Sagittal Balance and Spinopelvic Parameters After Lateral Lumbar Interbody Fusion for Degenerative Scoliosis

Study Design. Retrospective matched-cohort analysis. Objective. To evaluate the change in radiographical parameters in patients undergoing interbody fusion and posterior instrumentation compared with posterior spine fusion (PSF) alone for degenerative scoliosis. Summary of Background Data. Little is known about the effect of lateral interbody fusion (LIF) on sagittal plane correction in the setting of degenerative scoliosis. We performed a retrospective study to investigate these changes compared with PSF. Methods. Between 1997 and 2011, 33 patients had LIF at 181 levels between T8 and L5 vertebrae for the treatment of degenerative scoliosis (mean; 5 +/- 2 levels). Of those, 23 patients had additional anterior lumbar interbody fusion (ALIF) at 37 levels between L4 and S1 vertebrae (mean; 1.6 +/- 0.5 levels). A 1: 1 matched control of patients who underwent PSF was performed. Patients were matched by age, sex, and diagnosis. Clinical and radiographical data were collected and compared between the matched cohorts. Results. Lumbar lordosis (LL) was significantly restored in the LIF +/- ALIF compared with PSF cohort (44 degrees +/- 14 degrees vs. 36 degrees +/- 15 degrees, P = 0.02). The segmental LL over the 102 LIF levels signifi cantly improved from 12 degrees +/- 10 degrees to 21 degrees +/- 13 degrees postoperatively (P < 0.0001). However, the change over the 37 ALIF levels was not signifi cant (from 30 degrees +/- 15 degrees to 29 degrees +/- 9 degrees, P = 0.8). Sagittal plane alignment was improved in the LIF +/- ALIF compared with PSF cohort and trended toward but did not reach significance (3.8 +/- 3.2 cm vs. 6.2 +/- 5.7 cm, P = 0.09). Sacral slope was signifi cantly higher in the LIF +/- ALIF compared with PSF cohort (33 degrees +/- 11 degrees vs. 28 degrees +/- 10 degrees, P = 0.03). Pelvic tilt was lower in the LIF +/- ALIF compared with PSF cohort and trended toward but did not reach significance (22 degrees +/- 10 degrees vs. 26 degrees +/- 10 degrees, P = 0.08). Conclusion. LL and sacral slope had mildly but statistically improved in the interbody fusion cohort compared with PSF cohort. Sagittal alignment and pelvic tilt trended toward but did not reach statistical signifi cance. Segmental LL was improved at LIF levels more than at ALIF levels.