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

425 results found

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

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., 2018, The anterolateral complex of the knee: results from the International ALC Consensus Group Meeting, Knee Surgery, Sports Traumatology, Arthroscopy, 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

Halewood C, Athwal KK, Amis AA, 2018, Pre-clinical assessment of total knee replacement anterior-posterior constraint, JOURNAL OF BIOMECHANICS, Vol: 73, Pages: 153-160, ISSN: 0021-9290

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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

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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

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., Am J Sports Med, Vol: 46, Pages: 2922-2928

BACKGROUND: Anterolateral complex injuries are becoming more recognized. While these are known to affect tibiofemoral mechanics, it is not known how they affect patellofemoral joint behavior. PURPOSE: To determine the effect of (1) sectioning the anterolateral complex and (2) performing a MacIntosh tenodesis under various conditions on patellofemoral contact mechanics and kinematics. STUDY DESIGN: Controlled laboratory study. METHODS: Eight fresh-frozen cadaveric knees were tested in a customized rig, with the femur fixed and tibia free to move, with optical tracking to record patellar kinematics and with thin pressure sensors to record patellofemoral contact pressures at 0°, 30°, 60°, and 90° of knee flexion. The quadriceps and iliotibial tract were loaded with 205 N throughout testing. Intact and anterolateral complex-sectioned states were tested, followed by 4 randomized tenodeses applying 20- and 80-N graft tension, each with the tibia in its neutral intact alignment or left free to rotate. Statistical analyses were undertaken with repeated measures analysis of variance, Bonferroni post hoc analysis, and paired samples t tests. RESULTS: Patellar kinematics and contact pressures were not significantly altered after sectioning of the anterolateral complex (all: P > .05). Similarly, they were not significantly different from the intact knee in tenodeses performed when fixed tibial rotation was combined with 20- or 80-N graft tension (all: P > .05). However, grafts tensioned with 20 N and 80 N while the tibia was free hanging resulted in significant increases in lateral patellar tilt ( P < .05), and significantly elevated lateral peak patellofemoral pressures ( P < .05) were observed for 80 N. CONCLUSION: This work did not find that an anterolateral injury altered patellofemoral mechanics or kinematics, but adding a lateral tenodesis can elevate lateral contact pressures and induce lateral patellar tilting if the tibia is pulled into exte

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

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Kanca Y, Milner P, Dini D, Amis AAet al., 2018, Tribological properties of PVA/PVP blend hydrogels against articular cartilage, JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 78, Pages: 36-45, ISSN: 1751-6161

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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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Kittl C, Inderhaug E, Williams A, Amis AAet al., 2018, Biomechanics of the Anterolateral Structures of the Knee, CLINICS IN SPORTS MEDICINE, Vol: 37, Pages: 21-+, ISSN: 0278-5919

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

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

Marsland D, Stephen JM, Calder T, Amis AA, Calder JDFet al., 2018, Flexor digitorum longus tendon transfer to the navicular: tendon-to-tendon repair is stronger compared with interference screw fixation., Knee Surg Sports Traumatol Arthrosc

PURPOSE: To assess whether early rehabilitation could be safe after flexor digitorum longus (FDL) tendon transfer, the current biomechanical study aimed to measure tendon displacement under cyclic loading and load to failure, comparing a traditional tendon-to-tendon (TT) repair with interference screw fixation (ISF). METHODS: 24 fresh-frozen cadaveric below knee specimens underwent FDL tendon transfer. In 12 specimens a TT repair was performed via a navicular bone tunnel. In a further 12 specimens ISF was performed. Using a materials testing machine, the FDL tendon was cycled 1000 times to 150 N and tendon displacement at the insertion site measured. A final load to failure test was then performed. Statistical analysis was performed using two-way ANOVA and an independent t test, with a significance level of p < 0.05. RESULT: No significant difference in tendon displacement occurred after cyclic loading, with mean tendon displacements of 1.9 ± 1.2 mm (mean ± SD) in the TT group and 1.8 ± 1.5 mm in the ISF group (n.s.). Two early failures occurred in the ISF group, none in the TT group. Mean load to failure was significantly greater following TT repair (459 ± 96 N), compared with ISF (327 ± 76 N), p = 0.002. CONCLUSION: Minimal tendon displacement of less than 2 mm occurred during cyclic testing in both groups. The two premature failures and significantly reduced load to failure observed in the ISF group, however, indicate that the traditional TT technique is more robust. Regarding clinical relevance, this study suggests that early active range of motion and protected weight bearing may be safe following FDL tendon transfer for stage 2 tibialis posterior tendon dysfunction.

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Musahl V, Getgood A, Neyret P, Claes S, Burnham JM, Batailler C, Sonnery-Cottet B, Williams A, Amis A, Zaffagnini S, Karlsson Jet al., 2018, Erratum to: Contributions of the anterolateral complex and the anterolateral ligament to rotatory knee stability in the setting of ACL Injury: a roundtable discussion (Knee Surgery, Sports Traumatology, Arthroscopy, (2017), 25, 4, (997-1008), 10.1007/s00167-017-4436-7), Knee Surgery, Sports Traumatology, Arthroscopy, Vol: 26, ISSN: 0942-2056

© 2016, European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA). In the original article, one of the co-authors’ name has been published incorrectly. The correct name should be Jeremy M. Burnham. The original article has been updated accordingly.

