Epiphyseal scar of the femoral head: risk factor of osteonecrosis.

PURPOSE: To find out whether a correlation exists between the presence of epiphyseal scar within the femoral head and osteonecrosis at examination with magnetic resonance (MR) imaging.

MATERIALS AND

METHODS

A total of 117 femoral heads in 60 patients were examined. Lipogenic factors (defined as either the use of steroid or alcohol abuse) were positive in 46 patients (average age, 37 years) and absent in 14 (average age, 47 years). Both hip joints were examined simultaneously at 1.5 T; three pulse sequences were used in each imaging study. All images were interpreted for type of epiphyseal scar and presence or absence of osteonecrosis.

RESULTS

Six types of epiphyseal scar (A-F), each with a different shape, were seen. A total of 72 femoral heads had type A or B sealed-off scars; 32 of these 72 had osteonecrosis. Of the 45 femoral heads with type C, D, E, or F perforated scars, only one had osteonecrosis. The difference between these two groups was statistically significant (P < .001).

CONCLUSION

The presence of a sealed-off epiphyseal scar was associated with a very high risk of osteonecrosis of the femoral head.