Hirosuke Nishimura

Characteristics of Sagittal Spino-Pelvic Alignment in Japanese Young Adults

Study Design Radiological analysis of normal patterns of sagittal alignment of the spine. Purpose This study aimed to clarify the characteristics of normal sagittal spino-pelvic alignment in Asian people. Overview of Literature It is known that there are differences in these parameters based on age, gender, and race. In order to properly plan for surgical correction of the spine for Asian patients, it is necessary to understand the normal spino-pelvic alignment parameters for this population. Methods This study analyzed 86 Japanese healthy young adult volunteers (48 men and 38 women; age 35.9±11.1 (mean±standard deviation [SD]). The following parameters were measured on lateral standing radiographs of the entire spine: sagittal vertical axis (SVA), horizontal distance between the C7 plumb line and the posterior superior corner of the superior margin of S1, thoracic kyphotic angle (TK), lumbar lordotic angle (LLA), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). Results The values (mean±SD) of SVA, TK, LLA, SS, PT, and PI were 8.45±25.7 mm, 27.5±9.6°, 43.4±14.6°, 34.6±7.8°, 13.2±8.2°, and 46.7±8.9°, respectively. The Japanese young adults evaluated in this study tended to have a smaller PI, LLA, TK, and SVA than most Caucasian people. Regarding gender differences, SVA was significantly longer and TK was significantly smaller in men; however, there was no statistically significant difference in LLA, SS, PA, and PI. Conclusions Japanese young adults apparently have smaller PI and LLA values than Caucasian people. When making decisions for optimal sagittal spinal alignment, racial differences should be considered.

Gait Analysis in Cervical Spondylotic Myelopathy

Study Design Gait analysis of patients with cervical spondylotic myelopathy (CSM) by using a sheet-type gait analysis system. Purpose The aim of this study was to compare the gait patterns of patients with CSM, evaluated by the Nurick grades, and to determine the threshold values of gait parameters predicting the occurrence of a fall by using a gait recorder. Overview of Literature Gait disorder due to CSM may progress to severe paraplegia, following even a minor trauma such as a fall. The indications for the surgery of CSM without severe paralysis remain controversial. The quantitative gait analysis and the decision for decompressive surgery in patients with CSM are important in order to prevent severe paraplegia from a fall. Methods One hundred thirty-two subjects (normal, 34; CSM, 98) underwent gait analysis by using a sensor sheet. Measurements of gait cycle parameters included the step and stride length, step width, foot angle, swing phase, and stance phase. CSM was assessed by Nurick grade. Results Although the clinical symptoms were lacking, Nurick grade 1 had significant abnormalities in the parameters of velocity, step length, and step angle (p<0.05). Regarding the Nurick grade and walking phase, the length of the stance phase was increased to more than 70% of the entire walking cycle in Nurick grade 4. Conclusions Gait analysis was an objective tool for evaluating the gait stability. Our results suggested that when the percentage of the stance phase in the gait cycle increases to above 70%, the CSM patients have an increased fall risk.

Complications Associated With Spine Surgery in Patients Aged 80 Years or Older: Japan Association of Spine Surgeons with Ambition (JASA) Multicenter Study:

Study Design: Retrospective study of registry data. Objectives: Aging of society and recent advances in surgical techniques and general anesthesia have increased the demand for spinal surgery in elderly patients. Many complications have been described in elderly patients, but a multicenter study of perioperative complications in spinal surgery in patients aged 80 years or older has not been reported. Therefore, the goal of the study was to analyze complications associated with spine surgery in patients aged 80 years or older with cervical, thoracic, or lumbar lesions. Methods: A multicenter study was performed in patients aged 80 years or older who underwent 262 spinal surgeries at 35 facilities. The frequency and severity of complications were examined for perioperative complications, including intraoperative and postoperative complications, and for major postoperative complications that were potentially life threatening, required reoperation in the perioperative period, or left a permanent injury. Results: Perioperative complications occurred in 75 of the 262 surgeries (29%) and 33 were major complications (13%). In multivariate logistic regression, age over 85 years (hazard ratio [HR] = 1.007, P = 0.025) and estimated blood loss ≥500 g (HR = 3.076, P = .004) were significantly associated with perioperative complications, and an operative time ≥180 min (HR = 2.78, P = .007) was significantly associated with major complications. Conclusions: Elderly patients aged 80 years or older with comorbidities are at higher risk for complications. Increased surgical invasion, and particularly a long operative time, can cause serious complications that may be life threatening. Therefore, careful decisions are required with regard to the surgical indication and procedure in elderly patients.

