Congenital Hip, Leg, and Foot Abnormalities
Orthopedic abnormalities of the hip, leg, and foot are sometimes not apparent at birth. Causes include in utero positioning, ligamentous laxity, and skeletal deformities. Some abnormalities resolve without intervention; however, others require treatment.
DDH is abnormal development of the hip joint, leading to subluxation or dislocation; it can be unilateral or bilateral. High risk factors include
DDH seems to result from laxity of the ligaments around the joint or from in utero positioning. Asymmetric skin creases in the thigh and groin are common, but such creases also occur in infants without DDH. If DDH remains undetected and untreated, the affected leg eventually becomes shorter, and the hip may become painful. Abduction of the hip is often impaired due to adductor spasm.
All infants are screened by physical examination. Because physical examination has limited sensitivity, high-risk infants and those with abnormalities found during physical examination typically should have an imaging study.
Two screening maneuvers commonly are used. The Ortolani maneuver detects the hip sliding back into the acetabulum, and the Barlow maneuver detects the hip sliding out of the acetabulum. Each hip is examined separately. Both maneuvers begin with the infant supine and the hips and knees flexed to 90° (the feet will be off the bed). To do the Ortolani maneuver, the thigh of the hip being tested is abducted (ie, the knee is moved away from the midline into a frog-leg position) and gently pulled anteriorly. Instability is indicated by the palpable, sometimes audible, clunk of the femoral head moving over the posterior rim of the acetabulum and relocating in the cavity. Next, in the Barlow maneuver, the hip is returned to the starting position and then slightly adducted (ie, the knee is drawn across the body) and the thigh is pushed posteriorly. A clunk indicates that the head of the femur is moving out of the acetabulum. Also, a difference in knee height when the child is supine with hips flexed, knees bent, and feet on the examining table (Galeazzi sign—see Figure: Galeazzi sign.) suggests dysplasia, especially unilateral. Somewhat later (eg, by 3 or 4 mo of age), subluxation or dislocation is indicated by inability to completely abduct the thigh when the hip and knee are flexed; abduction is impeded by adductor spasm, which is often present even if the hip is not actually dislocated at the time of examination. Minor benign clicks are commonly detected. Although clicks usually disappear within 1 or 2 mo, they should be checked regularly. Because bilateral dysplasia may be difficult to detect at birth, periodic testing for limited hip abduction during the first year of life is advised.
Ultrasonography of the hips is recommended at 6 wk of age for infants at high risk, including those with a breech presentation, those born with other deformities (eg, torticollis, congenital foot deformity), and girls with a positive family history of DDH.
Imaging is also required when any abnormality is suspected during examination. Hip ultrasonography can accurately establish the diagnosis earlier in life. Hip x-rays are helpful after the bones have started to ossify, typically after age 4 mo.
Early treatment is critical. With any delay, the potential for correction without surgery decreases steadily. The hip usually can be reduced immediately after birth, and with growth, the acetabulum can form a nearly normal joint. Treatment is with devices, most commonly the Pavlik harness, which hold the affected hips abducted and externally rotated. The Frejka pillow and other splints may help. Padded diapers and double or triple diapering are not effective and should not be done to correct DDH.
The femoral head may be twisted. Torsion may be either internal (femoral anteversion—knees pointing toward each other with toes in) or external (femoral retroversion—knees pointing in opposite directions) and is common among neonates. At birth, internal torsion can be as much as 40° and still be normal. External torsion can also be prominent at birth and still be normal. Torsion is recognized by laying the child prone on the examining table. The hips are rotated externally and internally. Limitation of internal rotation indicates femoral anteversion, whereas limitation of external rotation indicates femoral retroversion.
Children with internal torsion may regularly sit in the W position (ie, knees are together and feet are spread apart) or sleep prone with legs extended or flexed and internally rotated. These children probably assume this position because it is more comfortable. The W sitting position was thought to worsen torsion, but there is little evidence that the position should be discouraged or avoided. By adolescence, internal torsion tends to gradually decrease to about 15° without intervention. Orthopedic referral and treatment, which includes derotational osteotomy (in which the bone is broken, rotated into normal alignment, and casted), is reserved for children who have a neurologic deficit such as spina bifida or those in whom torsion interferes with ambulation.
