L5-S1 Pseudoarthrosis Rate with ALIF Versus TLIF in Adult Spinal Deformity Surgeries: A Retrospective Analysis of 100 Patients

Abstract

Lumbosacral pseudoarthrosis is a common complication following adult spine deformity (ASD) surgery. This study assessed the reoperation rate for L5-S1 pseudoarthrosis in the ASD population. Compared with TLIFs, we hypothesized that ALIF would result in lower rates of L5-S1 pseudarthrosis. This is a single-center study with patient data retrieved from a prospective ASD Database. The patients had a long-segment fusion, ALIF or TLIF at the L5-S1 level with a 2-year follow-up and were divided into two groups (TLIF and ALIF). The study's primary outcome was to assess the difference in the reoperation rate for clinical pseudoarthrosis between the TLIF and the ALIF groups. The secondary outcomes measured the radiological pseudoarthrosis rate and identified risks for L5-S1 pseudoarthrosis development. 100 patients were included; forty-nine patients (mean age 62.9 years,77.5% females) were in TLIF, and 51 patients (mean age 64.4 years,70.6% females) were in the ALIF group. Baseline characteristics were similar in both groups. Thirteen (13%) patients with L5- S1 pseudoarthroses required reoperation. Clinical pseudoarthrosis was higher in the TLIF group than in the ALIF group (12/49 vs 1/51, p<0.001). Univariate analysis demonstrated a higher risk of L5-S1 pseudoarthrosis with TLIF than ALIF (RR 12.4; 95% CI: 1.68-92.4, p<0.001). Multivariate analysis revealed 4.86 times the risk of L5-S1 clinical pseudoarthrosis with TLIF than with ALIF (RR 4.86; 95% CI 0.57-47, P=0.17), but this ratio did not reach statistical significance. No difference in reoperation risk for L5-S1 pseudarthroses was observed based on the method of IF. rhBMP-2 was noted as a significant predictor.