Publications by authors named "Masaya Nakamura"

575 Publications

First-in-human clinical trial of transplantation of iPSC-derived NS/PCs in subacute complete spinal cord injury: Study protocol.

Regen Ther 2021 Dec 7;18:321-333. Epub 2021 Sep 7.

Department of Physiology, Keio University School of Medicine, Tokyo, Japan.

Introduction: Our group has conducted extensive basic and preclinical studies of the use of human induced pluripotent cell (iPSC)-derived neural stem/progenitor cell (hiPSC-NS/PC) grafts in models of spinal cord injury (SCI). Evidence from animal experiments suggests this approach is safe and effective. We are preparing to initiate a first-in-human clinical study of hiPSC-NS/PC transplantation in subacute SCI.

Setting: NS/PCs were prepared at a Good Manufacturing Practice-grade cell processing facility at Osaka National Hospital using a clinical-grade integration-free hiPSC line established by the iPSC Stock Project organized by the Kyoto University Center for iPS Cell Research and Application. After performing all quality checks, the long-term safety and efficacy of cells were confirmed using immunodeficient mouse models.

Methods: The forthcoming clinical study uses an open-label, single-arm design. The initial follow-up period is 1 year. The primary objective is to assess the safety of hiPSC-NS/PC transplantation in patients with subacute SCI. The secondary objective is to obtain preliminary evidence of its impact on neurological function and quality-of-life outcomes. Four patients with C3/4-Th10 level, complete subacute (within 24 days post-injury) SCI will be recruited. After obtaining consent, cryopreserved cells will be thawed and prepared following a multi-step process including treatment with a γ-secretase inhibitor to promote cell differentiation. A total of 2 × 10 cells will be transplanted into the injured spinal cord parenchyma 14-28 days post-injury. Patients will also receive transient immunosuppression. This study protocol has been reviewed and approved by the Certified Committee for Regenerative Medicine and the Japanese Ministry of Health, Labor and Welfare (University Hospital Medical Information Network Clinical Trials Registry [UMIN-CTR] number, UMIN000035074; Japan Registry of Clinical Trials [jRCT] number, jRCTa031190228).

Discussion/conclusion: We plan to start recruiting a patient as soon as the COVID-19 epidemic subsides. The primary focus of this clinical study is safety, and the number of transplanted cells may be too low to confirm efficacy. After confirming safety, a dose-escalation study is planned.
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http://dx.doi.org/10.1016/j.reth.2021.08.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8427225PMC
December 2021

Evaluation of Dynamic Carpal Arch Stability following Carpal Tunnel Release Using Four-Dimensional Computed Tomography.

J Hand Microsurg 2021 Jul 19;13(3):138-142. Epub 2020 Nov 19.

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.

 This study aimed to assess the carpal arch dynamics during active finger and wrist motion following carpal tunnel release using four-dimensional computed tomography (4D-CT).  Four patients who diagnosed with bilateral carpal tunnel syndrome and underwent unilateral carpal tunnel release were prospectively included. 4D-CT of the bilateral wrists during active finger and wrist motion was performed for 10 seconds at five frames per second. The distances between the tip of tuberosity of the scaphoid and the volar ridge of the pisiform (S-P distance) and volar ridge of trapezium and the tip of hook of hamate (T-H distance) were measured at each position and the values of S-P and T-H distances were compared between the postoperative and contralateral wrists.  During finger motion, the S-P and T-H distances were not different at any position between the postoperative side and contralateral side. Conversely, S-P and T-H distances gradually increased in the postoperative wrists. The differences between the sides of S-P distance were significant, with >0 degrees of wrist extension, and differences of T-H distance were significant with >15 degrees of wrist extension.  This study demonstrated the carpal arch dynamics using 4D-CT and revealed that the carpal arch was widened with the wrist in extension after carpal tunnel release. This study suggests that the transverse carpal ligament plays an important role in maintaining carpal arch stability.
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http://dx.doi.org/10.1055/s-0040-1718969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8426082PMC
July 2021

Markerless analysis of hindlimb kinematics in spinal cord-injured mice through deep learning.

Neurosci Res 2021 Sep 8. Epub 2021 Sep 8.

Department of Physiology, Keio University School of Medicine, Tokyo, Japan. Electronic address:

Rodent models are commonly used to understand the underlying mechanisms of spinal cord injury (SCI). Kinematic analysis, an important technique to measure dysfunction of locomotion after SCI, is generally based on the capture of physical markers placed on bony landmarks. However, marker-based studies face significant experimental hurdles such as labor-intensive manual joint tracking, alteration of natural gait by markers, and skin error from soft tissue movement on the knee joint. Although the pose estimation strategy using deep neural networks can solve some of these issues, it remains unclear whether this method is adaptive to SCI mice with abnormal gait. In the present study, we developed a deep learning based markerless method of 2D kinematic analysis to automatically track joint positions. We found that a relatively small number (< 200) of manually labeled video frames was sufficient to train the network to extract trajectories. The mean test error was on average 3.43 pixels in intact mice and 3.95 pixels in SCI mice, which is comparable to the manual tracking error (3.15 pixels, less than 1 mm). Thereafter, we extracted 30 gait kinematic parameters and found that certain parameters such as step height and maximal hip joint amplitude distinguished intact and SCI locomotion.
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http://dx.doi.org/10.1016/j.neures.2021.09.001DOI Listing
September 2021

Comparison of Drug Availability in the Inner Ear After Oral, Transtympanic, and Combined Administration.

Front Neurol 2021 19;12:641593. Epub 2021 Aug 19.

Department of Otolaryngology Head and Neck Surgery, Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China.

