WIDEBAND DS - CDMA FOR 3RD GENERATION MOBILE COMMUNICATION SYSTEMS

Nobuo Nakajima,Fumiyuki Adachi 에스케이텔레콤 (주) 1997 Telecommunications Review Vol.7 No.2

This paper describes the features and technology of the wideband DS-CDMA system for next generation mobile communication system. The wider the bandwidth, the more the capacity increases. In addition, wide range of data rates from as low as about 4kbps to 2 Mbps can be accommodated by the wideband system, In order to flexibly offer data services with a variety of rates multi-rate codes are employed and four different bandwidths of 1.25, 5, 10, and 20 Mcps are adopted. The system operates in an inter cell asynchronous mode to allow flexible and continuous system deployment from outdoors into indoors. New technologies are developed to enhance the capacity and quality of the wideband DS-CDMA. They are the interference canceler and adaptive antenna array. Exensive measurements and evaluations of a 2-㎓ band DS-CDMA system were carried out under real multipath fading environments.

The Effect of Simultaneous Antigravity Treadmill Training and Electrical Muscle Stimulation After Total Hip Arthroplasty: Short Follow-Up Time

Yukio Mikami,Naoya Orita,Takuma Yamasaki,Hiroaki Kimura,Nobuo Adachi 대한재활의학회 2019 Annals of Rehabilitation Medicine Vol.43 No.4

Objective To assess the effectiveness of our devised hybrid physiotherapy regime using an anti-gravity treadmill and a low-frequency electrical stimulation device, as measured in patients with hip osteoarthritis after total hip arthroplasty (THA). Methods The outcomes of the postoperative rehabilitation in 44 patients who underwent THA for hip osteoarthritis were retrospectively examined. The conventional group (n=22) underwent the postoperative rehabilitation according to our protocol, while the hybrid group (n=22) underwent the same training, along with training on an anti-gravity treadmill and training using a low-frequency therapeutic device. The outcome measures were recorded and reviewed with the Numerical Rating Scale for pain, which rates pain on an 11-point scale from 0 to 10, surgical side knee joint extension force, 10-m walking test, Timed Up and Go test, and the 6-minute walking distance (6MD). The outcome measurement was taken 2 weeks after conducting pre-operation and antigravity treadmill training and electrical muscle stimulation, and compared the respective results. Results At the timeframe of 2 weeks from the surgery after conducting a devised hybrid physiotherapy, the values of knee extension muscle strength and 6MD were not worse in the hybrid group than conventional group. In the evaluation at 2 weeks after surgery, the knee extension muscle strength and 6MD values significantly decreased compared with the preoperative values only in the conventional group. Conclusion Lower limb muscular strength and endurance were maintained in the hybrid group, which suggested that hybrid physiotherapy could maintain physical functions early after THA operation.

Rotational Acetabular Osteotomy

Yuji Yasunaga,Jiro Fujii,Ryuji Tanaka,Shinji Yasuhara,Takuma Yamasaki,Nobuo Adachi,Mitsuo Ochi 대한정형외과학회 2017 Clinics in Orthopedic Surgery Vol.9 No.2

Hip dysplasia is the most common cause of secondary osteoarthritis (OA). To prevent the early onset of secondary OA, Nishio’s transposition osteotomy, Steel’s triple osteotomy, Eppright’s dial osteotomy, Wagner’s spherical acetabular osteotomy, Tagawa’s rotational acetabular osteotomy (RAO), and Ganz’ periacetabular osteotomy (PAO) have been proposed. PAO and RAO are now commonly used in surgical treatment of symptomatic acetabular dysplasia in Europe, North America, and Asia. The aim of this paper is to present the followings: the patient selection criteria for RAO; the surgical technique of RAO; the long-term outcome of RAO; and the future perspectives.

