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Journal articleChoudhury A, Lambkin R, Auvinet E, et al., 2018,
P 004 - Patellofemoral arthroplasty improves gait in isolated patellofemoral arthritis, a prospective cohort gait analysis study.
, Gait Posture, Vol: 65 Suppl 1, Pages: 241-242 -
Journal articleZhao S, Arnold M, Ma S, et al., 2018,
Standardizing compression testing for measuring the stiffness of human bone
, BONE & JOINT RESEARCH, Vol: 7, Pages: 524-538, ISSN: 2046-3758 -
Journal articleZhao S, Arnold M, Ma S, et al., 2018,
Standardising compression testing for measuring the stiffness of human bone: a systematic review
, Bone and Joint Research, Vol: 7, Pages: 524-538, ISSN: 2046-3758Objectives: The ability to determine human bone stiffness is of clinical relevance in many fields, including bone quality assessment and orthopaedic prosthesis design. Stiffness can be measured using compression testing; an experimental technique commonly used to test bone specimens in vitro. This systematic review aims to determine how best to perform compression testing of human bone. Methods: A keyword search of all English language articles up until December 2017 of compression testing of bone was undertaken in Medline, Embase, PubMed and Scopus databases. Studies using bulk tissue, animal tissue, whole bone or testing techniques other than compression testing were excluded. Results: 4712 abstracts were retrieved with a total of 177 papers included in the analysis. 20 studies directly analysed the compression testing technique to improve the accuracy of the testing technique. Several influencing factors should be considered when testing bone samples in compression. These include the method of data analysis, specimen storage, specimen preparation, testing configuration and loading protocol. Conclusions: Compression testing is a widely used technique for measuring the stiffness of bone but there is a great deal of inter-study variation in experimental techniques across the literature. Based on best evidence from the literature, suggestions for bone compression testing are made in this review, though further studies are needed to help establish standardised bone testing techniques to increase the comparability and reliability of bone stiffness studies.
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Journal articleWiik AV, Brevadt M, Johal H, et al., 2018,
The loading patterns of a short femoral stem in total hip arthroplasty: gait analysis at increasing walking speeds and inclines.
, Journal of Orthopaedics and Traumatology, Vol: 19, ISSN: 1590-9921BACKGROUND: The purpose of this study was to examine the gait pattern of total hip arthroplasty (THA) patients with a new short femoral stem at different speeds and inclinations. MATERIALS AND METHODS: A total of 40 unilateral THA patients were tested on an instrumented treadmill. They comprised two groups (shorter stemmed THA n = 20, longer stemmed THA n = 20), both which had the same surgical posterior approach. The shorter femoral stemmed patients were taken from an ongoing hip trial with minimum 12 months postop. The comparative longer THR group with similar disease and severity were taken from a gait database along with a demographically similar group of healthy controls (n = 35). All subjects were tested through their entire range of gait speeds and inclines with ground reaction forces collected. Body weight scaling was applied and a symmetry index to compare the implanted hip to the contralateral normal hip. An analysis of variance with significance set at α = 0.05 was used. RESULTS: The experimental groups were matched demographically and implant groups for patient reported outcome measures and radiological disease. Both THA groups walked slower than controls, but symmetry at all intervals for all groups were not significantly different. Push-off loading was less favourable for both the shorter and longer stemmed THR groups (p < 0.05) depending on speed. CONCLUSIONS: Irrespective of femoral stem length, symmetry for ground reaction forces for both THA groups were returned to a normal range when compared to controls. However individual implant performance showed inferior (p < 0.05) push-off forces and normalised step length in both THR groups when compared to controls. LEVEL OF EVIDENCE: III.
