Percutaneous vertebroplasty has been applied widely to treat bone metastases. The injected cement may strengthen the affected bone to prevent pathological fractures and relieve the pain. Moreover, the thermal reaction (70°C) due to polymerisation of cement also contributes to tumour destruction. The cement dose and diffusion pattern may be significant factors for the treatment efficacy, which can be affected by the inner pressure of the metastases. The investigators will apply a rotary cutter to destroy the structure of metastases to alleviate the pressure in the metastases. Then, more cement will be injected, which may effectively interdigitates with the surrounding bone and generate more thermo to kill the tumor cells.