The present invention provides a novel minimally invasive surgical system and method for introducing instruments and/or biomaterial into the interior of a bone, particularly the interior of a vertebral body, using a unique cannulated screw that is sized and configured to penetrate the cortical bone and thereby provide access to the interior of the bone through the integral cannula of the screw. That same screw having a screw head that is then adaptable to employ a connector for securely holding a connecting device, such as a spinal rod or plate that can then be used to fix bones or bone fragments together. A method of fixing bones or bone fragments is also provided.