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Journal articleLord BR, Colaco HB, Gupte CM, et 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: 0942-2056PURPOSE: A common problem during ACL reconstruction is asymmetry of proximal-distal graft diameter leading to tunnel upsizing and graft-tunnel mismatch. Compression downsizing provides a graft of uniform size, allowing easy passage into a smaller tunnel. The purpose of this study was to quantify the graft compression technique and its effects on graft biomechanics and stability. It was hypothesised that compression downsizing would significantly reduce cross-sectional area (CSA); that no significant changes in graft biomechanics would occur; graft fixation stability would be improved. METHOD: Sixty-eight non-irradiated peroneus longus (PL) tendons were investigated. Twenty were halved and paired into ten four-strand grafts, 20 strands were compressed by 0.5-1 mm diameter and changes in CSA recorded using an alginate mould technique. The following properties were compared with 20 control strands: cyclic strain when loaded 70-220 N for 1000 cycles; stiffness; ultimate tensile load and stress; Young's modulus. 24 PL tendons were quadrupled into grafts, 12 were compressed and all 24 were submerged in Ringer's solution at 37 °C and the CSA recorded over 12 h. Twelve compressed and 12 control quadrupled grafts were mounted in porcine femurs, placed in Ringer's solution for 12 h at 37 °C and graft displacement at the bone tunnel aperture recorded under cyclic loading. RESULTS: Mean decreases in CSA of 31% under a stress of 471 kPa and 21% under a stress of 447 kPa were observed for doubled and quadrupled grafts, respectively. Compressed grafts re-expanded by 19% over 12 h compared to 2% for controls. No significant differences were observed between compressed and control grafts in the biomechanical properties and graft stability; mean cyclic displacements were 0.3 mm for both groups. CONCLUSIONS: No detrimental biomechanical effects of graft compression on allograft PL tendons were observed. Following compression, t
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Journal articleRawson T, Sivakumaran P, Lobo R, et al., 2018,
Development of a web-based tool for undergraduate engagement in medical research; the ProjectPal experience
, BMC Medical Education, Vol: 18, ISSN: 1472-6920BackgroundWe report the development and evaluation of a web-based tool designed to facilitate student extra-curricular engagement in medical research through project matching students with academic supervisors.UK based university students were surveyed to explore their perceptions of undergraduate research, barriers and facilitators to current engagement. Following this, an online web-based intervention (www.ProjectPal.org) was developed to support access of students to research projects and supervisors. A pilot intervention was undertaken across a London-based university in January 2013 to February 2016. In March 2016, anonymised data were extracted from the prospective data log for analysis of website engagement and usage. Supervisors were surveyed to evaluate the website and student outputs.ResultsFifty-one students responded to the electronic survey. Twenty-four (47%) reported frustration at a perceived lack of opportunities to carry out extra-curricular academic projects. Major barriers to engaging in undergraduate research reported were difficulties in identifying suitable supervisors (33/51; 65%) and time pressures (36/51; 71%) associated with this. Students reported being opportunistic in their engagement with undergraduate research. Following implementation of the website, 438 students signed up to ProjectPal and the website was accessed 1357 times. Access increased on a yearly basis. Overall, 70 projects were advertised by 35 supervisors. There were 86 applications made by students for these projects. By February 2016, the 70 projects had generated 5 peer-review publications with a further 7 manuscripts under peer-review, 14 national presentations, and 1 national prize.ConclusionThe use of an online platform to promote undergraduate engagement with extra-curricular research appears to facilitate extra-curricular engagement with research. Further work to understand the impact compared to normal opportunistic practices in enhancing student engagement is now
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Journal articleBoughton OR, Ma S, Zhao S, et al., 2018,
Measuring bone stiffness using spherical indentation
, PLoS ONE, Vol: 13, ISSN: 1932-6203ObjectivesBone material properties are a major determinant of bone health in older age, both in terms of fracture risk and implant fixation, in orthopaedics and dentistry. Bone is an anisotropic and hierarchical material so its measured material properties depend upon the scale of metric used. The scale used should reflect the clinical problem, whether it is fracture risk, a whole bone problem, or implant stability, at the millimetre-scale. Indentation, an engineering technique involving pressing a hard-tipped material into another material with a known force, may be able to assess bone stiffness at the millimetre-scale (the apparent elastic modulus). We aimed to investigate whether spherical-tip indentation could reliably measure the apparent elastic modulus of human cortical bone.Materials and methodsCortical bone samples were retrieved from the femoral necks of nineteen patients undergoing total hip replacement surgery (10 females, 9 males, mean age: 69 years). The samples underwent indentation using a 1.5 mm diameter, ruby, spherical indenter tip, with sixty indentations per patient sample, across six locations on the bone surfaces, with ten repeated indentations at each of the six locations. The samples then underwent mechanical compression testing. The repeatability of indentation measurements of elastic modulus was assessed using the co-efficient of repeatability and the correlation between the bone elastic modulus measured by indentation and compression testing was analysed by least-squares regression.ResultsIn total, 1140 indentations in total were performed. Indentation was found to be repeatable for indentations performed at the same locations on the bone samples with a mean co-efficient of repeatability of 0.4 GigaPascals (GPa), confidence interval (C.I): 0.33–0.42 GPa. There was variation in the indentation modulus results between different locations on the bone samples (mean co-efficient of repeatability: 3.1 GPa, C.I: 2.2–3.90 GPa). No cle