Foramen Magnum Decompression with Outer Dura Matter Layer Resection for Chiari Type I Malformation: Factors Correlated with Syrinx Reduction

Maruyama Toshiaki,Nakamae Toshio,Kamei Naosuke,Tanaka Nobuhiro,Fujiwara Yasushi,Harada Takahiro,Adachi Nobuo 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.2

Study Design: A retrospective cohort study.Purpose: We aimed to investigate the surgical results of foramen magnum decompression (FMD) to identify the potential factors associated with syrinx reduction in Chiari malformation type I (CMI).Overview of Literature: The predictive value of preoperative factors for syrinx reduction in patients with CMI remains debatable.Methods: We enrolled patients who underwent microscopic FMD with outer dural layer resection for CMI. The distance from the tip of the cerebellar tonsil to the C2 vertebral endplate on sagittal magnetic resonance imaging (MRI) was defined as the tonsillar distance (TD). Patients who showed a >20% syrinx diameter reduction on the 1-year follow-up MRI were defined as the syrinx reduction group while the others were categorized in the syrinx nonreduction group. Patients with syringomyelia were categorized into the clinically improved and unimproved groups using the Chicago Chiari Outcome Scale. The imaging and clinical parameters were evaluated pre- and postoperatively.Results: This study included 25 patients of whom 19 (76.0%) had syringomyelia. At the 1-year follow-up, the syrinx diameter had decreased in 11 patients (57.8%). The increased TD significantly differed between the syrinx reduction and nonreduction groups. At the 1-year follow-up, 12 and seven patients with syringomyelia were categorized into the clinically improved and unimproved groups, respectively. The clinically improved and unimproved groups showed significant differences in the mean age and increased TD.Conclusions: Postoperative syrinx reduction was significantly correlated with the upward shifting of the cerebellar tonsil in patients with CMI. Our quantitative evaluation of the alterations in hindbrain position after FMD was easily performed and reflects the clinical outcomes.

Quantitative Assessment of Bone Marrow Edema in Adolescent Athletes with Lumbar Spondylolysis Using Contrast Ratio on Magnetic Resonance Imaging

Nakamae Toshio,Kamei Naosuke,Tamura Takayuki,Kanda Tsukasa,Nakanishi Kazuyoshi,Adachi Nobuo 대한척추외과학회 2021 Asian Spine Journal Vol.15 No.5

Study Design: Prospective cohort study. Purpose: To quantitatively evaluate bone marrow edema (BME) in the pedicle on magnetic resonance imaging (MRI) for adolescent athlete patients with spondylolysis. Overview of Literature: Spondylolysis, a stress fracture of the pars interarticularis, is a common occurrence in adolescent athletes with low back pain. T2-weighed fat-saturated MRI is reportedly useful for the detection of BME in the pedicle in the early stage of spondylolysis; however, to our knowledge, the quantitative assessment of BME in spondylolysis has not been reported. Methods: Adolescent athletes with spondylolysis, including those with symptoms of low back pain, were enrolled. The sporting activity of the patients was restricted, and a hard brace was attached to the spine. The BME range of interest was taken on T2-weighed fat-saturated MRI, and the signal intensity (SI) of the BME (SIedema) was measured. The contrast ratio (CR) between the SI of the BME and SI of the spinal cord (SIcord) was calculated per the following formulae: CRedema=(SIedema–SIcord)/(SIedema+SIcord). The CR of the normal pedicle was measured as a control per the following formulae: CRcontrol=(SIcontrol–SIcord)/(SIcontrol+SIcord). Results: The study enrolled 32 men and one woman; the mean patient age was 15.2 years (range, 12–18 years). The average CR of the edema and normal pedicle at the first visit was 0.506 (range, 0.097–0.804) and 0.137 (range, -0.741 to 0.572), respectively. The CR of the edema was significantly higher as compared to that of the normal pedicle (p<0.01). MRI that was performed 1 month after the first visit showed that the CR of the edema had decreased to 0.204 (range, -0.152 to 0.517). The CR of the edema 1 month thereafter was significantly lower than that at the first visit (p<0.01). Conclusions: Quantitative assessment of BME using CR on MRI is useful in the evaluation of the healing process of spondylolysis.

