Kengo Yamamoto

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The volumetric wear in retrieved cups can be assessed by mathematical conversion based on linear measurements and by a fluid-displacement method. We used a hip simulator model to produce wear in 22-, 28-, and 32-mm hip implants and then assessed the volumetric wear using a gravimetric wear method. We then compared the findings with those obtained with the(More)
Accurate reproduction of anatomic relationship is important in non-constrained prosthetic arthroplasty. The accurate lateral glenohumeral offset, which indicates a parameter of the lever arm of the deltoid and supraspinatus muscles, is one of the most important elements in achieving the efficient shoulder functions after prosthetic reconstruction. However,(More)
Femoral component rollback and tibial rotation were evaluated using lateral radiographs taken during passive knee flexion under fluoroscopy in NexGen Legacy Posterior Stabilized Flex (Zimmer, Warsaw, Ind) total knee arthroplasties (TKAs; 30 with mobile insert and 26 with fixed insert). Measured maximal flexion angle demonstrated no significant differences.(More)
STUDY DESIGN Radiological analysis of normal patterns of sagittal alignment of the spine. PURPOSE This study aimed to clarify the characteristics of normal sagittal spino-pelvic alignment in Asian people. OVERVIEW OF LITERATURE It is known that there are differences in these parameters based on age, gender, and race. In order to properly plan for(More)
Lateral whole-spine radiography is a useful tool in the management of spinal deformity, but the most appropriate arm position during radiography has yet to be determined. In this prospective study, we evaluated 26 adult volunteers and 22 patients with lumbar spinal canal stenosis. Lateral whole-spine radiographs were acquired in the most stable and relaxed(More)
The values of hip rotation center (HRC) and femoral offset (FO) evaluated according to Caucasian anatomical landmarks have been regarded as a useful reference also for Japanese patients in total hip arthroplasty (THA). In a strict sense, however, since there can be racial differences among their anatomical morphologies, it is clinically important to(More)
STUDY DESIGN Gait analysis of patients with cervical spondylotic myelopathy (CSM) by using a sheet-type gait analysis system. PURPOSE The aim of this study was to compare the gait patterns of patients with CSM, evaluated by the Nurick grades, and to determine the threshold values of gait parameters predicting the occurrence of a fall by using a gait(More)
STUDY DESIGN Normal cervical sagittal length patterns were measured by magnetic resonance imaging (MRI). PURPOSE The aim of this study was to evaluate the relationship of sagittal length patterns between the cervical cord and the cervical canal in flexion-extension kinematics. OVERVIEW OF LITERATURE Cervical dynamic factors sometimes cause a cervical(More)
It has been recognized that perioperative hemostasis management after joint-replacement surgery for hemophilia patients is complicated and cumbersome, due to the necessity of rigorous monitoring for clotting-factor levels throughout the infusion. Between 2005 and 2014, we examined seven patients with hemophilia A (ten joints: six hips and four knees)(More)
The objective of this study was to compare the low temperature degradation (LTD) behavior of femoral heads made of 3Y-TZP as observed on retrievals with that induced in vitro upon prolonged exposures to a hydrothermal environment. The time-dependent evolution of tetragonal-to-monoclinic transformation and the related residual stresses were nondestructively(More)