Hiroaki Matsumori

Nara Medical University, Kashihara, Nara, Japan

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Publications (8)13.51 Total impact

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    ABSTRACT: Revision surgery after laminoplasty is rarely performed, and there are few reports of this procedure in the English literature. To evaluate the reasons why patients underwent revision surgery after laminoplasty, and to discuss methods of preventing the need for revision surgery. A literature review with a comparative analysis between previous reports and present cases was also performed. Case report and literature review. Five patients who underwent revision surgery after laminoplasty. Diagnosis was based on preoperative computed tomography and magnetic resonance imaging findings. Neurological findings were evaluated using the Japanese Orthopaedic Association score. A total of 237 patients who underwent cervical laminoplasty for cervical spondylotic myelopathy from 1990 to 2010 were reviewed. Patients with ossification of the posterior longitudinal ligament, renal dialysis, infection, tumor, or rheumatoid arthritis were excluded. Five patients who underwent revision surgery for symptoms of recurrent myelopathy or radiculopathy were identified, and the clinical courses and radiological findings of these patients were retrospectively reviewed. The average interval from the initial surgery to revision surgery was 15.0 years (range, 9-19 years). The patients were four males and one female with an average age at the time of the initial operation of 49.8 years (range, 34-65 years). Four patients developed symptoms of recurrent myelopathy after their initial surgery, for the following reasons: adjacent segment canal stenosis, restenosis after inadequate opening of the lamina with degenerative changes, and trauma after inadequate opening of the lamina. One patient developed new radiculopathy symptoms due to foraminal stenosis secondary to osteoarthritis at the Luschka and zygapophyseal joints. All patients experienced resolution of their symptoms after revision surgery. Revision surgery after laminoplasty is rare. Inadequate opening of the lamina is one of the important reasons for needing revision surgery. Degenerative changes after laminoplasty may also result in a need for revision surgery. Surgeons should be aware of the degenerative changes that can cause neurological deterioration after laminoplasty.
    The spine journal: official journal of the North American Spine Society 12/2013; · 2.90 Impact Factor
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    ABSTRACT: The incidence of neurological deficits is reportedly low after sacrificing the affected nerve root during spinal schwannoma treatment. Although the incidence has been widely reported, the operative method for nerve root resection has been not clarified. To evaluate the safety of pure nerve root resection, we focused on solitary spinal schwannomas below the thoracolumbar level and investigated the effect of affected nerve resection. Twenty-three spinal schwannoma patients were retrospectively examined. The mean age at surgery was 53 years. We investigated preoperative symptoms, duration of the disorder, postoperative neurological deficits, and clinical outcomes. In addition, we measured tumor size on computed tomography after myelography or on magnetic resonance images using image-analysis software. We retrospectively assessed correlations among duration of symptoms, tumor size, and postoperative neurological deficits. The tumors comprised 19 intradural schwannomas and 4 dumbbell-shaped schwannomas. No postoperative neurological deficits were observed in the intradural schwannoma patients. In contrast, three of the four dumbbell-shaped schwannoma patients experienced postoperative neurological deficits. Among these three patients, two recovered quickly whereas one never recovered. The mean duration of the disorder was 29 months. The postoperative modified JOA score (13.0) was significantly improved compared with the preoperative score (8.9). The mean maximum tumor sizes were 97.2 mm(2) for the intradural schwannomas and 884.0 mm(2) for the dumbbell-shaped schwannomas. There were no correlations among tumor size, duration of the disorder, and postoperative neurological deficits. On the basis of this study, we recommend pure single nerve resection for treatment of intradural spinal schwannomas before such tumors progress and involve other normal roots, because postoperative neurological deficits did not occur in our intradural schwannoma patients, irrespective of tumor size, when this procedure was used. However, dumbbell-shaped schwannoma patients should be carefully treated operatively, because high incidence of postoperative neurological deficits can be expected.
    Journal of Orthopaedic Science 02/2011; 16(2):148-55. · 0.96 Impact Factor
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    European Spine Journal 05/2010; · 2.47 Impact Factor
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    ABSTRACT: The objective of the study was to investigate the comorbidity of degenerative spondylolisthesis (DS), in elderly cervical spondylotic myelopathy (CSM) patients in our hospital, and the correlation between surgical results and preoperative DS. There are few studies on the outcome of laminoplasty for CSM with DS. A total of 49 elderly patients (>65 years old) who eventually had surgical treatment for CSM were evaluated. A slippage displacement of more than 2.5 mm at least at one level was classified to have a positive DS on flexion/extension radiographs (DS group). A slippage displacement less than 1.0 mm was considered a negative DS (non-DS group). Seventeen patients who had slippage of 1.0-2.5 mm were excluded from the study. The DS group (n = 15) included cases with DS at preoperation, while the remaining cases (n = 17) belonged to the non-DS group. The flexion/extension radiographs of the two groups were compared for range of motion and clinical results at 3 years after the operation. Of all elderly patients, 30.6% had DS. There was no significant difference between the two groups based on the clinical results. The range of motion of all cervical spines (DS group and non-DS group) was significantly limited. However, there was no significant difference between the two groups. New postoperative DS appeared in four patients, of which two were from the DS group and two from the non-DS group. These data suggest that degenerative spondylolisthesis does not influence surgical results in elderly cervical spondylotic myelopathy patients.
    European Spine Journal 02/2010; 19(5):720-5. · 2.47 Impact Factor
