A Morphometric Analysis of Neuroforamen in Grade I Isthmic Spondylolisthesis by Anterior Lumbar Interbody Fusion with Pedicle Screw Fixation

ABSTRACT

OBJECTIVES: The aim of this study was to evaluate the morphometric changes in neuroforamen in grade I isthmic spondylolisthesis by anterior lumbar interbody fusion (ALIF). METHODS: Fourteen patients with grade I isthmic spondylolisthesis who underwent single level ALIF with percutaneous pedicle screw fixation were enrolled. All patients underwent standing lateral radiography and magnetic resonance imaging (MRI) before surgery and at 1 week after surgery. For quantitative analysis, the foraminal height, foraminal width, epidural foraminal height, epidural foraminal width, and epidural foraminal area were evaluated at the mid-portion of 28 foramens using T2-weighted sagittal MRI. For qualitative analysis, degree of neural compression in mid-portion of 28 foramens was classified into 4 grades using T2-weighted sagittal MRI. Clinical outcomes were assessed using Visual Analogue Sale (VAS) scores for leg pain and Oswestry disability index before surgery and at 1 year after surgery. RESULTS: The affected levels were L4-5 in 10 cases and L5-S1 in 4. The mean foraminal height was increased (p<0.001), and the mean foraminal width was decreased (p=0.014) significantly after surgery. The mean epidural foraminal height (p<0.001), epidural foraminal width (p<0.001), and epidural foraminal area (p<0.001) showed a significant increase after surgery. The mean grade for neural compression was decreased significantly after surgery (p<0.001). VAS scores for leg pain (p=0.001) and Oswestry disability index (p=0.001) was decreased significantly at one year after surgery. CONCLUSION: Foraminal stenosis in grade I isthmic spondylolisthesis may effectively decompressed by ALIF with percutaneous pedicle screw fixation.