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Search Results: 1 - 10 of 1126 matches for " Arata Nakajima "
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Pathologic thoracic spine fracture in presence of Parkinson’s disease and diffuse ankylosis: successful management of a challenging condition
Aoki Yasuchika,Nakajima Arata,Sakakibara Ryuji,Ohtori Seiji
BMC Musculoskeletal Disorders , 2013, DOI: 10.1186/1471-2474-14-61
Abstract: Background Patients with Parkinson’s disease have higher risk of complications and revision surgery following spine surgery. Spinal fracture in an ankylosed spine is also difficult to treat. We recently treated a case of thoracic spine fracture in a patient with Parkinson’s disease complicating a severely ankylosed spine. There is no report describing surgical treatment of spine fracture in such a difficult condition, thus, we firstly report the case and discuss the reasons for a successful result. Case presentations A 68-year-old man with Parkinson’s disease had a pathologic thoracic spine fracture at T11. Four days after onset, he was referred to a local hospital because of gradually increasing back pain, but no spinal fracture was pointed out at that time. Because he developed lower extremity bilateral numbness and weakness, he was transported to our hospital, eight days after onset. When referred to our hospital, he exhibited severe back pain and paralysis of the lower extremities due to spinal cord involvement. Emergency surgery was performed. Decompression of T10-11 was performed followed by instrumented spinal fusion from T8 to L2. A dramatic neurological improvement was observed following surgery, and complete bony fusion was achieved. At the final two-year postoperative follow-up, the patient had no pathological symptoms related to spinal fracture and no instrument failure was observed. Conclusion This patient had Parkinson’s disease and a severely ankylosed spine, both of which may lead to unsatisfactory surgical results from spinal surgery. Generally, patients with Parkinson’s disease have an increased risk for adjacent segment disease and instrument failure. In this patient, fusion surgery did not change the number of fused segments because operated segments were already ankylosed. Because no stress force exists between adjacent vertebral bodies, a severely ankylosed spine may help prevent screw pullout. Thus, treatment of a spinal fracture in an ankylosed spinal segment is a less adverse condition for patients with Parkinson’s disease. Our experience led us to think that a combination of Parkinson’s disease with severely ankylosed spine does not necessarily suggest unsatisfactory outcomes after surgical treatment of spinal fracture.
Delayed Neurologic Deficit due to Foraminal Stenosis following Osteoporotic Late Collapse of a Lumbar Spine Vertebral Body
Yu Sasaki,Yasuchika Aoki,Arata Nakajima,Yoshifumi Shibata
Case Reports in Orthopedics , 2013, DOI: 10.1155/2013/682075
Abstract:
Changes in Joint Gap Balances between Intra- and Postoperation in Total Knee Arthroplasty
Arata Nakajima,Yasuchika Aoki,Masazumi Murakami,Koichi Nakagawa
Advances in Orthopedics , 2014, DOI: 10.1155/2014/790806
Abstract: Achieving correct soft tissue balance and preparing equal and rectangular extension and flexion joint gaps are crucial goals of TKA. Intraoperative gap balances would change postoperatively; however, changes in joint gap balances between pre- and postoperation remain unclear. To explore these changes associated with TKA, we prospectively investigated 21 posterior cruciate ligament retaining TKAs for varus knees. Intraoperative extension gap balance (iEGB) was 2.6 ± 2.0° varus versus postoperative extension gap balance (pEGB) of 0.77 ± 1.8° valgus ( ), while no significant difference between intraoperative flexion gap balance (iFGB) and postoperative flexion gap balance (pFGB) was observed. We also explored correlations between intraoperative and postoperative gap balances but found no significant correlations. These observations indicate that (i) surgeons should avoid excessive release of the medial soft tissue during TKA for varus knees and (ii) intraoperative gap balance may not be necessarily reflected on postoperative gap balance. 1. Introduction Achieving correct soft tissue balance of the knee is fundamental to the success of TKA [1], and an equal joint gap during extension and flexion is a prerequisite for satisfactory soft tissue balance [2–4]. In addition, equalizing the distance from the femoral component to the tibial surface (i.e., the joint gap) throughout the full range of knee motion prevents lift-off of the tibial component and theoretically assists in achieving proper contact pressure and kinematics. Thus, preparing equal and rectangular extension and flexion joint gaps is the most important goal of TKA. Meanwhile, most surgeons agree that accurate ligament balancing of the knee with varus deformity is difficult especially during posterior cruciate ligament retaining (CR)-TKA. The