Musculoskeletal Imaging

Legg calv perthes disease

(Arthur Thornton Legg, 1874 - 1939, American surgeon, Jacques Calv, 1875 - 1954, French orthopaedist and Georg Clemens Perthes, 1869 - 1927, German surgeon), a disorder characterized by osteonecrosis of the hip, seen predominantly in children between the ages of 4 and 8 years. A history of trauma is present in approximately 25% of cases. Legg Calv Perthes disease should be considered in a child with acute or chronic manifestations in the hip, such as acute irritable hip syndrome or chronic hip syndrome.

The early radiographic abnormalities of Legg Calv Perthes disease include:

  • soft tissue swelling on the lateral side of the joint;

     

  • small femoral ossification nucleus;

     

  • lateral displacement of the femoral ossification nucleus;

     

  • fissuring and fracture of the femoral ossific nucleus;

     

  • flattening and sclerosis of the femoral ossific nucleus; and

     

  • intraepiphyseal gas (vacuum phenomenon) (Fig.1).

    Metaphyseal cysts and widening and shortening of the femoral neck may also be seen in some patients. Widening and irregularity of the growth plate and broadening of the metaphysis are additional manifestations of this disorder. A radiodense curvilinear shadow at the base of the femoral neck, termed the sagging rope sign, probably represents the radiodense shadow cast by the anterior or lateral edge of a severely deformed femoral head. Osteochondritis dissecans may also be seen in some patients. Early radiographic changes that may indicate a capital femoral epiphysis at risk for collapse are

     

  • Gages sign (a small, osteoporotic segment that forms a V on the lateral side of the epiphysis),

     

  • calcification lateral to the epiphysis (reflecting the presence of extruded cartilage),

     

  • lateral subluxation of the femoral head, and

     

  • a transverse epiphyseal line.

    Arthrography, scintigraphy and ultrasonography have also been used in the evaluation of Legg Calv Perthes disease, and both angiography and intraosseous venography have been applied in estimating the prognosis for patients with this disease. MR imaging has aided in the identification of infarction of the femoral head.

    The disease may be due to vascular insufficiency to the femoral head, although trauma with compression of the femoral head by the adjacent acetabular roof, leading to fracture, flattening and sclerosis, has also been suggested as a causative mechanism. Likewise, the role of synovitis and raised intra-articular pressure in the pathogenesis of Legg Calv Perthes disease has been emphasized.

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    Fig.1

    a. AP radiograph of the pelvis in a 5-year old boy demonstrates fragmentation of the left femoral epiphysis and widening of the left femoral neck. b. The arthrogram shows the femoral head is completely covered by the acetabulum and the cartilaginous limbus (arrow).
    Legg calv perthes disease, Fig.1 (a)
    Legg calv perthes disease, Fig.1 (b)