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  • Author or Editor: Kazuhide Inage x
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Shiho Nakano, Masahiro Inoue, Hiroshi Takahashi, Go Kubota, Junya Saito, Masaki Norimoto, Keita Koyama, Atsuya Watanabe, Takayuki Nakajima, Yusuke Sato, Shuhei Ohyama, Sumihisa Orita, Yawara Eguchi, Kazuhide Inage, Yasuhiro Shiga, Masato Sonobe, Arata Nakajima, Seiji Ohtori, Koichi Nakagawa, and Yasuchika Aoki

OBJECTIVE

The authors sought to evaluate the relationship between the difference in lumbar lordosis (DiLL) in the preoperative supine and standing positions and spinal sagittal alignment in patients with lumbar spinal stenosis (LSS) and to determine whether this difference affects the clinical outcome of laminectomy.

METHODS

Sixty patients who underwent single-level unilateral laminectomy for bilateral decompression of LSS were evaluated. Spinopelvic parameters in the supine and standing positions were measured preoperatively and at 3 months and 2 years postoperatively. DiLL between the supine and standing positions was determined as follows: DiLL = supine LL − standing LL. On the basis of this determination patients were then categorized into DiLL(+) and DiLL(−) groups. The relationship between DiLL and preoperative spinopelvic parameters was evaluated using Pearson’s correlation coefficient. In addition, clinical outcomes such as visual analog scale (VAS) and Oswestry Disability Index (ODI) scores between the two groups were measured, and their relationship to DiLL was evaluated using two-group comparison and multivariate analysis.

RESULTS

There were 31 patients in the DiLL(+) group and 29 in the DiLL(−) group. DiLL was not associated with supine LL but was strongly correlated with standing LL and pelvic incidence (PI) − LL (PI − LL). In the preoperative spinopelvic alignment, LL and SS in the standing position were significantly smaller in the DiLL(+) group than in the DiLL(−) group, and PI − LL was significantly higher in the DiLL(+) group than in the DiLL(−) group. There was no difference in the clinical outcomes 3 months postoperatively, but low-back pain, especially in the sitting position, was significantly higher in the DiLL(+) group 2 years postoperatively. DiLL was associated with low-back pain in the sitting position, which was likely to persist in the DiLL(+) group postoperatively.

CONCLUSIONS

We evaluated the relationship between DiLL and spinal sagittal alignment and the influence of DiLL on postoperative outcomes in patients with LSS. DiLL was strongly correlated with PI − LL, and in the DiLL(+) group, postoperative low-back pain relapsed. DiLL can be useful as a new spinal alignment evaluation method that supports the conventional spinal sagittal alignment evaluation.

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Yawara Eguchi, Masaki Norimoto, Munetaka Suzuki, Ryota Haga, Hajime Yamanaka, Hiroshi Tamai, Tatsuya Kobayashi, Sumihisa Orita, Miyako Suzuki, Kazuhide Inage, Hirohito Kanamoto, Koki Abe, Tomotaka Umimura, Takashi Sato, Yasuchika Aoki, Atsuya Watanabe, Masao Koda, Takeo Furuya, Junichi Nakamura, Tsutomu Akazawa, Kazuhisa Takahashi, and Seiji Ohtori

OBJECTIVE

The purpose of this study was to determine the relationship between vertebral bodies, psoas major morphology, and the course of lumbar nerve tracts using diffusion tensor imaging (DTI) before lateral interbody fusion (LIF) to treat spinal deformities.

METHODS

DTI findings in a group of 12 patients (all women, mean age 74.3 years) with degenerative lumbar scoliosis (DLS) were compared with those obtained in a matched control group of 10 patients (all women, mean age 69.8 years) with low-back pain but without scoliosis. A T2-weighted sagittal view was fused to tractography from L3 to L5 and separated into 6 zones (zone A, zones 1–4, and zone P) comprising equal quarters of the anteroposterior diameters, and anterior and posterior to the vertebral body, to determine the distribution of nerves at various intervertebral levels (L3–4, L4–5, and L5–S1). To determine psoas morphology, the authors examined images for a rising psoas sign at the level of L4–5, and the ratio of the anteroposterior diameter (AP) to the lateral diameter (lat), or AP/lat ratio, was calculated. They assessed the relationship between apical vertebrae, psoas major morphology, and the course of nerve tracts.

RESULTS

Although only 30% of patients in the control group showed a rising psoas sign, it was present in 100% of those in the DLS group. The psoas major was significantly extended on the concave side (AP/lat ratio: 2.1 concave side, 1.2 convex side). In 75% of patients in the DLS group, the apex of the curve was at L2 or higher (upper apex) and the psoas major was extended on the concave side. In the remaining 25%, the apex was at L3 or lower (lower apex) and the psoas major was extended on the convex side. Significant anterior shifts of lumbar nerves compared with controls were noted at each intervertebral level in patients with DLS. Nerves on the extended side of the psoas major were significantly shifted anteriorly. Nerve pathways on the convex side of the scoliotic curve were shifted posteriorly.

CONCLUSIONS

A significant anterior shift of lumbar nerves was noted at all intervertebral levels in patients with DLS in comparison with findings in controls. On the convex side, the nerves showed a posterior shift. In LIF, a convex approach is relatively safer than an approach from the concave side. Lumbar nerve course tracking with DTI is useful for assessing patients with DLS before LIF.