standard procedure for ligament balancing of the medial side of the knees uses subperiosteal release of the medial collateral ligament (MCL) [5–7]. Despite performing such release of MCL, varus balance is likely to remain in most CR-TKAs because posterior cruciate ligament (PCL) is an important component of the medial supporting mechanism of the knee [8]. Recently, Sekiya et al. reported that residual lateral ligamentous laxity immediately after surgery subsequently corrected itself spontaneously in some instances [9]. This finding suggests that some degree of residual lateral laxity, namely, varus balance, may be tolerable for varus knees so long as proper valgus alignment is maintained. However, it has not been explored whether remaining varus balance is
Evaluation of Nonspecific Low Back Pain Using a New Detailed Visual Analogue Scale for Patients in Motion, Standing, and Sitting: Characterizing Nonspecific Low Back Pain in Elderly Patients
Yasuchika Aoki,Shiro Sugiura,Koichi Nakagawa,Arata Nakajima,Hiroshi Takahashi,Seiji Ohtori,Kazuhisa Takahashi,Satoru Nishikawa
Pain Research and Treatment , 2012, DOI: 10.1155/2012/680496
Abstract: Because we have a clinical impression that elderly patients have low back pain while in motion and standing, but less pain when sitting, we investigate characteristics of nonspecific low back pain (NSLBP), using a new detailed visual analog scale (VAS) scoring system. One hundred eighty-nine patients with NSLBP were divided into an elderly group (≥65 years old, ) and a young group (<65 years old, ). Low back pain was evaluated by a traditional VAS scoring system, the Oswestry Disability Index (ODI), and a new detailed VAS scoring system in which pain is independently evaluated in three different postural situations (in motion, standing, and sitting). No significant differences were observed in traditional VAS and ODI scores between the two groups. The results of the detailed VAS showed no significant differences between the two groups while in motion and standing. However, the elderly group showed significantly lower VAS score while sitting compared to the young group. In this study of the first use of a new detailed VAS scoring system, differences in characteristics of NSLBP between elderly and young patients were successfully detected. This minor modification of the traditional VAS may be useful for characterizing and evaluating low back pain. 1. Introduction Low back pain is a common clinical problem and a significant socioeconomic problem. Although the lifetime prevalence of back pain is 60–80% [1], little is known of its pathophysiology. Clinically, the natural course of low back pain is usually favorable; acute low back pain frequently disappears within one to two weeks. In some cases, however, acute low back pain becomes chronic and quite difficult to treat and has a major socioeconomic impact. Any of the spinal structures, including intervertebral discs, facet joints, vertebral bodies, ligaments, or muscles could be an origin of back pain, which is, unfortunately, quite difficult to determine [2]. In those cases in which the origin of back pain cannot be determined, the diagnosis given is nonspecific low back pain [2]. Nonspecific low back pain is defined as low back pain not attributable to a recognizable, known specific pathology, such as infection, tumor, osteoporosis, fracture, structural deformity, inflammatory disorder, radicular syndrome, or cauda equina syndrome [2]. The intensity of low back pain is usually evaluated by a visual analogue scale (VAS), numerical rating scale, or a disability scoring system, such as the Oswestry Disability Index (ODI), Roland Morris Disability Questionnaire, and others. However, the use of these
Intra-Articular Giant Heterotopic Ossification following Total Knee Arthroplasty for Charcot Arthropathy
Arata Nakajima,Shintaro Tsuge,Yasuchika Aoki,Masato Sonobe,Yoshifumi Shibata,Yu Sasaki,Koichi Nakagawa
Case Reports in Orthopedics , 2013, DOI: 10.1155/2013/472378
Abstract: Although the Charcot arthropathy may be associated with serious complications, total knee arthroplasty (TKA) is the preferred choice of treatment by patients. This case report presents an 80-year-old man with intra-articular giant heterotopic ossification following loosening of femoral and tibial implants and femoral condylar fracture. He had undergone TKA because of Charcot neuropathy seven years ago and had been doing well since. Immediately after a left knee sprain, he became unable to walk. Because he had developed a skin ulcer on his left calf where methicillin-resistant Staphylococcus aureus was detected, we postponed revision surgery until the ulcer was completely healed. While waiting, intra-articular bony fragments grew larger and formed giant heterotopic ossified masses. Eventually, the patient underwent revision surgery, and two major ossified masses were carefully and successfully extirpated. It should be noted that intra-articular heterotopic giant ossification is a significant complication after TKA for neuropathic arthropathy. 