Although combination of oral and transtympanic drug therapy (CT) has been proved more effective and safer for idiopathic sudden sensorineural hearing loss (ISSNHL) by some clinical trials, there are few laboratory researches on the pharmacokinetics in the inner ear following CT on account of structural limitations of the inner ear. The aim of the present study was to investigate the pharmacokinetic behaviors of CT in the inner ear of mice. Eighteen transgenic mice which express luciferase in cochlear spiral ganglion cells were divided into oral administration (OR) group, transtympanic injection route (TT) group and CT group, and luciferin was delivered into the inner ear of these mice through oral, transtympanic or combined routes, respectively. A new imaging system was used to observe luciferin/luciferase signals and the compare the pharmacokinetics of different administration routes in the inner ear of mice. Bioluminescence signals were observed in the inner ear 3.3 ± 2.6 min after CT, significantly earlier than that of OR group (15.8 ± 7.4 min). CT owned the longest reaching-peak time and largest area under the curve (AUC) among three groups. Compared to TT, CT had longer biological half-life and higher AUC value, but did not displayed stronger peak value. There were significant differences in the peak values between OR group and TT group and between OR group and CT group. This study suggests that the OR route is less effective than the TT or CT route, and combination of OR and TT can deliver more drugs into the inner ear and confer a longer therapeutic window, but cannot increase drug intensity.
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http://dx.doi.org/10.3389/fneur.2021.641593DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8420880PMC
August 2021

Influence of body weight-supported treadmill training with voluntary-driven exoskeleton on the quality of life of persons with chronic spinal cord injury: a pilot study.

Int J Rehabil Res 2021 Sep 3. Epub 2021 Sep 3.

Department of Orthopaedic Surgery, Keio University School of Medicine Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center Department of Rehabilitation Medicine, Keio University School of Medicine Department of Rehabilitation, Kyorin University, Tokyo, Japan.

The aim of this study was to investigate whether body weight-supported treadmill training with voluntary-driven exoskeleton body weight-supported treadmill training (VDE-BWSTT) improves the quality of life (QOL) of persons with chronic spinal cord injury (SCI). Nineteen individuals with chronic SCI with walking limitation underwent a total of 20 sessions of VDE-BWSTT using the hybrid assistant limb. The QOL was measured using the Short Form-36v2 (SF-36v2) questionnaire at preintervention and postintervention. The Walking Index for SCI-II (WISCI-II), Functional Independence Measure (FIM) motor score, and Neuropathic Pain Symptom Inventory (NPSI) self-questionnaire were also administered/completed. In SF-36v2, the mean values of all subscales in our participants were lower than those in healthy individuals. None of the measures showed significant improvement, even in individuals with some residual walking ability (baseline WISCI-II score of 6 or higher). In the correlation analysis between the baselines WISCI-II, FIM, or NPSI values and the mean SF-36v2 subscale changes throughout the training, the baseline FIM motor score was positively correlated with the mean changes in Role Emotional and Mental Health. In addition, NPSI was negatively correlated with the mean change in Vitality and Mental Health. In our protocol, although VDE-BWSTT did not improve the QOL of persons with chronic SCI, those with higher functional independence or lower pain at preintervention likely improved. Further study with combination of task-specific training or pain-targeting treatment with more patients should be considered to more effectively improve their QOL.
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http://dx.doi.org/10.1097/MRR.0000000000000496DOI Listing
September 2021

Neurological Deterioration After Hemivertebrectomy for Congenital Thoracic Kyphoscoliosis with Myelopathy: A Case Report.

JBJS Case Connect 2021 08 16;11(3). Epub 2021 Aug 16.

Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Case: A 14-year-old adolescent boy with congenital kyphoscoliosis with T5 hemivertebra visited our hospital complaining gait disturbance. The T5 hemivertebra was resected posteriorly, and kyphosis at T4 to T7 was corrected from 43° to 36°. However, neurological status gradually deteriorated after surgery. Surgery to reduce kyphosis by bending the rods was performed with intraoperative ultrasonography, which resulted in spinal cord decompression and repulsation of the spinal cord. The muscle strength of the lower extremities improved immediately after surgery.

Conclusion: Correction surgery for congenital kyphoscoliosis has high risk of perioperative neurological deterioration. Ultrasonography may be a useful tool for monitoring status of the spinal cord.
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http://dx.doi.org/10.2106/JBJS.CC.20.00420DOI Listing
August 2021

Myoelectric prosthesis application following radial nerve reconstruction for a case of duplicated amputation of the upper limb.

J Orthop Sci 2021 Aug 10. Epub 2021 Aug 10.

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan. Electronic address:

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http://dx.doi.org/10.1016/j.jos.2021.06.022DOI Listing
August 2021

Cobalt-Chromium Alloy Has Superior Antibacterial Effect Than Titanium Alloy: In Vitro and In Vivo Studies.

Spine (Phila Pa 1976) 2021 Sep;46(17):E911-E915

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Study Design: In vitro and in vivo laboratory studies.

Objective: This study aimed to compare bacterial survival on titanium alloy (Ti) and cobalt-chromium alloy (CC) using in vitro and in vivo experiments.

Summary Of Background Data: Spinal implants are frequently manufactured from Ti and CC. These foreign materials are thought to be susceptible to biofilm formation that contributes to the development of surgical site infections. Certain metals (i.e., silver, cobalt) are known to have antibacterial properties.

Methods: In the in vitro study, discs made of Ti or CC were incubated with one of two common bacteria: Staphylococcus aureus (S. aureus) and Propionibacterium acnes (P. acnes). After incubation, discs were assessed to determine the number of viable bacterial cells. In the in vivo study, the discs that were made of CC or Ti were implanted into the subcutaneous layer of BALB/c mice. After skin closure, a suspension including either S. aureus or P. acnes was directly inoculated on the implanted discs. The discs were retrieved and analyzed to determine the number of viable bacteria at 0.5, 1, and 3 days after inoculation.

Results: The number of viable S. aureus cultured from the CC discs was 0.9 ± 0.2 × 103 CFU/disc, which was significantly lower than the cultured Ti discs (114.8 ± 18.3 × 103 CFU/disc). Moreover, a significantly lower mean number of P. acnes were cultured with CC (1.9 ± 1.2 × 103 CFU/disc) compared with the Ti (180.0 ± 72.1 × 103 CFU/disc). The in vivo infection model testing against S. aureus or P. acnes showed a significantly lower number of viable S. aureus or P. acnes on CC discs than Ti discs. The result was seen at all measured time points.

