Radiographic Factors Affecting Lordosis Correction After Transforaminal Lumbar Interbody Fusion With Unilateral Facetectomy.

BACKGROUND The study design was a retrospective cohort study. The objective was to identify preoperative (preop) radiographic features that are associated with increased lordosis correction after transforaminal lumbar interbody fusion (TLIF). METHODS We retrospectively reviewed a single surgeon series of TLIF performed at L4-5 since 2010. The surgical technique involved unilateral facetectomy and insertion of a banana-type cage. A total of 107 cases were available with plain radiographs, and 62 with a preop computed tomography (CT) scan. We compared segmental lordosis correction between the preop and 6-week postoperative radiographs. Patients were divided into groups of those with or without more than 5° lordosis correction. Radiographic features were then compared, and a multivariate analysis was performed. RESULTS The mean lordosis correction of the entire cohort was 2.5° (range = -9° to 16°). The percentage of patients with a vacuum disc on the preop CT (40% vs 10%, P = 0.01) was higher in the group with greater than 5° lordosis correction, whereas the mean preop segmental lordosis (14.3° vs 18.6°) and the preop segmental disc angle (6.4° vs 8.4°) were both lower (P < 0.05 for each). The percentage of patients with a Meyerding grade of 2 or higher (28% vs 16%) trended higher but was not significant (P = 0.1). There was no significant difference in the mean body mass index, patient age, preop lumbar lordosis, or disc space height. CONCLUSIONS Patients with a preop vacuum disc sign on CT scan or those with a more kyphotic disc space on preop radiographs were more likely to achieve lordosis correction. This information may be useful in preop planning. LEVEL OF EVIDENCE 4. CLINICAL RELEVANCE Unilateral TLIF is likely to be neutral or kyphogenic in patients with a segmental disc angle that is neutral or lordotic pre-operatively, but is likely to increase segmental lordosis in patients with a disc angle that is kyphotic pre-oepratively.