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Journal articleArnold M, Zhao S, Ma S, et al., 2017,
Microindentation - a tool for measuring cortical bone stiffness?
, BONE & JOINT RESEARCH, Vol: 6, Pages: 542-549, ISSN: 2046-3758 -
Journal articleArnold M, Zhao S, Ma S, et al., 2017,
Microindentation: a tool for measuring cortical bone stiffness? A systematic review
, Bone & Joint Research, Vol: 6, Pages: 542-549, ISSN: 2046-3758Objectives: Microindentation hasthe potential to measuretheelasticity(stiffness)of individualpatients’bone. Bone elasticity plays a crucial role in the press-fit stability of orthopaedic implants.Arming surgeons with accuratebone elasticityinformation may reduce surgical complicationsincluding peri-prosthetic fractures. The question we address with this systematicreview is whether microindentation can accurately measure cortical bone stiffness.Methods: A systematic review of all English language articles using a keyword search was undertaken in Medline, Embase, PubMed, Scopus and Cochrane databases. Studies thatonly used nanoindentation, cancellous boneoranimal tissue were excluded.Results: 1094abstracts were retrieved and 32papers were included in the analysis, 20 of which used reference point indentation and 12of which used traditional depth sensing indentation.There are a number of factors thatmust be taken into account when using microindentation such as tip size, depth and method of analysis.Only two studies validated microindentation againsttraditional mechanical testing techniques. Bothstudies used reference point indentation(RPI) with one showing that RPI parameters correlate well with mechanical testing, butanother suggestedthatthey do not. Conclusion: Microindentation has been used in various studies to assess bone elasticity but only two studies with conflicting results compared microindentation to traditional mechanical testing techniques. Further research,includingmore studies comparingmicroindentationto other mechanical testing methodsare needed,before microindentation can be reliably used to calculate cortical bone stiffness.
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Conference paperFavier C, McGregor A, Phillips A, 2017,
Development of a combined MSK and FEA model of the lower back
, 13th Annual Bath Biomechanics Symposium -
Journal articleRivière C, FarhadIranpour, Auvinet E, et al., 2017,
Mechanical Alignment Technique For TKA: Are there Intrinsic Technical Limitations?
, Orthopaedics and Traumatology: Surgery and Research, ISSN: 1877-0568BACKGROUND: Mechanically aligned (MA) total knee arthroplasty (TKA) is affected by disappointing functional outcomes in spite of the recent improvements in surgical precision and implant designs. This might suggest the existence of intrinsic technical limitations. Our study aims to compare the prosthetic and native trochlear articular surfaces and to estimate the extent of collateral ligament imbalance which is technically un-correctable by collateral ligament release when TKA implants are mechanically aligned. STUDY HYPOTHESIS: conventional MA technique generates a high rate of prosthetic overstuffing of the distal groove, distal lateral trochlear facet and distal lateral femoral condyle (Hypothesis 1), and technically un-correctable collateral ligament imbalance (hypothesis 2)? Disregarding the distal femoral joint line obliquity (DFJLO) when performing femoral cuts explainsdistal lateral femoral prosthetic stuffing and un-correctable imbalance (hypothesis 3)? METHODS: Twenty patients underwent a conventional MA TKA. Pre-operative MRI-based 3D knee models were generated and MA TKA was simulated. Native and prosthetic trochlear articular surfaces were compared using in-house analysis software.Following the automatic determination by the planning software of the size of the extension and flexion gaps, an algorithm was applied to balance the gaps and the frequency and amplitude of technically un-correctable knee imbalance wereestimated. RESULTS: The conventional MA technique generateda significant slight distal lateral femoral prosthetic overstuffing (mean 0.6mm, 0.8mm, 1.25 mmfor the most distal lateral facet point, groove, and at the most distal point of lateral femoral condyle, respectively) and a high rate of type 1 and 2 un-corretable knee imbalance (30% and 40%, respectively). The incidence of distal lateral prosthetic overstuffing (trochlea and condyle) and un-correctable knee imbalance were strongly to very strongly correlated with the DFJLO (r=0.53 to 0.89).
