In infantile scoliosis, if the rib-vertebral angle of Mehta is less than 20 degrees, the curve will likely resolve spontaneously. If the angle is greater, the curve will likely progress.

Idiopathic scoliosis is about four or five times more common in girls. The disorder is usually asymptomatic in the adolescent years, but severe curvature can progress during adulthood causing pain or, in extreme cases, diminished pulmonary function as a result of reduced lung volumes due to deformity of the rib cage. The screening examination for scoliosis is performed by having the patient bend forward 90 degrees with the hands joined in the midline. Asymmetry of the height of the ribs or paravertebral muscles on one side indicates rotation of the trunk associated with lateral curvature. Because 30% of family members are also affected, siblings of an affected child should be examined.

Neurofibromatosis, Marfan syndrome, cerebral palsy, muscular dystrophy, poliomyelitis, and myelodysplasia are among several diseases that may be present with an associated scoliosis.

Congenital vertebral anomalies such as hemivertebra or unilateral vertebral bar account for 5%–7% of all scoliosis. These curves are more rigid than the more common idiopathic curve and will often increase with skeletal growth, especially during adolescence.

Olisthetic scoliosis may result from pressure on the spinal cord or roots by infectious processes or herniation of the nucleus pulposus; the underlying cause must be sought. Secondary curvature will resolve as the primary problem is treated.

Clinical Findings

A. Symptoms and Signs

Scoliosis in adolescents does not typically cause significant pain. If a patient has significant pain, then the source of the pain should be sought in order to rule out the possibility of some other disorder such as infection or tumor. Deformity of the rib cage and asymmetry of the waistline are clinically evident for curvatures of 30 degrees or more. Lesser curves may be detected through the forward bending test, which is designed to detect early abnormalities of rotation that may not be apparent when the patient is standing erect.

B. Imaging

Radiographs taken of the entire spine in the standing position in both the anteroposterior and lateral planes are the most valuable for diagnosis. Usually a primary curve is evident with compensatory curvature to balance the body. At times two primary curvatures may be seen (usually in the right thoracic and left lumbar regions). A left thoracic curvature should be suspected of being secondary to neurologic disease and prompt a more meticulous neurologic examination. If the curvatures of the spine are balanced (compensated), the head is centered over the center of the pelvis. If the spinal alignment is uncompensated, the head will be displaced to one side, which produces an unsightly deformity. Rotation of the spine may be measured with a scoliometer. Rotation is associated with a marked rib hump as the lateral curvature increases in severity.

Treatment

Treatment of scoliosis depends on the curve magnitude, skeletal maturity, and risk of progression. Treatment is indicated for any curvature that demonstrates progression on serial radiologic examination. Definitive spinal fusions should be delayed as long as possible in young children through the use of casting, bracing, and growth modulating surgeries such as growing rods or vertical expandable prosthetic titanium ribs (VEPTR).

Management of scoliosis is dependent on the Cobb angle, measured on standing anteroposterior x-rays of the spine. Curvatures of less than 20 degrees typically do not require treatment unless they show progression. Bracing is controversial, but often used for curvatures of 20–40 degrees in a skeletally immature child. Recent studies have shown bracing to be effective for female patients with a Cobb angle of 25–35 degrees. Bracing and casting may be a beneficial way to prevent the progression of scoliosis without the negative quality of life effects associated with other treatments. Curvatures greater than 40 degrees are resistant to treatment by bracing. Thoracic curvatures greater than 70 degrees have been correlated with poor pulmonary function in adult life, leading treatment algorithms toward preventing progression to this extreme. Curvatures reaching a magnitude of 40–60 degrees are indicated for surgical correction as they are highly likely to continue to progress, ultimately reaching the 70 degree threshold in adulthood. Surgical intervention should be geared to maximize pulmonary function, while improving spinal alignment.

The surgical procedure for scoliosis has two fundamental components: deformity correction and spinal fusion. Spinal instrumentation (rods, screws, hooks, etc) are applied to the region of the spine to be corrected. The instrumentation is then used to manually reposition the spine intraoperatively. Surgical fusion involves decortication of the bone over the laminas and spinous processes, with the addition of bone graft. The instrumentation is then secured/tightened in order to maintain postoperative correction, with activity restriction for several months until the bone fusion is solid. Treatment requires a team approach and is best done in centers with full support facilities.

Prognosis

Compensated small curves that do not progress may cause minor deformities but are well tolerated throughout life. Patients should be counseled about the genetic transmission of scoliosis and cautioned that their children’s backs should be examined as part of routine physicals. Early detection allows for simple brace treatment. Severe scoliosis may require correction by spinal fusion, although fusionless techniques are being developed.

SLIPPED CAPITAL FEMORAL EPIPHYSIS

Slipped capital femoral epiphysis (SCFE) is caused by displacement of the proximal femoral epiphysis due to disruption of the growth plate. The head of the femur is usually displaced medially and posteriorly relative to the femoral neck. This condition is most commonly seen in adolescent, obese males. It occurs when stress increases across the proximal femoral physis (growth plate) or resistance to shear is reduced. Factors that can lead to this increase in stress or decrease in resistance include endocrine disorders, obesity, coxa profunda (a deep acetabular socket), and femoral or acetabular retroversion. Femoral version refers to the angle of inclination (anteversion) of the femoral neck towards the hip joint (femoral head) relative to the shaft of the femur. Retroversion of the femur occurs when the same proximal femoral segment is angled posteriorly relative to the shaft of the femur. Acetabular retroversion refers to when the alignment of the mouth of the acetabulum does not face the normal anterolateral direction, but inclines more posterolaterally. Experimental evidence has shown that the strength of the perichondrial ring stabilizing the epiphyseal area is sufficiently weakened by hormonal changes during adolescence such that the overload of excessive body weight can produce a pathologic fracture through the growth plate. Hormonal studies in affected children are usually normal, although SCFE is associated with hypothyroidism.

Clinically, SCFE is classified as stable or unstable. SCFE is considered stable if the child is able to bear weight on the affected extremity. In unstable SCFE, the child is unable to bear weight. An increased rate of avascular necrosis is correlated with the inability to bear weight.

Acute SCFE occasionally occurs following a fall or direct trauma to the hip. More commonly, vague symptoms occur over a protracted period in an otherwise healthy child who presents with pain and limp. The pain can be referred into the thigh or the medial side of the knee, making examination of the hip joint important in any obese child complaining of knee pain. Physical examination consistently reveals a limitation of internal rotation of the hip. The diagnosis may be clearly apparent only in the lateral radiographic view.

Initial management consists of making the patient non–weight-bearing on crutches and immediate referral to an orthopedic surgeon. Treatment is based on the same principles that govern treatment of any fracture of the femoral neck: the head of the femur is internally fixed to the neck of the femur and the fracture line allowed to heal.

The long-term prognosis is guarded because most of these patients continue to be overweight and overstress their hip joints. Follow-up studies have shown a high incidence of premature degenerative arthritis, even in those who do not develop avascular necrosis. The development of avascular necrosis almost guarantees a poor prognosis, because new bone does not readily replace the dead bone at this late stage of skeletal development. About 30% of patients have bilateral involvement, which may occur as late as 1 or 2 years after the primary episode.

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