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  • Author or Editor: Shinji Takahashi x
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Sho Dohzono, Akinobu Suzuki, Tatsuya Koike, Shinji Takahashi, Kentaro Yamada, Hiroyuki Yasuda and Hiroaki Nakamura

OBJECTIVE

Increasing soft-tissue mass posterior to the odontoid process causes spinal cord compression. Retro-odontoid pseudotumors are considered to be associated with atlantoaxial instability in patients with rheumatoid arthritis (RA), but the exact mechanism by which these lesions develop has not been elucidated. The purpose of this study was to identify the relationships between retro-odontoid soft-tissue (ROST) thickness and radiological findings or clinical data in patients with RA.

METHODS

A total of 201 patients with RA who had been followed up at the outpatient clinic of the authors' institution were enrolled in this study. ROST thickness was evaluated on midsagittal T1-weighted MRI. The correlations between ROST thickness and radiographic findings or clinical data on RA were examined. The independent factors related to ROST thickness were analyzed using stepwise multiple regression analysis.

RESULTS

The average thickness of ROST was 3.0 ± 1.4 mm. ROST thickness showed an inverse correlation with disease duration (r = −0.329, p < 0.01), Steinbrocker stage (r = −0.284, p < 0.01), the atlantodental interval (ADI) in the neutral position (r = −0.326, p < 0.01), the ADI in the flexion position (r = −0.383, p < 0.01), and the ADI in the extension position (r = −0.240, p < 0.01). On stepwise multiple regression analysis, ADI in the flexion position and Steinbrocker stage were independent factors associated with ROST thickness.

CONCLUSIONS

Although the correlations were not strong, ROST thickness in patients with RA was inversely correlated with ADI and Steinbrocker stage. In other words, ROST thickness tends to be smaller as atlantoaxial instability and peripheral joint destruction worsen.

Clinical trial registration no.: UMIN000000980 (UMIN Clinical Trials Registry)

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Sho Dohzono, Hiromitsu Toyoda, Shinji Takahashi, Tomiya Matsumoto, Akinobu Suzuki, Hidetomi Terai and Hiroaki Nakamura

OBJECTIVE

Little is known about the relationship between sagittal spinal alignment in patients with lumbar spinal canal stenosis (LSS) and objective findings such as spinopelvic parameters, lumbar back muscle degeneration, and clinical data. The purpose of this study was to identify the preoperative clinical and radiological factors that predict improvement in sagittal spinal alignment after decompressive surgery in patients with LSS.

METHODS

The records of 61 patients with LSS who underwent microendoscopic laminotomy and had pre- and postoperative clinical data collected were retrospectively reviewed. Spinopelvic parameters, including sagittal vertical axis (SVA), lumbar lordosis (LL), sacral slope, pelvic tilt, and pelvic incidence (PI), were evaluated. On T2-weighted MRI, the cross-sectional area and the percentage of fat infiltration of the paravertebral muscles (PVMs) before surgery were calculated. For patients with preoperative SVA > 40 mm (n = 30), the correlation between SVA improvement and preoperative clinical and radiographic parameters was calculated.

RESULTS

SVA improvement correlated with preoperative LL (r = −0.39) and PI –LL (r = 0.54). Multiple regression analysis showed that preoperative PI –LL (beta = 0.62; p < 0.01) and symptom duration (beta = −0.40; p < 0.05) were independently associated with SVA improvement. The percentage of fat infiltration of the PVM at L4–5 was significantly greater in patients with preoperative SVA ≥ 40 mm than in those patients with SVA < 40 mm.

CONCLUSIONS

Preoperative PI –LL and symptom duration were independently associated with SVA improvement in LSS patients with forward-bending posture. PVM degeneration at the lower lumbar level was significantly greater among patients with preoperative SVA ≥ 40 mm than in patients with SVA < 40 mm.

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Masayoshi Iwamae, Akinobu Suzuki, Koji Tamai, Hidetomi Terai, Masatoshi Hoshino, Hiromitsu Toyoda, Shinji Takahashi, Shoichiro Ohyama, Yusuke Hori, Akito Yabu and Hiroaki Nakamura

OBJECTIVE

Although numbness is one of the chief complaints of patients with cervical spondylotic myelopathy (CSM), preoperative factors relating to residual numbness of the upper extremity (UE) and impact of the outcomes on cervical surgery are not well established. The authors hypothesized that severe preoperative UE numbness could be a risk factor for residual UE numbness after surgery and that the residual UE numbness could have a negative impact on postoperative outcomes. Therefore, this study aimed to identify the preoperative factors that are predictive of residual UE numbness after cervical surgery and demonstrate the effects of residual UE numbness on clinical scores and radiographic parameters.

METHODS

The study design was a retrospective cohort study. The authors analyzed data of 103 patients who underwent cervical laminoplasty from January 2012 to December 2014 and were followed up for more than 2 years postoperatively. The patients were divided into two groups: the severe residual-numbness group (postoperative visual analog scale [VAS] score for UE numbness > 40 mm) and the no/mild residual-numbness group (VAS score ≤ 40 mm). The outcome measures were VAS score, Japanese Orthopaedic Association scores for cervical myelopathy, physical and mental component summaries of the 36-Item Short-Form Health Survey (SF-36), radiographic film parameters (C2–7 sagittal vertical axis, range of motion, C2–7 lordotic angle, and C7 slope), and MRI findings (severity of cervical canal stenosis, snake-eye appearance, severity of foraminal stenosis). Following univariate analysis, which compared the preoperative factors between groups, the variables with p values < 0.1 were included in the multivariate linear regression analysis. Additionally, the changes in clinical scores and radiographic parameters after 2 years of surgery were compared using a mixed-effects model.

