Yuji Yasunaga

Hiroshima University, Hirosima, Hiroshima, Japan

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Publications (110)213.25 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to evaluate whether femoral antetorsion affects the range of motion (ROM) following total hip arthroplasty (THA) using 3D dynamic analysis.
    International Orthopaedics 08/2014; · 2.32 Impact Factor
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    ABSTRACT: Study design:An in vivo study in mouse models of spinal cord contusion.Objectives:To develop a novel indicator to anticipate the severity of spinal cord injury (SCI) during the acute phase and for the assessment of the efficacy of novel therapies. MicroRNAs (miRNAs) circulating in the peripheral blood are reported to modulate signaling between cells, and to be diagnostic markers for cancers. The purpose of this study was to identify circulating miRNAs for predicting the severity of SCI in the acute phase.Setting:Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.Methods:Mouse SCI models were made using Infinite Horizon impactor with 50 or 70 kdyn compressing power following thoracic laminectomy. The mice were then divided into four groups: normal (without surgery), sham (laminectomy only), mild (50 kdyn), and severe (70 kdyn). TaqMan low-density array analysis and real-time PCR were performed to identify candidate miRNAs that were increased in the serum relative to the severity of SCI.Results:The expression levels of miR-9*, miR-219 and miR-384-5p in the serum were significantly increased relative to the severity of SCI 12 h after injury. The expression of miR-9* was also significantly increased relative to injury severity at 3 and 24 h after injury.Conclusion:Serum miR-9*, miR-219 and miR-384-5p might be promising biomarkers for predicting the severity of SCI.Spinal Cord advance online publication, 3 June 2014; doi:10.1038/sc.2014.86.
    Spinal cord. 06/2014;
  • Journal of Orthopaedic Science 04/2014; · 0.96 Impact Factor
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    ABSTRACT: Intra-articular osteoid osteoma (OO) is uncommon, especially in the hip joint. Delayed treatment may cause early osteoarthritis; however, diagnosis and complete excision are often challenging. We describe the feasibility of the combination of T2 mapping magnetic resonance imaging evaluation and arthroscopic excision of OO in the acetabulum. A 12-year-old boy presented with a 6-month history of hip pain. An undifferentiated tumor of the medial wall of the acetabulum was suspected on radiographs and computed tomography. T2 mapping showed joint effusion, and the T2 value of the acetabular cartilage just above the tumor was significantly high. These findings suggested OO in the acetabulum. An arthroscopic excision was performed for biopsy and excision of the tumor to avoid damage to the normal cartilage and growth plate. Histologic examination confirmed the OO. At 16 months' follow-up, there was no evidence of recurrence. This is the first report to evaluate intra-articular OO by T2 mapping and to treat it arthroscopically. Arthroscopic treatment assisted by T2 mapping has excellent potential as a minimally invasive technique to enable us to approach the tumor from the area of discriminative abnormal cartilage with minimal damage to the normal cartilage and surrounding tissue.
    Arthroscopy Techniques. 04/2014;
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    ABSTRACT: A magnetic cell targeting system was previously developed to promote the accumulation of transplanted cells in sites of injury in order to effectively treat injured tissues. However, the optimum time of exposure to the magnetic field and the strength of the magnetic force have not yet been clarified. In this study, we investigated the optimum conditions of the magnetic force required to retain iron-labeled human mesenchymal stem cells (hMSCs) at the site of transplantation for muscle repair in a subchronic skeletal muscle injury nude rat model. First, the optimum strength and time of exposure to the magnetic force for cell retention at the transplantation site were investigated 2 days after cell transplantation (1 × 10(5) cells). Second, the degree of enhancement of muscle repair was investigated at 3 weeks after cell transplantation in the group treated without a magnetic force and two typical magnetic condition groups that exhibited different levels of cell integration in first part of the study. On the basis of the results of the first investigation, it was concluded that a magnetic strength of 1.5 T and 10 min of exposure to the magnetic force were efficient conditions to induce the retention of transplanted cells at the site of transplantation. In the second study, the groups exposed to a 1.5-T magnetic field for 10 min demonstrated significant enhancement of muscle repair, both histologically and electromechanically. This study identified the optimal conditions required to retain transplanted hMSCs at the site of transplantation using a magnetic targeting system. This study also showed that the restoration of subchronic muscle injuries can be enhanced by magnetically labeled hMSCs following the application of a magnetic force.
    Journal of Orthopaedic Science 02/2014; · 0.96 Impact Factor
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    ABSTRACT: In Japan, osteoarthritis (OA) of the hip secondary to acetabular dysplasia is very common, and there are few data concerning the pathogeneses and incidence of femoroacetabular impingement (FAI). We have attempted to clarify the radiological prevalence of painful FAI in a cohort of Japanese patients and to investigate the radiological findings. We identified 176 symptomatic patients (202 hips) with Tönnis grade 0 or 1 osteoarthritis, whom we prospectively studied between August 2011 and July 2012. There were 61 men (65 hips) and 115 women (137 hips) with a mean age of 51.8 years (11 to 83). Radiological analyses included the α-angle, centre-edge angle, cross-over sign, pistol grip deformity and femoral head neck ratio. Of the 202 hips, 79 (39.1%) had acetabular dysplasia, while 80 hips (39.6%) had no known aetiology. We found evidence of FAI in 60 hips (29.7%). Radiological FAI findings associated with cam deformity were the most common. There was a significant relationship between the pistol grip deformity and both the α-angle (p < 0.001) and femoral head-neck ratio (p = 0.024). Radiological evidence of symptomatic FAI was not uncommon in these Japanese patients. Cite this article: Bone Joint J 2013;96-B:172-6.
    The bone & joint journal. 02/2014; 96-B(2):172-6.
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    ABSTRACT: In this study, postoperative results of intertrochanteric curved varus osteotomy (CVO) for idiopathic osteonecrosis of the femoral head (ION) were studied retrospectively and optimal indication of CVO was considered. Between 1995 and 2011, CVO was performed in 51 patients (53 hips) for the treatment of ION in our department. The patients who had the potential to obtain acetabular coverage of more than one-third of the intact articular surface on pre-operative AP hip radiographs in maximum abduction were considered suitable for this operation. For radiological assessment, a ratio of necrotic volume, a ratio of postoperative intact surface on the weight-bearing area, progression of collapse, shortening length of the lower limb, and lateralization of great trochanter were evaluated. The mean ratio of necrotic volume was 16.9 %. The mean ratio of postoperative intact surface on the weight-bearing area of the femoral head was 51.7 %. The progression of collapse was observed in two hips (ratio of necrotic volume 10.4, 39.8 %; ratio of postoperative intact area 36.5, 38.1 %). The mean shortening length of the lower limb was 9 mm, and the mean lateralization of great trochanter was 3 mm. One hip (ratio of necrotic volume 11.6 %, ratio of intact area 35.8 %) was converted to THA because of the progression of osteoarthritis at 55 months after CVO. The results of CVO for ION were successful, if this procedure was indicated for cases with intact load-bearing area more than 40 %.
    Archives of Orthopaedic and Trauma Surgery 01/2014; · 1.36 Impact Factor
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    ABSTRACT: Background Acetabular dysplasia (AD) is the main cause of hip osteoarthritis in Japan. A simple method to evaluate acetabular dysplasia would be helpful for early treatment or prevention of hip osteoarthritis. Acetabular dysplasia is reported to be associated with pathological transverse growth of the pelvis, indicating that the distance between the 2 anterior superior iliac spines might be useful for screening and detection of acetabular dysplasia. The purpose of this study was to determine if the acetabular dysplasia radiographic parameters are related to the distance between the 2 anterior superior iliac spines in patients with hip osteoarthritis. Material and Methods In this study, data obtained in a previous multi-institutional examination of patients with hip osteoarthritis in Japan were evaluated. The anterior superior iliac spine distances of 176 female patients (mean age, 54 years; range, 18-85 years) were measured by physical examination. The relationship between the anterior superior iliac spine distance and acetabular dysplasia was analyzed, and the anterior superior iliac spine distances of the patients with acetabular dysplasia who were at relatively high risk for hip osteoarthritis were compared with that of the patients at lower risk. Results A statistically significant relationship between the anterior superior iliac spine distance and all of the acetabular dysplasia parameters was observed. The anterior superior iliac spine distances of the acetabular dysplasia patients with a relatively high risk for radiographic acetabular dysplasia parameters were significantly smaller than those of patients at lower risk. Even after adjustment for age, height, and weight, significantly increased relative risk for having high risk AD was found in patients with an ASIS distance of less than 24.5 cm. Conclusions There was a significant relationship between the anterior superior iliac spine distance and the degree of acetabular dysplasia.