Kinematic analysis of the cervical cord and cervical canal by dynamic neck motion.

Study Design Normal cervical sagittal length patterns were measured by magnetic resonance imaging (MRI). Purpose The aim of this study was to evaluate the relationship of sagittal length patterns between the cervical cord and the cervical canal in flexion-extension kinematics. Overview of Literature Cervical dynamic factors sometimes cause a cervical spondylotic myelopathy in elderly subjects and an overstretching myelopathy in juvenile subjects. Previous studies showed the length changing of the cervical cord in flexion and extension. However, there is no detailed literature about the relationship between cervical vertebral motion and cord distortion yet. Methods Sixty-two normal subjects (28 male and 34 female, 42.1±8.5 years old) without neck motion disturbances and abnormalities on cervical X-ray and MRI were enrolled in this study. Results The cervical cord length was significantly longer in flexion and significantly shorter in extension in all cervical cord sagittal lines. The cervical canal length pattern was also the same as the cervical cord. The elongation of the cervical cord and canal was the largest at the site of the posterior cervical canal and the shortest at the anterior canal site. The positions of the cerebellar tonsils were verified at each neck position. Conclusions The posterior elements of the cervical canal were most affected by neck motion. Movement directions of the upper cervical cord were verified among the various neck positions.

Relationship among cervical, thoracic, and lumbopelvic sagittal alignment in healthy adults

Purpose. To evaluate the association between cervical sagittal alignment and thoracic/lumbopelvic sagittal alignment in healthy Japanese adults. Methods. 30 male and 22 female healthy adults aged 22 to 50 years were recruited. Spinal parameters were measured on radiographs, including the cervical sagittal vertical axis, sagittal vertical axis, C7 tilt angle, Ishihara index for cervical lordosis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. Results. The C7 tilt angle positively correlated with the Ishihara index (r=0.52, p<0.0001) and thoracic kyphosis (r=0.53, p<0.0001). The Ishihara index positively correlated with thoracic kyphosis (r=0.34, p=0.01) and C7 tilt angle (r=0.52, p<0.0001). Pelvic incidence positively correlated with sacral slope (r=0.45, p=0.001), lumbar lordosis (r=0.26, p=0.07), and pelvic tilt (r=0.29, p=0.03). Compared with men, women had a smaller Ishihara index (0.07 vs. 0.001, p=0.03), thoracic kyphosis (30.5° vs 24.1°, p=0.02), and C7 tilt angle (23.1° vs. 16.8°, p=0.02). Women had less cervical lordosis and thoracic kyphosis, that is, a straighter cervico-thoracic sagittal alignment. Conclusion. In healthy Japanese adults, cervical sagittal alignment is associated with thoracic sagittal alignment but not with lumbopelvic alignment.

