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  • Conference paper
    Stephen JM, Halewood C, Kittl C, Bollen S, Williams A, Amis AAet al., 2015,

    The influence of posterior medial meniscocapsular lesions on tibiofemoral joint laxity in ACL deficient and reconstructed knees

    , British Association of Surgery of the Knee
  • Conference paper
    Halewood C, 2015,

    Anteroposterior laxity after bicruciate-retaining total knee replacement is closer to the intact knee than conventional ACL-resecting TKR: a biomechanical cadaver study

    , BASK
  • Journal article
    Kawaguchi Y, Kondo E, Takeda R, Akita K, Yasuda K, Amis AAet al., 2015,

    The role of fibers in the femoral attachment of the anterior cruciate ligament in resisting tibial displacement

    , ARTHROSCOPY-THE JOURNAL OF ARTHROSCOPIC AND RELATED SURGERY, Vol: 31, Pages: 435-444, ISSN: 0749-8063

    PurposeThe purpose was to clarify the load-bearing functions of the fibers of the femoral anterior cruciate ligament (ACL) attachment in resisting tibial anterior drawer and rotation.MethodsA sequential cutting study was performed on 8 fresh-frozen human knees. The femoral attachment of the ACL was divided into a central area that had dense fibers inserting directly into the femur and anterior and posterior fan-like extension areas. The ACL fibers were cut sequentially from the bone: the posterior fan-like area in 2 stages, the central dense area in 4 stages, and then the anterior fan-like area in 2 stages. Each knee was mounted in a robotic joint testing system that applied tibial anteroposterior 6-mm translations and 10° or 15° of internal rotation at 0° to 90° of flexion. The reduction of restraining force or moment was measured after each cut.ResultsThe central area resisted 82% to 90% of the anterior drawer force; the anterior fan-like area, 2% to 3%; and the posterior fan-like area, 11% to 15%. Among the 4 central areas, most load was carried close to the roof of the intercondylar notch: the anteromedial bundle resisted 66% to 84% of the force and the posterolateral bundle resisted 16% to 9% from 0° to 90° of flexion. There was no clear pattern for tibial internal rotation, with the load shared among the posterodistal and central areas near extension and mostly the central areas in flexion.ConclusionsUnder the experimental conditions described, 66% to 84% of the resistance to tibial anterior drawer arose from the ACL fibers at the central-proximal area of the femoral attachment, corresponding to the anteromedial bundle; the fan-like extension fibers contributed very little. This work did not support moving a single-bundle ACL graft to the side wall of the notch or attempting to cover the whole attachment area if the intention was to mimic how the natural ACL resists tibial displacements.Clinical RelevanceThere is ongoing debate about ho

  • Journal article
    Kittl C, Halewood C, Stephen JM, Gupte CM, Weiler A, Williams A, Amis AAet al., 2015,

    Length change patterns in the lateral extra-articular structures of the knee and related reconstructions

    , American Journal of Sports Medicine, Vol: 43, Pages: 354-362, ISSN: 0363-5465

    Background:Lateral extra-articular soft tissue reconstructions in the knee may be used as a combined procedure in revision anterior cruciate ligament surgery as well as in primary treatment for patients who demonstrate excessive anterolateral rotatory instability. Only a few studies examining length change patterns and isometry in lateral extra-articular reconstructions have been published.Purpose:To determine a recommended femoral insertion area and graft path for lateral extra-articular reconstructions by measuring length change patterns through a range of knee flexion angles of several combinations of tibial and femoral insertion points on the lateral side of the knee.Study Design:Controlled laboratory study.Methods:Eight fresh-frozen cadaveric knees were freed of skin and subcutaneous fat. The knee was then mounted in a kinematics rig that loaded the quadriceps muscles and simulated open-chain knee flexion. The length changes of several combinations of tibiofemoral points were measured at knee flexion angles between 0° and 90° by use of linear variable displacement transducers. The changes in length relative to the 0° measurement were recorded.Results:The anterior fiber region of the iliotibial tract displayed a significantly different (P < .001) length change pattern compared with the posterior fiber region. The reconstructions that had a femoral insertion site located proximal to the lateral epicondyle and with the grafts passed deep to the lateral collateral ligament displayed similar length change patterns to each other, with small length increases during knee extension. These reconstructions also showed a significantly lower total strain range compared with the reconstruction located anterior to the epicondyle (P < .001).Conclusion:These findings show that the selection of graft attachment points and graft course affects length change pattern during knee flexion. A graft attached proximal to the lateral femoral epicondyle and running deep

