Shigeshi Mori

Kinki University, Ōsaka, Ōsaka, Japan

Are you Shigeshi Mori?

Claim your profile

Publications (15)29.09 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background The patient-specific guide for total knee arthroplasty (TKA) is created from the data provided by magnetic resonance imaging (MRI) or computed tomography (CT) scans. It remains unknown which imaging technology is suitable for the patient-specific guide. The purpose of this study was to compare the accuracy of implant positioning and operative times between the two types of patient-specific guides for TKA. Methods Forty arthritic knees were divided into two treatment groups using MRI-based (PS-MRI group) or CT-based (PS-CT group) patient-specific guides in this prospective, comparative study. The guide in the PS-MRI group had a cutting slot, whereas that in the PS-CT group only had a pin locator. The operative times were compared between the two groups. The angular error and number of outliers (deviations > 3°) of the implant position using pre- and postoperative CT were investigated in both groups. Results The mean operative time was significantly shorter in the PS-MRI group (109.2 ± 16.5 min) than in the PS-CT group (129.5 ± 19.4 min) (p < 0.001). There were no significant differences in the accuracy of the implant position regarding the coronal, sagittal, and axial planes between the groups (p > 0.05). Conclusions To reduce the operative time, guides with additional functions, such as cutting and positioning, should be used. Both CT- and MRI-based-guides would result in the same accuracy in three planes but high inaccuracy in the sagittal plane. The use of patient-specific guide based on MRI might not be cost-effective. Level of evidence: level 2.
    The Knee 09/2014; 21(6). DOI:10.1016/j.knee.2014.08.015 · 1.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Deep venous thrombosis (DVT), which is often associated with pulmonary embolism (PE), is a serious complication after total knee arthroplasty (TKA). In the present study, we examined the overall thrombotic and thrombolytic status using Global Thrombosis Test (GTT) in non-anticoagulated blood of patients undergoing TKA to develop the predictable marker for the incidence of DVT. Methods DVT was diagnosed using doppler ultrasonography a day after the surgery in 31 patients with osteoarthritis (n = 24), rheumatoid arthritis (n = 6) and ankylosing spondylitis (n = 1) by the well-trained operator. We measured overall thrombotic and thrombolytic status using GTT and other biomarkers, which is associated with blood coagulation and fibrinolysis, before and immediately after the surgery. Results Newly-generated DVT during the operation was detected in 11 of 31 patients (35.4%) 1 day after TKA. There were no differences in markers of coagulation (PT and APTT), platelet activity (platelet aggregation-induced by ADP and collagen) and fibrinolysis (FDP and D-dimer) between non-DVT and DVT group both before and after the surgery. Both Pre- and Post-operative GTT-occlusion times (OT), an index of platelet reactivity, were tended to be shorter, but not significant, in DVT group compared with non-DVT group. Pre-operative GTT-lysis time (LT), an index of thrombolytic activity, was significantly shorter in DVT group compared with non-DVT group, while there were no differences in post-operative value of this index between DVT group and non-DVT group, suggesting overall thrombolytic activity was enhanced in DVT group before surgery. Conclusions Our data suggest that enhancement of pre-operative thrombolytic activity assessed by GTT may be a predictable marker for the incidence of DVT after TKA.
    Thrombosis Journal 05/2014; 12(1):11. DOI:10.1186/1477-9560-12-11 · 1.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The sagittal reference axes used for setting of the femoral component vary according to surgical methods. The purpose of the study was to clarify the relation of the sagittal reference axis with the anteroposterior (AP) length of the distal femur at the time of determining the femoral component size. Fifty consecutive varus osteoarthritic knees with primary total knee arthroplasty were divided into two groups according to surgical methods (intramedullary and extramedullary groups) and were examined based on CT data. AP length of the distal femur changed nearly 0.6mm corresponding to each 1° flexion of the sagittal reference axis. The size of the femoral component in the intramedullary group was larger than that in the extramedullary group. The sagittal reference axis had an influence on the component size.
    The Journal of arthroplasty 03/2013; 28(6). DOI:10.1016/j.arth.2012.12.004 · 2.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Tibia vara seen in Japanese patients reportedly influences the tibial component alignment when performing TKA. However, it is unclear whether tibia vara affects the component position and size selection. QUESTIONS/PURPOSES: We therefore determined (1) the amount of medial tibial bow, (2) whether the tibia vara influences the aspect ratio of the tibial resected surface in aligning the tibial component with the tibial shaft axis, and (3) whether currently available tibial components fit the shapes of resected proximal tibias in terms of aspect ratio. METHODS: We measured the tibia vara angle (TVA), proximal varus angle (PVA), and the mediolateral and middle AP dimensions of the resected surface using three-dimensional preoperative planning software in 90 knees of 74 female patients with varus osteoarthritis. We determined the correlations of the aspect ratio with TVA or PVA and compared the aspect ratios to those of five prosthesis designs. RESULTS: The mean TVA and PVA were 0.6° and 2.0°, respectively. The aspect ratio negatively correlated with both TVA and PVA (r = -0.53 and -0.55, respectively). The mean aspect ratio of the resected surface was 1.48 but gradually decreased with increasing AP dimension, whereas four of the five prostheses had a constant aspect ratio. CONCLUSIONS: The aspect ratio of resected tibial surface was inversely correlated to the degree of tibia vara, and currently available prosthesis designs do not fit well to the resected surface in terms of aspect ratio. CLINICAL RELEVANCE: The design of a tibial component with a smaller aspect ratio could be developed to obtain better bone coverage in Japanese patients.
    Clinical Orthopaedics and Related Research 01/2013; 471(5). DOI:10.1007/s11999-013-2800-6 · 2.77 Impact Factor

  • Journal of Orthopaedic Science 07/2012; 19(1). DOI:10.1007/s00776-012-0260-6 · 0.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE: The bi-malleolar technique for the extramedullary tibial guide is a representative method for determining the ankle center in total knee arthroplasty (TKA). The purpose of this study is to estimate three-dimensionally the lateral errors (difference between the real ankle center and the bi-malleolar center) and the varus angular errors of this technique under the condition that the malleolar prominences were correctly identified. METHODS: Magnetic resonance images of 51 lower limbs from 51 healthy volunteers were analyzed. The lateral errors were measured, including or excluding the subcutaneous thickness, along the line perpendicular to the transmalleolar axis (TMA) or along the tibial anteroposterior (AP) axis. Furthermore, we evaluated the effects of the tibial torsion and the difference between the subcutaneous thicknesses on the malleoli on the lateral error. RESULTS: When including the skin, the mean lateral errors of the ankle center observed along the line perpendicular to the TMA and along the tibial AP axis were 3.7±1.4mm and 1.2±1.5mm, respectively. The mean angular errors were 0.6±0.2° and 0.2±0.3°, respectively. A significant correlation between the tibial torsion and the lateral error was noted when observed along the tibial AP axis. The difference between the subcutaneous thicknesses on the malleoli affected the lateral error. CONCLUSION: The errors were small enough to determine the mechanical axis of the tibia if the tibial guide could catch the bi-malleolar prominences of the ankle accurately and align along the tibial AP axis.
    The Knee 04/2012; 19(6). DOI:10.1016/j.knee.2012.03.006 · 1.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to clarify the causes of the increase in the posterior tibial slope during open-wedge high tibial osteotomy (HTO) and to investigate whether its changes influenced the correction angle in frontal plane. We retrospectively reviewed 20 patients (26 knees) treated with open-wedge HTO. They were divided into the following two groups. Group A consisted of the knees whose opening gaps were fixed using a spacer plate having the trapezoidal block with a 2° posterior slope. In Group B, anterior and posterior opening gaps were fixed separately. The posterior tibial slope and the hip-knee-ankle angle were measured based on CT data. The relationship between the correction rate in frontal plane and the changes of posterior tibial slope was investigated. Increase in the posterior tibial slope was 2.1 ± 2.5° in Group A and 0.2 ± 1.2° in Group B, which showed a statistical difference (P = 0.02). The difference between the hip-knee-ankle angles before and after operation was 5.2 ± 2.3° in Group A and 5.5 ± 2.5° in Group B. The correction rate was statistically correlated with the changes of posterior tibial slope (R = -0.55, P = 0.003). To avoid increase in the posterior tibial slope, the trapezoidal block with a only 2° posterior slope in a spacer plate was not sufficient, and it was necessary to fix anterior and posterior gaps separately. The correction angle in frontal plane had a trade-off relationship with the changes in posterior tibial slope. Thus, we thought that increase in the posterior tibial slope might result in correction loss. Therapeutic study, Retrospective comparative study, Level III.
    Knee Surgery Sports Traumatology Arthroscopy 07/2011; 20(3):571-8. DOI:10.1007/s00167-011-1610-1 · 3.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Preoperative planning of total knee arthroplasty (TKA) based on computerized tomography (CT) data can produce a femoral rotational error due to lack of information on the femoral cartilage thickness. The research question of this study is how much femoral rotational error is expected due to the cartilage remnants when using the posterior condylar angles (PCA, angle between the posterior condylar line and the surgical epicondylar axis (SEA)) on CT data. CT arthrography was performed for 35 consecutive varus osteoarthritic knees in 31 patients who underwent TKA, on which the cartilage thicknesses of the posterior femoral condyles were measured. The PCAs when including or excluding the cartilage remnants were also measured. The cartilage thicknesses of the medial and lateral posterior condyles averaged 0.39mm (SD=0.53) and 1.55mm (SD=0.26), respectively (p<0.0001). When the cartilage was included or excluded, the PCA averaged 2.2° (SD=1.5) and 3.3° (SD=1.5), respectively (p=0.002). The cartilage remnants in the posterior femoral condyles produced an average of 1.1° and a maximum of 2.1° of additional femoral external rotation when using CT data for the preoperative planning. CT scan measurements of femoral rotation are subject to error. Although this is said to be small and within the safety margin for setting the femoral component parallel to the trans-epicondylar axis, this difference should be considered by surgeons who use the posterior condylar axis, in order to avoid excessive external rotation of the femoral component.
    The Knee 03/2011; 19(3):185-9. DOI:10.1016/j.knee.2011.02.008 · 1.94 Impact Factor
  • Shigeki Asada · Masao Akagi · Shigeshi Mori · Chiaki Hamanishi ·

    Journal of Orthopaedic Science 06/2008; 13(3):255-8. DOI:10.1007/s00776-007-1219-x · 0.94 Impact Factor

  • Rigakuryoho Kagaku 01/2008; 23(2):279-283. DOI:10.1589/rika.23.279
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the surface properties and wear performances of a standard cobalt-chromium (Co-Cr) alloy and 2 kinds of ceramic femoral components (alumina and zirconia) in tibial polyethylene inserts tested in a knee simulator. Hardness, wettability (lubricity), and presimulator and postsimulator test roughness values of the component surfaces were measured for each material. The simulator was run up to 5.0 million cycles using gait kinematics to determine the wear rate of the tibial polyethylene against each group. Vickers hardness values of the femoral components made of Co-Cr, alumina, and zirconia averaged 339 ± 14.8, 1869 ± 40.6, and 1382 ± 15.8, respectively. Contact angles with distilled water (in degrees) of the femoral components made of Co-Cr, alumina, and zirconia averaged 76.9 ± 3.2, 34.9 ± 1.5, and 73.5 ± 0.8, respectively. The aggregate volumetric wear rate for the Co-Cr femoral components was 3.35 ± 1.33 mm3 per million cycle; those of the alumina and zirconia femoral components were 0.15 ± 0.08 and 0.57 ± 0.18 mm3/M, respectively. Differences between the wear rate of the Co-Cr and ceramic femoral components were statistically significant (n = 3; P < 0.01). The posttest roughness values of ceramic femoral condyles were significantly smaller than that of the Co-Cr condyles. The reduction in the tibial polyethylene wear was likely attributable to the greater wettability and resistance to roughening of the ceramic components.
    Techniques in Knee Surgery 11/2007; 6(4):206-212. DOI:10.1097/BTK.0b013e31815bd423
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although mechanical forces are an essential factor in the regulation of cartilage metabolism, the precise mechanisms involved have not yet been determined. We previously demonstrated that mechanical forces on chondrocytes inhibited proteoglycan (PG) synthesis. We also demonstrated the induction of reactive oxygen species (ROS) is loaded on the chondrocytes. Our purpose was to determine the ROS induction with mechanical compression and its involvement in PG synthesis of cartilage slices. Bovine articular cartilage slices were subjected to cyclic compression loading. Synthesis of PG and ROS was measured using Na2[35S]-SO4 and a chemiluminescent probe, respectively. The induction of nitrotyrosine was determined using immunohistochemistry. The synthesis of PG was significantly inhibited with 2.0 MPa of compression stress; 1 h of compression was sufficient to inhibit PG synthesis. The ROS inhibitor ebselen reversed the compression-inhibited synthesis of PG. Compression on the cartilage induced synthesis of ROS and the expression of nitrotyrosine. Mechanical compression at 2.0 MPa inhibited PG synthesis by cartilage explants. ROS were involved in this action.
    The Journal of Rheumatology 04/2007; 34(3):556-62. · 3.19 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Axial micromotion of bone fragments enhances callus formation during fracture repair or limb lengthening. To examine this, we used an axial-shortening model of the tibial callus in rabbits and performed histological analyses. After 10-mm lengthening of the left tibia with an external fixator, we shortened the callus by 2 mm. Radiographs and quantitative evaluation of corrected bone mineral density showed a significant increase in mineralization in the shortened callus (57.3 