Kenichi Shinomiya’s research while affiliated with Tokyo Medical and Dental University and other places

Study design: Prospective multicenter study OBJECTIVE.: To analyze the incidence of intraoperative spinal neuromonitoring (IONM) alerts and neurological complications, as well as to determine which interventions are most effective at preventing postoperative neurological complications following IONM alerts in high risk spinal surgeries. Summary of background data: IONM may play a role in identifying and preventing neural damage; however, few studies have clarified the outcomes of intervention after IONM alerts. Methods: We analyzed 2867 patients who underwent surgery for high risk spinal pathology using transcranial electrical motor-evoked potentials (Tc(E)-MEPs) from 2010 to 2016. The high risk spinal surgery cases consisted of 1009 spinal deformity cases, 622 cervical ossification of posterior longitudinal ligament (c-OPLL) cases, 249 thoracic-OPLL (t-OPLL) cases, 771 extramedullary spinal cord tumor (EMSCT) cases, and 216 intramedullary spinal cord tumor (IMSCT) cases. We set a 70% amplitude reduction as the alarm threshold for Tc(E)-MEPs and analyzed the outcomes of the interventions following monitoring alerts and postoperative neurological deficits. Results: The true positive, false positive, true negative, false negative, and rescue cases of IOMN comprised 126, 234, 2362, nine, and 136 cases, respectively. Most alerts and interventions occurred during correction and release in deformity cases, posterior decompression and dekyphosis in OPLL cases, and tumor resection and surgery suspension with steroid injection in SCT cases; however, individual interventions varied. The rescue rates (number of patients rescued with intervention after IONM alert/number of true positive cases plus rescue cases) for deformity, c-OPLL, t-OPLL, EMSCT, and IMSCT cases were 61.4% (35/57), 82.1% (32/39), 40% (20/50), 52.5% (31/59), and 31.6% (18/57), respectively. Conclusions: Our prospective multicenter study identified potential neural damage in 9.5% of cases and 52% rescue cases using IONM. Although the rescue ratios for t-OPLL and IMSCT were relatively low, appropriate intervention immediately after an IONM alert may prevent neural damage even in high-risk spinal surgeries. Level of evidence: 3.

Background: There have been no prospective studies comparing anterior surgery and posterior method in terms of long-term outcomes. The purposes of this study is to clarify whether there is any difference in long-term clinical and radiologic outcomes of anterior decompression with fusion (ADF) and laminoplasty (LAMP) for the treatment of cervical spondylotic myelopathy (CSM). Methods: Ninety-five patients were prospectively treated with ADF or LAMP for CSM in our hospital from 1996 through 2003. On alternate years, patients were enrolled to receive ADF (1997, 1999, 2001, and 2003: ADF group, n = 45) or LAMP (1996, 1998, 2000, and 2002: LAMP group, n = 50). We excluded 19 patients who died during follow-up, and 25 who were lost to follow-up. Clinical outcomes were evaluated by the recovery rate of the Japanese Orthopaedic Association (JOA) score between the two groups. Sagittal alignment of the C2-7 lordotic angle and range of motion (ROM) in flexion and extension on plain X-ray were measured. Results: Mean age at the time of surgery was 58.3 years in the ADF group and 57.9 years in the LAMP group. Mean preoperative JOA score was 10.0 and 10.5, respectively. Mean recovery rate of the JOA score at 3-5 years postoperatively was significantly higher in the ADF group (p < 0.05). Reoperation was required in 1 patient for pseudarthrosis and in 1 patient for recurrence of myelopathy in the ADF group; no patient in the LAMP group underwent a second surgery. There was a significant difference in maintenance of the lordotic angle in the ADF group compared with the LAMP group (p < 0.05), but not in ROM. Conclusions: Both ADF and LAMP provided similar good outcomes at 10-year time-point whereas ADF could achieve more satisfactory outcomes and better sagittal alignment at the middle-term. However, the incidence of reoperation and complication in the ADF group were higher than those in the LAMP group. Study design: A prospective comparative study (not randomized).