RESULTS

Among 103 patients, 42 (40.8%) had residual UE numbness. In the multivariate analysis, sex and preoperative UE pain were found to be independent variables correlating with residual UE numbness (p = 0.017 and 0.046, respectively). The severity of preoperative UE numbness did not relate to the residual UE numbness (p = 0.153). The improvement in neck pain VAS score and physical component summary of the SF-36 was significantly low in the severe residual-numbness group (p < 0.001 and 0.040, respectively).

CONCLUSIONS

Forty-one percent of the CSM patients experienced residual UE numbness for at least 2 years after cervical posterior decompression surgery. Female sex and preoperative severe UE pain were the predictive factors for residual UE numbness. The patients with residual UE numbness showed less improvement of neck pain and lower physical status compared to the patients without numbness.

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Tetsuo Hayashi, Elizabeth L. Lord, Akinobu Suzuki, Shinji Takahashi, Trevor P. Scott, Kevin Phan, Haijun Tian, Michael D. Daubs, Keiichiro Shiba and Jeffrey C. Wang

OBJECTIVE

The efficacy of some demineralized bone matrix (DBM) substances has been demonstrated in the spinal fusion of rats; however, no previous comparative study has reported the efficacy of DBM with human mesenchymal stem cells (hMSCs). There is an added cost to the products with stem cells, which should be justified by improved osteogenic potential. The purpose of this study is to prospectively compare the fusion rates of 3 different commercially available DBM substances, both with and without hMSCs.

METHODS

Posterolateral fusion was performed in 32 mature athymic nude rats. Three groups of 8 rats were implanted with 1 of 3 DBMs: Trinity Evolution (DBM with stem cells), Grafton (DBM without stem cells), or DBX (DBM without stem cells). A fourth group with no implanted material was used as a control group. Radiographs were obtained at 2, 4, and 8 weeks. The rats were euthanized at 8 weeks. Overall fusion was determined by manual palpation and micro-CT.

RESULTS

The fusion rates at 8 weeks on the radiographs for Trinity Evolution, Grafton, and DBX were 8 of 8 rats, 3 of 8 rats, and 5 of 8 rats, respectively. A significant difference was found between Trinity Evolution and Grafton (p = 0.01). The overall fusion rates as determined by micro-CT and manual palpation for Trinity Evolution, Grafton, and DBX were 4 of 8 rats, 3 of 8 rats, and 3 of 8 rats, respectively. The Trinity Evolution substance had the highest overall fusion rate, however no significant difference was found between groups.

CONCLUSIONS

The efficacies of these DBM substances are demonstrated; however, the advantage of DBM with hMSCs could not be found in terms of posterolateral fusion. When evaluating spinal fusion using DBM substances, CT analysis is necessary in order to not overestimate fusion.

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Tetsuo Hayashi, Michael D. Daubs, Akinobu Suzuki, Trevor P. Scott, Kevin H. Phan, Monchai Ruangchainikom, Shinji Takahashi, Keiichiro Shiba and Jeffrey C. Wang

OBJECT

Most studies of Modic changes (MCs) have focused on investigating the relationship between MCs and lowback pain, whereas the kinematic characteristics and degenerative disc disease associated with MCs are not well understood. To the authors' knowledge, no previous study has reported on the kinematics of MCs. The purpose of this study was to elucidate the relationship of MCs to segmental motion and degenerative disc disease.

METHODS

Four hundred fifty symptomatic patients underwent weight-bearing lumbar kinematic MRI in the neutral, flexion, and extension positions. Segmental displacement and intervertebral angles were measured in 3 positions using computer analysis software. Modic changes, disc degeneration, disc bulging, spondylolisthesis, angular motion, and translational motion were recorded, and the relationship of MCs to these factors was analyzed using a logistic regression model. To control the influence of disc degeneration on segmental motion, angular and translational motion were analyzed according to mild and severe disc degeneration stages. The motion characteristics and disc degeneration among types of MCs were also evaluated.

RESULTS

Multivariate analysis revealed that age, disc degeneration, angular motion, and translational motion were factors significantly related to MCs. In the severe disc degeneration stage, a significant decrease of angular motion and significant increase of translational motion were found in segments with MCs, indicating that a disorder of the endplate had an additional effect on segmental motion. Disc degeneration increased and angular motion decreased significantly and gradually as the type of MC increased. Translational motion was significantly increased with Type 2 MCs.

CONCLUSIONS

Age, disc degeneration, angular motion, and translational motion were significantly linked to MCs in the lumbar spine. The translational motion of lumbar segments increased with Type 2 MCs, whereas angular motion decreased as the type of MC increased, indicating that Type 2 MCs may have translational instability likely due to degenerative changes. A disorder of the endplates could play an important role in spinal instability.