Bowlegs: Lateral and usually some anterior bowing of the proximal two-thirds of the tibias and/or the distal segments of the femora. Spurring of the medial aspect of the proximal tibia shaft or the posterior aspect of the distal femur shaft may also be present.

Idiopathic bowlegs of infancy disappear spontaneously after 2 to 3 years. Bowed limbs at birth may also be found in different forms of dwarfisms (e.g., achondroplasia and camptomelic and thanatophoric dwarfism).

Lateral bowing of the tibia characteristic. Sclerosis of the base of the skull and mastoids, tall vertebrae, ribbon-like appearance of the ribs, and metaphyseal flaring of short and long bones may also be evident.

Found only in females with small face, large ears, protruding eyes, micrognathia, malaligned teeth and short upper arms.

Occasional sequelae of the disease in adulthood include bowing of the limbs, mandibular asymmetry and osseous bridging between adjacent bones.

The disease becomes evident in infants of less than 5 months of age. Usually the clinical and radiographic features subside slowly within a few months to a few years.

Bowing deformities in slender overconstricted and osteoporotic long bones with tendency to fracture characteristic.

Inherited connective tissue disorder.

Bowing deformities and increased bone fragility are characteristically present both in the most severe form (seen in infants) and in the mildest form (seen in adults). In infancy, the disease resembles rickets (cupping and fraying of metaphyses), whereas in the adult the long bones are shortened and often demonstrate cortical thickening and pseudofractures.

Hypophosphatasia is a genetically determined metaphyseal dysplasia with failure to form primary spongiosa. Low serum alkaline phosphatase levels are characteristic.

Bowing deformities occur in the long bones of the lower extremities. Pseudofractures (Looser’s zones) may be associated and progress to complete fractures.

Extensive enteropathy and a general increase in bone density (especially in the axial skeleton) are characteristic features in adulthood. In the spine the disease may simulate ankylosing spondylitis without sacro-iliac joint involvement or DISH.

Radius is bowed and short and its distal articular surface demonstrates ulnar and volar angulation. The distal ulna is deformed and subluxed dorsally. The carpal bones are wedged between the deformed radius and ulna and assume a triangular configuration with the lunate at the apex. May be associated with short and bowed tibia, short fibula, and valgus deformity of the knee.

Rare hereditary mesomelic bone dysplasia with female preponderance. Process usually begins in adolescence with premature fusion of the medial aspect of the distal radial epiphysis resulting in asymmetrical growth. In the majority of cases, the patients are of short stature and the deformities are bilateral.

Medial tibia condyle is enlarged and deformed with an irregular, beak-like extension originating from the media! metaphysis and projecting medially and posteriorly. Medial aspect of proximal tibia epiphysis may also be deformed.

Osteochondrosis of the medial tibia metaphysis resulting in bowlegs. An infantile type (usually bilateral) is differentiated from an adolescent type (usually unilateral).

Bilateral and symmetrical anterior and medial bowing of the tibia and fibula, producing a “sabre-shin” deformity. The fibula shaft is typically thickened (“tibialization” of the fibula).

Congenital nonprogressive condition that has also been reported in the elderly.

Deformity and shortening of tubular bones containing round, often expansile lesions or alternating columnar radiolucent and radiodense streaks. Enchondromas may contain punctate or stippled calcifications. Disease may be relatively localized, unilateral, or generalized.

Disease is usually diagnosed in the first decade of life. May be associated with multiple hemangiomas containing phleboliths (Maffucci’s syndrome). In hereditary multiple exostoses bowing deformities typically are found in the radius and ulna.

Severe osteomyelitis may result in a deformed or bowed sclerotic tubular bone, particularly in the leg. Anterior bowing and cortical thickening of the tibia produces a “sabre-shin” appearance, characteristically found as late sequelae of both congenital and acquired syphilis and yaws. Bowing deformities confined to the distal half of the tibia associated with localized cortical thickening and solid periosteal reaction can be found in tropical ulcer.

Echinococcus rarely involves bones. Besides the spine, pelvis, and sacrum, the long bones may be affected with multiloculated cystic lesions, resulting occasionally in bone deformities.

Anteroposterior or lateral bending of radius, ulna or fibula. A fracture in the neighboring bone (e.g. radius or tibia) might be associated.

Usually in young children.

Common cause of bone deformity usually associated with locally increased sclerosis.

All ages may be affected. Bowlegs in infancy are occasionally secondary to trauma.

Bowed long tubular bones with narrowed, over-constricted shaft diameter due to decreased medullary cavity while the width of the cortex is relatively little affected.

In longstanding paralytic and pseudoparalytic conditions such as old poliomyelitis, muscular dystrophy, and juvenile rheumatoid arthritis.

Bowing deformities occur, besides in the pelvis, spine, and thorax, particularly in the lower extremities. The cortex is thinned as in osteoporosis, but bone deformities, pseudofractures and poor definition of the inner cortical margin and trabeculae help to differentiate osteomalacia from osteoporosis.

Bowing deformities are also a common feature in rickets of any etiology.

Bone deformities similar to osteomalacia occur in an advanced stage.