A case of rapidly-progressing cervical spine subependymoma with atypical features

This was a study of the case of a 60-year-old woman who presented with a six-month history of headache and numbness radiating to the right arm. MRI revealed a fusiform intramedullary spinal tumor spanning C2 to C5 at the hospital where she first presented. As her right upper limb weakness had presented gradually, she visited our hospital after one and a half years. Neurological examination revealed muscle weakness in the right deltoid, but no sensory disturbance. The patient underwent a C2-C6 total laminectomy and posterior midline myelotomy from the posterior median fissure of the spinal cord. The intraoperative histological diagnosis was glioma. Pathological findings in low magnification demonstrated clusters of small uniform nuclei embedded in a dense and fibrillary matrix in hematoxylin-eosin staining (H.E.). On immunohistochemical staining, the tumor cells were weakly positive for glial fibrillary acidic protein (GFAP), but negative for the epithelial membrane antigen (EMA). The histopathological findings were consistent with the diagnosis of a subependymoma. However, the MIB-1 labeling index was of moderately high level up to approximately 8%. In this case, we performed total resection because the tumor had rapidly increased in size and was of atypical form in histological findings. It should be minded that some of subependymomas have a possibility of rapidly increasing in size with progressing neurological deficits.

Radiographic Assessment of Spinopelvic Sagittal Alignment from Sitting to Standing Position

Introduction Most people in modern societies spend the majority of their time sitting. However, sagittal spinal alignment is usually analyzed in the standing position. For understanding the symptoms associated with postural changes, this alignment is better to be analyzed in various positions. The purpose of this study was to investigate lumbo-pelvic relationships between standing up and sitting (sit-to-stand) motion. Methods The study subjects were 25 healthy young adult volunteers without any spinal symptoms. The following parameters were measured, namely, intervertebral range of motion (IV ROM), lumbar lordotic angle (L1L5), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI), on lateral whole-spine radiographs while sitting upright, sitting anterior flexed (anteflexed), standing anteflexed, and standing upright. Results The measurements of spinopelvic parameters during sit-to-stand motion (sitting upright, sitting anteflexed, standing anteflexed, standing upright, respectively) were as follows: L1L5 (7.9, −4.4, 3.1, 31.9) and PT (31.5, 26.5, 11.9, 7.7). Regarding IV ROM, the lumbar segmental ROM after seat-off was wider than before seat-off (sitting anteflexed). In particular, the L4-L5 segments had a wide ROM from standing anteflexed to standing upright. Conclusions The pelvis was retroverted in the sitting upright position and gradually anteverted during sit-to-stand motion. Lumbar lordosis decreased in the sitting upright position, temporarily decreased further (sitting anteflexed), and then increased in the standing position (standing anteflexed and standing upright). The mechanical loads on lumbosacral segments were greater after seat-off due to the reverse movement between upper lumbar and pelvic segments.

Risk Factors for Proximal Junctional Fracture following Fusion Surgery for Osteoporotic Vertebral Collapse with Delayed Neurological Deficits: A Retrospective Cohort Study of 403 Patients

Introduction Approximately 3% of osteoporotic vertebral fractures develop osteoporotic vertebral collapse (OVC) with neurological deficits, and such patients are recommended to be treated surgically. However, a proximal junctional fracture (PJFr) following surgery for OVC can be a serious concern. Therefore, the aim of this study is to identify the incidence and risk factors of PJFr following fusion surgery for OVC. Methods This study retrospectively analyzed registry data collected from facilities belonging to the Japan Association of Spine Surgeons with Ambition (JASA) in 2016. We retrospectively analyzed 403 patients who suffered neurological deficits due to OVC below T10 and underwent corrective surgery; only those followed up for　≥2 years were included. Potential risk factors related to the PJFr and their cut-off values were calculated using multivariate logistic regression analysis and receiver operating characteristic (ROC) analysis. Results Sixty-three patients (15.6%) suffered PJFr during the follow-up (mean 45.7 months). In multivariate analysis, the grade of osteoporosis (grade 2, 3: adjusted odds ratio (aOR) 2.92; p=0.001) and lower instrumented vertebra (LIV) level (sacrum: aOR 6.75; p=0.003) were independent factors. ROC analysis demonstrated that lumbar bone mineral density (BMD) was a predictive factor (area under curve: 0.72, p=0.035) with optimal cut-off value of 0.61 g/cm2 (sensitivity, 76.5%; specificity, 58.3%), but that of the hip was not (p=0.228). Conclusions PJFr was found in 16% cases within 4 years after surgery; independent risk factors were severe osteoporosis and extended fusion to the sacrum. The lumbar BMD with cut-off value 0.61 g/cm2 may potentially predict PJFr. Our findings can help surgeons select perioperative adjuvant therapy, as well as a surgical strategy to prevent PJFr following surgery.

