Condition | Possible clues to the diagnosis |
Physiologic bowing | Age <2 years; bilateral and symmetric; involves the femurs and tibias; normal stature; no lateral thrust during ambulation; improves with age. |
Pathologic bowing | Short stature, intercondylar distance >6 cm when the legs are held with the patella facing forward and the medial malleoli touching. |
Blount disease | Asymmetry; focal angulation of proximal tibia; lateral thrust during ambulation; radiographs with medial beaking and downward slope of proximal tibial metaphysis and epiphysis. |
Rickets | |
Nutritional rickets | Breast-fed infant with inadequate supplementation of vitamin D; decreased serum calcium and/or vitamin D; widened physes and flared metaphyses. |
X-linked dominant hypophosphatemic rickets (OMIM #307800) | Growth retardation, rachitic and osteomalacic bone disease; hypophosphatemia; renal defects in phosphate resorption and vitamin D metabolism; widened physes and flared metaphyses may or may not be present. |
Skeletal dysplasia | Characteristic clinical and radiographic features vary according to the dysplasia. Most children with skeletal dysplasia do not present solely with bowed legs. Some examples of additional manifestations are provided below. |
Achondroplasia (OMIM #100800) | Short stature; rhizomelic shortening of the limbs; frontal bossing; midface hypoplasia; lumbar lordosis; elongated fibula; trident hand. |
Pseudoachondroplasia (OMIM #177170); associated with knock-knees in some patients | Autosomal dominant inheritance; short-limb dwarfism with onset by two years; joint laxity; vertebral anomalies. |
Metaphyseal chondrodysplasia (multiple types) | Persistent bowing and short stature. |
Multiple epiphyseal dysplasia syndrome (OMIM #132400) | Autosomal dominant inheritance; mild short-limb dwarfism; brachydactyly; small, irregular epiphyses on radiographs. |
Cartilage hair hypoplasia (OMIM #250250) | Autosomal recessive inheritance; short-limb dwarfism; fine, sparse hair; sparse eyebrows, eyelashes, and beard; short hands. |
Asymmetric growth | |
Fracture | History of fracture. |
Sepsis and DIC (eg, meningococcemia) | History of infection. |
Neoplasia (eg, focal fibrocartilaginous dysplasia of proximal tibial metaphysis) | Progressive, unilateral deformity; radiolucent, well-circumscribed lesion, often with rim of reactive bone. |
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