Study design:

A retrospective observational study.

Objectives:

The type of sagittal profile defined by Roussouly has affected spinal degeneration and surgical outcome. This study aimed to investigate the effect of preoperative Roussouly classification on pain intensity and radiological data of lumbar degenerative disease (LDD) patients who underwent indirect decompression with lateral lumbar interbody fusion (LLIF).

Methods:

We retrospectively investigated 102 patients who underwent LLIF without direct decompression. Patients were subdivided into four groups according to the Roussouly classification determined from preoperative full-length and lateral spine X-rays, and classified according to Roussouly types I, II, and IV in the nonstandard group and Roussouly type III in the standard group.

Results:

The nonstandard group showed improved sagittal vertical axis and lumbar lordosis after LLIF surgery, but the midsagittal canal diameter and axial central canal area of the thecal sac using T2-weighted sagittal and axial MRI were smaller than that in the standard group. On the other hand, each numeric rating scale (NRS) score one year after surgery improved in all patients. Changes in NRS scores in low back pain, leg pain, and numbness were not statistically significant between Roussouly classification types.

Conclusion:

These results suggest that the nonstandard group may have less indirect decompression effect from LLIF than the standard group. In the short term, we show for the first time after LLIF surgery that preoperative sagittal spinal alignment and the pelvic position may not significantly impact pain improvement.