Fig. 2From: Chondroblastoma of the patella with secondary aneurysmal bone cyst, an easily misdiagnosed bone tumor:a case report with literature reviewFigures before and after bone grafting at the focus during the surgery (a). The focus was debrided through the oval cortical window on the anterior patella. Multiple partitions of the focus were removed and the cartilage surface of the patella was complete (b). Autologous bone was grafted at the focus and filled the latter wellBack to article page