Visual Diagnosis and Treatment in Pediatrics, 3 Ed.

Leg Asymmetry

Approach to the Problem

Lower extremity asymmetry includes inequalities in length and size. Leg length inequality may be structural from abnormalities in any of the bones, nerves, or vasculature in the pelvis or limb, or functional as a result of contractures. Discrepancies in extremity size can also occur from a wide array of congenital, developmental, or acquired conditions that speed or slow growth. A thorough clinical history and careful physical examination are crucial to determining where the abnormality originates and its potential etiologies. The underlying etiology typically will dictate the course and outcome of the limb inequality.

Key Points in the History

• Timing of limb asymmetry is important: limb aplasias, hypoplasias, hyperplasias, and clubfoot are congenital, whereas discrepancies that become more evident as the child grows are usually acquired. Developmental dysplasia of the hip, and hemihypertrophy or hemihypotrophy are exceptions, as they may not be noted at birth.

• Risk factors for developmental dysplasia of the hip include firstborn status, female gender, breech position, positive family history, and oligohydramnios.

• Family history of any bony anomalies is helpful in elucidating if there is an underlying dysplasia, hemangioma, or other anomalies in the bony matrix that would affect growth.

• Skin abnormalities overlying the spine or progressive asymmetric deformities in the limbs may indicate the presence of spinal dysraphism or a tethered cord.

• Inflammatory processes, such as rheumatoid arthritis and hemophilia, can be associated with bony overgrowth.

• Hypotonia, weakness, or paralysis of a limb occurring in those with cerebral palsy or other neurologic disorders often results in growth inhibition from actual discrepancies or apparent ones due to contractures and posturing.

• Disorders or events that cause diminished blood flow to the leg, such as vascular injury, can result in growth interference.

• A medical and family history significant for cutaneous, arteriovenous malformations (AVMs) warrants evaluation for internal AVMs and underlying syndromes, such as Osler–Weber–Rendu.

• Vascular malformations on the limbs can stimulate growth in the limb that involves all growth plates, not just those adjacent to them.

• Tumors typically may cause shortened limbs in multiple ways, such as direct destruction and growth inhibition or postirradiation therapy; however, certain ones, such as Wilms tumor, may accompany accelerated growth.

• Infection and trauma history are important to elicit as they can cause leg length discrepancies by either impeding growth through physeal disruption or increasing growth by stimulating blood flow to the limb.

Key Points in the Physical Examination

• Perform a careful and complete head-to-toe examination to determine whether the asymmetry is confined to the lower extremities or exists elsewhere, which may indicate an underlying syndrome.

• Utilize body proportions to determine which limb appears to be the affected one—the pathologic one may be smaller, shorter, larger, or longer depending on the etiology; then evaluate limb segments to ascertain the exact location of the anomaly.

• The true leg length is determined by using a tape measure to measure from the anterior superior iliac spine to the tip of the medial malleolus and the apparent leg length from the umbilicus to the medial malleolus, which can help determine whether the inequality is structural or functional, respectively.

• Blocks can be placed under the heel of the short leg to level the pelvis and measure length discrepancy; the block height needed should correspond to the difference in true leg length.

• Children alter their gait to compensate for significant length inequalities over 2 cm by flexing the knee, circumducting the hip, and/or springing over the long extremity or by walking on tiptoe on the short extremity.

• Anterior bowing of the tibia with or without a dimple at the apex is often associated with fibular hemimelia.

• A hip clunk found on the Barlow maneuver (displacing the femoral head out of socket) or Ortolani maneuver (relocating the femoral head back into the socket), and/or a positive Galeazzi (femoral height discrepancy with hips and knees flexed) sign indicate possible developmental dysplasia of the hip.

• Hemihypertrophy associated with cutaneous lesions or other anomalies may indicate an underlying condition. Café au lait spots may be seen in neurofibromatosis type 1, macroglossia in Beckwith–Wiedemann syndrome, and vascular malformations in Klippel–Trenaunay–Weber syndrome.

• If hemihypertrophy is present, perform a thorough abdominal examination to rule out tumors, including Wilms, adrenal carcinoma, and hepatoblastoma.

• Hemihypotrophy (or hemiatrophy of the leg) should increase suspicion for neurologic etiologies, such as cerebral palsy, and warrants a thorough neurologic assessment, including examination of the back for midline cutaneous lesions indicating possible spinal abnormalities.

