•This is a diagnostic study for a classification for posterior spinal osteotomy procedures via the intervertebral space.•Proposed a novel classification with excellent reliability and validity, differ from the SRS-Schwab osteotomy classification.•Give a novel definition of "trans-intervertebral osteotomy" (TIO) for posterior spinal osteotomy procedures.•Thoroughly discussed about the histories of posterior spinal osteotomy procedures via the intervertebral space.•Systematically introduced the TIO technique with fine original schematics.
Keywords: Classification; Spinal deformity; Trans-intervertebral osteotomy.
© 2022 The Authors.