Cervical Kyphotic Deformity after Laminoplasty in Patients with Cervical Ossification of Posterior Longitudinal Ligament with Normal Sagittal Spinal Alignment

Background Preoperative cervico-thoracic kyphosis and cervical regional positive imbalance are the risk factors for postoperative cervical kyphosis after expansive laminoplasty (ELAP). However, the relationship between preoperative global sagittal spinal alignment and postoperative cervical kyphosis in patients with cervical ossification of the posterior longitudinal ligament (OPLL) is unclear. The purpose of this study was to investigate the relationship between the onset of postoperative cervical kyphosis after ELAP and the preoperative global spinal sagittal alignment in patients with OPLL with normal sagittal spinal alignment. Methods Sixty-nine consecutive patients without preoperative cervical kyphosis who underwent ELAP for OPLL and cervical spondylotic myelopathy (CSM) were enrolled. The global sagittal alignment radiography preoperatively and 1 year postoperatively were examined. The subjects were divided into a postoperative cervical lordosis group (LG) or a kyphosis group (KG) at 1 year postoperatively. The preoperative global sagittal spinal alignment between LG and KG in CSM and OPLL was compared. Results The occurrence of cervical kyphosis after ELAP was 7 of 27 cases (25.9%) in OPLL and 13 of 42 cases (31.0%) in CSM. In patients with CSM in the KG, C7 the sagittal vertical axis (SVA) was smaller than in the LG. In patients with cervical OPLL in the KG, C2-C7 angle, C2-C7 SVA, and thoracic kyphosis (TK) were smaller than those in the LG. In OPLL, the age of the KG was younger than that of LG; however, this was not a significant difference in CSM. Conclusion In patients with cervical OPLL without preoperative global spinal sagittal imbalance, preoperative small C2-C7 angle, C2-C7 SVA, TK, and younger age were typical characteristics of postoperative cervical kyphosis after ELAP.

Factors associated with bone metabolism in patients with cervical ossification of the posterior longitudinal ligament accompanied with diffuse idiopathic skeletal hyperostosis

Introduction: Diffuse idiopathic skeletal hyperostosis (DISH) and ossification of the posterior longitudinal ligament (OPLL) are both characterized as ossification in paravertebral ligaments and sometimes present simultaneously, however, the bone metabolism in patients with cervical OPLL accompanying/not accompanying DISH has not well been studied. Thus, a retrospective analysis was performed to understand any differences in bone metabolism in these patients. Methods: Male patients who underwent surgery for OPLL were divided into two groups based on the presence or absence of DISH (OD and O group, respectively). Patients with cervical spondylosis comprised the control group (CS group). Bone mineral density (BMD) and bone metabolism factors were compared among the groups. Results: The OD and O groups had significantly higher body mass indexes (BMIs) than did the CS group. Morphologically, the number of continuous type of OPLL was high in the OD group whereas that of segmental type was higher in the O group. The OD and O group had greater BMD than the CS group. Both TRACP-5b and P1NP were tended to be lower in the OD group whereas Ca and P concentrations were similar level among the groups. Intact parathyroid hormone in OD group was significantly higher than CS group. Discussion: Patients with OPLL accompanying DISH had significantly higher BMD whereas they tend to be lower in bone turnover. Significantly higher i-PTH levels was found in the OD group and would be the characteristic blood marker, but further research on the relationship between DISH and PTH was necessary.