AN IMPROVEMENT IN PROSTHESIS INTERSOMATIC OF LUMBAR AND SACRAL FUSION APPLIED IN THE TREATMENT OF PATHOLOGY OF TYPE MISALIGNMENT SAGITTAL, where a prosthesis (Pr) is formed by a monolithic body (1), provided with rounded corners (3), with superfies upper and lower (4) provided with grooves (4a) and also with openings passers-by (5) and holes signals with angulation (6) to which are applied the mounting bolts (Pa), being that the improvement is characterized by areas (4), upper and lower, submit each one angle variation (Δα) in the range between 30 and 75°.