Radiological evidence of healing of a simple bone cyst after hole drilling.

We report the long-term results with ten patients with simple bone cysts with special retrospective reference to the radiographic evidence of healing after hole drilling. Cortical thickening was initially observed within 3 months, and minimal new bone formation around Kirschner wires left in situ was observed within 4 months. New bone formation gradually progressed from the cyst wall and around the wire. Consolidation of a cyst cavity was uniformly observed 6-7 months after drilling. In several patients residual cysts were seen between the wire and cortical shell. In younger patients, a cystic cavity reappeared after extraction of the wire, although complete radiographic healing had been observed. These findings suggest that a Kirschner wire plays an important role in preventing relapse of simple bone cysts after hole drilling.