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Conference paperFavier C, McGregor A, Phillips A, 2018,
Combined musculoskeletal and structural finite element modelling of the lumbar spine
, 8th World Congress of Biomechanics -
Journal articleStevenson H, Parkes M, Austin L, et al., 2018,
The development of a small-scale wear test for CoCrMo specimens with human synovial fluid
, Biotribology, Vol: 14, Pages: 1-10, ISSN: 2352-5738A new test was developed to measure friction and wear of hip implant materials under reciprocating sliding conditions. The method requires a very small amount of lubricant (<3 ml) which allows testing of human synovial fluid. Friction and wear of Cobalt Chromium Molybdenum (CoCrMo) material pairs were measured for a range of model and human synovial fluid samples. The initial development of the test assessed the effect of fluid volume and bovine calf serum (BCS) concentration on friction and wear. In a second series of tests human synovial fluid (HSF) was used. The wear scar size (depth and volume) on the disc was dependent on protein content and reduced significantly for increasing BCS concentration. The results showed that fluid volumes of <1.5 ml were affected by evaporative loss effectively increasing the protein concentration resulting in anomalously lower wear. At the end of the test thick deposits were observed in and around the wear scars on the disc and ball; these were analysed by Infrared Reflection-Absorption Spectroscopy. The deposits were composed primarily of denatured proteins and similar IR spectra were obtained from the BCS and HSF tests. The analysis confirmed the importance of SF proteins in determining wear of CoCrMo couples.
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Journal articleWillmott H, Al-Wattar Z, Halewood C, et 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: 1268-7731BACKGROUND: The first metatarsophalangeal joint may be fused in order to treat arthritis or instability. The use of shape-memory staples for fixation is well recognised, but little work has been done into the optimal configuration of staples. METHODS: The structural behaviour of first metatarsophalangeal joint (MTPJ) arthrodeses using shape-memory staples or crossed screws was studied using cadaveric porcine joints. Five fixation configurations were tested: single vertical or horizontal staple, paired staples in dorsal-medial configuration (0-90° to the sagittal plane), paired staples in oblique orthogonal configuration (45-135°); or two crossed screws. Specimens were loaded in cyclical dorsiflexion for 1000 cycles. Plantar gapping and shearing were measured. Specimens were then loaded to failure. RESULTS: Cyclic testing caused more shear in the 45-135° staples than the crossed screws (1.0mm±0.5mm compared to 0.14mm±0.4mm, p<0.01). No significant difference was found in plantar gap formation. Single vertical and horizontal single staples failed at 15N and 19. CONCLUSIONS: N, respectively. Paired 0-90° staples failed at 43N±9N, significantly lower than the 45-135° staples (141N±25N; p<0.001) and crossed screws (180N±67N; p<0.001). There was no significant difference between the 45-135° staples and crossed screws. Screws failed by sudden cortical fracture; staples displayed gradual pull-out and shearing. First MTPJ arthrodeses fixed with single staples are not recommended. Arthrodeses fixed with staples at 0-90° to the sagittal plane were significantly less strong than two crossed screws. However, positioning oblique staples at 45-135° significantly improved stability, creating a construct as strong as, crossed screws. None of the constructs was strong enough for immediate weight bearing.
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Journal articlePapi E, Bull A, McGregor A, 2018,
Is there evidence to use kinematic/kinetic measures clinically in low back pain patients? A systematic review
, Clinical Biomechanics, Vol: 55, Pages: 53-64, ISSN: 0268-0033BackgroundCurrently, there is a widespread reliance on self-reported questionnaires to assess low back pain patients. However, it has been suggested that objective measures of low back pain patients' functional status should be used to aid clinical assessment. The aim of this study is to systematically review which kinematic /kinetic parameters have been used to assess low back pain patients against healthy controls and to propose clinical kinematic/kinetic measures.MethodsPubMed, Embase and Scopus databases were searched for relevant studies. Reference lists of selected studies and hand searches were performed. Studies had to compare people with and without non-specific low back pain while performing functional tasks and report body segment/joint kinematic and/or kinetic data. Two reviewers independently identified relevant papers.FindingsSixty-two studies were included. Common biases identified were lack of assessor blinding and sample size calculation, use of samples of convenience, and poor experimental protocol standardization. Studies had small sample sizes. Range of motion maneuvers were the main task performed (33/62). Kinematic/kinetic data of different individual or combination of body segments/joints were reported among the studies, commonest was to assess the hip joint and lumbar segment motion (13/62). Only one study described full body movement. The most commonly reported outcome was range of motion. Statistically significant differences between controls and low back pain groups were reported for different outcomes among the studies. Moreover, when the same outcome was reported disagreements were noted.InterpretationThe literature to date offers limited and inconsistent evidence of kinematic/kinetic measures in low back pain patients that could be used clinically.