Purpose: Cervical sagittal balance has received increased attention as an important determinant of radiological and clinical outcomes. However, no prospective studies have compared the impact of cervical sagittal balance between anterior and posterior surgeries. We previously conducted a prospective study comparing anterior decompression with fusion (ADF) and laminoplasty (LAMP) for degenerative cervical myelopathy (DCM) and reported; however, analysis of cervical alignment within the concept of sagittal balance has yet to be performed, because that concept has recently been proposed. This study aimed to review this prospective cohort, specifically focusing on cervical sagittal balance. Methods: We prospectively performed ADF or LAMP for DCM patients based on the year of enrollment: ADF was performed in odd-numbered years and LAMP in even-numbered years. Cervical lateral X-ray images taken in the neutral standing position were evaluated preoperatively and at a 1-year follow-up. The radiographic measurements included the following: (1) CL (cervical lordosis: C2-7 lordotic angle), (2) CGH (center of gravity of the head)-C7 SVA (sagittal vertical axis), and (3) C7 slope. The clinical results were evaluated using the Japanese Orthopedic Association scoring system for cervical myelopathy (C-JOA score). Results: We analyzed the data for 66 patients (ADF n = 28, LAMP n = 38). While the CL and CGH-C7 SVA in the ADF were unchanged after the operation, those in the LAMP group worsened, especially in patients with preoperative cervical sagittal imbalance. The C7 slopes were not affected by the operation in either group. The postoperative decreases in the CL in the LAMP group correlated with the preoperative CGH-C7 SVA (r = 0.618, P < 0.01), but those in ADF group did not. In patients with preoperative cervical sagittal imbalance (CGH-C7 SVA ≥40 mm), the recovery rate of the C-JOA score in the ADF group was superior to that in the LAMP group (67.3 vs. 39.8 %). In contrast, for patients without cervical sagittal imbalance, the recovery rate of the C-JOA score showed no significant difference between the ADF and LAMP groups (64.5 vs. 58.7 %). Conclusions: Postoperative cervical sagittal alignment and balance were maintained after ADF but deteriorated following LAMP, especially in patients with preoperative CGH-C7 SVA ≥40 mm. In these patients, neurological recovery after LAMP was unsatisfactory. LAMP is not suitable for degenerative cervical myelopathy patients with preoperative cervical sagittal imbalance.

Study design: Retrospective case control study. Objective: The purpose of this study was to examine the factors of postoperative paralysis in patients who have undergone thoracic OPLL surgery. Summary of background data: A higher percentage of thoracic OPLL cases experience postoperative aggravation of paralysis than cervical OPLL cases, including cases that presented great difficulties in treatment. However there was few report to prevent paralysis thoracic OPLL. Methods: The 156 cases who had received thoracic OPLL surgery were selected as the subjects of this study. The items for review were: the duration of disease; the preoperative muscle strength (Muscle Manual Testing: MMT); OPLL levels (T1/2-4/5: high, T5/6-8/9: middle, T9/10-11/12: low); the spinal canal occupancy ratio; the ratio of yellow ligament ossification as a complication; the ratio of Tc-MEP derivation; the preoperative/postoperative kyphotic angles in the thoracic vertebrae; the correction angle of kyphosis; the duration of surgery; and the amount of bleeding. The subjects were divided into two groups based on the absence or presence of postoperative paralysis to determine the factors of postoperative paralysis. Results: Twenty-three cases (14.7%) exhibited postoperative paralysis. Multivariate analysis identified factors associated with postoperative paralysis: the duration of disease (OR = 3.3); the correction angle of kyphosis (OR = 2.4); and the ratio of Tc-MEP derivation (OR = 2.2). Conclusions: The risk factors of postoperative paralysis are a short duration of disease and a small correction angle of kyphosis. Additionally, ratios of Tc-MEP derivation below 50% may anticipate paralysis. Level of evidence: 4.

