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Yasuchika Aoki, Masatsune Yamagata, Yoshikazu Ikeda, Fumitake Nakajima, Seiji Ohtori, Koichi Nakagawa, Arata Nakajima, Tomoaki Toyone, Sumihisa Orita, and Kazuhisa Takahashi


Many surgeons currently prefer to use transforaminal lumbar interbody fusion (TLIF), placing 1 unilateral pedicle screw (PS) and 1 cage. However, no study has examined whether unilateral fixation improves surgical outcome. The authors conducted a prospective randomized controlled trial with a minimum 2-year follow-up to analyze TLIF outcomes for 2 techniques: placement of a unilateral PS and a cage compared with placement of bilateral PSs and 2 cages.


Fifty patients with degenerative spondylolisthesis undergoing single-level TLIF were randomly assigned to receive either unilateral or bilateral fixation. Parameters compared between the groups were surgical invasiveness, severity of intermittent claudication, pre- and postoperative visual analog scale (VAS) scores (from 0 to 10 for back pain, lower-extremity pain, and lower-extremity numbness), postoperative disability scores for lumbar spinal disorders (Japanese Orthopaedic Association Back Pain Evaluation Questionnaire [JOABPEQ]), and fusion rates.


The mean operative time for TLIF was significantly (p = 0.05) shorter and mean estimated blood loss was significantly lower in the unilateral than in the bilateral group. Intermittent claudication improved in response to each technique, but there was no significant intergroup difference. The unilateral group had a nonsignificant tendency toward less improvement in VAS score for back pain (1.5 vs 3.7 for the bilateral group) and exhibited significantly less improvement in VAS score for lower-extremity pain (2.1 vs 5.1, respectively) and numbness (1.7 vs 4.4). There were no significant differences between the groups in postsurgical scores for all 5 items of the JOABPEQ. The fusion rates were 87.5% (21 of 24 patients) in the unilateral group and 95.7% (22 of 23) in the bilateral group.


Transforaminal lumbar interbody fusion involving unilateral PS fixation and a single-cage technique is less invasive than a 2-cage technique and bilateral fixation, and it improved patients' symptoms. However, it resulted in less improvement in back pain, lower-extremity pain, and lower-extremity numbness. When considering unilateral PS fixation and a single cage, the surgeon should be aware of the potential limitations of this technique. Clinical trial registration no.: UMIN000007833 (UMIN).

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Sei Yano, Yasuchika Aoki, Atsuya Watanabe, Takayuki Nakajima, Makoto Takazawa, Hiroyuki Hirasawa, Kazuhisa Takahashi, Koichi Nakagawa, Arata Nakajima, Hiroshi Takahashi, Sumihisa Orita, Yawara Eguchi, Takane Suzuki, and Seiji Ohtori

Pelvic ring fractures are defined as life-threatening injuries that can be treated surgically with external or internal fixation. The authors report on an 81-year-old woman with an unstable pelvic fracture accompanying multiple traumas that was successfully treated with a less invasive procedure. The patient was injured in a traffic accident and sustained a total of 20 fractures, including pelvic ring, bilateral rib, and lumbar transverse processes fractures, and multiple fractures of both upper and lower extremities. The pelvic ring fracture was unstable with fractures of the bilateral sacrum with right sacroiliac disruption, right superior and inferior pubic rami, left superior pubic ramus, and ischium. During emergency surgery, bilateral external fixation was applied to the iliac crest to stabilize the pelvic ring. Second and third surgeries were performed 11 and 18 days after the first emergency surgery, respectively, to treat the multiple fractures. At the third surgery, the pelvic ring fracture was stabilized surgically using a less invasive posterior fixation technique. In this technique, 2 iliac screws were inserted on each side following an 8-cm midline posterior incision from the S-1 to S-3 spinous process, with the subcutaneous tissue detached from the fascia of the paraspinal muscles. The S-2 spinous process was removed and 2 rods were connected to bilateral iliac screws to stabilize the bilateral ilium in a switchback fashion. A crosslink device was applied to connect the 2 rods at the base of the S-2 spinous process. Following pelvic fixation, percutaneous pedicle screws were inserted into L-4 and L-5 vertebral bodies on both sides, and connected to the cranial rod connecting the bilateral iliac screws, thus completing the lumbopelvic fixation. The postoperative course was favorable with no postoperative complications. At the 10-month follow-up, bone union had been achieved at the superior ramus of the pubis, the patient did not complain of pain, and her activities of daily life returned to preinjury status. Unstable pelvic ring fractures need to be sufficiently stabilized for good surgical outcome. However, to avoid postoperative complications, a less invasive treatment is preferred, particularly in cases with poor general condition. This procedure is less invasive and provides sufficient stabilization to the unstable pelvic ring fracture, and thus is the ideal surgical procedure for such cases.

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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


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.


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.


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.


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


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.


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.


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.


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.