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Journal articleJones GG, Clarke S, Jaere M, et al., 2018,
3D printing and unicompartmental knee arthroplasty
, EFORT Open Reviews, Vol: 3, Pages: 248-253, ISSN: 2058-5241In suitable patients, unicompartmental knee arthroplasty (UKA) offers a number of advantages compared with total knee arthroplasty. However, the procedure is technically demanding, with a small tolerance for error. Assistive technology has the potential to improve the accuracy of implant positioning. This review paper describes the concept of detailed UKA planning in 3D, and the 3D printing technology that enables a plan to be delivered intraoperatively using patient-specific instrumentation (PSI). The varying guide designs that enable accurate registration are discussed and described. The system accuracy is reported. Future studies need to ascertain whether accuracy for low-volume surgeons can be delivered in the operating theatre using PSI, and reflected in improved patient reported outcome measures, and lower revision rates.
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Journal articleJones GG, Jaere M, Clarke S, et al., 2018,
3D printing and high tibial osteotomy
, EFORT Open Reviews, Vol: 3, Pages: 254-259, ISSN: 2058-5241High tibial osteotomy (HTO) is a relatively conservative surgical option in the management of medial knee pain. Thus far, the outcomes have been variable, and apparently worse than the arthroplasty alternatives when judged using conventional metrics, owing in large part to uncer-tainty around the extent of the correction planned and achieved.This review paper introduces the concept of detailed 3D planning of the procedure, and describes the 3D printing technology that enables the plan to be performed.The different ways that the osteotomy can be undertaken, and the varying guide designs that enable accurate regis-tration are discussed and described. The system accuracy is reported.In keeping with other assistive technologies, 3D printing enables the surgeon to achieve a preoperative plan with a degree of accuracy that is not possible using conventional instruments. With the advent of low dose CT, it has been possible to confirm that the procedure has been under-taken accurately too.HTO is the ‘ultimate’ personal intervention: the amount of correction needed for optimal offloading is not yet com-pletely understood.For the athletic person with early medial joint line over-load who still runs and enjoys life, HTO using 3D printing is an attractive option. The clinical effectiveness remains unproven.
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Journal articleHalewood C, Athwal KK, Amis A, 2018,
Pre-clinical assessment of total knee replacement anterior-posterior constraint
, Journal of Biomechanics, Vol: 73, Pages: 153-160, ISSN: 0021-9290Pre-clinical, bench-top assessment of Total Knee Replacements (TKR) can provide information about the inherent constraint provided by a TKR, which does not depend on the condition of the patient undergoing the arthroplasty. However little guidance is given by the ASTM standard on test configurations such as medial-lateral (M:L) loading distribution, flexion angle or restriction of secondary motions. Using a purpose built rig for a materials testing machine, four TKRs currently in widespread clinical use, including medial-pivot and symmetrical condyle types, were tested for anterior-posterior translational constraint. Compressive joint loads from 710 to 2000 N, and a range of medial-lateral (M:L) load distributions, from 70:30% to 30:70% M:L, were applied at different flexion angles with secondary motions unconstrained. It was found that TKA constraint was significantly less at 60 and 90° flexion than at 0°, whilst increasing the compressive joint load increased the force required to translate the tibia to limits of AP constraint at all flexion angles tested. Additionally when M:L load distribution was shifted medially, a coupled internal rotation was observed with anterior translation and external rotation with posterior translation. This paper includes some recommendations for future development of pre-clinical testing methods.