    Medical science monitor: international medical journal of experimental and clinical research 01/2014; 20:116-22. · 1.22 Impact Factor
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    ABSTRACT: Adverse reactions to metal debris (ARMD) after receiving metal-on-metal (MoM) hip implants is a recent concern. However, no epidemiologic study has examined ARMD for MoM hip implants in Japan. The purposes of this study were to research the incidence of ARMD and to identify poorly performing MoM hip implants in Japan. From 2000 to 2011, 7 companies provided 23,226 MoM implants in Japan. A questionnaire regarding ARMD was sent to 101 hospitals at which 62 % of the 23,226 MoM implants had been used. Replies to the questionnaire were received from 82 hospitals. In these hospitals, surface hip replacement types (SRs) were used in 606 hips and stemmed types were used in 12,961 hips. ARMD were reported in 3 hips (0.5 %) with SRs and 160 hips (1.2 %) with stemmed types. ARMD in the 3 hips with SRs were asymptomatic and no revisions were performed. Among AMRD with stemmed implants, revision was performed in 83 hips and excision of an ARMD lesion was performed in 3 hips. The remaining 74 hips were asymptomatic and careful follow-up was continued. A significant difference in reoperation rate was evident between SRs (0 %) and stemmed types (0.7 %). Incidences of ARMD were significantly higher with Ultamet (P = 0.005), Conserve (P < 0.001), and Cormet (P < 0.001) MoM bearing couples than with Metasul bearings. The incidence of ARMD in large surgical volume hospitals in Japan from 2000 to 2011 was estimated to be 0.5 % with SRs and 1.2 % with stemmed types. The reoperation rate was significantly higher with stemmed types than with SRs. Three brands of MoM stemmed implants were identified as showing a higher incidence of ARMD.
    Journal of Orthopaedic Science 12/2013; · 0.96 Impact Factor
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    ABSTRACT: Background: The clinical results of total hip arthroplasty (THA) with a cementless prosthesis have been constantly improving due to progress in the area of stem design and surface finish. Cementless Spotorno stem (CLS stem; Zimmer, Warsaw, USA) is a double-tapered rectangular straight stem. The purpose of this study is to investigate the mean 10 year results of CLS stem and to evaluate the press-fit stability of CLS stem. Methods: One hundred and eighty-six consecutive patients (194 hips) were evaluated at more than five years after THA using CLS stems. The mean follow-up period was 111 months. The radiographic stability of the femoral stem was determined by Engh's criteria. The ascertained period of spot welds was noted by Gruen zones on the femoral side. The presence of stress shielding, and subsidence was also evaluated. Results: A stable stem with bony on growth was identified in all cases. The mean period of expression of spot welds was 10.8 months in zone 2, 9.9 months in zone 3, 8.5 months in zone 5, and 8.8 months in zone 6. Stress shielding of more than grade 2 was observed in only three hips, which was non-progressive at one year after surgery. Subsidence of more than 2 mm was not observed in any of the hips. Conclusions: Excellent stability of CLS stem has been maintained without abnormal bone reaction at the proximal femur. CLS stem is considered to achieve not only press-fit stability at trochanteric and subtrochanteric level, but bony fixation by osseointegration within one year after THA.
    Hip international: the journal of clinical and experimental research on hip pathology and therapy 10/2013; · 0.34 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate whether the bone morphology of the hip affects the range of motion (ROM) in total hip arthroplasty (THA). Using the CT data of 63 patients who underwent THA, we calculated the ROM of flexion (Flex), internal rotation (Int-R) and external rotation (Ext-R) using 3D dynamic analysis software. We measured the distance between the anterior surface of the stem and anterior aspect of the greater trochanter (GTa length) at the cutting point and between the tip of the antero-inferior iliac spine (AIIS) and coronal plane of both femoral heads (AIIS length), as a parameter of the femur and pelvis, respectively. The relationship between the ROM, bone anatomy and impingement site was evaluated. We found a significant decrease in the ROM of Flex and the Int-R to be inversely proportional to the GTa and AIIS length. In Flex and Int-R, the anterior intertrochanteric region often impinges on the AIIS in patients with larger bone anatomy. We demonstrated that the bone morphology of the hip substantially affects the ROM of Flex and Int-R, especially in patients with large bone anatomy. For these patients we should consider bony impingement in THA.
    International Orthopaedics 07/2013; · 2.32 Impact Factor
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    ABSTRACT: PURPOSE: The purpose of this study was to examine retrospectively the effectiveness of Sugioka's transtrochanteric valgus osteotomy (TVO) combined with the shelf procedure for patients who had advanced osteoarthritis (OA) of the hip with severe acetabular dysplasia. METHODS: Sixty-two hips in 61 patients were reviewed retrospectively between April 1993 and March 2009. Of these hips, 25 hips with the pre-operative acetabular head index (AHI) ≥ 60 % (single group) underwent a TVO, whereas the other 37 with AHI < 60 % (combined group) underwent a TVO combined with the shelf procedure. RESULTS: Using conversion to total hip arthroplasty as the endpoint, the Kaplan-Meier survival rates at ten years were calculated to be 85.5 % for the single group and 100 % for the combined group; there was a significant difference between the two groups (p < 0.05, log-rank test). Similarly, calculated using progressive OA as the endpoint, survival rates at ten years were 69.5 % and 89.3 % respectively; there was also a significant difference between the two groups (p < 0.05, log-rank test). In the single group, the latest radiographic evaluations of the patients with the pre-operative AHI ≥ 70 % were significantly better than those of the patients with the pre-operative AHI < 70 % (P < 0.05). CONCLUSION: More satisfactory ten year results of TVO were obtained in cases that had a pre-operative AHI of ≥70 %, or where the shelf procedure was added. It is desirable that acetabuloplasty be added for patients with pre-operative AHI < 70 %.
    International Orthopaedics 02/2013; · 2.32 Impact Factor
  • Yuji Yasunaga, Takuma Yamasaki, Mitsuo Ochi
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    ABSTRACT: BACKGROUND: Hip dysplasia is the most common cause of secondary osteoarthritis (OA). Periacetabular osteotomy (PAO) or rotational acetabular osteotomy (RAO) has been used as a joint-preserving procedure. However, the patient selection criteria are not clearly defined. QUESTIONS/PURPOSES: Based on a systematic review, we identified reported patient selection criteria for PAO or RAO. METHODS: We performed a systematic review of RAO and 18 studies met our inclusion criteria. For the PAO, the systemic review performed by Clohisy et al. was used. WHERE ARE WE NOW?: For patients with symptomatic hip dysplasia, lateral center-edge angle less than 10° to 30°, radiographic pre- or early OA, mean age at the time of surgery of 18 to 45 years, and improvement in joint congruency on AP radiograph with hip abduction, radiographic deformity correction consistently improved hip function in all studies. Radiographic OA progression was noted in 5% to 33% at 3.2 to 20 years postoperatively. Clinical score and prevention of radiographic OA progression of patients 50 years or older or with advanced stage were worse in younger patients or those with early stage. WHERE DO WE NEED TO GO?: The key challenges are (1) preoperative evaluation of articular cartilage; (2) indication for older patients; (3) prevention of secondary femoroacetabular impingement; and (4) intraarticular treatment combined with PAO or RAO. HOW DO WE GET THERE?: Future prospective, longitudinal cohort studies need to determine optimal patient selection criteria, risk factors for clinical failure, optimal deformity correction parameters, and the role of adjunctive surgical procedures.
