Fig. 4

Intraoperative findings. In order to resect and ablate the nidus, a computed tomography-guided procedure was selected to minimize the invasiveness of surgery. First, the positional relationship between the nidus, triradiate cartilage, and sciatic nerve was identified using a computed tomography marker (left). After making a small incision to avoid the sciatic nerve, a guide pin was inserted toward the nidus. A 5.0 mm cannulated drill was inserted over the guide pin to remove the lesion and the specimen which resided in the cannulated drill was sent for histological study. Subsequently, heat ablation was performed using a standard electrosurgical generator to destroy any residual tumors (middle). To preserve the triradiate cartilage, the position of the electrode tip was confirmed during each step using intraoperative images (right)