Coxa Valga

► [Vertically-oriented femoral neck]

Coxa valga is a nonspecific defect occurring in a variety of unrelated disorders, both congenital or acquired. Under normal circumstances, the shape of the proximal femur depends primarily upon lateral contributions of the trochanteric growth plate (TGP) and the femoral neck isthmus (FNI), balanced against the longitudinal and slightly medial contributions of the longitudinal growth plate (LGP). The resultant longitudinal vector of axial and medial (from the LGP), and lateral (from the TGP and FNI) directions of growth maintains biomechanical forces about the hip, while at the same time insuring the trajectory of growth in line with the axis of the femur. An understanding of the interrelationship of the growth zones of the proximal femur and their alterations as a result of genetic, environmental, and developmental influences allows early recognition of growth deformities and the opportunity to plan prompt corrective procedures.

As anticipated, coxa valga usually results from muscle power imbalance or a decrease in weight-bearing, especially in skeletally immature patients. In children with neuromuscular diseases, lack of upright posture reduces the vertical stress on the femur and allows the femoral neck to grow in a more vertical direction (Swischuk and John 1995) (Fig. 4.31). Furthermore, deficiency of the abductor and extensor musculature, often associated with spasticity of

Coxa Valga Cerebral Palsy
Fig. 4.31. Neuromuscular disease in a 6-year-old boy with cerebral palsy from perinatal asphyxia. There is bilateral coxa valga, with hip subluxation. The proximal femora are slender and osteoporotic, with thin cortices. The acetabular fossae are incompletely developed
Spondyloepiphyseal Dysplasia

Fig. 4.32. Spondyloepiphyseal dysplasia, Stanescu type in a 14-year-old boy. The proximal femora are characteristically broad and elongated, with marked coxa valga. The capital femoral epiphyses are flattened and only partially covered by the acetabular roofs, and the iliac bones are shortened in their longitudinal dimensions. (From Nishimura et al. 1998)

Fig. 4.32. Spondyloepiphyseal dysplasia, Stanescu type in a 14-year-old boy. The proximal femora are characteristically broad and elongated, with marked coxa valga. The capital femoral epiphyses are flattened and only partially covered by the acetabular roofs, and the iliac bones are shortened in their longitudinal dimensions. (From Nishimura et al. 1998)

the adductor musculature, reduces the growth stimulus to the TGP and FNI, thus resulting in a thin femoral neck with valgus deformity (Siffert 1981). Additional radiographic features commonly seen in patients with neuromuscular disorders include osteoporosis, multiple fractures, soft tissue and muscle atrophy/hypertrophy, scoliosis, pes cavus, patellar fragmentation, joint subluxation or dislocation, arthritis, osteomyelitis, heterotopic ossification, and cartilage atrophy. In poliomyelitis,premature closure of the growth plate, resulting in shortening of the parent bone, is common. The metatarsals and knees are affected most frequently. Unilateral or bilateral changes occur, according to the distribution of the neurological disease. When the disease is unilateral, all the skeletal changes, including osteoporosis, bony underdevelopment, coxa valga, and patella baja, are unilateral.

Coxa valga can also result from an inherent bone growth defect of the proximal femur, as observed in a number of constitutional bone diseases. In the condition known under the designation hypertrichotic osteochondrodysplasia (Cantu syndrome, OMIM 239850), the phenotypic spectrum includes early-onset hypertrichosis, cardiomegaly, narrow thorax with wide ribs, platyspondyly, hypoplastic ischiopu-bic branches, bilateral coxa valga, broad long bones with metaphyseal flaring and Erlenmeyer-flask deformity of the femurs, enlarged medullary canal, and generalized osteopenia (Cantu et al. 1982). The face has been described as 'coarse,' with abundant and curly eyebrows and eyelashes, epicanthal folds, strabismus, hypertelorism, and broad nasal bridge (Concolino et al. 2000). The condition is most probably due to a new dominant mutation or to a mi-crodeletion (Robertson et al. 1999). Bilateral coxa valga with subluxation of both hips has been described as part of the hirsutism-skeletal dyspla-sia-mental retardation syndrome (OMIM 142625), which presents as marked hirsutism, brachycephaly, abnormal facies, mental retardation, pes cavus, abnormal position of the thumbs, and elevated serum uric acid levels. Skeletal defects include long neck, narrow thorax, down-sloping shoulders, and prominent elbow joints (Wiedemann et al. 1993). In spondyloepiphyseal dysplasia with accumulation of glycoprotein in the chondrocytes (Stanescu type) the clinical hallmarks comprise progressive joint contracture with premature osteoarthritis of the knees, hips, and finger joints; swelling of the inter-phalangeal joints; and absence of short stature, which is a point of difference from other forms of spondyloepiphyseal dysplasia (Nishimura et al. 1998). Radiological manifestations include generalized platyspondyly with mild involvement of the end-plates, epiphyseal flattening and metaphyseal splaying of the long bones, and enlarged proximal and distal ends of the phalanges. It is notable that the proximal femurs are characteristically broad and elongated, with striking coxa valga (Fig. 4.32). Spon-dyloepiphyseal dysplasia tarda with mental retardation (OMIM 271620) is an association of platyspon-dyly, bilateral coxa valga, and mild to moderate men tal retardation. Additional features are an anterior tongue-like vertebral protrusion in the lumbar spine, absent dens epistrophei, flared iliac bones with short sacrosciatic notches, and bilateral deformity of the acetabulum (Kohn et al. 1987). Bilateral coxa valga, with widening of the femoral neck, is a characteristic finding of hereditary multiple exostoses (OMIM 133700, 133701, 600209) (Weiner and Hoyt 1978; Gierse 1983). Coxa valga is common in the dysostosis multiplex spectrum, specifically in mucopolysaccharidosis I-H (Hurler, OMIM 20580) and IV (Morquio, OMIM 252300), mucolipidosis type II (I-cell disease, OMIM 252500) and III (pseudo-Hurler polydystrophy, OMIM 252600), mannosidosis (OMIM 248500), and Niemann-Pick disease (OMIM 257200) (Lachman et al. 1973). In frontometaphyseal dysplasia (OMIM 305620) coxa valga is associated with widening of the femoral neck due to a tubula-tion defect. In Melnick-Needles syndrome (osteodys-plasty, OMIM 249420) the femoral necks are elongated and vertically oriented (coxa valga), with sub-trochanteric constriction. Achard syndrome (OMIM 100700), a disorder of uncertain origin resembling Marfan syndrome, is characterized by small mandible, arachnodactyly, joint laxity limited to the hands and feet, clubfoot, and bilateral coxa valga (Achard 1902). Brachycephaly and preserved body proportions are distinctive features allowing its differentiation from Marfan syndrome (Thursfield 1917). Coxa valga is also a manifestation of hemifacial hyperplasia with strabismus (Bencze syndrome, OMIM 141350), a condition characterized by excessive unilateral growth of the facial skeleton and its soft tissues, resulting in facial asymmetry. Convergent or alternating strabismus, of the eye on the affected or the unaffected side, and submucous cleft palate are also features. Additional skeletal findings include narrow iliac wings, pectus carinatum, and scoliosis (Bencze et al. 1973; Kurnit et al. 1979).

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  • Haile
    What is a bilateral coxa valga?
    8 years ago

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