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Journal articleAframian A, Auvinet E, Iranpour F, et al., 2017,
O95: An instrumented treadmill shows excellent reliability and repeatability at a range of speeds to maximal walking speedover a range of inclines and declines
, Gait and Posture, Vol: 57, ISSN: 0966-6362 -
Journal articleWiik AV, Logishetty K, Boughton O, et al., 2017,
Letter to the Editor regarding 'How symmetric are metal-on-metal hip resurfacing patients during gait? Insights for the rehabilitation'.
, Journal of Biomechanics, Vol: 63, Pages: 203-203, ISSN: 0021-9290 -
Journal articleLi J, Clarke S, Cobb JP, et al., 2017,
Novel curved surface preparation technique for knee resurfacing
, Medical Engineering and Physics, Vol: 49, Pages: 89-93, ISSN: 1350-4533Conventional 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.
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Journal articleAli AM, Newman S, Hooper P, et al., 2017,
The effect of implant position on bone strain following lateral unicompartmental knee arthroplasty. A biomechanical model using digital image correlation
, Bone and Joint Research, Vol: 6, Pages: 522-529, ISSN: 2046-3758ObjectivesUnicompartmental knee arthroplasty (UKA) is a demanding procedure, with tibial component subsidence or pain from high tibial strain being potential causes of revision. The optimal position in terms of load transfer has not been documented for lateral UKA. Our aim was to determine the effect of tibial component position on proximal tibial strain.MethodsA total of 16 composite tibias were implanted with an Oxford Domed Lateral Partial Knee implant using cutting guides to define tibial slope and resection depth. Four implant positions were assessed: standard (5° posterior slope); 10° posterior slope; 5° reverse tibial slope; and 4 mm increased tibial resection. Using an electrodynamic axial-torsional materials testing machine (Instron 5565), a compressive load of 1.5 kN was applied at 60 N/s on a meniscal bearing via a matching femoral component. Tibial strain beneath the implant was measured using a calibrated Digital Image Correlation system.ResultsA 5° increase in tibial component posterior slope resulted in a 53% increase in mean major principal strain in the posterior tibial zone adjacent to the implant (p = 0.003). The highest strains for all implant positions were recorded in the anterior cortex 2 cm to 3 cm distal to the implant. Posteriorly, strain tended to decrease with increasing distance from the implant. Lateral cortical strain showed no significant relationship with implant position.ConclusionRelatively small changes in implant position and orientation may significantly affect tibial cortical strain. Avoidance of excessive posterior tibial slope may be advisable during lateral UKA.
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Journal articleRidzwan M, Sukjamsri C, Pal B, et al., 2017,
Femoral fracture type can be predicted from femoral structure: a finite element study validated by digital volume correlation experiments
, Journal of Orthopaedic Research, Vol: 36, Pages: 993-1001, ISSN: 1554-527XProximal femoral fractures can be categorized into two main types: Neck and intertrochanteric fractures accounting for 53% and 43% of all proximal femoral fractures, respectively. The possibility to predict the type of fracture a specific patient is predisposed to would allow drug and exercise therapies, hip protector design, and prophylactic surgery to be better targeted for this patient rendering fracture preventing strategies more effective. This study hypothesized that the type of fracture is closely related to the patient-specific femoral structure and predictable by finite element (FE) methods. Fourteen femora were DXA scanned, CT scanned, and mechanically tested to fracture. FE-predicted fracture patterns were compared to experimentally observed fracture patterns. Measurements of strain patterns to explain neck and intertrochanteric fracture patterns were performed using a digital volume correlation (DVC) technique and compared to FE-predicted strains and experimentally observed fracture patterns. Although loaded identically, the femora exhibited different fracture types (six neck and eight intertrochanteric fractures). CT-based FE models matched the experimental observations well (86%) demonstrating that the fracture type can be predicted. DVC-measured and FE-predicted strains showed obvious consistency. Neither DXA-based BMD nor any morphologic characteristics such as neck diameter, femoral neck length, or neck shaft angle were associated with fracture type. In conclusion, patient-specific femoral structure correlates with fracture type and FE analyses were able to predict these fracture types. Also, the demonstration of FE and DVC as metrics of the strains in bones may be of substantial clinical value, informing treatment strategies and device selection and design.