Risk Factors for Cement Loosening after Vertebroplasty for Osteoporotic Vertebral Fracture with Intravertebral Cleft: A Retrospective Analysis

Toshio Nakamae,Kiyotaka Yamada,Yasuyuki Tsuchida,Orso Lorenzo Osti,Nobuo Adachi,Yoshinori Fujimoto 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.5

Study Design: Retrospective case-control study. Purpose: To evaluate the primary outcomes and radiographic results of percutaneous vertebroplasty (PVP) in patients with singlelevel osteoporotic vertebral fracture (OVF) with intravertebral cleft (IVC) to identify the risk factors for cement loosening after PVP. Overview of Literature: PVP is a widely accepted method for managing painful OVF; however, cement loosening occasionally occurs with poor outcomes. Methods: This retrospective study involved 195 patients treated with PVP for single-level OVF with IVC. Six months thereafter, the primary outcomes were evaluated using the Visual Analog Scale (VAS) for back pain and the modified Oswestry Disability Index. Computed tomography was conducted to detect cement loosening. Possible risk factors, such as age, sex, wedging angle, intravertebral instability, Parkinson’s disease, spinous process fracture, ankylosing spinal hyperostosis, split vertebrae, and adjacent intervertebral vacuum, were assessed. Results: Forty-nine patients (25%) experienced cement loosening 6 months after PVP. The mean VAS scores were significantly higher in patients with cement loosening than in those without (50 vs. 26 mm, respectively; p <0.01). Cement loosening was closely associated with intravertebral instability (odds ratio [OR], 1.20; 95% confidence interval [CI], 1.04–1.40; p =0.015), Parkinson’s disease (OR, 54.31; 95% CI, 4.47–659.53; p =0.002), spinous process fracture (OR, 7.11; 95% CI, 1.65–30.60; p =0.009), and split vertebrae (OR, 11.59; 95% CI, 1.64–82.02; p =0.014). Conclusions: Patients with cement loosening experienced worse back pain than those without cement loosening. The important risk factors that influenced cement loosening after PVP were high intravertebral instability, Parkinson’s disease, spinous process fracture, and split vertebrae.

Immediate Closed Reduction Technique for Cervical Spine Dislocations

Oae Kazunori,Kamei Naosuke,Sawano Makoto,Yahata Tadashi,Morii Hokuto,Adachi Nobuo,Inokuchi Koichi 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.5

Study Design: Retrospective study.Purpose: This research aimed to assess the clinical outcomes of patients with traumatic cervical spine dislocation who underwent closed reduction employing our approach.Overview of Literature: Bedside closed reduction is the quickest procedure for repairing traumatic cervical spine dislocations; nevertheless, it also possesses the risk of neurological deterioration.Methods: For closed reduction, the patient’s head was elevated on a motorized bed, the cervical spine was placed at the midline, traction of 10 kg was applied, the motorized bed was gradually returned to a flat position, the head was lifted off the bed, and the cervical spine was slowly adjusted to a flexed position. The weight of traction was elevated by 5-kg increments until the positional shift was attained. Subsequently, the bed was gradually tilted while traction was applied again to return the cervical spine to the midline position.Results: Of the 43 cases of cervical spine dislocation, closed reduction was carried out in 40 cases, of which 36 were successful. During repositioning, three patients experienced a temporary worsening of their neck pain and neurological symptoms that enhanced when the cervical spine was flexed. Closed reduction was conducted while the patient was awake; nevertheless, sedation was needed in three cases. Among the 24 patients whose pretreatment paralysis had been characterized by American Spinal Injury Association Impairment Scale (AIS) grades A–C, seven patients (29.2%) demonstrated an enhancement of two or more AIS grades at the last observation.Conclusions: Our closed reduction approach safely repaired traumatic cervical spine dislocations.

Quantifying Bone Marrow Edema Adjacent to the Lumbar Vertebral Endplate on Magnetic Resonance Imaging: A Cross-Sectional Study of Patients with Degenerative Lumbar Disease

Nakamae Toshio,Kamei Naosuke,Fujimoto Yoshinori,Yamada Kiyotaka,Tamura Takayuki,Tsuchikawa Yuji,Morisako Taiki,Harada Takahiro,Maruyama Toshiaki,Adachi Nobuo 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.2

