The prognostic significance of the triradiate cartilage in suppurative arthritis of the hip in infancy and early childhood.

Suppurative arthritis of the hip in infancy and early childhood inflicts permanent damage of variable severity if it is not treated promptly and aggressively (Paterson I 970). Damage is sometimes limited to the articular cartilage alone, but in neonatal infection there is commonly destruction and displacement of the joint. This often follows consistent patterns and presents opportunities for repair or reconstruction. Repair is possible when there is dislocation of the hip with an intact femoral neck, or a pathological fracture of the neck of the femur producing a pseudarthrosis with a mobile head within the acetabulum. When a fracture of the neck of the femur is associated with an adherent femoral head or when the head is destroyed, a decision may be made to attempt reconstruction by trochanteric arthroplasty (Weissman 1967) to perform an arthrodesis later, or to abandon treatment (Lloyd-Roberts and Ratliff 1978). It would be helpful to be able to distinguish between these favourable and unfavourable situations at an early age so that treatment may be planned accordingly. The aim should be to operate before walking begins in patients with favourable signs in order to prevent further displacement. In the presence of unfavourable signs there is less urgency. Unfortunately this distinction is seldom possible at this age. The radiographic appearance of the proximal femur is rarely helpful after neonatal disease because skeletal immaturity coupled with decalcification due to infection means that the significant structures are radiolucent. Furthermore, even when the head is radiopaque, its mobility cannot be assessed and arthrography is not of assistance (LloydRoberts 1 960). It is, however, helpful to assess the state of the triradiate cartilage of the acetabulum when, for some reason, early operation has been withheld.