Posterolateral fusion with interbody for lumbar spondylolisthesis is associated with less repeat surgery than posterolateral fusion alone

Objective Posterior or transforaminal lumbar interbody fusions (PLIF/TLIF) may improve the outcomes in patients with lumbar spondylolisthesis. This study aims to compare outcomes after posterolateral fusion (PLF) only versus PLF with interbody fusion (PLF + PLIF/TLIF) in patients with spondylolisthesis. Methods We retrospectively reviewed103 patients who underwent first-time instrumented lumbar fusions for degenerative or isthmic spondylolisthesis. Anterior techniques and multilevel interbody fusions were excluded. All patients were followed for at least 2 years postoperatively. Clinical outcomes including back pain, radiculopathy, weakness, sensory deficits, and loss of bowel/bladder function were ascertained from clinic notes. Radiographic measures were calculated with Tillard percentage of spondylolisthesis. Reoperation for progression of degenerative disease, a primary endpoint, was indicated for all patients with (1) persistent or new-onset neurological symptoms; and (2) radiographic imaging that correlated with clinical presentation. Results Of the 103 patients, 56.31% were managed with PLF and 43.69% with PLF + PLIF/TLIF. On radiographic studies, spondylolisthesis improved by a mean of 13.06% after PLF + PLIF/TLIF versus 5.67% after PLF (p < 0.001). In comparison to PLF + PLIF/TLIF, patients undergoing PLF experienced higher rates of postoperative improvement in back pain, sensory deficits, motor weakness, radiculopathy, and bowel/bladder difficulty; however, these differences did not reach statistical significance. The PLF cohort had a significantly higher incidence of reoperation (p = 0.011) and pseudoarthrosis/instrumentation failure (p = 0.043). In the logistical analyses, non-interbody fusion was the strongest predictor of reoperation for progression of degenerative disease. Conclusion Compared to PLF only, PLF + PLIF/TLIF were statistically significantly associated with a greater correction of spondylolisthesis. Patients with interbody fusions were less likely to undergo reoperation for degenerative disease progression compared to non-interbody fusions. However, greater listhesis correction and decreased reoperation in the PLF + PLIF/TLIF cohort should be weighed with favorable clinical outcomes in the PLF cohort.