L3-L4 Hyperlordosis and Decreased Lower Lumbar Lordosis Following Short-Segment L4-L5 Lumbar Fusion Surgery is Associated With L3-L4 Revision Surgery for Adjacent Segment Stenosis

Retrospective review of prospective cohort.Reoperation at L3-L4 for adjacent segment disease (ASD) is common after L4-L5 spine fusion. L4-S1 lower lumbar lordosis (LLL) accounts for the majority of global lumbar lordosis (GLL) and is modifiable during surgery. We sought to determine if a reduction in LLL leads to an increase in L3-L4 focal lumbar lordosis (L3-L4 FLL) and resulting risk of ASD at L3-L4.We reviewed the records of a prospective cohort with lumbar spinal stenosis who underwent L4-L5 or L4-L5-S1 fusion between 2006 and 2012. Radiographic parameters-GLL, LLL, L3-L4 FLL, upper lumbar lordosis, lordosis distribution index, pelvic tilt, and pelvic incidence-were extracted from preoperative and postoperative lumbar spine radiographs. Statistical comparisons were made between those who underwent revision for post-fusion adjacent level stenosis at L3-L4 (REVISION) and those who did not (NO REVISION).Inclusion criteria were met by 104 patients. The REVISION cohort included 19 individuals. No significant differences in baseline demographics or operative details for the index procedure were found between groups. Postoperatively, when compared to the NO REVISION cohort, the REVISION cohort had a decrease in LLL (-2.6° vs + 1.5°, P = .011) and LDI (-5.1% vs + 1.3%, P = .039), and an increase in L3-L4 FLL (+2.6° vs -.6°, P = .001).A reduction in LLL and compensatory increase in L3-L4 FLL after initial lower lumbar fusion surgery resulted in more reoperation at L3-L4 for post-fusion adjacent level spinal stenosis.