Ratio of lumbar 3-column osteotomy closure: patient-specific deformity characteristics and level of resection impact correction of truncal versus pelvic compensation.

PURPOSE: The resection point of a lumbar three-column osteotomy (3CO) creates separation of the spino-pelvic complex. This study investigates the impact of patients' baseline deformity and level of 3CO resection on the distribution of correction between the trunk and the pelvis following osteotomy closure. METHODS: Patients who underwent single lumbar 3CO, upper instrumented vertebra (UIV) T1-T10, and 6 month follow-up were included. The truncal and pelvic closures were calculated based on the vertebrae adjacent to the osteotomy level and the impact of radiographic parameters and level of 3CO on the closures were analyzed. RESULTS: 113 patients were included. Patients who experienced more pelvic correction had significantly higher Pelvic Tilt and lower Sagittal Vertical Axis at baseline. Patients who underwent more caudal osteotomies with higher pelvic compensation with modest SVA sustained more pelvic correction. CONCLUSIONS: The osteotomy closure is driven by patient's specific deformity. More caudal osteotomy level leads to greater pelvic tilt improvement. LEVEL OF EVIDENCE: III.