a method and system for fusing a region in the spine involve the use of at least one guide tube to pass instruments and substances into the spinal region in a minimally invasive manner . in the preferred practice of the method , a guide tube is anchored to a vertebra and the guide tube is moved to thereby position the vertebra . a steerable drilling tool is passed through the guide tube and steered into position to abrade at least a portion of an intervertebral disc and thereby create a cavity in the disc . a flowable substance is passed into the cavity and permitted to solidify to establish fusion in the cavity . optionally , an uninflated balloon is inserted into the cavity and the balloon is filled with the flowable substance to contain the flowable substance .