An instrument for correcting a position of one or more vertebrae of a spine is provided, the instrument includinga first implant extension (1) having a first end portion (1a) configured to releasably engage a vertebral implant, a second end portion (1b) and a longitudinal axis (21) extending between the first end portion and the second end portion,a second implant extension (2) having a first end portion (2a) configured to releasably engage a vertebral implant and a second end portion (2b) and a longitudinal axis (22) extending between the first end portion and the second end portion,a connecting device (5) for connecting the first implant extension (1) and the second implant extension (2)wherein the connecting device (5) comprises a first clamping member (6) configured to be fixed to the first implant extension (1) and a second clamping member (7) configured to be fixed to the second implant extension (2) and wherein the first clamping member (6) is connected to the second clamping member (7) through a connecting portion (8) and wherein the connecting portion (8) and the first and second clamping members (6, 7) are stnictured and arranged to allow polyaxial orientation between the first clamping member (6) and the connection portion (8) and between the second clamping member (7) and the connection portion (8)and wherein at least the first clamping member (6) is mountable onto the first implant extension (1) from the second end (1b) thereof.
