Femoral head histology subsequent to ischemia, reperfusion and steroid treatment.

An episode of ischemia followed by reperfusion of the femoral head (FH) is thought to be a common pathway in the pathogenesis of femoral head necrosis (FHN). Femoral head histology was investigated after short-term high-dose steroid treatment and femoral head ischemia and reperfusion in a large animal model. Twenty-two pigs were randomized to receive methylprednisolone 20mg/day/kg bodyweight intamuscularly for 3 days followed by methylprednisolone 10mg/day/kg bodyweight for 11 days (n=11), whereas the control group (n=11) received no treatment. After 6h of unilateral hip-joint pressure increase to 250mmHg, the pressure was discontinued and reperfusion was allowed for 4h. Undecalcified histology was performed for the femoral head subchondral region, the mid-region, and the region adjacent to the growth plate. Congestion phenomena were predominantly discerned in femoral head sections of the tamponaded hips. Histomorphometry revealed fat cell hyperthrophy and reduced hemopoetic marrow cells in the femoral heads of the steroid-treated group of animals. The number of blood vessels and bone trabeculae remained unchanged. These characteristics may correlate with early-stage femoral head necrosis.