Conditions: Avascular Necrosis of Femoral Head
Keywords: avascular necrosis of femoral head bisphosphonate collapse
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 110
Healthy volunteers: no

Brief summary:
The purpose of this study is to test the effect of zoledronic acid over 2 years in preventing early collapse and progression of joint dome depression (≥ 2 mm by X-ray) of the femoral head in patients with large (\> 30%: criteria according to Kim et al) nontraumatic osteonecrosis.

Detailed description:
Until now, the best treatment option in early (precollapse) large osteonecrosis femoral head is vascularizing fibular graft. However, it requires high microsurgical technique. Also it needs very long operation time (3-6hours), and morbidity associated with surgery is not low. In early stage osteonecrosis, osteoclasts are activated and resorb the necrotic portion of bone and osteoblasts are followed to lay down new bone. This process can weaken the bone function to support loading and can lead to collapse of bone. Bisphophonate can inhibit this osteoclastic bone resorption and enhance osteoblastic new bone formation. Recently, everyday oral intake of alendronate with vitamin D and calcium had a high success rate to prevent the collapse and decrease of hip joint pain in a short-term follow-up. However, the compliance or adherence to everyday oral intake is questionable. Moreover, the exact comparison based on MRI according to various classifications is not available currently. There is no report about the effect of zoledronic acid to prevent early collapse and progression of joint dome depression (≥2 mm by X-ray) of the early stage large nontraumatic osteonecrosis of the femoral head or its effect on MRI signal change after infusion of zoledronic acid in noncollapsed cases (estimated about 30% of cases) The investigators need a controlled randomized multicenter interventional study about the efficacy of bisphophonates in the treatment of ONFH.

Arms:
arm 1: aclasta group arm 2: control group

Interventions: intervention 1: zoledronic acid (aclasta)
Intervention descriptions: intervention 1: Once-yearly administration of 5mg zoledronic acid intravenously (dosage of treatment of osteoporosis) (+ calcium:1,200mg/day, VitD:800IU/day) during study period

Protocol document: