The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Ken Ueoka - One of the best experts on this subject based on the ideXlab platform.

  • A proposed new rotating Reference Axis for the tibial component after proximal tibial resection in total knee arthroplasty.
    PloS one, 2018
    Co-Authors: Takaaki Ohmori, Tamon Kabata, Yoshitomo Kajino, Daisuke Inoue, Tadashi Taga, Takashi Yamamoto, Tomoharu Takagi, Junya Yoshitani, Takuro Ueno, Ken Ueoka
    Abstract:

    Purpose During total knee arthroplasty, few rotating Reference axes can be reliably used after tibial resection. We speculated that a line that passes through the lateral edge of the posterior cruciate ligament (PCL) at its tibial attachment after resection and the most prominent point of the tibial tubercle [after-tibial resection (ATR) line] will provide a good Reference Axis. In this study, we aimed to evaluate the association between ATR and Akagi’s lines. Materials and methods In this case–control simulation study, we retrospectively evaluated 38 patients with varus knee and 28 patients with valgus knee. We defined the Reference cutting plane as 10 mm distal from the lateral articular surface of the tibia in varus group and as 7 mm distal from the medial articular surface in the valgus group. We measured angles between Akagi’s line and the ATR line (ATR line angle) as well as between Akagi’s line and 1/3 Akagi’s line (1/3 Akagi’s line angle), which passes through the midpoint of PCL and the medial third of the patellar tendon. We used paired t-tests to determine the significance of differences between these angles, with p < 0.05 indicating statistical significance. Intra- and interclass correlation coefficients for the reproducibility of 1/3 Akagi’s line angle and ATR line angle were analyzed by two surgeons. Results We found that 1/3 Akagi’s line angle was 10.2° ± 1.3° in the varus group and 10.9° ± 1.3° in the valgus group (p = 0.017). The ATR line was positioned externally compared with Akagi’s line in all patients. Mean ATR line angles at 0°, 3° and 7° posterior slopes were 6.1° ± 1.9°, 5.8° ± 2.0° and 6.0° ± 1.7° in the varus group and 6.3° ± 2.3°, 6.2° ± 2.3° and 5.4° ± 2.1° in the valgus group, respectively. There were no significant differences in the ATR line angle between the varus and valgus groups. (p = 0.34–0.67) Intra- and interclass correlation coefficients for the reproducibility of 1/3 Akagi’s line angle were 0.936 and 0.986 and those for the reproducibility of ATR line angle were 0.811 and 0.839. Conclusions The ATR line was positioned between Akagi’s line and 1/3 Akagi’s line in all patients and was a valid option for evaluating rotational tibial alignment after tibial resection.

Ian A F Stokes - One of the best experts on this subject based on the ideXlab platform.

  • the central hip vertical Axis a Reference Axis for the scoliosis research society three dimensional classification of idiopathic scoliosis
    Spine, 2010
    Co-Authors: Archana P Sangole, Carleric Aubin, Hubert Labelle, Lawrence G Lenke, Roger P Jackson, Peter O Newton, Ian A F Stokes
    Abstract:

    STUDY DESIGN: Reliability comparison of 2 radiographic Axis systems by inter- and intraobserver variability. OBJECTIVE: To determine whether the central hip vertical Axis (CHVA) provides a more reliable Reference Axis for the evaluation of scoliosis. SUMMARY OF BACKGROUND DATA: Current practices in the evaluation of the scoliotic spine use the central sacral vertical line (CSVL), a true vertical drawn upward from the middle of S1, to assess the spinal deformity. However, the CVSL is defined only in the coronal radiographic view and has no corresponding definition in the sagittal view. Therefore, it represents a 2-dimensional positioning of the scoliotic segments relative to the pelvis. In view of this limitation, the Scoliosis Research Society 3-dimensional (3D) scoliosis committee proposed the CHVA, a true vertical bisecting the line segment joining the centers of the 2 femoral heads, as a Reference line for the 3D evaluation of the spinal deformity. Unlike the CSVL, the CHVA can be identified in both radiographic views (coronal and sagittal) and has been shown to represent the physiologic center of balance of the spino-pelvic unit. METHODS: A vertical Axis was established on preoperative radiographs of 68 Lenke 1 main thoracic curves twice by 5 members of the Scoliosis Research Society 3D scoliosis committee assisted by dedicated software. The user digitized separately on the postero-anterior radiographs, the lateral borders of the S1 facets (for the CSVL), and 3 points on the 2 femoral heads (for the CHVA). The software then drew lines representing both axes. Then the observers determined the lumbar modifier (A, B, and C) using both axes. RESULTS.: There was no intra- and interobserver difference in the position of the CHVA (P > 0.1; SD: 0.4 mm), whereas intraobserver differences were found for the CSVL (P B-->C) in the assignment of the lumbar modifier. CONCLUSION: The CHVA is more reproducible and showed better intra- and interobserver agreement, when compared with the CSVL for the identification of the lumbar modifier. The CHVA can be easily computed in 3D and represents the physiologic center of balance of the spino-pelvic unit because it takes into account femoral head support. We recommend keeping the CSVL for 2-dimensional measurement to adapt the measures relative to the CSVL to the proposed CHVA Axis and adopting CHVA as the Reference Axis for 3D evaluation of idiopathic scoliosis.

Ye-yeon Won - One of the best experts on this subject based on the ideXlab platform.

