A system for displacing vertebral bodies, comprising: a first connecting element affixable to a first vertebra of a spine, the first connecting element including a first pedicle screw and a first cage coupled to the first pedicle screw, the first connecting element having a first passageway device connected thereto and extending proximally therefrom along a first longitudinal axis, the first passageway device defining a first passageway configured to receive a spinal fusion rod; a second connecting element affixable to a second vertebra of the spine, the second connecting element including a second pedicle screw and a second cage coupled to the second pedicle screw, the second connecting element having a second passageway device connected thereto and extending proximally therefrom along a second longitudinal axis, the second passageway device defining a second passageway configured to receive the spinal fusion rod; a first extender having a proximal end and a distal end, the distal end of the first extender having a first engagement portion configured to be advanced distally into the first passageway of the first passageway device connected to the first connecting element until the first extender reaches a first received position, in which the first engagement portion is securely engaged with the first connecting element and the first extender is received within the first passageway device along the first longitudinal axis; a second extender having a proximal end and a distal end, the distal end of the second extender having a second engagement portion configured to be advanced distally into the second passageway of the second passageway device connected to the second connecting element until the second extender reaches a second received position, in which the second engagement portion is securely engaged with the second connecting element and the second extender is received within the second passageway device along the second longitudinal axis; and a manipulation device engageable with the first and second extenders, wherein the manipulation device is configured to displace the first and second vertebrae (22, 24) with respect to one another by inducing movement of the first extender with respect to the second extender when the first and second extenders are securely engaged with the affixed first and second connecting elements, respectively, characterized in that the first engagement portion of the first extender is configured to be securely engaged with the first connecting element by receiving the first engagement portion within the first cage, and the second engagement portion of the second extender is configured to be securely engaged with the second connecting element by receiving the second engagement portion within the second cage. a first connecting element affixable to a first vertebra of a spine, the first connecting element including a first pedicle screw and a first cage coupled to the first pedicle screw, the first connecting element having a first passageway device connected thereto and extending proximally therefrom along a first longitudinal axis, the first passageway device defining a first passageway configured to receive a spinal fusion rod; a second connecting element affixable to a second vertebra of the spine, the second connecting element including a second pedicle screw and a second cage coupled to the second pedicle screw, the second connecting element having a second passageway device connected thereto and extending proximally therefrom along a second longitudinal axis, the second passageway device defining a second passageway configured to receive the spinal fusion rod; a first extender having a proximal end and a distal end, the distal end of the first extender having a first engagement portion configured to be advanced distally into the first passageway of the first passageway device connected to the first connecting element until the first extender reaches a first received position, in which the first engagement portion is securely engaged with the first connecting element and the first extender is received within the first passageway device along the first longitudinal axis; a second extender having a proximal end and a distal end, the distal end of the second extender having a second engagement portion configured to be advanced distally into the second passageway of the second passageway device connected to the second connecting element until the second extender reaches a second received position, in which the second engagement portion is securely engaged with the second connecting element and the second extender is received within the second passageway device along the second longitudinal axis; and a manipulation device engageable with the first and second extenders, wherein the manipulation device is configured to displace the first and second vertebrae (22, 24) with respect to one another by inducing movement of the first extender with respect to the second extender when the first and second extenders are securely engaged with the affixed first and second connecting elements, respectively, characterized in that the first engagement portion of the first extender is configured to be securely engaged with the first connecting element by receiving the first engagement portion within the first cage, and the second engagement portion of the second extender is configured to be securely engaged with the second connecting element by receiving the second engagement portion within the second cage.