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Journal articleAgbesi MPK, Borsuk HS, Hunt JN, et al., 2017,
Motion-driven flow in an unusual piscine nasal region
, Zoology, Vol: 119, Pages: 500-510, ISSN: 0944-2006 -
Conference paperGreen A, Salman M, Yentis S, et al., 2017,
Trainer/trainee trainer training
, Association-of-Anaesthetists-of-Great-Britain-and-Ireland (AAGBI) GAT Annual Scientific Meeting, Publisher: WILEY, Pages: 81-81, ISSN: 0003-2409 -
Journal articleDuffell LD, Jordan SJ, Cobb JP, et al., 2017,
Gait adaptations with aging in healthy participants and people with knee joint osteoarthritis
, Gait and Posture, Vol: 57, Pages: 246-251, ISSN: 0966-6362The relationship between age and gait characteristics in people with and without medial compartment osteoarthritis (OA) remains unclear. We aimed to characterize this relationship and to relate biomechanical and structural parameters in a subset of OA patients. Twenty five participants with diagnosed unilateral medial knee OA and 84 healthy participants, with no known knee pathology were recruited. 3D motion capture was used to analyse sagittal and coronal plane gait parameters while participants walked at a comfortable speed. Participants were categorized according to age (18–30, 31–59 and 60+ years), and those with and without OA were compared between and within age groups. In a subset of OA patients, clinically available Computed Tomography images were used to assess joint structure. Differences in coronal plane kinematics at the hip and knee were noted in participants with OA particularly those who were older compared with our healthy controls, as well as increased knee moments. Knee adduction moment correlated with structural parameters in the subset of OA patients. Increased knee moments and altered kinematics were observed in older participants presenting with OA only, which seem to be related to morphological changes in the joint due to OA, as opposed to being related to the initial cause of medial knee OA.
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Journal articleLong MJ, Papi E, Duffell LD, et al., 2017,
Predicting knee osteoarthritis risk in injured populations
, Clinical Biomechanics, Vol: 47, Pages: 87-95, ISSN: 1879-1271BackgroundIndividuals who suffered a lower limb injury have an increased risk of developing knee osteoarthritis. Early diagnosis of osteoarthritis and the ability to track its progression is challenging. This study aimed to explore links between self-reported knee osteoarthritis outcome scores and biomechanical gait parameters, whether self-reported outcome scores could predict gait abnormalities characteristic of knee osteoarthritis in injured populations and, whether scores and biomechanical outcomes were related to osteoarthritis severity via Spearman's correlation coefficient.MethodsA cross-sectional study was conducted with asymptomatic participants, participants with lower-limb injury and those with medial knee osteoarthritis. Spearman rank determined relationships between knee injury and outcome scores and hip and knee kinetic/kinematic gait parameters. K-Nearest Neighbour algorithm was used to determine which of the evaluated parameters created the strongest classifier model.FindingsDifferences in outcome scores were evident between groups, with knee quality of life correlated to first and second peak external knee adduction moment (0.47, 0.55). Combining hip and knee kinetics with quality of life outcome produced the strongest classifier (1.00) with the least prediction error (0.02), enabling classification of injured subjects gait as characteristic of either asymptomatic or knee osteoarthritis subjects. When correlating outcome scores and biomechanical outcomes with osteoarthritis severity only maximum external hip and knee abduction moment (0.62, 0.62) in addition to first peak hip adduction moment (0.47) displayed significant correlations.InterpretationThe use of predictive models could enable clinicians to identify individuals at risk of knee osteoarthritis and be a cost-effective method for osteoarthritis screening.
