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  • JOURNAL ARTICLE
    Ghouse S, Reznikov N, Boughton OR, Babu S, Ng KCG, Blunn G, Cobb JP, Stevens MM, Jeffers JRTet al., 2019,

    The design and in vivo testing of a locally stiffness-matched porous scaffold

    , Applied Materials Today, Vol: 15, Pages: 377-388

    © 2019 The Authors An increasing volume of work supports utilising the mechanobiology of bone for bone ingrowth into a porous scaffold. However, typically during in vivo testing of implants, the mechanical properties of the bone being replaced are not quantified. Consequently there remains inconsistencies in the literature regarding ‘optimum’ pore size and porosity for bone ingrowth. It is also difficult to compare ingrowth results between studies and to translate in vivo animal testing to human subjects without understanding the mechanical environment. This study presents a clinically applicable approach to determining local bone mechanical properties and design of a scaffold with similar properties. The performance of the scaffold was investigated in vivo in an ovine model. The density, modulus and strength of trabecular bone from the medial femoral condyle from ovine bones was characterised and power-law relationships were established. A porous titanium scaffold, intended to maintain bone mechanical homeostasis, was additively manufactured and implanted into the medial femoral condyle of 6 ewes. The stiffness of the scaffold varied throughout the heterogeneous structure and matched the stiffness variation of bone at the surgical site. Bone ingrowth into the scaffold was 10.73 ± 2.97% after 6 weeks. Fine woven bone, in the interior of the scaffold, and intense formations of more developed woven bone overlaid with lamellar bone at the implant periphery were observed. The workflow presented will allow future in vivo testing to test specific bone strains on bone ingrowth in response to a scaffold and allow for better translation from in vivo testing to commercial implants.

  • JOURNAL ARTICLE
    Logishetty K, van Arkel R, Ng KC, Muirhead-Allwood S, Cobb J, Jeffers Jet al., 2019,

    Hip capsule biomechanics after arthroplasty - the effect of implant, approach and surgical repair

    , Bone and Joint Journal, ISSN: 2049-4394
  • JOURNAL ARTICLE
    Ng KCG, Daou HE, Bankes MJK, Rodriguez y Baena F, Jeffers JRTet al., 2019,

    Hip Joint Torsional Loading Before and After Cam Femoroacetabular Impingement Surgery

    , AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 47, Pages: 420-430, ISSN: 0363-5465
  • JOURNAL ARTICLE
    Reznikov N, Boughton OR, Ghouse S, Weston AE, Collinson L, Blunn GW, Jeffers JRT, Cobb JP, Stevens MMet al., 2019,

    Individual response variations in scaffold-guided bone regeneration are determined by independent strain- and injury-induced mechanisms

    , BIOMATERIALS, Vol: 194, Pages: 183-194, ISSN: 0142-9612
  • JOURNAL ARTICLE
    Getgood A, Brown C, Lording T, Amis A, Claes S, Geeslin A, Musahl V, Amis A, Brown C, Cavaignac E, Claes S, Daggett M, Dejour D, Engebretsen L, Feng H, Fleming B, Fu F, Geeslin A, Getgood A, Guenther D, Helito CP, Herbst E, Inderhaug E, Karlsson J, Kittl C, Kuroda R, LaPrade R, Landreau P, Lording T, Mueller W, Musahl V, Neyret P, Noyes F, Pearle A, Saithna A, Smigielski R, Sonnery-Cottet B, Spalding T, Van Dyck P, Verdonk P, Williams A, Wilson A, Zaffagnini Set al., 2019,

    The anterolateral complex of the knee: results from the International ALC Consensus Group Meeting

    , Knee Surgery, Sports Traumatology, Arthroscopy, Vol: 27, Pages: 166-176, ISSN: 0942-2056

    © 2018, European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA). The structure and function of the anterolateral complex (ALC) of the knee has created much controversy since the ‘re-discovery’ of the anterolateral ligament (ALL) and its proposed role in aiding control of anterolateral rotatory laxity in the anterior cruciate ligament (ACL) injured knee. A group of surgeons and researchers prominent in the field gathered to produce consensus as to the anatomy and biomechanical properties of the ALC. The evidence for and against utilisation of ALC reconstruction was also discussed, generating a number of consensus statements by following a modified Delphi process. Key points include that the ALC consists of the superficial and deep aspects of the iliotibial tract with its Kaplan fibre attachments on the distal femur, along with the ALL, a capsular structure within the anterolateral capsule. A number of structures attach to the area of the Segond fracture including the capsule-osseous layer of the iliotibial band, the ALL and the anterior arm of the short head of biceps, and hence it is not clear which is responsible for this lesion. The ALC functions to provide anterolateral rotatory stability as a secondary stabiliser to the ACL. Whilst biomechanical studies have shown that these structures play an important role in controlling stability at the time of ACL reconstruction, the optimal surgical procedure has not yet been defined clinically. Concern remains that these procedures may cause constraint of motion, yet no clinical studies have demonstrated an increased risk of osteoarthritis development. Furthermore, clinical evidence is currently lacking to support clear indications for lateral extra-articular procedures as an augmentation to ACL reconstruction. The resulting statements and scientific rationale aim to inform readers on the most current thinking and identify areas of needed basic science and clinical research to help impro

