This trial will be a pilot study to find out if zoledronic acid improves the response to chemotherapy in high grade osteosarcoma. In arm A of the study, 40 adult patients will be randomised into two groups. One group will get standard chemotherapy and the other group will get Zoledronic acid in addition to chemotherapy. The investigators will assess the histological necrosis as well as disease status for up to 2 years.

In Arm B, adult patients with relapsed disease or advanced disease who are unable to take any other therapy and are given only symptomatic care will be given 6 doses of zoledronic acid and followed up for disease status. This will be to determine the role of zoledronic acid as a single agent.

Inclusion Criteria:

1. Adult patients (between the ages of 18 to 65 years) with a recently diagnosed high grade osteosarcoma of the extremity
2. Non Metastatic at presentation. The metastases are ruled out by a CT scan of the chest and a PET scan.
3. Patients are willing and able to afford the standard chemotherapy.

Exclusion Criteria:

1. Non-extremity sarcomas. (pelvis and spine)
2. Age less than 18 years or greater than 65 years
3. Metastatic at presentation
4. Pregnant or lactating women
5. Renal dysfunction in the form of elevated serum creatinine
6. Dental treatment anticipated after evaluation.
7. Patients who have received or are likely to receive steroids.