Abstract: Ancillary equipment for subjecting a portion of the spine to sustained stress in order to correct and/or maintain the shape of and/or the forces exerted on the vertebrae before and during the positioning of spinal implants. The equipment includes at least two engagement ends (6a, 6b, 6c, . . . and/or 6a', 6b', 6c', . . . ) for engaging one or preferably both sides of at least two separate respective vertebrae, while at the same time engaging the parallel longitudinal rails (3) of a frame-like support (1) via corresponding corrective branches (4a, 4b, 4c, . . . and/or 4a', 4b', 4c', . . . ) and a removable base (5) of said engagement ends, and further includes members (13, 17, 43, 65) for adjusting and locking the engagement ends (6a, 6b, 6c, . . . and/or 6a', 6b', 6c', . . . ) in their relative positions in each or a combination of three orthogonal directions.