Aim: Unicameral bone cysts are difficult to treat as partial cyst healing may reverse and it may be difficult to assess between active and latent types.

Materials and Methods: 19 patients with unicameral bone cysts were reviewed with a mean age of 8.5 years (16 males and 3 females). These 19 patients were reviewed over a period of fifteen years and all except one, had an active cyst abutting the growth plate. 18 cases were treated with curettage and burring using a dental burr and six cases were treated with elastic nailing. 12 cases were treated with bone marrow injection either alone or in combination with the above procedures. 2 cases were treated with steroid injections. No cases were bone grafted.

Results: The best results were obtained with curettage and burring of the lining of the cysts. Bone marrow injection alone did not produce resolution of any of the cysts. Migration of the cysts away from the growth plate in response to treatment (conversion from active to latent status) was predictive of successful treatment with no symptoms and no further fractures, irrespective of the age of the patient.

Conclusion: Successful treatment of unicameral bone cysts can be predicted by the appearance of normal bone formation by the physis and subsequent migration of the cyst away from the growth plate. The association of successful treatment and conversion to latency of the cyst has not previously been reported.