[Treatment of solitary bone cysts by intra-medullary nailing or steroid injection in children].

PURPOSE OF THE STUDY

Several methods are used to treat essential bone cysts in children: curettage with bone graft, simple drainage, steroid injection, intramedullary nailing. No one method is preferred by all. We compared two retrospective series of children with solitary bone cysts treated by steroid injection or intramedullary nailing.

MATERIAL AND METHODS

Seventy-two cysts were treated by the same team: 54 by injection of methylprednisolone, and 18 by intramedullary nailing. Fifty cysts were disclosed by bone fracture. The others were revealed by pain or discovered fortuitously. Seventy-five percent of the patients were boys. The humerus was involved in two-thirds of the cases. Patient age ranged from 5 to 10 years. Intramedullary nailing was used for the femur in 10 cases and the humerus for 8. Steroid injections were given after cyst opacification using 160 mg per injection, total mean dose 800 mg (range 80-2400 mg).

RESULTS

Cure was obtained at 4 years on the average, with no difference between the two series. Complications observed were transient or definitive and more severe in patients treated by steroid injections. Most of the complications were transient effects of steroid overdosage or limb length discrepancy: 7 shortenings (1-8 cm) for injected cysts (all in patients given > 100 mg methylprednisolone), compared with 2 shortenings<2 cm after intramedullary nailing.

DISCUSSION

Steroid injections have been used for many years with variable results depending on the reported series. Cyst opacification before injection is recommended to identify anomalies which could compromise outcome. Strict compliance with the rules of steroid treatment is required to avoid complications, as observed in our patients, which are dose dependent. The percutaneous method is attractive but can be used with other products such as bone marrow or bone substitutes to optimize results. Intramedullary nailing has the advantage of providing immediate support of the damaged bone while allowing cyst drainage and evacuation of the lytic segments. This method should probably be preferred for weight-bearing segments whether the cyst is associated with fracture or not. For non-weight-bearing segments, the choice between percutaneous treatment, and the substance to use, and intramedullary nailing depends largely on bone quality.