A study to evaluate safety and feasibility of zoledronic acid to prevent joint complication (osteonecrosis) following chemotherapy for acute lymphoblastic leukemia or lymphoma in children and adolescents.

This study is testing whether a bone-protecting drug called zoledronic acid can prevent osteonecrosis — a painful condition where bone tissue dies near joints — in children and teenagers being treated for acute lymphoblastic leukaemia (ALL) or lymphoblastic lymphoma. Chemotherapy can sometimes damage bone tissue, especially in larger joints. Children over 10 will receive zoledronic acid as an IV infusion twice during chemotherapy, while those aged 5–10 will be observed closely without the drug. All participants will be monitored with blood tests and imaging for up to 2 years. You may be eligible if: - Your child is between 5 and 16 years old - Your child has been diagnosed with acute lymphoblastic leukaemia or lymphoblastic lymphoma - Children aged 5–10 must be able to have an MRI scan without general anaesthesia You may NOT be eligible if: - Your child has very low vitamin D levels (25-hydroxy vitamin D below 50 nmol/L) - Your child has low blood calcium - Your child has previously used bisphosphonate medications - Your child has severely reduced kidney function (GFR below 35 ml/min) - Your child has active uveitis (eye inflammation) - Your child has a primary bone disease such as osteogenesis imperfecta - Your child requires general anaesthesia for MRI Talk to your doctor about whether this trial might be right for you.