Fig. 2

A typical case of COO subgroup, male, 49 years, the patient had a history of talus fractures 10 years ago, and followed by aseptic necrosis talus with ankle arthritis for 5 years. a, b Anteroposterior and lateral X-ray film 3 days before operation, we can found that the talus was severely varus and collapsed, and was hardened with a lot of sequestrum. c, d Anteroposterior and lateral X-ray film 3 days after operation; we made distal fibular osteotomy and large lesion cleaning, the distal fibula was separated and crushed, for impacted and structural bone grafting, the joint space was filled and pressurized. e, f Anteroposterior and lateral X-ray film 3 months after operation; no obvious internal fixation loosening was observed, and a small number of bone bridges were found in the joint space. However, the ankle fusion was not ideal at this point, and the patient had been found a good fusion 6 months after operation