This novel clinical research protocol will aim to provide further evidence of the protective value of alendronate or zoledronic acid in patients with ON of the hip. It will determine whether bisphosphonates slow the progression of symptoms as well as the progression to total collapse of the hip. Additionally it will seek to answer questions regarding the comparative effectiveness and also cost-effectiveness of the use of bisphosphonates in early disease. The results of this study can lead to change in treatment of early disease ON and delay and possibly prevent surgical intervention.