Circumferential ALIF Provides Superior Sagittal Alignment and Lower Reoperation Rates Than TLIF in Patients ≤50 Years Undergoing Lumbar Interbody Fusion.

OBJECTIVE: To compare sagittal alignment, reoperation rates, and patient-reported outcomes between anterior lumbar interbody fusion (ALIF) and transforaminal lumbar interbody fusion (TLIF) in patients ≤50 years.

SUMMARY OF BACKGROUND DATA: ALIF and TLIF are commonly used lumbar fusion techniques with known differences in alignment restoration and complication profiles. However, comparative outcomes in younger patients, who have greater long-term biomechanical demands, remain poorly defined.

METHODS: A single-institution retrospective analysis was performed on patients ≤50 years undergoing 1-2 level ALIF (stand-alone or with posterior instrumentation) or TLIF at L4-S1. Radiographic parameters (lumbar lordosis [LL], PI-LL mismatch, pelvic tilt [PT]) were assessed preoperatively and up to 2 years postoperatively. Reoperation rates and indications were recorded, with Kaplan-Meier and Cox regression analyses evaluating reoperation-free survival. Patient-reported outcomes included PROMIS Global Mental Health (GMH) and Physical Health (GPH). Multivariable regression adjusted for age, BMI, CCI, and multilevel fusion.

RESULTS: A total of 218 patients were included (ALIF stand-alone: n=60; ALIF+posterior (ALIF +P): n=47; TLIF: n=111). At 2 years, ALIF+P demonstrated greater LL and lower PI-LL mismatch compared to TLIF (P≤0.02). Reoperation rates were highest in TLIF (20.7%) versus ALIF stand-alone (10.0%) and ALIF+P (8.5%) (P=0.03). TLIF was associated with increased reoperation risk compared to ALIF+P (HR 2.13, 95% CI 1.62-2.71). Adjacent segment disease was more common in TLIF (P=0.040). Early (6-week) GMH and GPH favored TLIF (P<0.001), whereas final GPH was highest in ALIF+P (P=0.001). Subsidence rates were similar across groups (P=0.627).

CONCLUSION: In patients ≤50 years, ALIF with posterior instrumentation provides superior and durable sagittal alignment, lower reoperation rates, and improved long-term physical health compared to TLIF. Although TLIF demonstrates favorable early recovery, circumferential ALIF may offer greater long-term biomechanical and clinical benefit in younger patients.

STUDY DESIGN: Retrospective cohort study.