  • JOURNAL ARTICLE
    Doyle R, Boughton O, Plant D, Desoutter G, Cobb JP, Jeffers JRTet al., 2019,

    An in vitro model of impaction during hip arthroplasty

    , JOURNAL OF BIOMECHANICS, Vol: 82, Pages: 220-227, ISSN: 0021-9290
  • JOURNAL ARTICLE
    El Daou H, Ng KCG, Van Arkel R, Jeffers JRT, Rodriguez Y Baena Fet al., 2019,

    Robotic hip joint testing: Development and experimental protocols.

    , Med Eng Phys, Vol: 63, Pages: 57-62

    The use of robotic systems combined with force sensing is emerging as the gold standard for in vitro biomechanical joint testing, due to the advantage of controlling all six degrees of freedom independently of one another. This paper describes a novel robotic platform and the experimental protocol used for hip joint testing. An experimental protocol implemented optical tracking and registration techniques in order to define the position of the hip joint centre of rotation (COR) in the coordinate system of the robot's end effector. The COR coordinates defined the origin of the task-related coordinate system used to control the robot, with a hybrid force/position law to simulate standard clinical tests. The axes of this frame were defined using the International Society of Biomechanics (ISB) anatomical coordinate system. Experiments were carried out on two cadaveric hip joint specimens using the robotic testing platform and a mechanical testing rig previously developed and described by our group. Simulated internal-external and adduction/abduction laxity tests were carried out with both systems and the resulting peak range of motion (ROM) was measured. Similarities and differences were observed in these experiments, which were used to highlight some of the limitations of conventional systems and the corresponding advantages of robotics, further emphasising their added value in vitro testing.

  • JOURNAL ARTICLE
    Correa TA, Pal B, van Arkel RJ, Vanacore F, Amis AAet al., 2018,

    Reduced tibial strain-shielding with extraosseous total knee arthroplasty revision system

    , MEDICAL ENGINEERING & PHYSICS, Vol: 62, Pages: 22-28, ISSN: 1350-4533
  • JOURNAL ARTICLE
    Stephen JM, Sopher R, Tullie S, Amis AA, Ball S, Williams Aet al., 2018,

    The infrapatellar fat pad is a dynamic and mobile structure, which deforms during knee motion, and has proximal extensions which wrap around the patella

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 26, Pages: 3515-3524, ISSN: 0942-2056
  • JOURNAL ARTICLE
    Inderhaug E, Stephen JM, Williams A, Amis AAet al., 2018,

    Effect of Anterolateral Complex Sectioning and Tenodesis on Patellar Kinematics and Patellofemoral Joint Contact Pressures

    , AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 46, Pages: 2922-2928, ISSN: 0363-5465
  • JOURNAL ARTICLE
    Hoogeslag RAG, Brouwer RW, in't Veld RH, Stephen JM, Amis AAet al., 2018,

    Dynamic augmentation restores anterior tibial translation in ACL suture repair: a biomechanical comparison of non-, static and dynamic augmentation techniques

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 26, Pages: 2986-2996, ISSN: 0942-2056
  • JOURNAL ARTICLE
    Stephen J, Alva A, Lumpaopong P, Williams A, Amis AAet al., 2018,

    A cadaveric model to evaluate the effect of unloading the medial quadriceps on patellar tracking and patellofemoral joint pressure and stability.

    , J Exp Orthop, Vol: 5, ISSN: 2197-1153

    BACKGROUND: Vastus Medialis Muscles (VMM) damage has been widely identified following patellar dislocation. Rehabilitation programmes have been suggested to strengthen the VMM and reduce clinical symptoms of pain and instability. This controlled laboratory study investigated the hypothesis that reduced Vastus Medialis Obliquus (VMO) and Vastus Medialis Longus (VML) muscle tension would alter patellar tracking, stability and PFJ contact pressures. METHODS: Nine fresh-frozen dissected cadaveric knees were mounted in a rig with the quadriceps and iliotibial band loaded to 205 N. An optical tracking system measured joint kinematics and pressure sensitive film between the patella and trochlea measured PFJ contact pressures. Measurements were repeated for three conditions: 1. With all quadriceps heads and iliotibial band (ITB) loaded; 2. as 1, but with the VMO muscle unloaded and 3. as 1, but with the VMO and VML unloaded. Measurements were also repeated for the three conditions with a 10 N lateral displacement force applied to the patella. RESULTS: Reduction of VMM tension resulted in significant increases in lateral patellar tilt (2.8°) and translation (4 mm), with elevated lateral and reduced medial joint contact pressures from 0.48 to 0.14 MPa, and reduced patellar stability (all p < 0.05). CONCLUSIONS: These findings provide basic scientific rationale to support the role of quadriceps strengthening to resist patellar lateral maltracking and rebalance the articular contact pressure away from the lateral facet in patients with normal patellofemoral joint anatomy.

