Imperial College London

ProfessorAndrewAmis

Faculty of EngineeringDepartment of Mechanical Engineering

Professor
 
 
 
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Contact

 

+44 (0)20 7594 7062a.amis

 
 
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Assistant

 

Ms Fabienne Laperche +44 (0)20 7594 7033

 
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Location

 

713City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

344 results found

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

Amirthanayagam TD, Amis AA, Reilly P, Emery RJHet al., 2017, Rotator cuff-sparing approaches for glenohumeral joint access: an anatomic feasibility study, JOURNAL OF SHOULDER AND ELBOW SURGERY, Vol: 26, Pages: 512-520, ISSN: 1058-2746

JOURNAL ARTICLE

Amis AA, 2017, Anterolateral knee biomechanics, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 25, Pages: 1015-1023, ISSN: 0942-2056

JOURNAL ARTICLE

Athwal KK, El Daou H, Inderhaug E, Manning W, Davies AJ, Deehan DJ, Amis AAet al., 2017, An in vitro analysis of medial structures and a medial soft tissue reconstruction in a constrained condylar total knee arthroplasty, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 25, Pages: 2646-2655, ISSN: 0942-2056

JOURNAL ARTICLE

Athwal KK, El Daou H, Inderhaug E, Manning W, Davies AJ, Deehan DJ, Amis AAet al., 2017, An in vitro analysis of medial structures and a medial soft tissue reconstruction in a constrained condylar total knee arthroplasty (vol 25, pg 2646, 2016), KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 25, Pages: 2656-2656, ISSN: 0942-2056

JOURNAL ARTICLE

Athwal KK, El Daou H, Lord B, Davies AJ, Manning W, Rodriguez y Baena F, Deehan DJ, Amis AAet al., 2017, Lateral soft-tissue structures contribute to cruciate-retaining total knee arthroplasty stability, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 35, Pages: 1902-1909, ISSN: 0736-0266

JOURNAL ARTICLE

Cheong VS, Karunaratne A, Amis AA, Bull AMJet al., 2017, Strain rate dependency of fractures of immature bone, JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 66, Pages: 68-76, ISSN: 1751-6161

JOURNAL ARTICLE

Colaco HB, Lord BR, Back DL, Davies AJ, Amis AA, Ajuied Aet al., 2017, Biomechanical properties of bovine tendon xenografts treated with a modern processing method, JOURNAL OF BIOMECHANICS, Vol: 53, Pages: 144-147, ISSN: 0021-9290

JOURNAL ARTICLE

El Daou H, Lord B, Amis A, Rodriguez y Baena Fet al., 2017, Assessment of pose repeatability and specimen repositioning of a robotic joint testing platform, MEDICAL ENGINEERING & PHYSICS, Vol: 47, Pages: 210-213, ISSN: 1350-4533

JOURNAL ARTICLE

Geraldes DM, Hansen U, Amis AA, 2017, Parametric Analysis of Glenoid Implant Design and Fixation Type, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 35, Pages: 775-784, ISSN: 0736-0266

JOURNAL ARTICLE

Geraldes DM, Hansen U, Jeffers J, Amis AAet al., 2017, Stability of small pegs for cementless implant fixation., J Orthop Res

Most glenoid implants rely on large centrally located fixation features to avoid perforation of the glenoid vault in its peripheral regions. Upon revision of such components there may not be enough bone left for the reinsertion of an anatomical prosthesis. Multiple press-fit small pegs would allow for less bone resection and strong anchoring in the stiffer and denser peripheral subchondral bone. This study assessed the fixation characteristics, measured as the push-in (Pin ) and pull-out (Pout ) forces, and spring-back, measured as the elastic displacement immediately after insertion, for five different small press-fitted peg configurations manufactured out of UHMWPE cylinders (5 mm diameter and length). A total of 16 specimens for each configuration were tested in two types of solid bone substitute: Hard (40 PCF, 0.64 g/cm(3) , worst-case scenario of Pin ) and soft (15 PCF, 0.24 g/cm(3) , worst-case scenario of spring-back and Pout ). Two different diametric interference-fits were studied. Geometries with lower stiffness fins (large length to width aspect ratio) were the best performing designs in terms of primary fixation stability. They required the lowest force to fully seat, meaning they are less damaging to the bone during implantation, while providing the highest Pout /Pin ratio, indicating that when implanted they provide the strongest anchoring for the glenoid component. It is highlighted that drilling of chamfered holes could minimize spring-back displacements. These findings are relevant for the design of implants press-fitted pegs because primary fixation has been shown to be an important factor in achieving osseointegration and longevity of secondary fixation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

JOURNAL ARTICLE

Inderhaug E, Stephen JM, El-Daou H, Williams A, Amis AAet al., 2017, The Effects of Anterolateral Tenodesis on Tibiofemoral Contact Pressures and Kinematics., Am J Sports Med

BACKGROUND: Anterolateral tenodeses are increasingly popular in combination with intra-articular anterior cruciate ligament reconstructions. Despite the perception of risk of overconstraint and lateral osteoarthritis, evidence is lacking regarding the effect of graft tensioning on knee kinematics and intra-articular compartmental joint pressures. PURPOSE: To investigate tibiofemoral joint contact pressures and kinematics related to an anterolateral lesion and the effectiveness of a MacIntosh tenodesis in restoring these when varying (1) graft tension and (2) tibial rotation during graft fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Eight fresh-frozen cadaveric knees were tested in a customized rig with femur fixed and tibia free to move from 0° to 90° of flexion. The quadriceps and iliotibial band were loaded by means of a weighted pulley system. At 30° intervals of knee flexion, tibiofemoral contact pressures were measured with a Tekscan sensor and tibiofemoral kinematics were recorded by use of an optical tracking system. The knee was tested intact and then with an anterolateral soft tissue transection. MacIntosh tenodeses were then tested in a randomized order with 20 N or 80 N of graft tension, each with the tibia held in neutral intact alignment or free to rotate. RESULTS: Tibial anterior translation and internal rotation were significantly increased and lateral contact pressures significantly reduced compared with the intact knee following anterolateral soft tissue cutting ( P < .05). Contact pressures were restored with fixed neutral tibial rotation combined with 20 N or 80 N of graft tension or by a free-hanging tibia with 20 N of graft tension (all P values > .5). Grafts tensioned with 80 N caused significant overconstraint both when the tibia was fixed and free hanging (all P values < .05). Increases in the lateral tibiofemoral contact pressures were also seen when the tibia was free hanging and 80 N was used for graft

JOURNAL ARTICLE

Inderhaug E, Stephen JM, Williams A, Amis AAet al., 2017, Biomechanical Comparison of Anterolateral Procedures Combined With Anterior Cruciate Ligament Reconstruction, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 45, Pages: 347-354, ISSN: 0363-5465

JOURNAL ARTICLE

Iranpour F, Merican AM, Teo SH, Cobb JP, Amis AAet al., 2017, Femoral articular geometry and patellofemoral stability, KNEE, Vol: 24, Pages: 555-563, ISSN: 0968-0160

JOURNAL ARTICLE

Junaid S, Sanghavi S, Anglin C, Bull A, Emery R, Amis AA, Hansen Uet al., 2017, Treatment of the Fixation Surface Improves Glenoid Prosthesis Longevity in vitro., J Biomech, Vol: 61, Pages: 81-87

Many commercial cemented glenoid components claim superior fixation designs and increased survivability. However, both research and clinical studies have shown conflicting results and it is unclear whether these design variations do improve loosening rates. Part of the difficulty in investigating fixation failure is the inability to directly observe the fixation interface, a problem addressed in this study by using a novel experimental set-up. Cyclic loading-displacement tests were carried out on 60 custom-made glenoid prostheses implanted into a bone substitute. Design parameters investigated included treatment of the fixation surface of the component resulting in different levels of back-surface roughness, flat-back versus curved-back, keel versus peg and more versus less conforming implants. Visually-observed failure and ASTM-recommended rim-displacements were recorded throughout testing to investigate fixation failure and if rim displacement is an appropriate measure of loosening. Roughening the implant back (Ra>3µm) improved resistance to failure (P<0.005) by an order of magnitude with the rough and smooth groups failing at 8712±5584 cycles (mean±SD) and 1080±1197 cycles, respectively. All other design parameters had no statistically significant effect on the number of cycles to failure. All implants failed inferiorly and 95% (57/60) at the implant/cement interface. Rim-displacement correlated with visually observed failure. The most important effect was that of roughening the implant, which strengthened the polyethylene-cement interface. Rim-displacement can be used as an indicator of fixation failure, but the sensitivity was insufficient to capture subtle effects. LEVEL OF EVIDENCE: Basic Science Study, Biomechanical Analysis.

JOURNAL ARTICLE

Li J, Clarke S, Cobb JP, Amis AAet al., 2017, Novel curved surface preparation technique for knee resurfacing., Med Eng Phys

Conventional tools are incapable of preparing the curved articular surface geometry required during cartilage repair procedures. A novel curved surface preparation technique was proposed and tested to provide an accurate low-cost solution. Three shapes of samples, with flat, 30 mm radius and 60 mm radius surfaces, were manufactured from foam bone substitute for testing. Registering guides and cutting guides were designed and 3-D printed to fit onto the foam samples. A rotational cutting tool with an adapter was used to prepare the surfaces following the guidance slots in the cutting guides. The accuracies of the positions and shapes of the prepared cavities were measured using a digital calliper, and the surface depth accuracy was measured using a 3-D scanner. The mean shape and position errors were both approximately ± 0.5 mm and the mean surface depth error ranged from 0 to 0.3 mm, range - 0.3 to + 0.45 mm 95% CI. This study showed that the technique was able to prepare a curved surface accurately; with some modification it can be used to prepare the knee surface for cartilage repair.

