Several deformities of the spine exist such as the anterior imbalance. These deformities can generate functional discomfort and limit the patient's quality of life.

In the event of severe trunk imbalance and progression of the deformity, operative correction of the spinal deformity by instrumentation and posterior arthrodesis may be indicated.

Surgical techniques and instrumentation have evolved over the past 5 years. These changes in surgical strategies have a potential impact on the patient's quality of life and the correction results in the medium and long term.

the aim of the study is to analyze the surgical corrections obtained by transpedicular osteotomy and radiological changes over time with classic 2-rod techniques versus modern 4-rod instrumentation techniques

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

Major subjects with a surgical indication for arthrodesis and surgical correction of anterior imbalance by transpedicular osteotomy