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    ABSTRACT: Wires and cables have been used extensively for spinal sublaminar wiring, but damages to the spinal cord due to compression by metal wires have been reported. We have used more flexible ultra-high-molecular-weight polyethylene cable (Tekmilon tape) instead of metal wires since 1999 and have obtained good clinical outcomes. Although the initial strength of Tekmilon tape is equivalent to metal wires, the temporal changes in the strength of Tekmilon tape in the body should be investigated to show that sufficient strength is maintained over time until bone union is complete. Tekmilon tape was embedded into the paravertebral muscle of 10-week-old male Japanese white rabbits. Samples were embedded for 0, 1, 3, 6 or 12 months. At the end of each period, sequential straight tensile strength and sequential knot-pull tensile strength were measured. The initial strength of Tekmilon tape in muscle tissue was maintained over time, with 92% straight tensile strength and 104% knot-pull tensile strength at 6months, and values of 77% and 100% at 12 months, respectively. Since single knot is clinically relevant, it is very important that the knot-pull tensile strength did not decrease over a 12-month period. This suggests that temporal changes in the tensile strength of Tekmilon tape are negligible at 1 year. Tekmilon tape maintains sufficient strength in vivo until bone union has occurred. It is useful for sublaminar wiring instead of metal materials due to its flexibility and strength and may reduce the risk of neurological damage.
    Clinical biomechanics (Bristol, Avon) 11/2009; 25(2):173-6. · 1.76 Impact Factor
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    ABSTRACT: Raloxifene acts like estrogen in preventing bone loss in postmenopausal women, but it selectively activates biological responses in bone tissue. It has a direct effect on osteoblasts' differentiation and bone formation in bone marrow culture. However, the point at which raloxifene has an effect on bone marrow-derived mesenchymal stem cells (MSCs), regardless of sex difference, is not known. The purpose of this study was to examine the osteogenic effect of raloxifene on MSCs derived from female and male rats and to assess the sex difference of raloxifene with or without osteogenic supplements (OSs) in the regulation of bone formation. Female and male rat bone marrow cells were cultured with or without OSs. In each experimental group, 10-6 M or 10-8 M raloxifene was added. As a control, cells were cultured without raloxifene. Histologically, mineralization was assessed by alizarin red S staining. Biochemically, alkaline phosphatase (ALP) activity, calcium content, and osteocalcin content were assessed. On histological analysis, mineralized nodules were seen on alizarin red S staining in the groups treated with OS. On the biochemical analysis, OS increased ALP activity, calcium content, and osteocalcin content. Among female groups with OSs, 10-6 M raloxifene significantly increased ALP activity, calcium content, and osteocalcin content compared with the controls. Among male groups, raloxifene had negligible effects. 10-6 M Raloxifene had no ossification-inducing effect on female MSCs, but it had an ossification-promoting effect; it had no osteogenic effect on male MSCs. Therefore, raloxifene has a sex difference with regard to its osteogenic effect on MSCs. Moreover, combined treatment with raloxifene plus OS has an effect on female MSCs. These results provide a useful insight into the possible influence of raloxifene after MSC transplantation in clinical practice.
    Journal of Orthopaedic Science 09/2009; 14(5):640-5. · 0.96 Impact Factor
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    ABSTRACT: In clinical practice, surgeons differentiate color changes in repaired cartilage compared with surrounding intact cartilage, but cannot quantify these color changes. Objective assessments are required. A spectrocolorimeter was used to evaluate whether intact and repaired cartilage can be quantified. We investigated the use of a spectrocolorimeter and the application of two color models (L* a* b* colorimetric system and spectral reflectance distribution) to describe and quantify articular cartilage. In this study, we measured the colors of intact and repaired cartilage after a microfracture. Histologically, the repaired cartilage was a mixture of fibrocartilage and hyaline cartilage. In the L* a* b* colorimetric system, the L* and a* values recovered to close to the values of intact cartilage, whereas the b* value decreased over time after the operation. Regarding the spectral reflectance distribution at 12 weeks after the operation, the repaired cartilage had a higher spectral reflectance ratio than intact cartilage between wavelengths of 400 to 470 nm. This study reports the first results regarding the relationship between spectrocolorimetric evaluation and the histological findings of repair cartilage after a microfracture. Our findings demonstrate the ability of spectrocolorimetric measurement to judge the repair cartilage after treatment on the basis of objective data such as the L*, a* and b* values and the SRP as a coincidence index of the spectral reflectance curve.
    BMC Research Notes 10/2008; 1:87.
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    ABSTRACT: The purpose of this study was to investigate the prevalence of developmental canal stenosis in patients with cervical spondylotic myelopathy (CSM), and the correlation between surgical results and degree of developmental canal stenosis. A total of 112 patients who eventually had surgical treatment for CSM were evaluated. Male patients whose sagittal spinal diameter was < 14 mm and females whose sagittal diameter was < 13 mm even at one level were classified as having developmental canal stenosis. Two groups of patients were used in this study; the "positive" group (57 cases) included patients with developmental canal stenosis preoperatively, whereas the "negative" group (55 cases) excluded such patients. Lateral functional radiographs obtained in patients in the 2 groups were compared for range of motion and clinical results. Developmental canal stenosis was found in 50.9% of all cases. Based on clinical results, there was no significant difference between the 2 groups. Patients with CSM showed a high incidence of preoperative developmental canal stenosis. However, there were no significant differences in clinical results between patients with and without this disorder. These results indicate that developmental canal stenosis is not a factor that influences surgical results.
    Journal of Neurosurgery Spine 10/2008; 9(4):358-62. · 1.98 Impact Factor