JOURNAL ARTICLE

Lord BR, El-Daou H, Sabnis BM, Gupte CM, Wilson AJ, Amis AAet al., 2017, Biomechanical comparison of graft structures in anterior cruciate ligament reconstruction (vol 25, pg 559, 2017), KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 25, Pages: 988-988, ISSN: 0942-2056

JOURNAL ARTICLE

Lord BR, El-Daou H, Sabnis BM, Gupte CM, Wilson AM, Amis AAet al., 2017, Biomechanical comparison of graft structures in anterior cruciate ligament reconstruction, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 25, Pages: 559-568, ISSN: 0942-2056

JOURNAL ARTICLE

Sopher RS, Amis AA, Calder JD, Jeffers JRTet al., 2017, Total ankle replacement design and positioning affect implant-bone micromotion and bone strains, MEDICAL ENGINEERING & PHYSICS, Vol: 42, Pages: 80-90, ISSN: 1350-4533

JOURNAL ARTICLE

Sopher RS, Amis AA, Davies DC, Jeffers JRTet al., 2017, The influence of muscle pennation angle and cross-sectional area on contact forces in the ankle joint, JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN, Vol: 52, Pages: 12-23, ISSN: 0309-3247

JOURNAL ARTICLE

van Arkel RJ, Jeffers JRT, Amis AA, 2017, Editorial Commentary: Anatomical Vandalism of the Hip? Hip Capsular Repair Seems a Sound Adjunct to Hip Arthroscopic Surgery, ARTHROSCOPY-THE JOURNAL OF ARTHROSCOPIC AND RELATED SURGERY, Vol: 33, Pages: 314-316, ISSN: 0749-8063

JOURNAL ARTICLE

Athwal KK, El Daou H, Kittl C, Davies AJ, Deehan DJ, Amis AAet al., 2016, The superficial medial collateral ligament is the primary medial restraint to knee laxity after cruciate-retaining or posterior-stabilised total knee arthroplasty: effects of implant type and partial release, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 24, Pages: 2646-2655, ISSN: 0942-2056

JOURNAL ARTICLE

Chong DYR, Hansen UN, Amis AA, 2016, CEMENTLESS MIS MINI-KEEL PROSTHESIS REDUCES INTERFACE MICROMOTION VERSUS STANDARD STEMMED TIBIAL COMPONENTS, JOURNAL OF MECHANICS IN MEDICINE AND BIOLOGY, Vol: 16, ISSN: 0219-5194

JOURNAL ARTICLE

Geraldes D, Hansen U, Jeffers J, Amis Aet al., 2016, Interference fit optimisation for small press-fitted pegs, International Society for Technology in Arthroplasty 2015, Publisher: BRITISH EDITORIAL SOCIETY OF BONE & JOINT SURGERY, Pages: 150-150, ISSN: 2049-4416

CONFERENCE PAPER

Ghosh KM, Manning WA, Blain AP, Rushton SP, Longstaff LM, Amis AA, Deehan DJet al., 2016, Influence of increasing construct constraint in the presence of posterolateral deficiency at knee replacement: A biomechanical study, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 34, Pages: 427-434, ISSN: 0736-0266

JOURNAL ARTICLE

Kittl C, El-Daou H, Athwal KK, Gupte CM, Weiler A, Williams A, Amis AAet al., 2016, The Role of the Anterolateral Structures and the ACL in Controlling Laxity of the Intact and ACL-Deficient Knee, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 44, Pages: 345-354, ISSN: 0363-5465

JOURNAL ARTICLE

Kittl C, El-Daou H, Athwal KK, Gupte CM, Weiler A, Williams A, Amis AAet al., 2016, The Role of the Anterolateral Structures and the ACL in Controlling Laxity of the Intact and ACL-Deficient Knee: Response, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 44, Pages: NP15-NP18, ISSN: 0363-5465

JOURNAL ARTICLE

Stephen JM, Halewood C, Kittl C, Bollen SR, Williams A, Amis AAet al., 2016, Posteromedial Meniscocapsular Lesions Increase Tibiofemoral Joint Laxity With Anterior Cruciate Ligament Deficiency, and Their Repair Reduces Laxity, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 44, Pages: 400-408, ISSN: 0363-5465

JOURNAL ARTICLE

Stephen JM, Kittl C, Williams A, Zaffagnini S, Muccioli GMM, Fink C, Amis AAet al., 2016, Effect of Medial Patellofemoral Ligament Reconstruction Method on Patellofemoral Contact Pressures and Kinematics, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 44, Pages: 1186-1194, ISSN: 0363-5465

JOURNAL ARTICLE

Barcellona MG, Morrissey MC, Milligan P, Clinton M, Amis AAet al., 2015, The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 23, Pages: 3168-3177, ISSN: 0942-2056

JOURNAL ARTICLE

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