New diagnostic support tool for lumbosacral foraminal stenosis using radiographs of the lumbar spine

Detection of lumbar foraminal stenosis (LFS) is difficult using common diagnostic methods, resulting in poor outcomes after lumbar spine surgery. This study aimed to develop a new support tool to detect lumbosacral foraminal stenosis. At our hospital, the following parameters were examined on standing radiographs of the lumbar spine in 100 patients who underwent surgery for lumbar spinal canal and/or foraminal stenosis: 1) presence or absence of the inclination of L5 toward the symptomatic side, 2) distance between the pedicle of L5 and S1, 3) width of the transverse process of L5, 4) distance between the transverse process of L5 and the sacral ala, 5) length of the lateral osteophyte of L5, 6) lumbosacral angle, 7) disc height of L5-S1, and 8) presence or absence of spondylolisthesis of L5. Logistic regression analysis, using cut-off values calculated by receiver operating characteristic (ROC) curve analysis, indicated that the presence of inclination in L5, length of the lateral osteophyte (≥4 mm), distance between the transverse process of L5 and the sacral ala (≤9 mm), and disc height of L5-S1 (≤5 mm) were significantly related to LFS at L5-S1 with odds ratios of 29.07, 38.83, 5.04, and 27.84, respectively. The p-value of the support tool, consisting of the odds ratios above, was 0.724 as per the Hosmer-Lemeshow analysis. ROC analysis demonstrated a cut-off value of 62 for this scoring system with 98% sensitivity and 80% specificity. Hence, we propose that this support tool could be reliably used in clinical practice.