    Clinical Orthopaedics and Related Research 08/2012; · 2.79 Impact Factor
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    ABSTRACT: A role of microRNAs (miRNAs), which are ≈ 22-nucleotide non-coding RNAs, has recently been recognized in human diseases. The objective of this study was to identify the expression pattern of miRNA (miR)-210, known to be associated with angiogenesis, in bone from patients with osteonecrosis (ON) of the femoral head. The expression of miR-210 in bone from 10 patients with osteoarthritis (OA) of the hip and ten with ON was analyzed by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and by in situ hybridization. In addition, immunohistochemical staining for von Willebrand factor (vWF) and vascular endothelial growth factor (VEGF) was performed to identify the miR-210 expressing cells. We found that in ON samples, the expression of mature, primary miR-210, VEGF, matrix metalloproteinase (MMP)-2, and MMP-7 was significantly higher than that of OA samples. Section in situ hybridization of mature miR-210 revealed that mature miR-210 is expressed around the necrotic area. vWF and VEGF were also strongly expressed in the miR-210 expressing cells. This study shows that miR-210 is intensely expressed in ON, and might play a role in ON pathogenesis. The present study provides a solid basis for further functional analyses of miRNAs in ON.
    Journal of Orthopaedic Research 01/2012; 30(8):1263-70. · 2.88 Impact Factor
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    ABSTRACT: One of the major components of telomerase is the human telomerase reverse transcriptase (hTERT) as the catalytic protein. hTERT mRNA expression are reported to be associated with prognosis and tumor progression in several sarcomas. However, there is no clear understanding of the mechanisms of hTERT in human sarcomas. Recent studies have suggested that signals transmitted through p38 mitogen-activated protein kinase (MAPK) can increase or decrease hTERT transcription in human cells. The purpose of this study was to analyse the correlation between p38 MAPK and hTERT in sarcoma samples. We investigated 36 soft tissue malignant fibrous histiocytomas (MFH), 24 liposarcomas (LS) and 9 bone MFH samples for hTERT and p38 MAPK expression. Quantitative detection of hTERT and p38 MAPK was performed by RT-PCR. There was a significant positive correlation between the values of hTERT and p38 MAPK in all samples (r = 0.445, p = 0.0001), soft tissue MFH (r = 0.352, p = 0.0352), LS (r = 0.704, p = 0.0001) and bone MFH samples (r = 0.802, p = 0.0093). Patients who had a higher than average expression of p38 MAPK had a significantly worse prognosis than other patients (p = 0.0036). p38 MAPK may play a role in up-regulation of hTERT, and therefore, p38 MAPK may be a useful marker in the assessment of hTERT and patients' prognosis in sarcomas.
    Journal of Experimental & Clinical Cancer Research 01/2012; 31:5. · 3.07 Impact Factor
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    ABSTRACT: The thrust plate hip prosthesis (TPP) is a bone-reserving prosthesis for cementless fixation at the metaphysis of the proximal femur. We retrospectively evaluated the results of 162 patients (179 hips) who underwent hip arthroplasty using TPP. Eighty-three patients (87 hips) suffered from osteoarthritis of the hip joint (OA group), 79 patients (92 hips) from osteonecrosis of the femoral head (ON group). The mean age at surgery was 55 years in the OA group and 47.4 years in the ON group. The mean follow-up period was 97 months in the OA group and 104 months in the ON group. For these patients, we evaluated the results clinically and radiographically. The mean Merle d'Aubigne's score improved from 8.2 to 16.9 in the OA group and from 9.1 to 16.6 in the ON group at the final follow-up. Early mechanical loosening of TPP was observed in two hips of OA and one hip of ON. In one patient of ON, bilateral TPPs had to be removed 5 years postoperatively because of infection. Two female patients with ON suffered from a spontaneous femoral fracture below the tip of the lateral plate. Kaplan-Meier survivorship using TPP removed for any reason as the end point was 97.7% in the OA group and 90.3% in the ON group after 13 years. The middle-term results of the TPP were satisfactory if the indication for the TPP and the operative procedure were appropriate. The TPP is a useful and safe prosthesis for relatively young patients with not only osteoarthritis of the hip but also osteonecrosis of the femoral head.