  • Conference paper
    Stephen JM, Kittl C, Williams A, Marcheggiani Muccioli GM, Zaffagnini S, Fink C, Amis AAet al., 2015,

    The effect of graft type and femoral positioning on patellofemoral contact pressure and kinematics after medial patellofemoral ligament reconstruction

    , British Association for Surgery of the Knee
  • Conference paper
    Geraldes D, Hansen U, Amis A, 2015,

    Parametric analysis of glenoid implant design

    , European Society of Biomechanics 2015
  • Book chapter
    Keller R, Amis AA, 2015,

    Anatomy and Biomechanics of the Natural Knee and After TKR

    , The Unhappy Total Knee Replacement, Editors: Hirschmann, Becker, Publisher: Springer, Pages: 3-15, ISBN: 978-3-319-08098-7

    This book addresses the need for improved diagnostic and treatment guidelines for patients in whom total knee arthroplasty (TKA) has had an unsatisfactory outcome. It opens by discussing the basics of TKA and the various causes of failure and pain. Diagnostic aspects are considered in detail, with attention to advances in clinical investigation, laboratory analysis and in particular, imaging techniques. In addition, helpful state of the art diagnostic algorithms are presented. Specific pathology-related treatment options, including conservative approaches and salvage and revision TKA strategies, are then explained, with identification of pitfalls and key points. A series of illustrative cases cover clinical scenarios frequently encountered in daily clinical practice. The evidence-based, clinically focused guidance provided in this book, written by internationally renowned experts, will assist surgeons in achieving the most effective management of these challenging cases.

  • Journal article
    Hunt NC, Ghosh KM, Athwal KK, Longstaff LM, Amis AA, Deehan DJet al., 2014,

    Lack of evidence to support present medial release methods in total knee arthroplasty

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 22, Pages: 3100-3112, ISSN: 0942-2056
  • Journal article
    Halewood C, Risebury M, Thomas NP, Amis AAet al., 2014,

    Kinematic behaviour and soft tissue management in guided motion total knee replacement

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 22, Pages: 3074-3082, ISSN: 0942-2056
  • Conference paper
    Geraldes D, Hansen U, Amis A, 2014,

    A framework for parametric analysis of glenoid implant design

    , MECBioengineering 2014
  • Conference paper
    Sukjamsri C, Geraldes D, Gregory T, Hansen Uet al., 2014,

    Micro computed tomography and digital volume correlation techniques to determine micromotion in cementless arthroplasty

    , World Congress of Biomechanics 2014
  • Journal article
    Geraldes DM, Phillips ATM, 2014,

    A comparative study of orthotropic and isotropic bone adaptation in the femur

    , International Journal for Numerical Methods in Biomedical Engineering, Vol: 30, Pages: 873-889, ISSN: 2040-7947

    Functional adaptation of the femur has been studied extensively by embedding remodelling algorithms in finite element models, with bone commonly assumed to have isotropic material properties for computational efficiency. However, isotropy is insufficient in predicting the directionality of bone's observed microstructure. A novel iterative orthotropic 3D adaptation algorithm is proposed and applied to a finite element model of the whole femur. Bone was modelled as an optimised strain-driven adaptive continuum with local orthotropic symmetry. Each element's material orientations were aligned with the local principal stress directions and their corresponding directional Young's moduli updated proportionally to the associated strain stimuli. The converged predicted density distributions for a coronal section of the whole femur were qualitatively and quantitatively compared with the results obtained by the commonly used isotropic approach to bone adaptation and with ex vivo imaging data. The orthotropic assumption was shown to improve the prediction of bone density distribution when compared with the more commonly used isotropic approach, whilst producing lower comparative mass, structurally optimised models. It was also shown that the orthotropic approach can provide additional directional information on the material properties distributions for the whole femur, an advantage over isotropic bone adaptation. Orthotropic bone models can help in improving research areas in biomechanics where local structure and mechanical properties are of key importance, such as fracture prediction and implant assessment.