Study Design: Cross-sectional study. Purpose: We aimed to quantitatively assess bone marrow edema (BME) on magnetic resonance imaging (MRI) for patients with degenerative lumbar diseases. Overview of Literature: BME adjacent to a sclerotic endplate of the lumbar spine, detected using T2-weighted fat-saturated MRI, is closely associated with low back pain in patients with degenerative lumbar diseases. However, currently, there no quantitative evaluation methods for BME adjacent to the vertebral endplate. Methods: Patients with degenerative lumbar diseases, whose MRIs detected BME, were enrolled. On a T2-weighted fat-saturated MRI, BME appeared as a high-intensity region adjacent to the vertebral endplate. We calculated the contrast ratios (CRs) of BME and normal bone marrow using the signal intensities of BME, normal bone marrow, and the spinal cord. On computed tomography, we calculated Hounsfield unit (HU) values in the same area as BME, the sclerotic endplate, and normal bone marrow to assess bone density. Results: There were 16 men and 14 women, with an average age of 73.5 years. The mean CRs of BME and normal bone marrow were −0.015±0.056 and −0.407±0.023, respectively. BME’s CR was significantly higher than that of normal bone marrow (p<0.01). The HU values in the same area as BME, the sclerotic endplate, and normal bone marrow were 251.9±24.6, 828.3±35.6, and 98.1±9.3, respectively; these values were significantly different from each other (p<0.01). Conclusions: The CR on MRI is a useful quantitative assessment tool for BME in patients with degenerative lumbar diseases.

Evaluation of the flexion gap with a distal femoral trial component in posterior-stabilized total knee arthroplasty

( Goki Kamei ),( Shigeki Ishibashi ),( Koki Yoshioka ),( Satoru Sakurai ),( Hiroyuki Inoue ),( Yu Mochizuki ),( Masakazu Ishikawa ),( Nobuo Adachi ) 대한슬관절학회 2022 대한슬관절학회지 Vol.34 No.-

Purpose: A distal femoral trial component was manufactured, and flexion gap size and inclination were evaluated with or without the distal femoral trial component in total knee arthroplasty (TKA). This study aimed to evaluate the effect of the distal femoral trial component on flexion gap size and joint inclination in posterior-stabilized (PS)-TKA. Materials and methods: A total of 84 patients with medial osteoarthritis who underwent mobile-bearing PSTKA using modified gap techniques were included in this retrospective study. The flexion gap size and inclination before and after setting the distal femoral trial component were evaluated and compared with the final gap size and inclination. Results: The joint gap size and inclination were significantly lower in those with than in those without the distal femoral trial component (P = 0.005, P < 0.001). The final gap size and inclination were similar to the gap size and inclination with the distal trial component (P = 0.468, P = 0.158). Conclusions: The joint gap size and medial tension in PS-TKA were significantly reduced after setting the distal femoral trial component. The flexion gap measured using the distal femoral trial component was similar to that when the final trial component was set. To more accurately perform the gap technique TKA, the flexion gap should be measured using the distal femoral trial component.

Novel Hybrid Hydroxyapatite Spacers Ensure Sufficient Bone Bonding in Cervical Laminoplasty

Nobuhiro Tanaka,Kazuyoshi Nakanishi,Naosuke Kamei,Toshio Nakamae,Shinji Kotaka,Yoshinori Fujimoto,Mitsuo Ochi,Nobuo Adachi 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.6

Study Design: Prospective observational study. Purpose: This prospective analysis aimed to evaluate the efficacy and bone-bonding rate of hybrid hydroxyapatite (HA) spacers in expansive laminoplasty. Overview of Literature: Various types of spacers or plates have been developed for expansive laminoplasty. Methods: Expansive open-door laminoplasty was performed in 146 patients with cervical myelopathy; 450 hybrid HA spacers and 41 autogenous bone spacers harvested from the spinous processes were grafted into the opened side of each lamina. The patients were followed up using computed tomography (CT), and their bone-bonding rates for hybrid HA and autogenous spacers, bone-fusion rates of the hinges of the laminae, and complications associated with the implants were then examined. Results: Clinical symptoms significantly improved in all patients, and no major complications related to the procedure were noted. The hybrid HA spacers exhibited sufficient bone bonding on postoperative CT. The hinges completely fused in over 95% patients within 1 year of the procedure. Only 4 spacers (0.9%) developed lamina sinking, and most expanded laminae maintained their positions without sinking or floating throughout the follow-up period. Conclusions: Hybrid HA spacers contributed to high bone-fusion rates of the spacers and hinges of the laminae, and no complications were associated with their use. Cervical laminoplasty with these spacers is safe and simple, and it yields sufficient fixation strength while ensuring sufficient bone bonding during the immediate postoperative period.