  • JOURNAL ARTICLE
    Junaid S, Gregory T, Fetherston S, Emery R, Amis AA, Hansen Uet al., 2018,

    Cadaveric study validating in vitro monitoring techniques to measure the failure mechanism of glenoid implants against clinical CT

    , JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 36, Pages: 2524-2532, ISSN: 0736-0266
  • JOURNAL ARTICLE
    Athwal KK, Milner PE, Bellier G, Amis AAet al., 2018,

    Posterior capsular release is a biomechanically safe procedure to perform in total knee arthroplasty.

    , Knee Surg Sports Traumatol Arthrosc

    PURPOSE: Surgeons may attempt to strip the posterior capsule from its femoral attachment to overcome flexion contracture in total knee arthroplasty (TKA); however, it is unclear if this impacts anterior-posterior (AP) laxity of the implanted knee. The aim of the study was to investigate the effect of posterior capsular release on AP laxity in TKA, and compare this to the restraint from the posterior cruciate ligament (PCL). METHODS: Eight cadaveric knees were mounted in a six degree of freedom testing rig and tested at 0°, 30°, 60° and 90° flexion with ± 150 N AP force, with and without a 710 N axial compressive load. After the native knee was tested, a deep dished cruciate-retaining TKA was implanted and the tests were repeated. The PCL was then cut, followed by releasing the posterior capsule using a curved osteotome. RESULTS: With 0 N axial load applied, cutting the PCL as well as releasing the posterior capsule significantly increased posterior laxity compared to the native knee at all flexion angles, and CR TKA states at 30°, 60° and 90° (p < 0.05). However, no significant increase in laxity was found between cutting the PCL and subsequent PostCap release (n.s.). In anterior drawer, there was a significant increase of 1.4 mm between cutting the PCL and PostCap release at 0°, but not at any other flexion angles (p = 0.021). When a 710 N axial load was applied, there was no significant difference in anterior or posterior translation across the different knee states (n.s.). CONCLUSIONS: Posterior capsular release only caused a small change in AP laxity compared to cutting the PCL and, therefore, may not be considered detrimental to overall AP stability if performed during TKA surgery. LEVEL OF EVIDENCE: Controlled laboratory study.

  • JOURNAL ARTICLE
    Heilpern G, Stephen J, Ball S, Amis A, Williams Aet al., 2018,

    It is safe and effective to use all inside meniscal repair devices for posteromedial meniscal 'ramp' lesions

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 26, Pages: 2310-2316, ISSN: 0942-2056
  • JOURNAL ARTICLE
    Ghouse S, Babu S, Nai K, Hooper PA, Jeffers JRTet al., 2018,

    The influence of laser parameters, scanning strategies and material on the fatigue strength of a stochastic porous structure

    , ADDITIVE MANUFACTURING, Vol: 22, Pages: 290-301, ISSN: 2214-8604
  • JOURNAL ARTICLE
    Lord BR, Colaco HB, Gupte CM, Wilson AJ, Amis AAet al., 2018,

    ACL graft compression: a method to allow reduced tunnel sizes in ACL reconstruction

    , KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 26, Pages: 2430-2437, ISSN: 0942-2056
  • JOURNAL ARTICLE
    van Arkel RJ, Ng KCG, Muirhead-Allwood SK, Jeffers JRTet al., 2018,

    Capsular Ligament Function After Total Hip Arthroplasty

    , JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME, Vol: 100, ISSN: 0021-9355
  • JOURNAL ARTICLE
    Marsland D, Stephen JM, Calder T, Amis AA, Calder JDFet al., 2018,

    Strength of Interference Screw Fixation to Cuboid vs Pulvertaft Weave to Peroneus Brevis for Tibialis Posterior Tendon Transfer for Foot Drop

    , FOOT & ANKLE INTERNATIONAL, Vol: 39, Pages: 858-864, ISSN: 1071-1007
  • JOURNAL ARTICLE
    Kanca Y, Milner P, Dini D, Amis AAet al., 2018,

    Tribological evaluation of biomedical polycarbonate urethanes against articular cartilage

    , JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 82, Pages: 394-402, ISSN: 1751-6161

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