External torsion may occur if in utero forces result in an abduction or external rotation of the lower extremity. If external torsion is prominent at birth, a thorough evaluation (including x-rays or ultrasonography) for hip dislocation is indicated. External torsion typically corrects spontaneously, especially after children begin to stand and walk, but orthopedic referral is needed when excessive torsion persists after 8 yr. Treatment includes derotational osteotomy.
The 2 major types of knee or femoral-tibial angular deformities are genu varum (bowlegs) and genu valgum (knock-knees). Untreated, both can cause osteoarthritis of the knee in adulthood.
Genu varum is common among toddlers and usually resolves spontaneously by age 18 mo. If it persists or becomes more severe, Blount disease (tibia vara) should be suspected, and rickets and other metabolic bone diseases should also be ruled out (see Hypophosphatemic Rickets). Blount disease is due to a growth disturbance of the medial aspect of the proximal tibial growth plate; genu varum and tibial torsion may occur. Blount disease may occur in early childhood or in adolescence (when it is associated with overweight). Early diagnosis of Blount disease is difficult because x-rays may be normal; the classic x-ray finding is angulation (beaking) of the medial metaphysis. Early use of splints or braces can be effective, but surgery with or without an external fixator is often needed.
Genu valgum is less common and, even if severe, usually resolves spontaneously by age 9 yr. Skeletal dysplasia or hypophosphatasia should be excluded. If marked deformity persists after age 10 yr, surgical stapling of the medial distal femoral epiphysis is indicated.
Anterior knee dislocation with hyperextension is rare at birth but requires emergency treatment. It may occur with Larsen syndrome, which consists of multiple congenital dislocations (eg, elbows, hips, knees), clubfoot, and characteristic facies (eg, prominent forehead, depressed nasal bridge, wide-spaced eyes), or with arthrogryposis (see Arthrogryposis Multiplex Congenita). The dislocation may be related to muscle imbalance (if myelodysplasia or arthrogryposis is present) or intrauterine positioning. Ipsilateral hip dislocation often coexists.
On examination the leg is extended and cannot be flexed more than a few degrees.
If the infant is otherwise normal, immediate treatment with daily passive flexion movements and splinting in flexion usually results in a functional knee.
Tibial torsion can be external (lateral) or internal (medial) twisting. External torsion occurs normally with growth: from 0° at birth to 20° by adulthood. External torsion is rarely a problem.
Internal torsion is common at birth, but it typically resolves with growth. However, an excessive degree of torsion may indicate a neuromuscular problem. Torsion also occurs with Blount disease (see Congenital Hip, Leg, and Foot Abnormalities : Genu varum and genu valgum). Persistent, excessive torsion can lead to toeing-in and bowlegs.
To evaluate for tibial torsion, the angle between the axis of the foot and the axis of the thigh is measured with the child prone and the knees flexed to 90°. Typically the foot axis is 10°lateral relative to the thigh axis. This angle can also be measured by seating the child and drawing an imaginary line connecting the lateral and medial malleoli.
Sometimes called clubfoot, talipes equinovarus is characterized by plantar flexion, inward tilting of the heel (from the midline of the leg), and adduction of the forefoot (medial deviation away from the leg’s vertical axis). It results from an abnormality of the talus. It occurs in about 2/1000 live births, is bilateral in up to 50% of affected children, and may occur alone or as part of a syndrome. Developmental dysplasia of the hip (see Congenital Hip, Leg, and Foot Abnormalities : Developmental dysplasia of the hip (DDH—formerly congenital dislocation of the hip)) is more common among these children. Similar deformities that result from in utero positioning can be distinguished from talipes equinovarus because they can be easily corrected passively.
Treatment requires orthopedic care, which consists initially of repeated cast applications, taping, or use of malleable splints to normalize the foot’s position. If casting is not successful and the abnormality is severe, surgery may be required. Optimally, surgery is done before 12 mo, while the tarsal bones are still cartilaginous. Talipes equinovarus may recur as children grow.
The foot is flat or convex and dorsiflexed with the heel turned outward. The foot can easily be approximated against the lower tibia. Developmental dysplasia of the hip is more common among these children. Early treatment with a cast (to place the foot in the equinovarus position) or with corrective braces is usually successful.
The forefoot turns toward the midline. The foot may be supinated at rest. Usually, the foot can be passively abducted and everted beyond the neutral position when the sole is stimulated. Occasionally, an affected foot is rigid, not correcting to neutral. Developmental dysplasia of the hip is more common among these children.
The deformity usually resolves without treatment during the first year of life. If it does not, casting or surgery (abductory midfoot osteotomy) is required.