23 Disorders of the Hip and Lower Extremity
The pediatrician’s knowledge of orthopedic disorders must be broad because the clinical presentation and diagnostic approach vary widely with age. Although many of the disorders discussed here are managed in conjunction with orthopedic surgeons, they can often be diagnosed by history and physical examination alone, and some do not require surgical intervention. In addition, delayed diagnosis of relatively common disorders such as developmental hip dysplasia remains one of the largest causes of litigation against primary care pediatricians, and more importantly, results in preventable long-term disability. Furthermore, mismanagement of disorders of rapidly changing bones may lead to chronic morbidity.
We divide several common disorders of the hips and lower extremities into one of three categories: congenital, developmental, or acquired.
Congenital
A vast array of genetic diseases may present with lower limb anomalies at birth. In utero teratogen exposure can also lead to limb deformities. For instance, thalidomide has been off the market in the United States for many years secondary to its association with severe limb deformities. Illicit drugs or alcohol can also cause limb foreshortening. Amniotic bands can also cause structural changes, leading to amputation or dysplasia of limbs.
Clubfoot
Clubfoot, or talipes equinovarus, affects one in 1000 live births and is often diagnosed in utero. The condition is characterized by a smaller foot on the affected side, rigidity to plantar flexion, adductus of the forefoot, and inward angulation of the hindfoot (Figure 23-1). Half of cases are bilateral. Although many cases are idiopathic, maternal smoking, certain ethnic backgrounds, and genes affecting both the musculoskeletal and nervous systems have been identified as risk factors. Some believe that disordered development of the talus in utero causes the disorder.
Management of clubfoot has trended away from immediate surgical reconstruction because of the need for multiple corrective procedures, which can result in muscle weakness or stiffening. Currently, patients with the disorder are treated by progressive treatments that include more specific surgical repair if indicated to prepare for normal ambulation. The Ponseti method is typically used, which begins with tenotomy in most cases and is followed by serial casting and manipulation procedures. The less common French method involves daily physical therapy and binding over the first 2 months of life. Both methods are started early in the neonatal period, so early referral to a pediatric orthopedist is necessary. This visit may be arranged prenatally if the diagnosis is known. Clubfeet that do not respond to these conservative measures necessitate operative management.
Developmental
In utero packaging causes some expected changes in every infant; some of these variations may take 3 to 4 years to resolve. Some of the more common disorders associated with packaging include rotational problems of the lower extremities such as in-toeing and out-toeing, which are often noted when a child begins to walk.
In-toeing
In-toeing is expected in children until the lower limbs laterally rotate with time; adult walking patterns are not observed until about 7 or 8 years of age. The cause of in-toeing varies by age, often caused by metatarsus adductus in infants, internal tibial torsion in toddlers, and excessive femoral anteversion in preschool-aged children.
Metatarsus Adductus
Metatarsus adductus is the medial deviation of the tarsometatarsal joints in the transverse plane. This variant is observed in 1% to 2% of infants. Metatarsus adductus is observed in infants who were crowded in utero, such as with oligohydramnios or twin gestation, and soon self-corrects; 85 to 90% resolve by 1 year of age. Indeed, the majority of children with metatarsus adductus have no long-term functional impairment and do not require surgical repair. Severe cases can increase development of bunions and hammertoes, so serial casting or bracing is helpful when the deformity does not resolve on its own.
Internal Tibial Torsion
Internal tibial torsion is the most common cause of in-toeing and can be associated with metatarsus adductus. It is usually noted in toddlerhood when children begin to walk. It affects boys and girls equally and is bilateral in about two-thirds of cases. On examination, the knee remains in neutral position while the foot is medially rotated (Figure 23-2). Most cases self-resolve as children begin to walk independently, with normal alignment noted as early as 4 years or as late as 10 years of age.
Femoral Anteversion
Excessive femoral anteversion is seen in preschool-aged children and is thought to be either a remnant of in utero positioning or increased ligamentous laxity. It is more common in girls and is almost universally bilateral. On physical examination, the knees are medially rotated, distinguishing this entity from internal tibial torsion. Normal growth usually leads to resolution by 8 to 10 years of age. For all causes of in-toeing, surgery may be considered for persistent cases or those causing functional impairment.
Bowlegs
Bowlegs, or genu varum, are noted when children begin walking and can be considered normal until about 3 years of age. Past this age group, however, bowing of the legs is pathologic, and other causes must be considered to establish proper treatment plans.
Blount’s Disease and Adolescent Tibia Vara
Blount’s disease, also known as osteochondrosis deformans tibia or tibia vara, is an abnormality seen more frequently in obese African American girls younger than 3 years of age and can be inherited in an autosomal recessive fashion. A less aggressive cause of progressive bowing is adolescent tibia vara, seen in boys older than 8 years of age. Similar to Blount’s disease, adolescent tibia vara is observed more commonly in obese African Americans. Both disorders are associated with early walking. Starting corrective bracing early may prevent progressive deformity, and this additional support is especially crucial while walking. Tibial osteotomy may be considered for correction of bowlegs based on symptoms such as pain or asymmetry despite proper bracing for 1 year.
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