Conclusion: CC suppressed S. aureus and P. acnes proliferation compared with Ti in vitro and in an in vivo infection model.Level of Evidence: N/A.
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http://dx.doi.org/10.1097/BRS.0000000000003970DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8357039PMC
September 2021

Treadmill training based on the overload principle promotes locomotor recovery in a mouse model of chronic spinal cord injury.

Exp Neurol 2021 Nov 8;345:113834. Epub 2021 Aug 8.

Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address:

Rehabilitative treatment, including treadmill training, is considered an important strategy for restoring motor function after spinal cord injury (SCI). However, many unexplained problems persist regarding the appropriate rehabilitative method and the mechanism underlying the beneficial effects of rehabilitation. Moreover, only a few preclinical studies have been performed on rehabilitative interventions for chronic SCI, although most patients have chronic injuries. In fact, several preclinical studies reported that rehabilitative training was less effective when applied during the chronic phase than when applied sooner. While numerous studies have examined the effects of treadmill training during the subacute phase, the training conditions vary considerably among preclinical reports. Therefore, establishing a standard training protocol is essential for achieving beneficial rehabilitation effects at the chronic stage. Since the difficulty of applying an appropriate training load hinders training at constant speeds, it is important to adjust the training intensity in accordance with the exercise tolerance of an individual animal to provide further functional recovery benefits. Here, we created a novel quadrupedal treadmill training protocol based on the overload principle for mice with incomplete thoracic SCI. We subjected SCI model mice to rehabilitative training according to the protocol for two consecutive weeks starting at 42 days after injury. We examined the treadmill speeds at which the mice were able to run based on the severity of paresis and investigated the impact of the protocol on functional recovery. Assessment of running speed changes during the treadmill training period revealed faster treadmill speeds for mice with mild paresis than for those with severe paresis. The training parameters, including the speed and distance traveled, were positively correlated with the changes in motor function. These results suggest that the most suitable running speed during treadmill training differs according to the level of motor dysfunction and that running longer distances has a positive impact on motor functional recovery. Based on this established protocol, we compared functional and histological results between the chronic SCI groups with and without rehabilitation. The gait analyses showed significantly better functional improvement in the rehabilitation group than in the nonrehabilitation group. Histological analyses revealed that the BDNF- and VGLUT1-positive areas of lumbar enlargement were significantly increased in the rehabilitation group. These findings implied that rehabilitation promoted not only motor performance but also motor control, including forelimb-hindlimb coordination, even in chronic SCI, resulting in functional improvement by treadmill training alone. Therefore, rehabilitative training based on the overload principle appears to be one of the appropriate treatment options for incomplete thoracic SCI, and evidence of its efficacy exists in actual clinical settings.
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http://dx.doi.org/10.1016/j.expneurol.2021.113834DOI Listing
November 2021

Impact of musculoskeletal disorders on healthy life expectancy in Japan.

BMC Musculoskelet Disord 2021 Aug 6;22(1):661. Epub 2021 Aug 6.

Department of Orthopaedic Surgery, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.

Background: Musculoskeletal disorders are a key cause of morbidity in elderly people. How musculoskeletal disorders relate to healthy life expectancy remain elusive. Hence, we aimed to estimate gains in healthy life expectancy from the elimination of musculoskeletal diseases and injuries by using recent national health statistics data in Japan.

Methods: Mortality data were taken from Japanese national life tables and death certificates in 2016. Information on medical diagnoses, injuries, and activity were obtained from the 2016 Comprehensive Survey of Living Conditions. We examined five disorders: rheumatoid arthritis, arthrosis, low back pain, osteoporosis, and fracture. The prevalence of limitations in activities of daily living (ADL) in the population after eliminating the disorder was estimated as the proportion of outpatients without the disorder and ADL limitations, inpatients without the disorder in hospitals and clinics, and people without the disorder who reside in long-term elderly care facilities.

Results: There were small gains in life expectancy from elimination of all selected musculoskeletal disorders (0.0-0.1 years). Elimination of rheumatoid arthritis, osteoporosis, and fracture slightly increased the expected years without activity limitation (0.1-0.4) and slightly decreased years with activity limitation (0.1-0.4 years). Meanwhile, elimination of arthrosis, low back pain, and arthrosis and low back pain moderately increased expected years without activity limitation (0.3-1.5 years) and decreased years with activity limitation (0.3-1.5 years). In addition, elimination of rheumatoid arthritis, arthrosis, low back pain, osteoporosis, and fracture decreased expected years with ADL limitations (0.0-0.8 years) and non-ADL limitations (0.0-0.3 years). A combination of arthrosis and low back pain showed a moderate decrease in expected years with both ADL limitations (0.7-1.1 years) and non-ADL limitations (0.3-0.4).

Conclusions: These findings provide clinical evidence that among the musculoskeletal disorders low back pain and arthrosis are the key factors for the elongation of healthy life expectancy.
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http://dx.doi.org/10.1186/s12891-021-04539-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8348995PMC
August 2021

Impact of Diabetes Mellitus on Cervical Spine Surgery for Ossification of the Posterior Longitudinal Ligament.

J Clin Med 2021 Jul 29;10(15). Epub 2021 Jul 29.

Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Tokyo 113-8510, Japan.

Ossification of the posterior longitudinal ligament (OPLL) is commonly associated with diabetes mellitus (DM); however, the impact of DM on cervical spine surgery for OPLL remains unclear. This study was performed to evaluate the influence of diabetes DM on the outcomes following cervical spine surgery for OPLL. In total, 478 patients with cervical OPLL who underwent surgical treatment were prospectively recruited from April 2015 to July 2017. Functional measurements were conducted at baseline and at 6 months, 1 year, and 2 years after surgery using JOA and JOACMEQ scores. The incidence of postoperative complications was categorized into early (≤30 days) and late (>30 days), depending on the time from surgery. From the initial group of 478 patients, 402 completed the 2-year follow-up and were included in the analysis. Of the 402 patients, 127 (32%) had DM as a comorbid disease. The overall incidence of postoperative complications was significantly higher in patients with DM than in patients without DM in both the early and late postoperative periods. The patients with DM had a significantly lower JOA score and JOACMEQ scores in the domains of lower extremity function and quality of life than those without DM at the 2-year follow-up.
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http://dx.doi.org/10.3390/jcm10153375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8347558PMC
July 2021

Transient alendronate administration to pregnant or lactating mothers prevents bone loss in mice without adverse effects on offspring.

