After performing lumbar spine fusion (LSF) for degenerative lumbar spine disease, the researchers wanted to see if poor postoperative sagittal alignment increased revisions for adjacent segment disease (ASD). Degenerative lumbar spine illness is treated by LSF initially but eventually requires ASD revisions. Some theories propose a combination of factors as the root cause of ASD. Even so, the function of postoperative sagittal balance in this process is still debatable. Researchers looked at data from 215 consecutive patients who had LSF surgery for spinal stenosis, either with (80%) or without (20%) spondylolisthesis. The number of spinal procedures that had to be repeated was compiled from patient charts. Standing radiographs were used to assess sagittal alignment both before and after surgery. Cox proportional hazards regression model was utilized to assess the threat of ASD re-evaluations. After controlling for age, sex, pelvic incidence, fusion length, and the level of the caudal end of fusion, the researchers found that poor postoperative balance [pelvic incidence – lumbar lordosis (LL) >9°] did not significantly increase the risk of revisions for ASD crude hazard ratio [HR]=1.5 [95% CI]: 0.8-2.7), adjusted (by age, sex, pelvic incidence, fusion length, and the level of the caudal end of fusion): HR=1.7 (95% CI: 0.9–3.3). Increases in LL outside the fusion segment (segmental lordosis) were associated with a lower probability of revisions for ASD HR=0.9 (95% CI: 0.9-1.0). There was scant evidence that poor sagittal balance is a significant risk factor for ASD revisions in patients with the degenerative spinal illness. Patients with little spinal motion may be at the greatest risk for ASD.