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Journal articleClunie GM, Kinshuck AJ, Sandhu GS, et al., 2017,
Voice and swallowing outcomes for adults undergoing reconstructive surgery for laryngotracheal stenosis
, CURRENT OPINION IN OTOLARYNGOLOGY & HEAD AND NECK SURGERY, Vol: 25, Pages: 195-199, ISSN: 1068-9508Purpose of review Adult laryngotracheal stenosis is a rare, multifactorial condition which carries a significant physical and psychosocial burden. Surgical approaches have developed in recent years, however, voice and swallowing function can be affected prior to treatment, in the immediate postoperative phase, and as an ongoing consequence of the condition and surgical intervention. In this study we discuss: the nature of the problem; surgical interventions to address airway disorders; optimal patterns of care to maximize voice and swallowing outcomes.Recent findings Studies in this field are limited and focused on surgical outcomes and airway status with voice and swallowing a secondary consideration. Retrospective studies of swallowing have focused on factors such as the duration of dysphagia symptoms following airway surgery and made comparisons between type of surgery, use of stent, and length of swallowing problems. The literature suggests that patients are likely to return to their preoperative diet. There has been a focus on voice outcomes following cricotracheal resection which results in a postoperative decrease in the fundamental frequency. However, study comparisons are limited by the use of inconsistent outcome measures (for both voice and swallowing) which are often not validated, with heterogeneous groups and varying surgical techniques.Summary The limited literature suggests that swallowing function is more likely to recover to presurgical status than voice function. Further prospective studies incorporating consistent instrumental, clinician, and patient-reported outcome measurement are required to understand the nature and extent of dysphagia and dysphonia resulting from this condition and its treatment.
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Journal articleNg CTJ, Newman S, Harris S, et al., 2017,
Patient-specific instrumentation improves alignment of lateral unicompartmental knee replacements by novice surgeons.
, International Orthopaedics, Vol: 41, Pages: 1379-1385, ISSN: 0341-2695PurposePatient-specific instrumentation (PSI) has the potential to offer numerous benefits—not least of all, improved resection accuracy; but its potential has not been realised in clinical studies. An explanation may be the focus of such studies on the total knee replacement (TKR—a common procedure, with which surgeons are generally very familiar. Consequently, we sought to investigate the potential role of PSI in guiding novice surgeons to perform the more technically demanding and less familiar lateral unicondylar knee replacement (LUKR).MethodsTwelve orthopaedic trainees naive to LUKR were instructed to perform the procedure according to a pre-operative plan. These were carried out on synthetic sawbones and were completed once with conventional instrumentation alone and once with the adjunct of PSI, allowing a comparison of the plan adherence achieved by the two sets of instrumentation.ResultsThere was a tendency for PSI to demonstrate improved plan adherence, though a statistically significant improvement was only seen in compound rotational error of the femoral implant (p = 0.004). PSI was, however, able to produce narrower standard deviations in the mean translational displacement of the femoral implant and also the mean rotational displacement of both implants, suggesting a higher degree of precision.ConclusionsOur study provides some evidence that PSI can improve the ability of novice surgeons to replicate a pre-operative plan, but our results suggest the need for larger-scale clinical studies to establish the role of PSI in this procedure.
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Journal articleWilliams A, Stephen J, Kittl C, et al., 2017,
The Role of the Lateral Soft Tissues in Controlling Anterior Translation And Internal Rotation of the Tibia, and An Investigation of Lateral Reconstructions Accompanying ACL Reconstruction
, Orthopaedic journal of sports medicine, Vol: 5, ISSN: 2325-9671<h4>Introduction:</h4> There is considerable current interest in the role of the lateral soft tissue structures in the context of ACL deficiency (ACLD). Of course the topic is not new but a re-visitation, although with improved experimental techniques available. It was clear that there was a rush to create surgical techniques based on the ‘Anterolateral Ligament’ (ALL) but without investigative ‘due-diligence’ and without consideration that other structures may be important, or more important. <h4>Objectives:</h4> To study the anatomy and biomechanics of the lateral soft tissues relevant to the ACL and ACL reconstruction techniques investigating isometricity, structures’ contributions to resistance of anterior tibial