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  • Journal article
    Berwin JT, Burton TMW, Taylor J, McGregor AH, Roche Aet al., 2015,

    Plantar Loading Forces While Walking in a Below-Knee Cast With an Attached Loadbearing Frame

    , Foot & Ankle International, Vol: 36, Pages: 722-729, ISSN: 1944-7876

    Background: We measured loading forces across different points of the plantar foot surface to examine how different types of casts affect load distribution through the foot and ankle. The patella tendon-bearing (PTB) or Sarmiento cast is the current “gold-standard” casting method for offloading force through the foot and ankle. We aimed to determine if a rocker bottom frame attached to a below-knee cast (Beagle Böhler Walker) would be as effective or better at reducing load distribution during full weightbearing.Method: We applied TekScan FlexiForce A201 force sensors to the first and fifth metatarsal heads and the plantar surface of the calcaneus of 14 healthy volunteers. All volunteers had force measurements taken without a cast applied and then with a traditional Sarmiento cast, a standard below-knee cast, and a below-knee cast with the Böhler Walker frame fitted.Results: Compared with a standard below-knee cast, the Böhler Walker frame reduced the mean peak force through the head of the first metatarsal by 58.9% (P < .0001), 73.1% through the head of the fifth metatarsal (P < .0001), and 32.2% (P < .0001) through the calcaneus. The Sarmiento cast demonstrated a mean percentage reduction in peak force of 8.6% (P = .39) and 4.4% (P = .87) through the first and fifth metatarsal heads, respectively, but increased the mean peak force by 5.9% (P = .54) through the calcaneus.Conclusion: Using a Böhler Walker frame applied to a below-knee cast significantly reduced weight transfer through the foot compared with a Sarmiento cast or standard below-knee cast.Clinical Relevance: This reduction in force through the foot could mean early weightbearing would be safer in patients with a wide variety of foot and ankle pathologies such as ankle fractures or operative fixations. This may reduce the incidence of immobility-dependent morbidity.

  • Journal article
    Ghosh KM, Hunt N, Blain A, Athwal KK, Longstaff L, Amis AA, Rushton S, Deehan DJet al., 2015,

    Isolated popliteus tendon injury does not lead to abnormal laxity in posterior-stabilised total knee arthroplasty

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 23, Pages: 1763-1769, ISSN: 0942-2056
  • Book chapter
    Halewood C, Masouros S, Amis AA, 2015,

    Structure and function of the menisci

    , Meniscal Allograft Transplantation. A comprehensive review., Editors: Getgood, Spalding, Cole, Gersoff, Verdonk, ISBN: 978-0-9558873-5-2
  • Book chapter
    Halewood C, Lumpaopong P, Stephen JM, Amis AAet al., 2015,

    Functional Biomechanics with Cadaver Specimens

    , Experimental Research Methods in Orthopedics and Trauma, Editors: Simpson, Augat, Publisher: Thieme Medical Publishers, ISBN: 9783131731111

    This book provides a comprehensive summary of all current research methodologies for translational and pre-clinical studies in biomechanics and orthopedic trauma surgery.

  • Journal article
    Halewood C, Amis AA, 2015,

    Clinically relevant biomechanics of the knee capsule and ligaments

    , Knee Surgery, Sports Traumatology, Arthroscopy, Vol: 23, Pages: 2789-2796, ISSN: 0942-2056

    The paper describes the concepts of primary and secondary restraints to knee joint stability and explains systematically how the tibia is stabilised against translational forces and rotational torques in different directions and axes, and how those vary across the arc of flexion–extension. It also shows how the menisci act to stabilise the knee, in addition to load carrying across the joint. It compares the properties of the natural stabilising structures with the strength and stiffness of autogenous tissue grafts and relates those strengths to the strength of graft fixation devices. A good understanding of the biomechanical behaviour of these various structures in the knee will help the surgeon in the assessment and treatment of single and multi-ligament injuries.