1. Introduction Neuropathic arthropathy was described by Jean Martin Charcot (1825–1893) as the progressive destruction of bone and soft tissues in a patient with peripheral neuropathy. Charcot also noted the relationship between syphilis and severe arthropathy in 1868 [1]. Diabetes mellitus is currently the most common cause of Charcot arthropathy, especially of the foot and ankle. The diagnosis of Charcot arthropathy in the knee is rare. However, we can expect the increasing number of diabetic patients living longer due to improvements in medical treatment to show an increasing incidence of neuropathic arthropathy as a late effect of peripheral neuropathy. The optimal treatment for Charcot arthropathy of the knee is controversial. Some investigators [2–4] consider it as an absolute contraindication to total knee arthroplasty (TKA). Recently, however, several studies [5] have shown satisfactory results from TKA. In general, TKA for Charcot arthropathy is associated with high incidence of such serious complications as periprosthetic fractures, aseptic loosening, dislocation of the patella and tibiofemoral joint, and deep infection [6–8]. However, due to excellent functional recovery compared with conservative therapy and arthrodesis, TKA should not be contraindicated. We present a case report of an 80-year-old man with intra-articular, giant, heterotopic ossification and a femoral condylar fracture following loosening of femoral and tibial implants. To date, the occurrence of intra-articular, giant, heterotopic
Remarks on the Erroneous Dispersion Surfaces From a Pair of a Hyperbolic Branch and An Elliptical Arc of the Intersected Two Laue Spheres Based on the Usual Crude Approximation  [PDF]
Tetsuo Nakajima
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.23022
Abstract: In almost all previous works, the hyperbolic dispersion surfaces of the central proper quadrics have been crudely derived from the degree of reduction from the bi-quadratic equation by use of some roughly indefinable approximate relations. Moreover, neglecting the high symmetry of the hyperbola, both the branches have been approximated on the asymmetric surfaces composed of a pair of a branch of the hyperbola and a vertex of the ellipse without the presentation of reasonable evidence. Based upon the same dispersion surfaces equation, a new original gapless dispersion surfaces could be rigorously introduced without crude omission of even a term in the bi-quadratic equation based upon usual analogy with the extended band theory of solid as the close approximation to the truth.
Migration, Employment, and Industrial Development in Japan  [PDF]
Tetsuya Nakajima
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.48083
Abstract: Industrial development in Japan is accompanied by massive migration from agricultural to industrial areas. In a modified Harrod-Domar model, this paper compares two steady states, the first and the second, which emerge before and after the termination of such migration, respectively. Then, the paper shows that employment rates must be lower in the second steady state. Further, by examining the effects of fiscal policy, the paper shows that the balanced budget multiplier exceeds unity, and fiscal policy raises households’ disposable income and consumption.
Fourier analysis of the flux-tube distribution in SU(3) lattice QCD
Arata Yamamoto
Physics , 2009, DOI: 10.1016/j.physletb.2010.04.022
Abstract: This letter presents a novel analysis of the action/energy density distribution around a static quark-antiquark pair in SU(3) lattice quantum chromodynamics. Using the Fourier transformation of the link variable, we remove the high-momentum gluon and extract the flux-tube component from the action/energy density. When the high-momentum gluon is removed, the statistical fluctuation is drastically suppressed, and the singularities from the quark self-energy disappear. The obtained flux-tube component is broadly distributed around the line connecting the quark and the antiquark.
QCD Dirac spectrum and components of the gauge field
Arata Yamamoto
Physics , 2010, DOI: 10.1016/j.nuclphysb.2010.10.027
Abstract: We analyze the relation between the Dirac spectrum and the gauge field in SU(3) lattice QCD. We focus on how components of the gauge field are related to the Dirac spectrum. First, we consider momentum components of the gauge field. It turns out that the broad region of momentum components is relevant for the low-lying Dirac spectrum and zero modes, i.e., topological charges. The connection with chiral random matrix theory is also discussed. Second, we consider an SU(2) subgroup component of the SU(3) gauge field. The SU(2) subgroup component behaves like the SU(2) gauge field in the low-lying Dirac spectrum.
Lattice Dirac operators with chiral chemical potential
Arata Yamamoto
Physics , 2011,
Abstract: This paper has been withdrawn by the author.
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