Disclosed herein are tissue-removal devices and methods for treating spinal diseases using such devices. The tissue-removal devices may comprise a cable and/or extendable elements with a retracted and a deployed configuration. The cable and/or extendable elements may be distally supported and restrained by a support element such that the support element may be pushed transversely away when the extendable element is distally extended into its deployed configuration. An annular cutting element may be provided about the distal end of the extendable element or the support element. Various configurations of the extendable and support elements are described herein, as well as methods of using tissue-removal devices with extendable and support elements coupled by an annular cutting element for treating spinal diseases.