 

PHOTOGRAPHS OF SELECTED DIAGNOSES

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Figure 45-1 Positive Galeazzi sign. Note asymmetry in femoral heights. (Courtesy of Douglas A. Barnes, MD.)

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Figure 45-2 Developmental dysplasia of the hip. Note the asymmetry of this infant’s thigh folds. (Courtesy of Texas Scottish Rite Hospital for Children, Dallas, Texas.)

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Figure 45-3 Hemihypertrophy secondary to Proteus syndrome. Note the hypertrophy of the right lower extremity and the left upper extremity. (Courtesy of Shriners Hospitals for Children, Houston, Texas.)

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Figure 45-4 Isolated hemihypertrophy. Note the hypertrophy of the right lower extremity. (Courtesy of Shriners Hospitals for Children, Houston, Texas.)

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Figure 45-5 Polio. The deformed leg of this child is due to polio. (Photo courtesy of World Health Organization.)

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Figure 45-6 Slipped capital femoral epiphysis. Note how Klein line (drawn as an extension of a line drawn along the top border of the femoral neck) does not intersect any part of the femoral head of the abnormal left side. (Courtesy of Texas Scottish Rite Hospital for Children, Dallas, Texas.)

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Figure 45-7 Proximal femoral focal deficiency. Note how the diagnosis of this child’s congenital leg length discrepancy can be delineated to the right femur by having this child stand on blocks. (Courtesy of Texas Scottish Rite Hospital for Children, Dallas, Texas.)

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Figure 45-8 Hemi-atrophy from linear scleroderma. Note normal appearing size, muscle mass, and overall bulk of the normal right leg. (Courtesy of Shriners Hospitals for Children, Houston, Texas.)

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Figure 45-9 Klippel–Trenaunay–Weber syndrome: port-wine stain, varicose veins, and bony and soft-tissue hypertrophy. (Used with permission from image provided by Stedman’s.)

DIFFERENTIAL DIAGNOSIS

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Other Diagnoses to Consider

• Clubfoot

• Congenital pseudarthrosis of the tibia, femur, or fibula

• Hemophilia

• Juvenile idiopathic arthritis

• Mosaic Turner syndrome

• Proteus syndrome

• Radiation therapy

• Scleroderma or scarring and fibrosis from other etiologies (e.g., severe burns)

• Skeletal dysplasias or dyostoses

• Thrombosis of iliac or femoral veins

• Tumors

When to Consider Further Evaluation or Treatment

• Leg length inequalities less than 2 cm are typically managed conservatively with shoe lifts, and discrepancies greater than 2 cm require orthopedic referral for possible surgical intervention.

• Consider radiographic evaluation in female infants with breech presentation, especially if firstborn, have a positive family history, or history of oligohydramnios.

• Legg–Calvé–Perthes disease rarely requires surgical intervention, but slipped capital femoral epiphysis almost always does.

• Children with hemihypertrophy should undergo evaluation for abdominal masses due to the increased incidence of malignancies.

• Limb asymmetry associated with vascular anomalies requires a thorough evaluation for an underlying syndrome and other vascular malformations in view of the life-threatening complications that can occur.

• Although the etiology of limb asymmetry is diverse, all patients benefit from orthopedic referrals to manage either orthopedic causes of the asymmetry, the musculoskeletal issues arising from the asymmetry, or both.

SUGGESTED READINGS

Ballock RT, Wiesner GL, Myers MT, et al. Hemihypertrophy. Concepts and controversies. J Bone Joint Surg Am. 1997;79(11):1731–1738.

Enjolras O, Chapot R, Merland JJ. Vascular anomalies and the growth of limbs: A review. J Pediatr Orthop B. 2004;13(6):349–357.

Herring JA, ed. Tachdjian’s Pediatric Orthopedics. 4th ed. Philadelphia, PA: NB Saunders Company; 2008.

Morrissy RT, Weinstein SL, eds. Lovell and Winter’s Pediatric Orthopaedics. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.

Staheli LT, ed. Practice of Pediatric Orthopedics. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.

Storer SK, Skaggs DL. Developmental dysplasia of the hip. Am Fam Physician. 2006;74(8):1310–1316.



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