Bone 2021 Jul 28;153:116133. Epub 2021 Jul 28.

Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan; Department of Advanced Therapy for Musculoskeletal Disorders II, Keio University School of Medicine, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan; Department of Musculoskeletal Reconstruction and Regeneration Surgery, Keio University School of Medicine, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan; Department of Orthopedic Surgery, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan. Electronic address:

Changes in bone metabolism occur in mothers during pregnancy or lactation that may decrease bone mass and result in fragility fractures after partum. However, use of drugs during pregnancy or lactation to counteract these effects is often prohibited or strongly discouraged. Therefore, approaches to protect mothers from fragility fractures have not been established. Here we show that bone mineral density was significantly lower in female mice after partum than in age-matched female mice without partum. We also show that temporary administration of the bisphosphonate alendronate, either just before or just after pregnancy, to female mice was protective against bone loss due to pregnancy or lactation and had no adverse effects on offspring, such as growth retardation. Furthermore, we show that alendronate administration to female mice during lactation was effective in increasing bone mass in mothers without promoting bone abnormalities or growth retardation in offspring. Calcium levels in milk from female mice administered alendronate during lactation were equivalent to those in milk from mothers not treated with alendronate. Overall, we propose that alendronate administration to mothers could prevent bone loss and fragility fractures during pregnancy and lactation.
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http://dx.doi.org/10.1016/j.bone.2021.116133DOI Listing
July 2021

Lignin valorization through efficient microbial production of β-ketoadipate from industrial black liquor.

Bioresour Technol 2021 Oct 2;337:125489. Epub 2021 Jul 2.

Bio-based Solution Division, Kantechs Co. Ltd., Bunkyo, Tokyo 112-0004, Japan.

Vanillin and vanillate are the major lignin-derived aromatic compounds produced through the alkaline oxidation of softwood lignin. Because the production of higher-value added chemicals from these compounds is essential for lignin valorization, the microbial production of β-ketoadipate, a promising raw material for the synthesis of novel nylons, from lignin was considered. Pseudomonas putida KT2440 was engineered to convert vanillin and vanillate to β-ketoadipate. By examining the culture conditions with an initial culture volume of 1 L, the engineered strain completely converted 25 g of vanillin and 25 g of vanillate and produced approximately 23 g of β-ketoadipate from each of them with a yield of 93% or higher. Furthermore, this strain showed the ability to efficiently produce β-ketoadipate from softwood lignin extracts in black liquor, a byproduct of pulp production. These results suggest that the production of β-ketoadipate from industrial black liquor is highly feasible for substantial lignin valorization.
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http://dx.doi.org/10.1016/j.biortech.2021.125489DOI Listing
October 2021

Clinical outcomes and a therapeutic indication of intramedullary spinal cord astrocytoma.

Spinal Cord 2021 Jul 26. Epub 2021 Jul 26.

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Study Design: Retrospective cohort study.

Objectives: Although intramedullary astrocytoma is associated with a high mortality rate, the optimal treatment has not reached a consensus. This study aimed at evaluating neurologic function and overall survival rate (OSR) in the treatment of this tumor.

Setting: The single institution in Japan.

Methods: This study enrolled 67 subjects who underwent surgical treatment for intramedullary astrocytoma. Demographic, imaging, and surgical information were collected from each participant. Tumors were histologically categorized using the World Health Organization classification, and subjects were divided into low-grade (I and II; n = 40) and high-grade (III and IV; n = 27) groups. Neurologic status was evaluated using the modified McCormick scale (MMS). OSR was assessed using Kaplan-Meier methods.

Results: The OSR decreased when the pathological grade increased (p < 0.01). Regarding the therapeutic efficacy for low-grade astrocytomas, subjects who underwent gross total resection (GTR) showed a higher OSR than those who did not (p = 0.02). GTR prevented worsening of MMS score, while non-GTR increased the MMS score (p < 0.01). In the high-grade group, 19 and 10 underwent radiation therapy and chemotherapy, respectively. However, both treatments did not improve OSR. Cordotomy was performed for subjects whose lesional area was at the thoracic level, but the OSR did not significantly increase.

Conclusions: The most beneficial therapeutic strategy for low-grade astrocytomas was GTR, whereas that for the high-grade tumors was unclear. Further studies with a larger sample size are warranted to validate the effective treatment for malignant astrocytomas.
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http://dx.doi.org/10.1038/s41393-021-00676-8DOI Listing
July 2021

Can Postoperative Distal Adding-On be Predicted in Lenke Type 1B and 1C Curves with Intraoperative Radiographs?

Spine (Phila Pa 1976) 2021 Jul 16. Epub 2021 Jul 16.

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan Department of Environmental and Occupational Health, School of Medicine, Toho University. Tokyo, Japan.

Study Design: A retrospective study of consecutive collected data.

Objective: To investigate risk factors for postoperative distal adding-on (DA) in Lenke Type 1B and 1C curves using intraoperative radiographs.

Summary Of Background Data: In adolescent idiopathic scoliosis (AIS), DA radiographic complication can negatively affect postoperative clinical results. However, few studies have focused on assessing risk factors for DA using intraoperative radiographs.

Methods: We retrospectively evaluated 69 AIS patients with Lenke Type 1B or 1C curves who underwent posterior selective thoracic fusion. We divided patients into DA and non-DA groups based on radiograph data at 2-year follow-up using Wang et al. (Spine 2011) definition of DA. We compared coronal radiographic parameters, including relative positions of end vertebra (EV), stable vertebra (SV), neutral vertebra (NV), and last touching vertebra (LTV) to lowest instrumented vertebra (LIV), and intraoperative radiographic parameters, between the two groups.

