Study Design
Retrospective matched–cohort analysis.
Objective
To evaluate the change in radiographic parameters in patients undergoing interbody fusion and posterior instrumentation compared to posterior spine fusion alone (PSF) 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 to 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, gender, and diagnosis. Clinical and radiographic data were collected and compared between the matched cohorts.
Results
Lumbar lordosis was significantly restored in LIF±ALIF compared to PSF cohort (44°±14° versus 36°±15°, p=0.02). The segmental lumbar lordosis 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 LIF±ALIF compared to PSF cohort and trended toward but did not reach significance (3.8±3.2 cm versus 6.2±5.7 cm, p=0.09). Sacral slope was significantly higher in LIF±ALIF compared to PSF cohort (33°±11° versus 28°±10°, p=0.03). Pelvic tilt was lower in LIF±ALIF compared to PSF cohort and trended toward but did not reach significance (22°±10° versus 26°±10°, p=0.08).
Conclusion
Lumbar lordosis and sacral slope were mildly but statistically improved in the interbody fusion cohort compared to PSF cohort. Sagittal alignment and pelvic tilt trended toward but did not reach statistical significance. Segmental lumbar lordosis was improved at LIF levels more than at ALIF levels.