Abstract
This report is of a proximal femoral unicameral bone cyst in a patient presented at 3 years. Intra-lesional steroid injection was used to treat this large active lesion. The response to treatment was monitored with the use of dual-energy X-ray absorptiometry (DXA) scan as an indirect method of monitoring the activity of the bone cyst. The patient had developed stress fracture during the course of treatment which had remodelled fully after successful treatment with multiple injections; at 12-year follow-up, the patient reached skeletal maturity. The affected femur had remodelled back to normal radiological appearance without avascular necrosis. This has demonstrated that steroid injection is a safe and effective procedure to achieve regression of a large active bone cyst in the proximal femur. It is a minimal invasive procedure resulting in no scar. DXA scan is a useful method combining clinical assessment to monitor status of the bone cyst to allow timing of injection.