Results: DA was present in 13 patients (18.8%) at 2-year follow-up. The mean LIV-EV, LIV-NV, LIV-SV, and LIV-LTV relative positions were significantly smaller in the DA group than in the non-DA group. Multivariate analysis showed that LIV-LTV was significantly associated with DA (DA:-0.2 ± 0.7, non-DA: 0.6 ± 0.7). Intraoperative radiographs showed that the mean angulation of the first disc below the LIV after final adjustment was significantly larger in the DA group (2.3° ± 1.1°) than in the non-DA group (0.9° ± 0.7°). Patients whose angulation of the first disc below the LIV was more than 3° were significantly associated with DA.

Conclusion: The LIV selected at more cranial to the LTV may be a risk factor for postoperative DA in Lenke Type 1B and 1C curves. Moreover, it was suggested that LIV extension might be considered when the first disc's angulation below the LIV is > 3° in intraoperative radiographs.Level of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000004174DOI Listing
July 2021

Neurorehabilitation using a voluntary driven exoskeletal robot improves trunk function in patients with chronic spinal cord injury: a single-arm study.

Neural Regen Res 2022 Feb;17(2):427-432

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Body weight-supported treadmill training with the voluntary driven exoskeleton (VDE-BWSTT) has been shown to improve the gait function of patients with chronic spinal cord injury. However, little is known whether VDE-BWSTT can effectively improve the trunk function of patients with chronic spinal cord injury. In this open-label, single-arm study, nine patients with chronic spinal cord injury at the cervical or thoracic level (six males and three females, aged 37.8 ± 15.6 years, and time since injury 51.1 ± 31.8 months) who underwent outpatient VDE-BWSTT training program at Keio University Hospital, Japan from September 2017 to March 2019 were included. All patients underwent twenty 60-minute gait training sessions using VDE. Trunk muscular strength, i.e., the maximum force against which patient could maintain a sitting posture without any support, was evaluated in four directions: anterior, posterior, and lateral (right and left) after 10 and 20 training sessions. After intervention, lateral muscular strength significantly improved. In addition, a significant positive correlation was detected between the change in lateral trunk muscular strength after 20 training sessions relative to baseline and gait speed. The change in trunk muscular strength after 20 training sessions relative to baseline was greatly correlated with patient age. This suggests that older adult patients with chronic spinal cord injury achieved a greater improvement in trunk muscle strength following VDE-BWSTT. All these findings suggest that VDE-BWSTT can improve the trunk function of patients with chronic spinal cord injury and the effect might be greater in older adult patients. The study was approved by the Keio University of Medicine Ethics Committee (IRB No. 20150355-3) on September 26, 2017.
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http://dx.doi.org/10.4103/1673-5374.317983DOI Listing
February 2022

The impact of ossification spread on cervical spine function in patients with ossification of the posterior longitudinal ligament.

Sci Rep 2021 Jul 12;11(1):14337. Epub 2021 Jul 12.

Department of Orthopaedic Surgery, Keio University, School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo , Japan.

Ossification of the posterior longitudinal ligament (OPLL) is a progressive disease. The bridging of ossified lesions to the vertebral body gradually increases, thereby decreasing the mobility of the cervical spine; thus, cervical spine function may decrease over time. However, cervical spine function in patients with cervical OPLL has not been evaluated in large prospective studies. Therefore, we conducted a prospective multicenter study to clarify whether ossification spread can influence cervical spine function and quality of life (QOL) in patients with cervical OPLL. In total, 238 patients (162 men, 76 women; mean age, 63.9 years) were enrolled from 16 institutions. Each patient underwent whole spine computed tomography and was evaluated for cervical spine function and QOL using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). In the multivariate regression analysis, a higher neck VAS score and a larger number of bridge formations of OPLL in the whole spine were significant predictors of adverse outcomes related to cervical spine function. This is the first prospective multicenter study to reveal the impact of ossification spread on cervical spine function. These findings are important to understand the natural course of OPLL and can serve as controls when evaluating postoperative cervical spine function.
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http://dx.doi.org/10.1038/s41598-021-93602-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8275804PMC
July 2021

Total elbow arthroplasty using an augmented reality-assisted surgical technique.

J Shoulder Elbow Surg 2021 Jun 25. Epub 2021 Jun 25.

Department of Orthopedic Surgery, Keio University, Tokyo, Japan.

Background: Precision placement of implants in total elbow arthroplasty (TEA) using conventional surgical techniques can be difficult and riddled with errors. Modern technologies such as augmented reality (AR) and 3-dimensional (3D) printing have already found useful applications in many fields of medicine. We proposed a cutting-edge surgical technique, augmented reality total elbow arthroplasty (ARTEA), that uses AR and 3D printing to provide 3D information for intuitive preoperative planning. The purpose of this study was to evaluate the accuracy of humeral and ulnar component placement using ARTEA.

Methods: Twelve upper extremities from human frozen cadavers were used for experiments performed in this study. We scanned the extremities via computed tomography prior to performing TEA to plan placement sites using computer simulations. The ARTEA technique was used to perform TEA surgery on 6 of the extremities, whereas conventional (non-ARTEA) techniques were used on the other 6 extremities. Computed tomography scanning was repeated after TEA completion, and the error between the planned and actual placements of humeral and ulnar components was calculated and compared.

Results: For humeral component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 1.4° ± 0.6° vs. 4.4° ± 0.9° in total rotation (P = .002) and 1.5 ± 0.6 mm vs. 8.6 ± 1.3 mm in total translation (P = .002). For ulnar component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 5.5° ± 3.1° vs. 19.5° ± 9.8° in total rotation (P = .004) and 1.5 ± 0.4 mm vs. 6.9 ± 1.6 mm in total translation (P = .002). Both rotational accuracy and translational accuracy were greater for joint components replaced using the ARTEA technique compared with the non-ARTEA technique (P < .05).

Conclusion: Compared with conventional surgical techniques, ARTEA had greater accuracy in prosthetic implant placement when used to perform TEA.
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http://dx.doi.org/10.1016/j.jse.2021.05.019DOI Listing
June 2021

Polygenic Risk Score of Adolescent Idiopathic Scoliosis for Potential Clinical Use.

