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Journal articleRiviere C, Lazic S, Boughton OR, et al., 2018,
Current concepts for aligning knee implants: patient-specific or systematic?
, EFORT Open Reviews, Vol: 3, Pages: 1-6, ISSN: 2058-5241 -
Book chapterClarke S, Cobb J, Jaere M, et al., 2018,
Osteotomies: Advanced and complex techniques
, Esska Instructional Course Lecture Book Glasgow 2018, Pages: 129-151We started performing precise surgery based upon CT plans in the last century - the first embodiment of this approach was a robotic assistant built for total knee replacement, the “Acrobot” [1]. Abundant evidence now exists to confirm that assistive technologies enable surgeons to achieve their preoperative goals [2]. The concept of planned surgery is therefore not novel. Patient-matched instruments share several key elements with the robotic platform, and these formed the basis of this current project. The essential elements include image segmentation, planning, and registration. We applied the know-how of these dimensions to design and build patient-matched guides for a range of tasks using biocompatible polymer 3D printers. Having established a workflow for arthroplasty, the adaptation of the same principles to osteotomy was a short step, requiring software to be developed to deliver semiautomated useful information regarding limb segment alignment and the shapes of bones.
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Journal articleNewman SDS, Altuntas A, Alsop H, et al., 2017,
Up to 10 year follow-up of the Oxford Domed Lateral Partial Knee Replacement from an independent centre
, KNEE, Vol: 24, Pages: 1414-1421, ISSN: 0968-0160- Author Web Link
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- Citations: 18
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Conference paperMa S, Hansen U, Cobb J, et al., 2017,
Long-term effects of bisphosphonate therapy: perforations, microcracks and mechanical properties.
, Annual Meeting of the American-Society-for-Bone-and-Mineral-Research (ASBMR), Publisher: WILEY, Pages: S106-S107, ISSN: 0884-0431 -
Journal articleRivière C, Iranpour F, Auvinet E, et al., 2017,
Mechanical alignment technique for TKA: Are there intrinsic technical limitations?
, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 103, Pages: 762-772, ISSN: 1877-0517 -
Journal articleRivière C, Iranpour F, Harris S, et al., 2017,
The kinematic alignment technique for TKA reliably aligns the femoral component with the cylindrical axis
, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 103, Pages: 773-777, ISSN: 1877-0517 -
Journal articleRiviere C, Iranpour F, Harris S, et al., 2017,
The kinematic alignment technique for TKA reliably aligns the femoral component with the cylindrical axis
, ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH, Vol: 103, Pages: 1069-1073, ISSN: 1877-0568- Author Web Link
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- Citations: 38
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Journal articleRiviere C, Iranpour F, Auvinet E, et al., 2017,
Alignment options for total knee arthroplasty: A systematic review
, ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH, Vol: 103, Pages: 1047-1056, ISSN: 1877-0568- Author Web Link
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- Citations: 293
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Journal articleJin A, Cobb JP, Hansen U, et al., 2017,
The effect of long term bisphosphonate therapy on trabecular bone strength and microcrack density
, Bone & Joint Research, Vol: 6, Pages: 602-609, ISSN: 2046-3758ObjectivesBisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding the efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While DEXA scanning may show a gain in bone density the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate for this study), and correlate this with the microarchitecture and density of microcracks in comparison with untreated controls. MethodsTrabecular bone from hip-fracture patients treated with BP (n=10) was compared to naïve fractured (n=14) and non-fractured controls (n=6). Trabecular cores were synchrotron and micro-CT scanned for microstructural analysis including quantification of bone volume fraction, micro-architecture and microcracks, then mechanically tested in compression. ResultsBP bone was 28% lower in strength than untreated hip-fracture bone and 48% lower in strength than and non-fracture control bone (4.6 vs 6.4 vs 8.9 MPa). BP treated bone had 24% more microcracks than naïve fractured bone and 51% more than non-fractured control (8.12 vs 6.55 vs 5.25 /cm2). BP and naïve fracture bone exhibited similar trabecular microarchitecture, with significantly lower bone volume fraction and connectivity than non-fractured controls. ConclusionsBP therapy had no detectable mechanical benefit. Instead its use was associated with substantially reduced bone strength. This low strength was probably due to the greater accumulation of microcracks and a lack of any discernible improvement in bone volume or microarchitecture. This preliminary study suggests that the clinical impact of BP induced microcrack accumulation may be substantial and long term.
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Journal articleGupte CM, 2017,
Knee Arthroscopy SimulationA Randomized Controlled Trial Evaluating the Effectiveness of the Imperial Knee Arthroscopy Cognitive Task Analysis (IKACTA) Tool
, Journal of Bone and Joint Surgery, American Volume, ISSN: 0021-9355 -
Journal articlePapi E, Koh WS, McGregor AH, 2017,
Wearable technology for spine movement assessment: A systematic review
, Journal of Biomechanics, Vol: 64, Pages: 186-197, ISSN: 0021-9290Continuous monitoring of spine movement function could enhance our understanding of low back pain development. Wearable technologies have gained popularity as promising alternative to laboratory systems in allowing ambulatory movement analysis. This paper aims to review the state of art of current use of wearable technology to assess spine kinematics and kinetics.Four electronic databases and reference lists of relevant articles were searched to find studies employing wearable technologies to assess the spine in adults performing dynamic movements. Two reviewers independently identified relevant papers. Customised data extraction and quality appraisal form were developed to extrapolate key details and identify risk of biases of each study. Twenty-two articles were retrieved that met the inclusion criteria: 12 were deemed of medium quality (score 33.4-66.7%), and 10 of high quality (score> 66.8%). The majority of articles (19/22) reported validation type studies. Only 6 reported data collection in real-life environments. Multiple sensors type were used: electrogoniometers (3/22), strain gauges based sensors (3/22), textile piezoresistive sensor (1/22) and accelerometers often used with gyroscopes and magnetometers (15/22). Two sensors units were mainly used and placing was commonly reported on the spine lumbar and sacral regions. The sensors were often wired to data transmitter/logger resulting in cumbersome systems. Outcomes were mostly reported relative to the lumbar segment and in the sagittal plane, including angles, range of motion, angular velocity, joint moments and forces.This review demonstrates the applicability of wearable technology to assess the spine, although this technique is still at an early stage of development.
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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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