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

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 Surg Sports Traumatol Arthrosc

PURPOSE: The infrapatellar fat pad (IFP) is a common cause of knee pain and loss of knee flexion and extension. However, its anatomy and behavior are not consistently defined. METHODS: Thirty-six unpaired fresh frozen knees (median age 34 years, range 21-68) were dissected, and IFP attachments and volume measured. The rectus femoris was elevated, suprapatellar pouch opened and videos recorded looking inferiorly along the femoral shaft at the IFP as the knee was flexed. The patellar retinacula were incised and the patella reflected distally. The attachment of the ligamentum mucosum (LMuc) to the intercondylar notch was released from the anterior cruciate ligament (ACL), both menisci and to the tibia via meniscotibial ligaments. IFP strands projecting along both sides of the patella were elevated and the IFP dissected from the inferior patellar pole. Magnetic resonance imaging (MRI) of one knee at ten flexion angles was performed and the IFP, patella, tibia and femur segmented. RESULTS: In all specimens the IFP attached to the inferior patellar pole, femoral intercondylar notch (via the LMuc), proximal patellar tendon, intermeniscal ligament, both menisci and the anterior tibia via the meniscotibial ligaments. In 30 specimens the IFP attached to the anterior ACL fibers via the LMuc, and in 29 specimens it attached directly to the central anterior tibia. Proximal IFP extensions were identified alongside the patella in all specimens and visible on MRI [medially (100% of specimens), mean length 56.2 ± 8.9 mm, laterally (83%), mean length 23.9 ± 6.2 mm]. Mean IFP volume was 29.2 ± 6.1 ml. The LMuc, attached near the base of the middle IFP lobe, acting as a 'tether' drawing it superiorly during knee extension. The medial lobe consistently had a pedicle superomedially, positioned between the patella and medial trochlea. MRI scans demonstrated how the space between the anterior tibia and patellar t

JOURNAL ARTICLE

Willmott H, Al-Wattar Z, Halewood C, Dunning M, Amis Aet al., 2018, Evaluation of different shape-memory staple configurations against crossed screws for first metatarsophalangeal joint arthrodesis: A biomechanical study, FOOT AND ANKLE SURGERY, Vol: 24, Pages: 259-263, ISSN: 1268-7731

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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

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Amis A, Zaffagnini S, Musahl V, 2017, The anterolateral aspect of the knee: the state of play., Knee Surg Sports Traumatol Arthrosc, Vol: 25, Pages: 989-990

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

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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

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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

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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

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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

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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

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Geraldes DM, Hansen U, Jeffers J, Amis AAet al., 2017, Stability of small pegs for cementless implant fixation, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 35, Pages: 2765-2772, ISSN: 0736-0266

JOURNAL ARTICLE

Getgood A, LaPrade RF, Verdonk P, Gersoff W, Cole B, Spalding T, Amendola A, Amis A, Bin SI, Bugbee W, Caborn D, Carter T, Chan KM, Cohen C, Cohen M, Condello V, DeBerardino T, Dirisamer F, Engebretsen L, Farr J, Gomoll A, Harner C, Heard M, Hiemstra L, Kim JG, Kim JM, Kim JM, Kon E, Laggae K, Lee BS, Litchfield R, Marcacci M, McCormack R, McDermott I, Monlau JC, Myers P, Noyes F, Patsch C, Robinson J, Rodeo S, Seo SS, Sherman S, Siebold R, Snow M, Stone K, Tashman S, Thompson P, Van Arkel E, Van Der Merwe W, Verdonk R, Williams A, Zaffagnini Set al., 2017, International Meniscus Reconstruction Experts Forum (IMREF) 2015 Consensus Statement on the Practice of Meniscal Allograft Transplantation, American Journal of Sports Medicine, Vol: 45, Pages: 1195-1205, ISSN: 0363-5465

© 2017 The Author(s). Meniscal allograft transplantation (MAT) has become relatively commonplace in specialized sport medicine practice for the treatment of patients with a symptomatic knee after the loss of a functional meniscus. The technique has evolved since the 1980s, and long-term results continue to improve. However, there still remains significant variation in how MAT is performed, and as such, there remains opportunity for outcome and graft survivorship to be optimized. The purpose of this article was to develop a consensus statement on the practice of MAT from key opinion leaders who are members of the International Meniscus Reconstruction Experts Forum so that a more standardized approach to the indications, surgical technique, and postoperative care could be outlined with the goal of ultimately improving patient outcomes.

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, AMERICAN JOURNAL OF SPORTS MEDICINE, Vol: 45, Pages: 3081-3088, ISSN: 0363-5465

JOURNAL ARTICLE

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