    Archives of Orthopaedic and Trauma Surgery 11/2011; 132(4):547-54. · 1.36 Impact Factor
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    ABSTRACT: The Japanese Orthopaedic Association Hip Score is widely used in Japan, but this tool is designed to reflect the viewpoint of health-care providers rather than that of patients. In gauging the effect of medical therapies in addition to clinical results, it is necessary to assess quality of life (QOL) from the viewpoint of patients. However, there is no tool evaluating QOL for Japanese patients with hip-joint disease. With the aim of more accurately classifying QOL for Japanese patients with hip-joint disease, we prepared a questionnaire with 58 items for the survey derived from 464 opinions obtained from approximately 100 Japanese patients with hip-joint disease and previously devised evaluation criteria. In the survey, we collected information on 501 cases, and 402 were subjected to factor analysis. From this, we formulated three categories-movement, mental, and pain-each comprising 7 items, for a total of 21 items to be used as evaluation criteria for hip-joint function. The Cronbach's α coefficients for the three categories were 0.93, 0.93, and 0.95, respectively, indicating the high reliability of the evaluation criteria. The 21 items included some related to the Asian lifestyle, such as use of a Japanese-style toilet and rising from the floor, which are not included in other evaluation tools. This self-administered questionnaire may become a useful tool in the evaluation of not only Japanese patients, but also of members of other ethnic groups who engage in deep flexion of the hip joint during daily activities.
    Journal of Orthopaedic Science 11/2011; 17(1):25-38. · 0.96 Impact Factor
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    ABSTRACT: An abstract is unavailable. This article is available as HTML full text and PDF.
    Current Orthopaedic Practice 10/2011; 22(6):577–581.
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    ABSTRACT: The purpose of this study was to evaluate the outcome of femoral impaction bone grafting with an allograft combined with hydroxyapatite (HA). Fifty-four consecutive femoral reconstructions that were performed with the use of frozen morselized allografts and HA were followed up retrospectively. The average follow-up period was 92 months. A femoral head and HA were mixed and used as allograft. The average Merle d'Aubigné clinical score improved from 8.9 preoperatively to 13.1 points postoperatively. Stem subsidence was seen in 26 hips; however, it was not progressive after 1 year postoperatively. Cortical repair was detected at an average of 7 months postoperatively. Impaction bone grafting with an allograft combined with HA provided favorable results, with bone remodeling and less subsidence.
    The Journal of arthroplasty 09/2011; 27(3):470-6. · 1.79 Impact Factor
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    ABSTRACT: Telomere studies in carcinomas have been extensively reported for prognostic utility and effective methods for targeting telomerase therapy has been described, but efficacy of telomerase inhibitor remained unknown in sarcoma cells. In this study, we investigated the effects of telomerase inhibitor cationic porphyrin TMPyP4 on telomerase activity, telomere length, cell growth, and apoptosis in osteosarcoma cell lines. TMPyP4 significantly inhibited telomerase activity in telomerase positive HOS and Saos-2, but not in MG-63. TMPyP4 significantly induced telomere shortening, and inhibition of the cell growth in HOS and Saos-2 with over 17% apoptosis rates. In terms of MG-63, TMPyP4 did not induce inhibition of both telomerase activity and cell growth, although it induced significant telomere shortening. Telomere length after treatment was 5.60 kb in HOS, 4.00 kb in Saos-2, and 9.89 kb in MG-63. These results may suggest that both telomerase activity loss and sufficient telomere shortening are necessary to inhibit cell growth in telomerase positive osteosarcoma cells. TMPyP4 did not induced telomere shortening but significantly inhibited the growth with 22.6% apoptosis rate in telomerase negative with extremely longer telomere-U2OS, may indicating the antitumor effect of TMPyP4 may be related to DNA damage including telomere dysfunction through G-quadruplex stabilization, independent on telomere length.
    Journal of Orthopaedic Research 05/2011; 29(11):1707-11. · 2.88 Impact Factor

Publication Stats

1k Citations
213.25 Total Impact Points

Institutions

  • 2004–2014
    • Hiroshima University
      • Department of Orthopaedic Surgery
      Hirosima, Hiroshima, Japan
  • 2012
    • Kure Medical Centre
      Kure, Hiroshima, Japan
  • 2005
    • Miyoshi Central Hospital
      Miyosi, Hiroshima, Japan
  • 2003
    • Matsuyama Red Cross Hospital
      Matuyama, Ehime, Japan