Distal femoral intraosseous ganglia: cause or result of a degenerative process: 17-year follow-up of a case.

We report a case of recurrent, resistant, huge, multilocular intraosseous ganglia cyst localized at the distal femur. A 25-year-old man presented with left knee pain. Imaging studies and histological analysis confirmed the diagnosis. Treatment was curettage and bone grafting. Long-term follow-up revealed degenerative changes at radiographs and MRI. This case may contribute to make distinction between degenerative subchondral cyst and intraosseous ganglia cyst and help to understand pathogenesis of this entity.