Comparison of adjacent segment disease after minimally invasive or open transforaminal lumbar interbody fusion.

Adjacent segment disease (ASD) is a potential long-term risk after lumbar fusion. Its incidence has been evaluated in anterior and posterior lumbar interbody fusions, but few studies have focused on transforaminal lumbar interbody fusion (TLIF). Relative risk of ASD with open or minimally invasive (MI) TLIF is poorly understood. To report our experience with risk for ASD in patients receiving TLIF and test its association with surgical approach, we performed a retrospective cohort study based on medical record review at a single institution. Eligible patients were ⩾ 18 years old at operation, underwent single-level TLIF during the period 2007-2008, and had at least 6 months postoperative follow-up. Patients were categorized by surgical approach (open versus MI). Primary outcome of interest was development of symptomatic ASD, defined by (1) new back and/or leg pain, (2) imaging findings adjacent to original surgical level, and (3) decision to treat. A total of 68 patients (16 open, 52 MI) were included in the analysis. Groups had similar baseline characteristics, except the open group tended to be older (p=0.04). Seven (10%) patients developed ASD. Mean patient age was 62 years and three were male. Three underwent open and four underwent MI TLIF. Risk of ASD did not differ significantly by surgical approach. The MI group showed a trend toward decreased risk of ASD compared to the open group, although it was not statistically significant. This suggests MI TLIF may be associated with decreased long-term morbidity compared to the open approach. Large prospective studies are needed to confirm these findings.