In renal osteodystrophy (secondary hyperparathyroidism) bone deformities may be secondary to both osteomalacia and hyperparathyroidism.

Bone deformities are common in the lower extremities involved by combined (sclerotic and lytic) phase of the disease. This results characteristically in coxa vara (“shepherd’s crook” deformity of the upper femur) and anterior bowing of the tibia. In this stage, the involved long bones are widened, and both cortex and disorganized-looking trabeculae are thickened.

Common cause of bone deformities in the elderly patient. Hereditary hyperphosphatasia (“juvenile Paget’s disease”), which occurs in children, presents characteristically with bowing and thickening of all long bones in the upper and lower extremities.

Marked deformities of the long bones occur, particularly in the polyostotic form, where the bone involvement is generally more extensive. “Shepherd’s crook” deformity (upper femur), cortical thickening, widening of the bone, and accentuated or abnormal trabeculation may be present, similar to Paget’s disease. The presence of radiolucent or cyst-like lesions or “ground-glass” appearance of the involved bone are useful in differentiating fibrous dysplasia from Paget’s disease.

In contrast to Paget’s disease, fibrous dysplasia is usually diagnosed in children and young adults. Skin pigmentations (“café-au-lait” spots with irregular outline) and sexual prematurity in females may be present in the polyostotic form (Albright’s syndrome).

Overgrowth of the long bones may result in bowed appearance. The fibula frequently is slender (overconstricted). Pseudarthrosis (especially of the tibia) is common with this presentation. Bowed long bones may occasionally also demonstrate cortical thickening and increased sclerosis.

Hereditary disease often associated with skin neurofibromas and smoothly marginated “café-au-lait” spots.

Congenital pseudarthrosis of the radius and ulna may also be associated with bowing, but this condition is not related to neurofibromatosis.

Undertubulation and “Erlenmeyer flask” deformities combined with signs of osteoporosis and rickets are seen.

Congenital malformation resulting in progressive obstructive jaundice. Usually fatal within 2 years unless corrected surgically.

Undertubulation of the long bones with alternating radiolucent and sclerotic longitudinal streaks (“celery-stick pattern”) and irregular metaphyses with radiolucent bands.

Osseous changes regress in those infants who grow normally, but may persist in those who fail to thrive.

Periosteal new bone formation, cortical thickening and widening, primarily of the mandible, scapulae, clavicles, ribs and ulnae, are characteristic.

Disease develops in the first 5 months of life. Fever of abrupt onset, hyperirritability, and tender soft-tissue swelling over the affected bones are characteristic. The radiographic changes tend to regress spontaneously within one year.

Symmetrical involvement of the long bones with undertubulation and cortical thickening of the midshaft resulting in a spindle-shaped appearing bone.

Rare hereditary disease associated with progressive midshaft cortical thickening and neuromuscular dystrophy. Usually diagnosed between 4 and 12 years, causing a wide-based, waddling gate.

Thickened undertubulated shafts, often with irregular wavy contours, are common findings. Metaphyseal flaring can be seen with Morquio’s disease, whereas tapering of the small tubular bones suggests Hurler’s disease.

Clinical and radiographic findings of different mucopolysaccharidoses and mucolipidoses are similar. A large dolichocephalic skull with J-shaped sella turcica, oval or hook-shaped vertebral bodies with gibbus formation in the thoracolumbar region, underdevelopment of the supra-acetabular region resulting in a widened acetabular roof, and coxa valga deformities with widened femoral necks, are characteristic.

Long tubular bones are shortened and have “dumbbell” appearance that is caused by the markedly enlarged metaphyses at both ends.

Short-limb dwarfism, which is normal at birth with progressive kyphoscoliosis, finally resembling Morquio’s disease. Flaring of the metaphyses with very short limbs are also seen in thanatophoric dwarfism, but this condition results in stillbirth or death in the neonatal period.

Initially the epiphyses are small and flattened and the metaphyses wide with dense, mushroom-shaped provisional zones ofcalcifications. In the adults the tubular bones are short and expanded at their end.

Spondyloepimetaphyseal dysplasias and epimetaphyseal dysplasias consist of a heterogeneous group of conditions that have metaphyseal flaring in common.

Metaphyses of the long bones are often markedly widened and may contain irregular calcifications while the shaft is overconstricted and may show severe bending deformities and multiple fractures of different ages. Osteopenia is usually a dominant feature.

Radiographic findings are more severe in the congenital than tarda form of osteogenesis imperfecta.

Widened metaphyses and epiphyses with usually severe osteopenia and prominent growth lines are seen. In addition, Marfan-like changes (e.g., arachnodactyly) may be present.

Inborn error of the methionine metabolism.

“Erlenmeyer flask” deformity or paddle-shapped enlargement of the metaphyses and, to a lesser degree, undertubulation of the long bones associated with cortical thinning and osteoporosis are characteristic. Thickened ribs and symmetrically enlarged proximal portions of the clavicles may be associated.

Rare hereditary disorder that can be differentiated from craniometaphyseal dysplasia by the lack of skull changes.

