Inclusion criteria:  Major subjects> 18 years old Subject operated at HUS between 01/01/2010 to 31/12/2020 Subject with a surgical indication for arthrodesis and surgical correction of anterior imbalance by transpedicular osteotomy Subject not having expressed his opposition, after information, to the reuse of his data for the purposes of this research.  Exclusion criteria:  Subject having expressed opposition to participating in the study Subject under guardianship or guardianship Subject under safeguard of justice