translation (ATT), internal rotation (IR), and pivot shift (PS). Also we studied the impact of various reconstructions on restoration of kinematics and potential over-constraint and effects on articular surface compression load. <h4>Methods:</h4> Several studies were undertaken. In all healthy fresh-frozen cadaveric specimens were used. Descriptive anatomy was described. Length changes of suture fixed at structure and reconstruction attachment points on the tibia and femur were measured with linear variable displacement transducers (LVDTs). To investigate structures’ contribution to resist translation and torque a 6-degrees of freedom robot with a universal force-moment sensor was used in a classic ‘cutting study’. The robot replayed the same movement with sequential sectioning of structures recording the decrease in force / torque needed to reach the same movement limit. In this way the structure’s resistance to motion as a percentage of the total could be calculated. In other studies knees were mounted in a test rig where knee kinematics were recorded from 0° to 100° of flexion by use of an optical tracking system. Joint surface compression was measured w
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Journal articleFeola AJ, Coudrillier B, Mulvihill J, et al., 2017,
Deformation of the Lamina Cribrosa and Optic Nerve Due to Changes in Cerebrospinal Fluid Pressure
, INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE, Vol: 58, Pages: 2070-2078, ISSN: 0146-0404 -
Journal articleIranpour F, Merican AM, Teo SH, et al., 2017,
Femoral articular geometry and patellofemoral stability
, KNEE, Vol: 24, Pages: 555-563, ISSN: 0968-0160Background:Patellofemoral instability is a major cause of anterior knee pain. The aim of this study was to examine how the medial and lateral stability of the patellofemoral joint in the normal knee changes with knee flexion and measure its relationship to differences in femoral trochlear geometry.Methods:Twelve fresh-frozen cadaveric knees were used. Five components of the quadriceps and the iliotibial band were loaded physiologically with 175 N and 30 N, respectively. The force required to displace the patella 10 mm laterally and medially at 0°, 20°, 30°, 60° and 90° knee flexion was measured. Patellofemoral contact points at these knee flexion angles were marked. The trochlea cartilage geometry at these flexion angles was visualized by Computed Tomography imaging of the femora in air with no overlying tissue. The sulcus, medial and lateral facet angles were measured. The facet angles were measured relative to the posterior condylar datum.Results:The lateral facet slope decreased progressively with flexion from 23° ± 3° (mean ± S.D.) at 0° to 17 ± 5° at 90°. While the medial facet angle increased progressively from 8° ± 8° to 36° ± 9° between 0° and 90°. Patellar lateral stability varied from 96 ± 22 N at 0°, to 77 ± 23 N at 20°, then to 101 ± 27 N at 90° knee flexion. Medial stability varied from 74 ± 20 N at 0° to 170 ± 21 N at 90°. There were significant correlations between the sulcus angle and the medial facet angle with medial stability (r = 0.78, p < 0.0001).Conclusions:These results provide objective evidence relating the changes of femoral profile geometry with knee flexion to patellofemoral stability.
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Journal articleMcGregor AH, 2017,
Injury prevention, performance and return to sport: How can science help?
, Chinese Journal of Traumatology, Vol: 20, Pages: 63-66, ISSN: 1008-1275 -
Journal articleMa S, Goh EL, Jin A, et al., 2017,
Long-term effects of bisphosphonate therapy: perforations, microcracks and mechanical properties
, Scientific Reports, Vol: 7, Pages: 1-10, ISSN: 2045-2322Osteoporosis is characterised by trabecular bone loss resulting from increased osteoclast activation and unbalanced coupling between resorption and formation, which induces a thinning of trabeculae and trabecular perforations. Bisphosphonates are the frontline therapy for osteoporosis, which act by reducing bone remodelling, and are thought to prevent perforations and maintain microstructure. However, bisphosphonates may oversuppress remodelling resulting in accumulation of microcracks. This paper aims to investigate the effect of bisphosphonate treatment on microstructure and mechanical strength. Assessment of microdamage within the trabecular bone core was performed using synchrotron X-ray micro-CT linked to image analysis software. Bone from bisphosphonate-treated fracture patients exhibited fewer perforations but more numerous and larger microcracks than both fracture and non-fracture controls. Furthermore, bisphosphonate-treated bone demonstrated reduced tensile strength and Young’s Modulus. These findings suggest that bisphosphonate therapy is effective at reducing perforations but may also cause microcrack accumulation, leading to a loss of microstructural integrity and consequently, reduced mechanical strength.
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