ORTHOPAEDICS

MARCO ANTÔNIO ROCHA AFONSO, MD

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Legg-Calvé-Perthes Disease

Legg-Calvé-Perthes is a disorder of the epiphysis , that involves the secondary ossification center of the femoral head.

The cause remais controversial . In general , vascular disturbance , possible secondary to trauma , is thought to result in avascular necrosis of the involved epiphysis . Probably there is also an underlying genetic defect in epiphyseal cartilage as a predisposing factor .

The pathology is that of osteonecrosis of the ossification center of the femoral epiphysis ,but the cause is unknown.

The disease has been reported in 1to 3 percent of patients following transient synovitis of the hip . In most cases there is no indentifiable antecedent event .

Epidemiologically , some risk factors have been indentified , including age beetwen 4 to 8 years old , delayed bone growth , low socioeconomic status , breech delivery , and beeing a child of older parents .

Clinical presentation includes a prodromal stage with a limp , hip and/or knee pain , loss of abduction and external rotation secondary to mucle spasm initially , but later due to deformity and flattening of the femoral head . hip effusion (from synovitis) is also common .

With the restoration phase the clinical symptoms resolve and the ossifc nucleus reconstitutes , although some permanent femoral head deformity and restriction of abduction and hip rotation ocasionaly remain .

At radiographs findngs ; ossifc nucleus fails to grow and looks smaller , sorrounding bone may become osteopenic , causing nucleus to look more dense , cartilage of the femoral head and therefore medial joint space looks windend , caffey's sing may be seen too (it represents a pathologic fracture of resorbing femoral head and is best seen on frog leg view of the pelvis).

Lateral ossification , Gage's sing (Vshaped defct laterally) , lateral subluxation , metaphyseal cysts and horizontal growth plate are associated with poor prognosis .

In diagnosis , hipotireoidsm , multipe epiphyseal displasia ,spondiloepiphyseal displasia tardia , and sickle cell disease must be considered in bilateral Perthes .

In unilateral Perthes , the diferential diagnosis includes , septic arthritis , sickle cell disease , espondiloepiphyseal displasia tardia , Gaucher's disease , eosinophilic granuloma , and transient synovitis .

The tretment is based on containment of the diseased epiphysis in the acetabulum until reossification is complete , which affords best chance of obtaining a spherical femoral head . Keeping hip abduced and internally rotated , until transmit weigth througth the acetabulum over a wide area of head , which prevents collapse of the bone . It takes from 2 to 3 years for complete recontitution of child's femoral head following avascular necrosis . Improving radioghrafic findings of healing may indicate that patient may be weaned from bracing .

Surgical treatments are reserved for patients with severe impairment . The procedures include ; the excision of the extruded portion of head for hinge abdution , Chiary osteotomy which cover femoral head , valgus osteotomy to to increased abduction , and arthodesis at skeletal maturity for severe unilateral impairment .

These pictures show an evolution of a 6 yars old male with the disease in two years .