An extender comprising: an inner member defining a longitudinal axis (a) and including an outer wall defining a thread form, the inner member further including at least one extension including a first sliding contact surface which includes a keyway surface and a keyway surface, wherein said surfaces (54, 56) are spaced apart about an expandable axial slot which is expandable and contractible, wherein the surfaces (54, 56) respectively include a proximal portion (60, 276), an intermediate portion (62, 278) and a distal portion (64, 280); and an outer member including an actuator having a first part, the outer member further including at least one arm having a first projection slidably engagable within the portions (60, 62, 64) of the one of the surfaces (54, 56) and a second projection slidably engagable within the portions (276, 278, 280) of the other of the surfaces (54, 56), wherein the actuator is rotatable so that the first part engages the thread form to axially translate the inner member relative to the outer member such that the projections (130, 132) are disposable between a first position such that the projections are engaged within the distal portions (64, 280) of the respective surface (54, 56) and the inner member is disposed in a non-expanded orientation, a second position such that projections (130, 132) are engaged within the intermediate portions (62, 278) of the respective surface (54, 56) and the inner member is disposed in an expanded orientation, and a third position such that the projections (130, 132) are engaged within the proximal portions (60, 276) of the respective surface (54, 56) and the inner member is disposed in an expanded orientation. an inner member defining a longitudinal axis (a) and including an outer wall defining a thread form, the inner member further including at least one extension including a first sliding contact surface which includes a keyway surface and a keyway surface, wherein said surfaces (54, 56) are spaced apart about an expandable axial slot which is expandable and contractible, wherein the surfaces (54, 56) respectively include a proximal portion (60, 276), an intermediate portion (62, 278) and a distal portion (64, 280); and an outer member including an actuator having a first part, the outer member further including at least one arm having a first projection slidably engagable within the portions (60, 62, 64) of the one of the surfaces (54, 56) and a second projection slidably engagable within the portions (276, 278, 280) of the other of the surfaces (54, 56), wherein the actuator is rotatable so that the first part engages the thread form to axially translate the inner member relative to the outer member such that the projections (130, 132) are disposable between a first position such that the projections are engaged within the distal portions (64, 280) of the respective surface (54, 56) and the inner member is disposed in a non-expanded orientation, a second position such that projections (130, 132) are engaged within the intermediate portions (62, 278) of the respective surface (54, 56) and the inner member is disposed in an expanded orientation, and a third position such that the projections (130, 132) are engaged within the proximal portions (60, 276) of the respective surface (54, 56) and the inner member is disposed in an expanded orientation.