Sagittal balance and spinopelvic parameters after lateral lumbar interbody fusion for degenerative scoliosis: a case-control study

Abstract

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° ± 14° vs. 36° ± 15°, P = 0.02). The segmental LL over the 102 LIF levels significantly improved from 12°± 10° to 21°± 13° postoperatively (P < 0.0001). However, the change over the 37 ALIF levels was not significant (from 30° ± 15° to 29° ± 9°, 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 significantly higher in the LIF ± ALIF compared with PSF cohort (33° ± 11° vs. 28° ± 10°, P = 0.03). Pelvic tilt was lower in the LIF ± ALIF compared with PSF cohort and trended toward but did not reach significance (22° ± 10° vs. 26° ± 10°, 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 significance. Segmental LL was improved at LIF levels more than at ALIF levels.

Level of evidence: 3.

Figure 1

Preoperative and postoperative full–length coronal and sagittal standing radiographs for a 66–year old male patient diagnosed with progressive degenerative scoliosis. He had a surgical history of posterior in situ fusion (L4–Sacrum). He underwent circumferential spine surgery with a total of eight lateral interbody fusion levels and percutaneous posterior fusion using pedicle screws (T8–Sacrum).

	Coronal Cobb angle (°)	SVA	LL	PT	SS	PI
Preoperative	15°	13 cm	43°	33°	34°	67°
Postoperative	6°	4.1 cm	57°	29°	35°	64°
Sagittal Vertical Alignment (SVA), Lumbar Lordosis (LL), Pelvic Tilt (PT), Sacral Slope (SS), and Pelvic Incidence (PI).

Figure 1

Preoperative and postoperative full–length coronal and sagittal standing radiographs for a 66–year old male patient diagnosed with progressive degenerative scoliosis. He had a surgical history of posterior in situ fusion (L4–Sacrum). He underwent circumferential spine surgery with a total of eight lateral interbody fusion levels and percutaneous posterior fusion using pedicle screws (T8–Sacrum).

	Coronal Cobb angle (°)	SVA	LL	PT	SS	PI
Preoperative	15°	13 cm	43°	33°	34°	67°
Postoperative	6°	4.1 cm	57°	29°	35°	64°
Sagittal Vertical Alignment (SVA), Lumbar Lordosis (LL), Pelvic Tilt (PT), Sacral Slope (SS), and Pelvic Incidence (PI).

Figure 2

The mean and upper standard deviation for preoperative and postoperative radiographical parameters of the LIF ± ALIF cohort and PSF cohort were shown. P values of paired t tests were also presented. LIF indicates lateral interbody fusion; ALIF, anterior lumbar interbody fusion; PSF, posterior spine fusion.

Figure 2

The mean and upper standard deviation for preoperative and postoperative radiographical parameters of the LIF ± ALIF cohort and PSF cohort were shown. P values of paired t tests were also presented. LIF indicates lateral interbody fusion; ALIF, anterior lumbar interbody fusion; PSF, posterior spine fusion.