Undertubulation and “Erlenmeyer flask” deformities characteristic and usually most pronounced in the distal femur, radius, and ulna. Osteoporosis may be associated. Skull may show sclerosis of the base and calvarium, lack of aeration of paranasal sinuses and mastoids, and thickening and sclerosis of the mandible.

Rare congenital and familial bone dysplasia. Clinical features include hypertelorism, a broad flat nose, and defective dentition.

Undertubulation and often bowing of the long bones of both upper and lower extremities with multiple osteochrondromas in the metaphyseal regions, but usually sparing the elbow, are characteristic. Shortening of ulna and fibula is often present, Shortening of the ulna may result in congenital dislocation of the radial head, false articulation between the distal ulna and radius, and ulnar deviation of the carpus.

The inherited disease is usually diagnosed in the first decade of life. Transformation to chondrosarcoma occurs in approximately 5% of cases, although higher malignant transformation rates have been described.

Undertubulation, deformity, and shortening of the involved bones are common. Longitudinal radiolucent streaks interspersed with normal to sclerotic-appearing streaks may extend from the metaphysis into the shaft, or expansile radiolucent lesions with or without stippled calcifications may be seen. The metaphyses are usually most severly involved and often show “Erlenmeyer flask” deformities.

The generalized form of the disease is usually discovered in the first decade of life. The disease may also be unilateral or present only with a few enchondromas, characteristically located near a joint. Malignant degeneration in this nonhereditary disease is reported in 5–25% of cases.

Localized widening usually near the end of long bones is caused by a variety of benign expansile mass lesions.

For further differentiation, see Chapter 5.

Marked thickening of the involved area with scattered radiolucent, destructive lesions, solid periosteal new bone formation and sclerosis is characteristic.

In chronic sclerosing osteomyelitis (Carre), diffuse uniform sclerosis of the involved bone may be seen (Fig. 14.24b).

Localized to generalized widening of the shaft often associated with a bone deformity. Elevated solid periosteal reaction may initially simulate a double cortex or even “bone-within-bone” appearance during the healing phase, particularly in infants and children, but will disappear with further bone remodeling. Cortex may be thickened by periosteal bone formation, but may become normal or even thinned at a later stage. A metaphyseal injury may result in an “Erlenmeyer flask” deformity.

Common cause of localized undertubulation and deformity of a long bone.

Thinned cortices and a uniform reticular to cystic trabecular pattern in the widened diametaphyses with “Erlenmeyer flask” deformities characteristic, especially in the young patient.

A group of different hereditary hypochromic microcytic anemias, caused by the synthesis of abnormal hemoglobin polypeptide chains. Usually found in “Mediterranean” people and their descendants. Bone changes are caused by erythroid hyperplasia and are most pronounced in thalassemia major. Initially, all bones may be involved. With the conversion of red to yellow marrow in the tubular bones later in life the lesions may regress at these locations.

Cortical thinning and coarsening of the trabecular pattern due to bone marrow hyperplasia occur, but are less pronounced than in thalassemia. Changes in the long bones are caused by osteomyelitis and/or infarction and include destructive changes and new bone formation that may result in irregular diametaphyseal widening. Cortical infarcts may result in cortical thickening or “splitting of the cortex.” Layering of new bone along the inner cortex may produce a “bone-within-bone” appearance.

Sickle-cell anemia is a hereditary disorder limited almost exclusively to blacks, and caused by an abnormal hemoglobin HbS, where in position 6 of the β-globin chain, valine is substituted for glutamic acid.

Lower extremities are involved more often. Characteristic is the combination of avascular necrosis of the femoral head and an “Erlenmeyer flask” deformity at the distal femur. The shaft of the long bones may be locally expanded. Bone resorption and reparation may result in generalized osteopenia, lytic lesions of varying sizes simulating metastases, and patchy areas of sclerosis. Similarly, the cortex may be thinned, with a scalloped inner margin, or thickened and “split.” An inner layer of new bone formation may produce “bone-within-bone” appearance. Solid or lace-like periosteal reaction can occur, probably secondary to infarction.

Hereditary metabolic disease characterized by the accumulation of cerebrosides in the reticuloendothelial cells, resulting in hepatosplenomegaly. There is no sex predilection. The most common “adult” type occurs in Ashkenazic Jews, with the earliest manifestations appearing in childhood and progressing in the second and third decade of life. The acute type of Gaucher’s disease is a rare, fatal neurodegenerative disorder with no ethnic predilection, that usually becomes manifest shortly after birth and has an average survival time of one year.

Widening of the diametaphyses (undertubulation) and osteopenia with thinned cortices and coarsening of the trabecular pattern characteristic. Coxa valga occurs commonly. An “Erlenmeyer flask” deformity in the distal femur may simulate Gaucher’s disease.

Hereditary metabolic disorder characterized by the accumulation of phospholipids (sphingomyelins) in the reticuloendothelial cells. Niemann-Pick disease can be differentiated radiographically from Gaucher’s disease by the usual absence of avascular epiphyseal necroses, bone infarcts, and well-circumscribed radiolucent lesions.

Expansile lytic lesion and periosteal new bone formation may produce irregular localized widening of the long bones.