In patients with contraction osteochondrosis in segment L V/S I, spondylodesis in segment L V/S I is - for anatomical reasons - more likely to be linked to reversible nerve irritations than with segment L IV/V. In some cases, conversion from TLIF on ALIF is necessary. In patients with degenerative spine disease, TLIF in segments L IV/V and L V/S I is absolutely accepted as a safe and up-to-date procedure.