vs. 36.2%, p = 0.001). Histologically, greater osteoblast proliferation and more vigorous trabecular bone formation were noted in the shortened calluses than in the controls. Around the front of membranous bone formation in the shortened callus, there was a significant decrease in mean percentage area of vascular lumens (1.8 vs. 4.5%, p = 0.009), which seemed attributable to compressive force, and a significantly increased production of vascular endothelial growth factor (VEGF; 422.5 vs. 142.7 pg/mg protein, p = 0.007) and its receptors. There were also increased numbers of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts and proliferating cell nuclear antigen (PCNA)-positive cells. A marked increase of hypoxia inducible factor-1alpha (HIF-1alpha) expression in osteoblasts was also observed in this area. Thus, enhancement of membranous bone formation by static compression or axial dynamization may be at least partly attributable to HIF-1alpha-mediated VEGF induction following the local hypoxia caused by collapse of vascular lumens.
    Journal of Orthopaedic Research 04/2006; 24(4):653-63. DOI:10.1002/jor.20076 · 2.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Anatomic reference axes that determine rotational alignment of the tibial component have not been established. To assess variability of three anatomic reference axes (a new tibial anteroposterior axis that we proposed, the transmalleolar axis of the ankle, and the second metatarsus bone axis of the foot), we measured the angles between a defined anteroposterior axis of the tibia (a line perpendicular to the transepicondylar axis) and each of the three axes in 57 knees of healthy subjects using computed tomography scans. The angle between the defined anteroposterior axis and our proposed anteroposterior axis (a line connecting the middle of the posterior cruciate ligament and the medial edge of the patellar tendon attachment) averaged -0.2 degrees +/- 2.8 degrees (range, -5.5 degrees -6.3 degrees). The angle between the defined anteroposterior axis and the transmalleolar axis averaged 25.9 degrees +/- 9 degrees (range, 8 degrees -49.4 degrees), and the angle between the defined anteroposterior axis and the second metatarsus bone axis averaged 5.2 degrees +/- 10 degrees (range, -21.9 degrees -24 degrees). The variability of the anteroposterior axis was less than than the other reference axes. These data indicate that our proposed tibial anteroposterior axis is more reliable for determining rotational alignment of the tibial component in total knee arthroplasty.
    Clinical Orthopaedics and Related Research 08/2005; 436(436):172-6. DOI:10.1097/01.blo.0000160027.52481.32 · 2.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Alumina-on-alumina bearings for total hip arthroplasty have been introduced as a promising alternative to reduce wear debris and to increase the life expectancy of the prosthesis. We report a case of a late dissociation of an alumina-on-alumina bearing modular acetabular component, which occurred 2 years, 8 months after surgery. Detailed analysis of the retrieved prosthesis suggested that the cause of the failure may be strong rotational torque developed by a roughening of the bearing's alumina surface caused by edge loading (microseparation). The strong friction torque in articulation may explain the higher reported rate of mechanical loosening of the acetabular component in alumina-on-alumina bearing total hip prostheses.
    The Journal of Arthroplasty 09/2004; 19(5):647-51. DOI:10.1016/j.arth.2004.02.027 · 2.67 Impact Factor