Impact of Spina Bifida Occulta on Sacral Morphology and Facet Tropism in Adolescents

Study Design: Cross-sectional, observational. Objective: To investigate the impact of SBO on sacral morphology and facet tropism in adolescents. Summary of Background Data: Limited information is available on sacral morphology and facet joint changes associated with SBO in adolescents. The association between SBO and sagittal facet tropism is not well described in this age group. Materials and Methods: Lumbosacral computed tomography (CT) was used to assess sacral morphology and facet joint orientation in 100 adolescents with low back pain. Evaluated parameters included the presence of SBO, lumbosacral transitional vertebrae, and spondylolysis. Morphologic features assessed were sacral laminar fusion (graded on a 5-point scale), iliac crest height (classified into 6 types), and facet joint orientation in both the axial and sagittal planes. The patients were divided into SBO-positive (SBO+) and SBO-negative (SBO–) groups and investigated for associations with lumbar spondylolysis, sacral morphology, and facet tropism. Results: SBO was present in 50% of all patients, lumbosacral transitional vertebra in 7%, and lumbar spondylolysis in 42%. Facet tropism was identified in 13% of patients in the axial plane and 21% in the sagittal plane. The SBO+ group contained a significantly higher proportion of men ( P =0.035) and a greater prevalence of spondylolysis ( P =0.013), particularly at L5 ( P =0.044). Sacral laminar fusion grades were significantly lower at the S1/S2 level in the SBO+ group ( P =0.049). Sagittal facet tropism (≥7.1°) was more frequent in the SBO+ group ( P =0.024). Unilateral L5 spondylolysis occurred in 16% of the SBO+ group and 8% of the SBO– group, with vertical facet concordance rates of 50% and 75%. SBO correlated positively with sagittal facet tropism (r=0.307, P =0.002) and lower S1/S2 fusion grades (r=−0.197, P =0.049). Multivariable logistic regression identified sagittal facet tropism as an independent risk factor for SBO (odds ratio: 1.175, 95% CI: 1.002–1.395, P =0.047). Conclusions: Sagittal facet tropism was independently associated with SBO. SBO was also linked with male sex, delayed sacral fusion, and higher rates of spondylolysis, particularly at L5.