Introduction

Osteonecrosis (ON) is a bone disease characterized by death of osteocytes and loss of associated hematopoietic elements usually occurring as focal lesions in weight bearing joints such as the hip. The pathophysiology of the disease is still unclear and osteonecrosis can be viewed as both a vascular and a bone disease. The number of mesenchymal stem cells (precursors of osteoblastic cells) has been shown to be depressed in patients with osteonecrosis. Also, the proliferation rate of the osteoblastic cells in the proximal femur may be depressed. These findings raised the possibility that osteonecrosis might be a disease of bone cells or bone metabolism. On this basis, we started this study to evaluate bone metabolism status among patients with osteonecrosis.