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

OBJECTIVE: Lumbosacral pseudoarthrosis is a common complication following adult spine deformity (ASD) sur-gery. This study assessed the reoperation rate for L5-S1 pseudoarthrosis in the ASD population. Compared with transforaminal lumbar interbody fusions (TLIFs), we hy-pothesized that anterior lumbar interbody fusion (ALIF) would result in lower rates of L5-S1 pseudarthrosis. -METHODS: 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 2 groups (TLIF and ALIF). The study's primary outcome was to assess the dif-ference in the reoperation rate for clinical pseudoarthrosis between the TLIF and the ALIF groups. The secondary out-comes measured the radiological pseudoarthrosis rate and identified risks for L5-S1 pseudoarthrosis development. -RESULTS: A total of 100 patients were included; 49 pa-tients (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 pseu-doarthrosis 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 (risk ratio, 12.4; 95% confidence interval: 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 (risk ratio, 4.86; 95% confidence interval 0.57-47; P [ 0.17), but this ratio did not reach statistical significance. -CONCLUSIONS: No difference in reoperation risk for L5 -S1 pseudarthrosis was observed based on the method of IF. rhBMP-2 was noted as a significant predictor.