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Journal articleLogishetty K, Western L, Morgan R, et al.,
Augmented reality for arthroplasty training - a randomised controlled trial of simulator-based training for acetabular cup orientation skills
, Clinical Orthopaedics and Related Research, ISSN: 0009-921XBackground:Accurate implant orientation reduces wear and increases stability in arthroplasty. This is a technically demanding skill. Augmented Reality headsets overlay digital information over the real world. We have developed an enhanced AR headset capable of tracking bony anatomy in relation to an implant. Questions/Purposes:The purpose of this study was to validate this enhanced AR headset in the training simulator setting as determined by (1) quantitative assessments accurately orientating an acetabular component, and (2) a questionnaire regarding the realism of the task, acceptability ofthe technology, and its potential role for surgical training. Methods:Twenty-four novice surgeons voluntarily participated in a simulation trial. Demographics and baseline performance in orientating an acetabular implant to six patient-specific values on the phantom pelvis, were collected prior to training. All participants received standardised educational lectures based around four clinical vignettes on hip surgery to normalise their knowledge. Participants were randomised to two groups, completing four, once-weekly sessions of baseline assessment, training, and re-assessment. One group trained using AR (with live holographic feedback of orientation), and the other received one-on-one tuition from an expert surgeon (ES). The solid-angle error in degrees between the planned and achieved orientations was measured. Participants completed baseline assessments, then training, and then assessment in this fashion after each weekly session, and a validated post-training questionnaire evaluating their experiences. Results:Novice surgeons of similar experience in both groups performed with a similar error prior to training (Baseline ES mean error 16° ± SD 7° compared to AR 14±7°, p>0.05). During training, participants achieved average errors in orientations of 1±1° using AR, and 6±4° when guided by the ES (p<0.001). At fin
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Journal articlePapi E, Bo YN, McGregor A, 2018,
A flexible wearable sensor for knee flexion assessment during gait
, Gait and Posture, Vol: 62, Pages: 480-483, ISSN: 0966-6362Background:Gait analysis plays an important role in the diagnosis and management of patients with movement disorders but it is usually performed within a laboratory. Recently interest has shifted towards the possibility of conducting gait assessments in everyday environments thus facilitating long-term monitoring. This is possible by using wearable technologies rather than laboratory based equipment.Research questionThis study aims to validate a novel wearable sensor system’s ability to measure peak knee sagittal angles during gait.Methods:The proposed system comprises a flexible conductive polymer unit interfaced with a wireless acquisition node attached over the knee on a pair of leggings. Sixteen healthy volunteers participated to two gait assessments on separate occasions. Data was simultaneously collected from the novel sensor and a gold standard 10 camera motion capture system. The relationship between sensor signal and reference knee flexion angles was defined for each subject to allow the transformation of sensor voltage outputs to angular measures (degrees). The knee peak flexion angle from the sensor and reference system were compared by means of root mean square error (RMSE), absolute error, Bland-Altman plots and intra-class correlation coefficients (ICCs) to assess test-retest reliability.Results:Comparisons of knee peak flexion angles calculated from the sensor and gold standard yielded an absolute error of 0.35(±2.9°) and RMSE of 1.2(±0.4)°. Good agreement was found between the two systems with the majority of data lying within the limits of agreement. The sensor demonstrated high test-retest reliability (ICCs>0.8).Significance:These results show the ability of the sensor to monitor knee peak sagittal angles with small margins of error and in agreement with the gold standard system. The sensor has potential to be used in clinical settings as a discreet, unobtrusive wearable device allowing for long-term gait analysis.
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Journal articleRiviere C, Iranpoura F, Harris S, et al., 2018,
Differences in trochlear parameters between native and prosthetic kinematically or mechanically aligned knees
, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 104, Pages: 124-130, ISSN: 1877-0517 -
Journal articleRiviere C, Iranpour F, Harris S, et al., 2018,
Differences in trochlear parameters between native and prosthetic kinematically or mechanically aligned knees
, ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH, Vol: 104, Pages: 165-170, ISSN: 1877-0568- Author Web Link
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Journal articleRiviere C, Lazic S, Villet L, et al., 2018,
Kinematic alignment technique for total hip and knee arthroplasty: the personalized implant positioning surgery
, EFORT OPEN REVIEWS, Vol: 3, Pages: 98-105, ISSN: 2058-5241 -
Journal articleKaria M, Masjedi M, Duffell L, et al., 2018,
Comparison of gait biomechanics in patients with and without knee osteoarthritis during different phases of gait
, Journal of Orthopaedics, Trauma and Rehabilitation, Vol: 25, Pages: 11-15, ISSN: 2210-4917Background: This study aimed to characterise knee adduction angles (KAA) and knee adduction moments (KAM) and compare this with foot centre of pressure (COP) in volunteers with and without knee osteoarthritis (OA). Methods: A total of 108 participants were recruited; 84 had no known pathology, 18 had medial knee OA, and six had lateral knee OA. Linear regression was used to determine correlations between the normalised COP, KAM, and KAA during each phase of gait for all participants. Results: The first phase of gait demonstrated significant differences between groups for all measures: KAA in all phases, COP in phases one and two, and KAM in phase one only. Conclusion: The largest mechanical changes are seen in the first phase of gait in osteoarthritic patients. Although COP is an easy to measure tool, it is not as sensitive as KAA and did not demonstrate a significant difference between healthy and medial OA patients.
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