J Bone Miner Res 2021 08 22;36(8):1481-1491. Epub 2021 Jun 22.

Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Adolescent idiopathic scoliosis (AIS) is a common disease causing three-dimensional spinal deformity in as many as 3% of adolescents. Development of a method that can accurately predict the onset and progression of AIS is an immediate need for clinical practice. Because the heritability of AIS is estimated as high as 87.5% in twin studies, prediction of its onset and progression based on genetic data is a promising option. We show the usefulness of polygenic risk score (PRS) for the prediction of onset and progression of AIS. We used AIS genomewide association study (GWAS) data comprising 79,211 subjects in three cohorts and constructed a PRS based on association statistics in a discovery set including 31,999 female subjects. After calibration using a validation data set, we applied the PRS to a test data set. By integrating functional annotations showing heritability enrichment in the selection of variants, the PRS demonstrated an association with AIS susceptibility (p = 3.5 × 10 with area under the receiver-operating characteristic [AUROC] = 0.674, sensitivity = 0.644, and specificity = 0.622). The decile with the highest PRS showed an odds ratio of as high as 3.36 (p = 1.4 × 10 ) to develop AIS compared with the fifth in decile. The addition of a predictive model with only a single clinical parameter (body mass index) improved predictive ability for development of AIS (AUROC = 0.722, net reclassification improvement [NRI] 0.505 ± 0.054, p = 1.6 × 10 ), potentiating clinical use of the prediction model. Furthermore, we found the Cobb angle (CA), the severity measurement of AIS, to be a polygenic trait that showed a significant genetic correlation with AIS susceptibility (rg = 0.6, p = 3.0 × 10 ). The AIS PRS demonstrated a significant association with CA. These results indicate a shared polygenic architecture between onset and progression of AIS and the potential usefulness of PRS in clinical settings as a predictor to promote early intervention of AIS and avoid invasive surgery. © 2021 American Society for Bone and Mineral Research (ASBMR).
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http://dx.doi.org/10.1002/jbmr.4324DOI Listing
August 2021

Upper End Vertebra of Proximal Thoracic Curve At T1 is a Novel Risk Factor of Postoperative Shoulder Imbalance in Lenke Type 2 Adolescent Idiopathic Scoliosis.

Global Spine J 2021 Jun 14:21925682211023049. Epub 2021 Jun 14.

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Study Design: Retrospective single-center study.

Objective: We investigated the risk factors of postoperative shoulder imbalance (PSI) in patients with Lenke type 2 adolescent idiopathic scoliosis (AIS) including the position of preoperative upper end vertebra (UEV).

Methods: Seventy-five patients with Lenke type 2 AIS who underwent posterior correction and fusion surgeries from 2008 to 2018 were included. We included only patients whose upper instrumented vertebrae were at T2. The patients were divided into 2 groups based on radiographic shoulder height (RSH) at final follow-up, namely PSI group and non-PSI group, and PSI was defined as RSH > 10 mm. UEV, RSH, Cobb angle, curve flexibility, T1 and T2 tilt, correction rate, Risser grade, Scoliosis Research Society-22 scores, and demographic data were compared between the groups using independent tests or chi-square tests. Variables with value < 0.20 in univariate analysis were assessed in logistic regression analysis.

Results: Thirty-four patients in the PSI group and 37 patients in the non-PSI group were analyzed. Univariate analysis revealed that there were more patients with UEV at T1 (PSI: 85%, non-PSI: 54%, < 0.01) and Risser grade ≥ 3 (PSI: 88%, non-PSI: 62%; < 0.05) in the PSI group than in the non-PSI group. Logistic regression analysis revealed that UEV at T1 (odds ratio [OR] = 4.1 [1.2-14.4], < 0.05) and Risser grade ≥ 3 (OR = 3.9 [1.1-14.5], < 0.05) are significantly associated with PSI.

Conclusions: UEV at T1 and Risser grade ≥ 3 at the time of surgery are significant risk factors of PSI.
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http://dx.doi.org/10.1177/21925682211023049DOI Listing
June 2021

Spontaneous Reduction of Chiari Malformation and Syringomyelia After Posterior Spinal Fusion for Scoliosis: A Case Report.

JBJS Case Connect 2021 06 11;11(2). Epub 2021 Jun 11.

Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Case: A 22-year-old skeletally mature man with scoliosis accompanied by syringomyelia associated with Chiari malformation type 1 was presented to our hospital. Because the maximal syrinx/cord ratio was small, and he had no neurological deficit, he underwent corrective surgery without the treatment of the syringomyelia.

Conclusion: The scoliosis was corrected without any neurological complications. Magnetic resonance imaging taken 8 days after the surgery showed the reduction of the size of the syringomyelia. The syringomyelia almost disappeared at the 8-year follow-up.
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http://dx.doi.org/10.2106/JBJS.CC.20.00779DOI Listing
June 2021

Neurological improvement is associated with neck pain attenuation after surgery for cervical ossification of the posterior longitudinal ligament.

Sci Rep 2021 Jun 7;11(1):11910. Epub 2021 Jun 7.

Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan.

Although favourable surgical outcomes for myelopathy caused by cervical ossification of the posterior longitudinal ligament (OPLL) have been reported, factors significantly associated with post-operative neck pain attenuation still remain unclear. The primary aim of the present study was to determine factors significantly associated with post-operative neck pain attenuation in patients with cervical OPLL using a prospective multi-centre registry of surgically treated cervical OPLL. Significant postoperative neck pain reduction (50% reduction of neck pain) was achieved in 31.3% of patients. There was no significant difference in neck pain attenuation between surgical procedures. Statistical analyses with univariate analyses followed by stepwise logistic regression revealed neurological recovery as a factor having a significant positive association with post-operative neck pain attenuation (p = 0.04, odds ratio 5.68 (95% confidence interval: 1.27-22.2)). In conclusion, neurological recovery was an independent factor having a significant positive association with post-operative neck pain attenuation in patients with cervical myelopathy caused by OPLL who underwent cervical spine surgery.
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http://dx.doi.org/10.1038/s41598-021-91268-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8184776PMC
June 2021

The characteristics of the young patients with cervical ossification of the posterior longitudinal ligament of the spine: A multicenter cross-sectional study.