  • Conference paper
    Geraldes D, Hansen U, Jeffers J, Amis Aet al., 2014,

    A framework for parametric analysis of glenoid implant design

    , International Society for Technology in Arthroplasty 2014
  • Conference paper
    Halewood C, 2014,

    Pre-clinical stability assessment methods for total knee replacements

    , 2014 ESSKA Congress, Amsterdam
  • Conference paper
    Halewood C, 2014,

    How to do a Proper Biomechanical Study

    , 2014 ESSKA Congress, Amsterdam
  • Book chapter
    Halewood C, Samuelsson K, Kopf S, Alentorn-Geli E, Musahl Vet al., 2014,

    How to do proper research

    , ESSKA Instructional Course Lecture Book Amsterdam 2014, Publisher: Springer, ISBN: 9783642539824

    This book provides an update on a wide variety of hot topics in the field of knee surgery, sports trauma and arthroscopy, covering the latest developments in basic science and clinical and surgical methods.

  • Journal article
    Merican AM, Ghosh KM, Baena FRY, Deehan DJ, Amis AAet al., 2014,

    Patellar thickness and lateral retinacular release affects patellofemoral kinematics in total knee arthroplasty

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 22, Pages: 526-533, ISSN: 0942-2056
  • Journal article
    Stoddard JE, Deehan DJ, Bull AMJ, McCaskie AW, Amis AAet al., 2014,

    No difference in patellar tracking between symmetrical and asymmetrical femoral component designs in TKA

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 22, Pages: 534-542, ISSN: 0942-2056
  • Journal article
    Dodds AL, Halewood C, Gupte CM, Williams A, Amis AAet al., 2014,

    The anterolateral ligament ANATOMY, LENGTH CHANGES AND ASSOCIATION WITH THE SEGOND FRACTURE

    , BONE & JOINT JOURNAL, Vol: 96B, Pages: 325-331, ISSN: 2049-4394
  • Journal article
    Gregory T, Hansen U, Khanna M, Mutchler C, Urien S, Amis AA, Augereau B, Emery Ret al., 2014,

    A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty

    , Acta Orthopaedica, Vol: 85, Pages: 91-96, ISSN: 0001-6470

    Background and purpose It is difficult to evaluate glenoid component periprosthetic radiolucencies in total shoulder arthroplasties (TSAs) using plain radiographs. This study was performed to evaluate whether computed tomography (CT) using a specific patient position in the CT scanner provides a better method for assessing radiolucencies in TSA.Methods Following TSA, 11 patients were CT scanned in a lateral decubitus position with maximum forward flexion, which aligns the glenoid orientation with the axis of the CT scanner. Follow-up CT scanning is part of our routine patient care. Glenoid component periprosthetic lucency was assessed according to the Molé score and it was compared to routine plain radiographs by 5 observers.Results The protocol almost completely eliminated metal artifacts in the CT images and allowed accurate assessment of periprosthetic lucency of the glenoid fixation. Positioning of the patient within the CT scanner as described was possible for all 11 patients. A radiolucent line was identified in 54 of the 55 observed CT scans and osteolysis was identified in 25 observations. The average radiolucent line Molé score was 3.4 (SD 2.7) points with plain radiographs and 9.5 (SD 0.8) points with CT scans(p = 0.001). The mean intra-observer variance was lower in the CT scan group than in the plain radiograph group (p = 0.001).Interpretation The CT scan protocol we used is of clinical value in routine assessment of glenoid periprosthetic lucency after TSA. The technique improves the ability to detect and monitor radiolucent lines and, therefore, possibly implant loosening also.

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