Devices and methods for performing percutaneous spinal surgery under direct visualization and through a single cannula are shown. A device (10) is provided which includes an elongated cannula (20) having a first inner diameter (D.sub.I) and an outer diameter (D.sub.O) sized for percutaneous introduction...http://www.google.es/patents/US6206822?utm_source=gb-gplus-sharePatente US6206822 - Devices and methods for percutaneous surgery