J Orthop Sci 2021 Jun 3. Epub 2021 Jun 3.

Department of Orthopedic Surgery, Keio University, School of Medicine, Tokyo, Japan; Japanese Organization of the Study for Ossification of Spinal Ligament (JOSL), Tokyo, Japan.

Background: Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by heterotopic bone formation in the posterior longitudinal ligament of the spine. Although the patients with OPLL are more common in the 60s and 70s, we know that there are markedly young patients (e.g., early 40s). However, to the best of our knowledge, there is few reports characterize young patients with cervical OPLL in terms of the imaging features, subjective symptoms, and ADL problems.

Methods: This is the multicenter cross-sectional study. Two hundred and thirty-seven Japanese symptomatic patients with cervical OPLL confirmed by standard X-rays collected from 16 institutions belonging to the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament formed by the Japanese Ministry of Health, Labor and Welfare were recruited. Whole spine CT data as well as demographic data such as age, gender, patients-based evaluations, and the 36-item Short Form Health Survey (SF-36) were evaluated.

Results: Young group (≦ 45 years old) consisted of 23 patients (8 females and 15 males), accounting for 9.7% of the total. Their characteristics were high body mass index (BMI), significant involvement of trauma in the onset and deterioration of symptoms, and the predominance of thoracic OPLL. The patient-based evaluations did not show a significant difference between the young and non-young groups, or between the genders in the young group except for bodily pain (BP) of SF-36. Female patients in young group had significantly lower BP score of SF-36 than that of male in young group.

Conclusions: Characteristics of young patients with cervical OPLL were high BMI, significant involvement of trauma in the onset and deterioration of symptoms, lower BP score of SF-36 in female, and the predominance of thoracic OPLL.
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http://dx.doi.org/10.1016/j.jos.2021.04.010DOI Listing
June 2021

Serum C-reactive protein is an early, simple and inexpensive prognostic marker for the progression of intramedullary lesion on magnetic resonance imaging from acute to subacute stage in patients with spinal cord injury.

Spinal Cord 2021 May 27. Epub 2021 May 27.

Department of Orthopaedic Surgery, Hokkaido University Graduate School of Medicine, Hokkaido, Japan.

Study Design: Retrospective chart audit.

Objectives: This study aimed to identify conventional routine blood testing biomarkers associated with the progression of intramedullary injured area in patients with spinal cord injury (SCI).

Setting: A spinal cord injury center in Hokkaido, Japan.

Methods: We retrospectively reviewed 71 consecutive adults with acute SCI who were admitted within 24 h after injury and diagnosed as American Spinal Injury Association Impairment Scale Grade A or B at admission. Participants were divided into the progression (P group) and no progression group (NP group) based on the change of the hyperintense signal abnormality in the spinal cord on magnetic resonance imaging from the time of admission to 4 weeks after injury. Individual characteristics and blood testing data obtained in the first 4 weeks after injury were compared between groups.

Results: The P and NP groups were comprised of 16 and 55 participants, respectively. In univariate analyses, white blood cell (WBC) count on day 3 was significantly higher in group P than group NP (P = 0.021), as was serum C-reactive protein (CRP) level on day 3 (P = 0.015) and day 7 (P = 0.047). Multivariable analysis identified serum CRP level on day 3 as a significant independent prognostic factor for the progression of secondary SCI (OR, 1.138; 95% confidence interval, 1.01-1.28; P = 0.034).

Conclusions: Serum CRP level on day 3 after injury was a good predictor for the progression of intramedullary signal intensity change on MRI from acute to subacute stage in patients with SCI.
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http://dx.doi.org/10.1038/s41393-021-00640-6DOI Listing
May 2021

Cervical intramedullary recurrent Ewing sarcoma after 10-year disease-free survival in an adult: a case report and review of literature.

Spinal Cord Ser Cases 2021 May 27;7(1):45. Epub 2021 May 27.

Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.

Introduction: Intramedullary metastasis of Ewing sarcoma is extremely rare. Here, we report an adult case of cervical intramedullary recurrent Ewing sarcoma after a 10-year disease-free survival after the initial surgery for a thoracic lesion.

Case Presentation: A 39-year-old man with a history of surgery and chemoradiotherapy for thoracic Ewing sarcoma ten years ago presented with neck pain and incomplete motor paralysis in the right upper extremity, which had suddenly appeared three months before. Cervical magnetic resonance imaging revealed a tear-drop-shaped intramedullary lesion at the C3 level accompanied by diffuse edematous change. Because of the rapid progression of his myelopathy, he underwent surgery for this intramedullary lesion. Intraoperatively, the tumor exhibited an orangish exophytic appearance. The unclearness of the tumor boundary compelled us to perform a partial resection. The histopathology showed the tumor comprised small round atypical cells with immunoreactivity for Nkx2.2 and CD99, diagnosing a metastatic Ewing sarcoma. Postoperatively, although his myelopathy improved transiently and adjuvant chemotherapy radiation was undergone, he died of cranial dissemination of the tumor two months and a half later.

Discussion: To our knowledge, 31 cases of primary and only 4 cases of recurrent intramedullary spinal Ewing sarcoma have been reported to date; however, this is the first case of recurrent intramedullary Ewing sarcoma with a 10-year disease-free survival. Sadly, the prognosis of the current case was extremely poor. There is no clear treatment guideline for recurrent intramedullary Ewing sarcoma because of its rarity, and further collection of similar cases would be required.
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http://dx.doi.org/10.1038/s41394-021-00406-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8160263PMC
May 2021

Comparison of Surgical Outcomes After Open- and Double-Door Laminoplasties for Patients with Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Multicenter Study.

Spine (Phila Pa 1976) 2021 May 6. Epub 2021 May 6.