Background: Reconstruction of large bone defects is a great challenge in orthopedic research. In the present study, we prepared composites of bone marrow-derived stromal cells (BMSCs) and β-tricalcium phosphate (β-TCP) with three novel aspects: proliferation of BMSCs with continuous dexamethasone treatment, cell loading under low pressure, and use of autologous plasma as the cell loading medium. The effectiveness of the resulting composite for large bone-defect reconstruction was tested in a non-human primate model, and the bone union capability of the regenerated bones was examined. Materials and methods: Primary surgery: Bone defects (5 cm long) were created in the left femurs of nine cynomolgus monkeys with resection of the periosteum (five cases) or without resection (four cases), and porous β-TCP blocks were transplanted into the defects. Secondary surgery: Bone marrow aspirates harvested from seven of the nine monkeys were cultured with dexamethasone, and BMSCs were obtained. BMSCs were suspended in autologous plasma and introduced into a porous β-TCP block under low-pressure conditions. The BMSC/β-TCP composites were transplanted into bone defects created at the same sites as the primary surgery. Bone union evaluation: Five regenerated femurs were shortened by osteotomy surgery 8 to 15 months after transplantation of the β-TCP/BMSC composites, and bone union was evaluated radiographically. Results: After the primary surgery and treatment with β-TCP alone, one of the five periosteum-resected monkeys and two of the four periosteum-preserved monkeys exhibited successful bone reconstruction. In contrast, five of the seven cases treated with the β-TCP/MSC composite showed successful bone regeneration. In four of the five osteotomy cases, bone union was confirmed. Conclusion: We validated the effectiveness of a novel β-TCP/BMSC composite for large bone defect regeneration and confirmed the bone union capability of the regenerated bone.

Background: Porous hydroxyapatite/collagen composite (HAp/Col) is a bioresorbable bone substitute composed of nano-scale HAp and porcine type 1 collagen. In this study, the efficacy and safety were assessed in comparison to commercially available porous β-tricalcium phosphate (β-TCP). Methods: Patients with bone defects caused by benign bone tumors, fractures, or harvesting of autografts were randomly allocated for implantation of porous HAp/Col (n = 63) or porous β-TCP (n = 63). X-ray images were scored and used to evaluate the efficacy of the implantation until 24 weeks after surgery. Blood tests and observation of the surgical site were also performed to evaluate the safety of the implants. In total, 59 and 60 cases were analyzed in the porous HAp/Col and β-TCP groups, respectively. Results: At 18 and 24 weeks after surgery, the highest grade of bone regeneration was more frequent in the porous HAp/Col group than in the porous β-TCP group (p = 0.0004 and 0.0254 respectively). Wilcoxon's rank sum test confirmed the superiority of porous HAp/Col from early time points onward (p = 0.0084, 4 w; p = 0.0037, 8 w; p = 0.0030, 12 w; p < 0.0001, 18 w; and p = 0.0316, 24 w). The incidence of adverse effects was higher in the porous HAp/Col group than in the β-TCP group. However, no serious adverse events were reported and no cases needed to drop out of the clinical trial. Conclusions: The superiority of porous HAp/Col for bone regeneration in comparison to an established porous β-TCP was confirmed. Although the incidence of side effects associated with the porous HAp/Col implant was higher than that in the β-TCP group, no serious adverse events occurred that resulted in rejection of the implants.

Study Design Surgeon survey. Objective To analyze multimodal intraoperative monitoring (MIOM) for different combinations of methods based on the collected data and determine the best combination. Methods A questionnaire was sent to 72 training institutions to analyze and compile data about monitoring that had been conducted during the preceding 5 years to obtain data on the following: (1) types of monitoring; (2) names and number of diseases; (3) conditions of anesthesia; (4) condition of stimulation, the monitored muscle and its number; (5) complications; and (6) preoperative and postoperative manual muscle testing, presence of dysesthesia, and the duration of postoperative motor deficit. Sensitivity and specificity, false-positive rates, and false-negative rates were examined for each type of monitoring, along with the relationship between each type of monitoring and the period of postoperative motor deficit. Results Comparison of the various combinations showed transcranial electrical stimulation motor evoked potential (TcMEP) + cord evoked potential after stimulation to the brain (Br-SCEP) combination had the highest sensitivity (90%). The TcMEP + somatosensory evoked potential (SSEP) and TcMEP + spinal cord evoked potential after stimulation to the spinal cord (Sp-SCEP) combinations each had a sensitivity of 80%, exhibiting little difference between their sensitivity and that obtained when TcMEP alone was used. Meanwhile, the sensitivity was as low as 50% with Br-SCEP + Sp-SCEP (i.e., the cases where TcMEP was not included). Conclusions The best multimodality combination for intraoperative spinal cord monitoring is TcMEP + Br-SCEP, which had the highest sensitivity (90%), the lowest false-positive rate (6.1%), and the lowest false-negative rate (0.2%).

