Evaluation of the efficacy of methyl prednisolone injection in treatment o f simple bone cyst to prevent all possible complications as pathological fractures and to avoid prolonged restriction of physical activity

unicameral bone cysts (UBCs) are benign, fluid-filled cavities that develop in tubular and flat bones (eg,humerus, femur). These cysts tend to expand and weaken the local bone,but they are not true neoplasms. In 1876, Virchow1 first described these lesions as cystic structures caused by abnormalities in local circulation.

UBCs are also known as simple or solitary bone cysts. They occur almost exclusively in children and adolescents (up to 85% of cases), with a reported peak between ages 3 and14 years and the average age at diagnosis being 9 years.

These lesions represent approximately 3% of all bone tumors and occur more commonly in boys than in girls (2:1). Several treatment options exist for unicameral bone cysts (UBCs), including observation, steroid injection, bone marrow injection, and Surgical procedures have ranged from simple curettage with autologous bone graft or allograft to sub periosteal resection with internal fixation and grafting

.Treatment by multiple injection of steroids produce minimal surgical approach, no hospital stay, and very low morbidity. Three or four injections over a period of 12 month may be enough

Inclusion Criteria:

• age .: all children eighteen years of age or younger with unicameral bone cyst
• Patient with previous fracture on top of unicameral bone cyst

Exclusion Criteria:

• patient age more than 18 years old
• patients with malignant tumors
• patients on chronic steroid treatment
• pregnancy

Each patient will receive a maximum of three or four injections, with at least three months between injections. The indication for a second or third injection will be based on the surgeon's judgment regarding whether the cyst will be healed or not..

Injections will be performed with the patient under general anesthesia. Under image intensifier. The diagnosis of a unicameral bone cyst will be confirmed by needle aspiration of clear or straw-colored fluid.

• Methylprednisolone acetate, 3 mg/cm3 of cyst volume with amaximum dose of 180 mg will be injected into the cyst .

If the cyst was multilocular, each cavity will be injected separately follow up of patients by radiological and clinical outcomes

radiological follow up of patients after one month of injection follow up again by x.ray after three months clinical outcome of patients after injection by visual analogue scale of pain