Department of Orthopaedic Surgery, School of Medicine, Keio University, Shinjuku Ward, Tokyo, Japan Department of Orthopedic Surgery, Tokyo Medical and Dental University, Bunkyo Ward, Tokyo, Japan Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, Kawaguchishi, Saitama, Japan Department of Orthopedic Surgery, Kudanzaka Hospital, Chiyodaku, Japan Department of Orthopaedic Surgery, Wakayama Medical University Kihoku Hospital, Katsuragi-cho, Itogun, Wakayama, Japan Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan Department of Orthopedic Surgery, Niigata University Medicine and Dental General Hospital, Chuo Ward, Niigata, Niigata, Japan Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan Department of Orthopedics, Jichi Medical University, Shimotsuke, Tochigi, Japan Department of Orthopedic Surgery, Chiba University Graduate School of Medicine, Chuo Ward, Chiba, Japan Department of Orthopedic Surgery, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan Department of Orthopedic Surgery, Osaka Rosai Hospital, Sakaishi, Osaka, Japan Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine,, Showa Ward, Nagoya, Aichi, Japan Department of Orthopaedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan Department of Orthopaedic Surgery, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga, Japan Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences University of Fukui, Eiheiji-cho, Yoshida-gun, Fukui, Japan Department of Orthopedic Surgery, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan Department of Orthopedic Surgery, Imakiire General Hospital, Kagoshimashi, Japan Department of Orthopedic Surgery, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan Department of Orthopaedic Surgery, Kurume University School of Medicine, Kurume-shi, Fukuoka, Japan Department of Orthopedic Surgery, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan Department of Orthopedic Surgery, University of Yamanashi, Chuo Ward, Yamanashi, Japan Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, Mibu-machi, Shimotsuga-gun, Tochigi, Japan Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Shogoin, Sakyo-ku, Kyoto, Japan Department of Orthopedic Surgery, Surgical Science, Tokai University School of Medicine, Isehara, Kanagawa, Japan Department of Orthopaedic Surgery, Tohoku University School of Medicine, Aoba Ward, Sendai, Miyagi, Japan Department of Orthopedic Surgery, Faculty of Medicine, University of Toyama, Toyama, Toyama, Japan Japanese Multicenter Research Organization for Ossification of the Spinal Ligament.

Study Design: A prospective multicenter study.

Objective: To evaluate and compare the surgical outcomes after open-door (OD) and double-door (DD) laminoplasties in subjects with cervical ossification of the posterior longitudinal ligament (OPLL).

Summary Of Background Data: Although previous studies compared clinical results after OD and DD laminoplasties, they were performed at a single institution with a relatively small sample size targeting mixed pathologies, including cervical spondylotic myelopathy.

Methods: This study was performed by the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. A total of 478 patients with myelopathy caused by cervical OPLL from 28 institutions were prospectively registered from 2014 to 2017 and followed up for 2 years. Of these, 41 and 164 patients received OD and DD laminoplasties, respectively. Demographic information, medical history, and imaging findings were collected. Clinical outcomes were assessed using the cervical Japanese Orthopaedic Association (JOA), JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and visual analog scale (VAS) scores.

Results: Age, sex, symptom duration, and comorbidities were not significantly different between the groups. Segmental ossification was the most frequent in both groups. No significant differences in K-line type, canal occupying ratio, C2-C7 angles, and range of motion (ROM) were found. Both procedures reduced the cervical ROM postoperatively. A comparable frequency of perioperative complications was observed between the groups. The cervical JOA scores showed a similar improvement at 2 years postoperatively. The reduction in VAS score for neck pain was favorable in the OD group (P = 0.02), while other pain assessments did not show any significant differences between the groups. The functional outcomes assessed using the JOACMEQ presented equivalent effective rates.

Conclusion: The results demonstrated almost comparable surgical outcomes between OD and DD laminoplasties. Laminoplasty is a valuable technique as a therapeutic option for cervical OPLL.Level of Evidence: 5.
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http://dx.doi.org/10.1097/BRS.0000000000004094DOI Listing
May 2021

Coronal Plane Gap Increases Postoperative Pseudoarthrosis after Lateral Interbody Fusion for Adult Spinal Deformity.

Asian Spine J 2021 May 6. Epub 2021 May 6.

Department of Orthopaedic Surgery, Keio University School of Medicine, Shinjuku, Japan.

Study Design: This is a retrospective study.

Purpose: This study aims to evaluate the risk factor associated with pseudoarthrosis after placement of lateral interbody fusion (LIF) cages for adult spinal deformity (ASD) treatment.

Overview Of Literature: LIF technique is widely used for ASD correction. Furthermore, pseudoarthrosis is a major complication of fusion surgery required for revision surgery.

Methods: This study included 42 patients with ASD (two men and 40 women; 112 segments; mean, 68.5±8.4 years; and mean follow-up, 31.6±17.0 months) who underwent LIF and posterior correction surgery. The concave slot of the LIF cage was filled with an autologous iliac crest bone graft (IBG), and the convex slot with a porous hydroxyapatite/collagen (HAp/Col) composite was soaked with bone marrow aspirate. Endplate injury, the gap between vertebral endplate and cage in the coronal or sagittal plane, and fusion status were evaluated using computed tomography multiplanar reconstruction at 12 months after surgery. Moreover, the associated risk factors for pseudoarthrosis were analyzed.

Results: Fusion at LIF segments were observed in 71.4% segments at 12 months after surgery. Fusion on the concave slot (autologous IBG side), convex slot (porous HAp/Col composite side), and both concave and convex slots were observed in 66.1%, 37.5%, and 36.6% of patients, respectively. Moreover, pseudoarthrosis was observed in 28.6% at 12 months after surgery. Consequently, logistic regression analysis of the fusion at the LIF segment revealed that the gap between the LIF cage and endplate in the coronal plane (p=0.030; odds ratio, 0.183; 95% confidence interval, 0.030-0.183) was significantly associated with pseudoarthrosis at the LIF segments.

Conclusions: ASD surgery fusion rate using LIF cages was 71.4% at 12 months after surgery. The fusion rate was higher on the concave slot filled with autologous IBG than on the convex slot filled with a porous HAp/Col composite. The gap in the coronal plane was a risk factor for pseudoarthrosis at the LIF segment.
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http://dx.doi.org/10.31616/asj.2020.0336DOI Listing
May 2021
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