  • Comparison of alternate References for femoral rotation in female patients undergoing total knee arthroplasty.
    Knee surgery sports traumatology arthroscopy : official journal of the ESSKA, 2015
    Co-Authors: Dong San Jin, Jun Han, Ho-sik Choo, Ye-yeon Won
    Abstract:

    Purpose Accurate rotational alignment of the femoral component is of vital importance for successful total knee arthroplasty (TKA). Two anatomical References located on the anterior femur were recently introduced. To determine which is more reliable Reference Axis for the femoral component rotation in female patients receiving TKA, the trochlear anterior line was compared with the femoral anterior tangent line.

  • An Additional Reference Axis for Determining Rotational Alignment of the Femoral Component in Total Knee Arthroplasty
    The Journal of arthroplasty, 2007
    Co-Authors: Ye-yeon Won, Wen-quan Cui, Myong-hyun Baek, Tae-bong Yun, Seung-ho Han
    Abstract:

    No studies have examined the trochlear line connecting the most anterior projections of the lateral and medial femoral condyles in relation to the surgical epicondylar Axis. To determine if the trochlear line is more consistent relative to the transepicondylar Axis than the posterior condylar Axis and the Whiteside's line, the angles between the surgical epicondylar Axis and each of the 3 axes in 50 knees of cadavers were measured using computed tomography scans. The results showed that the variability in the trochlear line for referencing the transepicondylar Axis was comparable to those of the Whiteside line and the posterior condylar Axis. The trochlear line may be considered as an additional Reference Axis for determining the rotational alignment of the femoral component in total knee arthroplasty.

Eun Kyoo Song - One of the best experts on this subject based on the ideXlab platform.

  • Rotational profile of lower limb and Axis for tibial component alignment in varus osteoarthritic knees.
    The Journal of arthroplasty, 2011
    Co-Authors: Mohammad Shahnawaz Khan, Jong Keun Seon, Eun Kyoo Song
    Abstract:

    The purposes of this study were to describe the changes in tibial torsion and knee rotation in varus osteoarthritic knees and to check the reliability of Reference Axis, for tibial component placement, based on femoral transepicondylar Axis in these patients. A secondary goal was to determine which Reference Axis based on proximal tibia is most accurate for determining tibial component rotation. Fifty-two varus osteoarthritic knees and 20 normal knees were analyzed using computed tomographic scan. Tibial torsion and knee rotation were significantly reduced in patients with osteoarthritis. Reference Axis based on posterior tibial condyles was most accurate and least variable for tibial component alignment. A significant negative correlation was found between knee rotation and tibial Axis based on transepicondylar Axis (r = -0.485).

Raymond A. Applegate - One of the best experts on this subject based on the ideXlab platform.

  • Importance of fixation, pupil center, and Reference Axis in ocular wavefront sensing, videokeratography, and retinal image quality.
    Journal of cataract and refractive surgery, 2009
    Co-Authors: Raymond A. Applegate, Larry N. Thibos, Michael D. Twa, Edwin J. Sarver
    Abstract:

    Purpose To examine the impact of the location of the fixation target, pupil center, and Reference Axis of ophthalmic aberrometers and videokeratographers on the measurement of corneal aberrations relevant to vision. Setting Clinical Research, Visual Optics Institute, College of Optometry, University of Houston, Houston, Texas, USA. Methods The design features of a generic aberrometer and videokeratographer and their interaction with the eye were examined. The results provided a theoretical framework for experimental assessment of pupil translation errors on corneal aberrations relevant to vision and their correction in 129 eyes. Results Two key principles emerged. First, the aberrometer's measurement Axis must coincide with the eye's line-of-sight (LoS). Second, the videokeratographer's measurement Axis (the vertex normal) must be parallel with the eye's LoS. When these principles are satisfied, the eye will be in the same state of angular rotation and direct comparison of measurements is justified, provided any translation of the pupil from the vertex normal is taken into account. The error incurred by ignoring pupil displacement in videokeratography varies between eyes and depends on the type of aberration and amount of displacement, with the largest residual correction root-mean-square wavefront error being 1.26 μm over a 6.0 mm pupil, which markedly decreases retinal image quality. Conclusion Translation of the pupil center with respect to the vertex normal in videokeratography should not be ignored in the calculation of the corneal first-surface, internal aberrations of the eye relevant to vision, or the design of refractive corrections based on videokeratography.

  • Reference Axis Selection: Subcommittee Report of the OSA Working Group to Establish Standards for Measurement and Reporting of Optical Aberrations of the Eye
    2000
    Co-Authors: Raymond A. Applegate, Larry N. Thibos, Arthur Bradley, Susana Marcos, Austin Roorda, Thomas O. Salmon, David A. Atchison
    Abstract:

    It is the committee’s recommendation that the ophthalmic community use the line of sight as the Reference Axis for the purpose of calculating and measuring the ocular optical aberrations

  • Reference Axis selection: subcommittee report of the OSA Working Group to establish standards for measurement and reporting of optical aberrations of the eye.
    Journal of refractive surgery (Thorofare N.J. : 1995), 2000
    Co-Authors: Raymond A. Applegate, Larry N. Thibos, Arthur Bradley, Susana Marcos, Austin Roorda, Thomas O. Salmon, David A. Atchison
    Abstract:

    It is the committee’s recommendation that the ophthalmic community use the line of sight as the Reference Axis for the purposes of calculating and measuring the ocular optical aberrations. [J Refract Surg 2000;16:S656-S658]