  • Journal article
    Kwasnicki RM, Ali R, Jordan SJ, Atallah L, Leong JJH, Jones GG, Cobb J, Yang GZ, Darzi Aet al., 2015,

    A wearable mobility assessment device for total knee replacement: A longitudinal feasibility study

    , International Journal of Surgery, Vol: 18, Pages: 14-20, ISSN: 1743-9191

    BackgroundTotal knee replacement currently lacks robust indications and objective follow-up metrics. Patients and healthcare staff are under-equipped to optimise outcomes. This study aims to investigate the feasibility of using an ear-worn motion sensor (e-AR, Imperial College London) to conduct objective, home-based mobility assessments in the peri-operative setting.MethodsFourteen patients on the waiting list for knee replacement, and 15 healthy subjects, were recruited. Pre-operatively, and at 1, 3, 6, 12 and 24 weeks post-operatively, patients underwent functional mobility testing (Timed Up and Go), knee examination (including range of motion), and an activity protocol whilst wearing the e-AR sensor. Features extracted from sensor motion data were used to assess patient performance and predict patients' recovery phase.ResultsSensor-derived peri-operative mobility trends correlated with clinical measures in several activities, allowing functional recovery of individual subjects to be profiled and compared, including the detection of a complication. Sensor data features enabled classification of subjects into normal, pre-operative and 24-week post-operative groups with 89% (median) accuracy. Classification accuracy was reduced to 69% when including all time intervals.DiscussionThis study demonstrates a novel, objective method of assessing peri-operative mobility, which could be used to supplement surgical decision-making and facilitate community-based follow-up.

  • Journal article
    van Arkel RJ, Amis AA, Cobb JP, Jeffers JRTet al., 2015,

    The capsular ligaments provide more hip rotational restraint than the acetabular labrum and the ligamentum teres

    , Bone & Joint Journal, Vol: 97B, Pages: 484-491, ISSN: 2049-4394

    In this in vitro study of the hip joint we examined which soft tissues act as primary and secondary passive rotational restraints when the hip joint is functionally loaded. A total of nine cadaveric left hips were mounted in a testing rig that allowed the application of forces, torques and rotations in all six degrees of freedom. The hip was rotated throughout a complete range of movement (ROM) and the contributions of the iliofemoral (medial and lateral arms), pubofemoral and ischiofemoral ligaments and the ligamentum teres to rotational restraint was determined by resecting a ligament and measuring the reduced torque required to achieve the same angular position as before resection. The contribution from the acetabular labrum was also measured. Each of the capsular ligaments acted as the primary hip rotation restraint somewhere within the complete ROM, and the ligamentum teres acted as a secondary restraint in high flexion, adduction and external rotation. The iliofemoral lateral arm and the ischiofemoral ligaments were primary restraints in two-thirds of the positions tested. Appreciation of the importance of these structures in preventing excessive hip rotation and subsequent impingement/instability may be relevant for surgeons undertaking both hip joint preserving surgery and hip arthroplasty.

  • 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
  • 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


    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
    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.

  • Conference paper
    Spulber I, Chen Y-M, Papi E, Anastasova-Ivanova S, Bergmann J, McGregor AH, Georgiou Pet al., 2015,

    Live demonstration: Wearable electronics for a smart garment aiding rehabilitation

    , Pages: 1912-1912
  • 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
  • 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
    Nigam C, Masjedi M, Houston J, Marquardt C, Aqil A, Cobb Jet al., 2014,

    Does cam osteochondroplasty compromise proximal femur strength?

  • Journal article
    Wilson F, McGregor A, 2014,

    Mythbusters in rowing medicine and physiotherapy: nine experts tackle five clinical conundrums

    , British Journal of Sports Medicine, Vol: 48, Pages: 1525-1528, ISSN: 0306-3674
  • Journal article
    Wilson F, Gissane C, McGregor A, 2014,

    Ergometer training volume and previous injury predict back pain in rowing; strategies for injury prevention and rehabilitation

    , BRITISH JOURNAL OF SPORTS MEDICINE, Vol: 48, Pages: 1534-U27, ISSN: 0306-3674
  • Conference paper
    Geraldes D, Hansen U, Amis A, 2014,

    A framework for parametric analysis of glenoid implant design

    , MECBioengineering 2014
  • Journal article
    Cobb JP, 2014,

    Patient safety after partial and total knee replacement

    , The Lancet, Vol: 384, Pages: 1405-1407, ISSN: 0140-6736

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