In the last decade, researchers and clinicians have reported that transplantation of bone marrow stromal cells (BMSCs) promotes functional recovery after brain or spinal cord injury (SCI). However, an appropriate scaffold designed for the injured spinal cord is needed to enhance the survival of transplanted BMSCs and to promote nerve regeneration. We previously tested a honeycomb collagen sponge (HC), which when applied to the transected spinal cord allowed bridging of the gap with nerve fibers. In this study, we examined whether the HC implant combined with rat BMSCs increases nerve regeneration in vitro and enhances functional recovery in vivo. We first evaluated the neurite outgrowth of rat dorsal root ganglion (DRG) explants cultured on HC with or without BMSCs in vitro. Regeneration of neurites from the DRGs was increased by BMSCs combined with HC scaffolds. In the in vivo study, 3-mm-long HC scaffolds with or without BMSCs were implanted into the hemisected rat thoracic spinal cord. Four weeks after the procedure, rats implanted with HC scaffolds containing BMSCs displayed better motor and sensory recovery than those implanted with HC scaffolds only. Histologically, more CGRP-positive sensory fibers at the implanted site and 5-HT-positive serotonergic fibers contralateral to the implanted site were observed in spinal cords receiving BMSCs. Furthermore, more rubrospinal neurons projected distally to the HC implant containing BMSCs. Our study indicates that the application of BMSCs in a HC scaffold in the injured spinal cord directly promoted sensory nerve and rubrospinal tract regeneration, thus resulting in functional recovery.

Pedicle screw insertions are commonly used for posterior fixation to treat various spine disorders. However, the misplacement of pedicle screws can lead to disastrous complications. Inaccurate pedicle screw placement is relatively common even when placement is performed under fluoroscopic control. In order to improve the accuracy of the screw placement, we applied a technique using guide wires and a cannulated tapping device with the assistance of a fluoroscopic pedicle axis view. From 2006 to 2011, 854 pedicle screws were placed in 176 patients in lumbosacral spinal fusion surgeries. The accuracy of screw placement was evaluated using postoperative reconstructed computed tomography images. Screw misplacement was classified as minor (cortical perforation <3 mm), moderate (cortical perforation 3-6 mm), or severe (cortical perforation >6 mm). Using logistic regression analysis, we also investigated the potential risk factors associated with screw misplacement. Pedicle screw misplacement was observed in 37 screws (4.3 %) in 34 patients. In the sub-classification analysis, 28 screws (3.3 %) were determined to be minor perforations, 7 screws (0.8 %) were considered to be moderate perforations, and 2 screws (0.2 %) was judged to be a severe perforation (cortical perforation >6 mm). None of the 28 screws that were considered to be minor perforations were associated with any significant symptoms in the patients. However, 2 of the 9 screws that were determined to be moderate or severe perforations caused neurological symptoms (1 of which required revision). No significant differences were observed in the incidence of screw misplacement among the vertebral levels. Significant risk factors for screw misplacement were obesity and degenerative scoliosis. The odds ratios of these significant risk factors were 3.593 (95 % confidence interval (CI), 1.061-12.175) for obesity and 8.893 for degenerative scoliosis (95 % CI, 1.200-76.220). A modified fluoroscopic technique using a pedicle axis view and a cannulated tapping instrument can achieve safe and accurate pedicle screw placement. In addition, obesity and degenerative scoliosis were identified as significant risk factors for screw misplacement.