Publications
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Garner A, van Arkel RJ, Cobb J, 2019, Classification of combined partial knee arthroplasty, Bone and Joint Journal, Vol: 101B, Pages: 922-928, ISSN: 2049-4394
AimsThere has been a recent resurgence in interest in combined partial knee arthroplasty (PKA) as an alternative to total knee arthroplasty (TKA). The varied terminology used to describe these procedures leads to confusion and ambiguity in communication between surgeons, allied health professionals, and patients. A standardized classification system is required for patient safety, accurate clinical record-keeping, clear communication, correct coding for appropriate remuneration, and joint registry data collection.Materials and MethodsAn advanced PubMed search was conducted, using medical subject headings (MeSH) to identify terms and abbreviations used to describe knee arthroplasty procedures. The search related to TKA, unicompartmental (UKA), patellofemoral (PFA), and combined PKA procedures. Surveys were conducted of orthopaedic surgeons, trainees, and biomechanical engineers, who were asked which of the descriptive terms and abbreviations identified from the literature search they found most intuitive and appropriate to describe each procedure. The results were used to determine a popular consensus.ResultsSurvey participants preferred “bi-unicondylar arthroplasty” (Bi-UKA) to describe ipsilateral medial and lateral unicompartmental arthroplasty; “medial bi-compartmental arthroplasty” (BCA-M) to describe ipsilateral medial unicompartmental arthroplasty with patellofemoral arthroplasty; “lateral bi-compartmental arthroplasty” (BCA-L) to describe ipsilateral lateral unicompartmental arthroplasty with patellofemoral arthroplasty; and tri-compartmental arthroplasty (TCA) to describe ipsilateral patellofemoral and medial and lateral unicompartmental arthroplasties. “Combined partial knee arthroplasty” (CPKA) was the favoured umbrella term.ConclusionWe recommend bi-unicondylar arthroplasty (Bi-UKA), medial bicompartmental arthroplasty (BCA-M), lateral bicompartmental arthroplasty (BCA-L), and tricompartmental arthroplasty (
Ghouse S, Reznikov N, Boughton O, et al., 2019, The design and in vivo testing of a locally stiffness-matched porous scaffold, Applied Materials Today, Vol: 15, Pages: 377-388, ISSN: 2352-9407
An increasing volume of work supports utilising the mechanobiology of bone for bone ingrowth into a porous scaffold. However, typically during in vivo testing of implants, the mechanical properties of the bone being replaced are not quantified. Consequently there remains inconsistencies in the literature regarding ‘optimum’ pore size and porosity for bone ingrowth. It is also difficult to compare ingrowth results between studies and to translate in vivo animal testing to human subjects without understanding the mechanical environment. This study presents a clinically applicable approach to determining local bone mechanical properties and design of a scaffold with similar properties. The performance of the scaffold was investigated in vivo in an ovine model.The density, modulus and strength of trabecular bone from the medial femoral condyle from ovine bones was characterised and power-law relationships were established. A porous titanium scaffold, intended to maintain bone mechanical homeostasis, was additively manufactured and implanted into the medial femoral condyle of 6 ewes. The stiffness of the scaffold varied throughout the heterogeneous structure and matched the stiffness variation of bone at the surgical site. Bone ingrowth into the scaffold was 10.73 ± 2.97% after 6 weeks. Fine woven bone, in the interior of the scaffold, and intense formations of more developed woven bone overlaid with lamellar bone at the implant periphery were observed. The workflow presented will allow future in vivo testing to test specific bone strains on bone ingrowth in response to a scaffold and allow for better translation from in vivo testing to commercial implants.
Boughton O, Ma S, Cai X, et al., 2019, Computed tomography porosity and spherical indentation for determining cortical bone millimetre-scale mechanical properties, Scientific Reports, Vol: 9, ISSN: 2045-2322
The cortex of the femoral neck is a key structural element of the human body, yet there is not a reliable metric for predicting the mechanical properties of the bone in this critical region. This study explored the use of a range of non-destructive metrics to measure femoral neck cortical bone stiffness at the millimetre length scale. A range of testing methods and imaging techniques were assessed for their ability to measure or predict the mechanical properties of cortical bone samples obtained from the femoral neck of hip replacement patients. Techniques that can potentially be applied in vivo to measure bone stiffness, including computed tomography (CT), bulk wave ultrasound (BWUS) and indentation, were compared against in vitro techniques, including compression testing, density measurements and resonant ultrasound spectroscopy. Porosity, as measured by micro-CT, correlated with femoral neck cortical bone’s elastic modulus and ultimate compressive strength at the millimetre length scale. Large-tip spherical indentation also correlated with bone mechanical properties at this length scale but to a lesser extent. As the elastic mechanical properties of cortical bone correlated with porosity, we would recommend further development of technologies that can safely measure cortical porosity in vivo.Introduction
Uemura K, Boughton O, Logishetty K, et al., 2019, A single-use, size-specific, nylon arthroplasty guide: a preliminary study, Hip International, ISSN: 1120-7000
Logishetty K, van Arkel RJ, Ng KC, et al., 2019, Hip capsule biomechanics after arthroplasty - the effect of implant, approach and surgical repair, Bone and Joint Journal, Vol: 101-B, Pages: 426-434, ISSN: 2049-4394
AimsThe hip’s capsular ligaments passively restrain extreme range of movement (ROM) by wrapping around the native femoral head/neck. We determined the effect of hip resurfacing arthroplasty (HRA), dual-mobility total hip arthroplasty (DM-THA), conventional THA, and surgical approach on ligament function.Materials and MethodsEight paired cadaveric hip joints were skeletonized but retained the hip capsule. Capsular ROM restraint during controlled internal rotation (IR) and external rotation (ER) was measured before and after HRA, DM-THA, and conventional THA, with a posterior (right hips) and anterior capsulotomy (left hips).ResultsHip resurfacing provided a near-native ROM with between 5° to 17° increase in IR/ER ROM compared with the native hip for the different positions tested, which was a 9% to 33% increase. DM-THA generated a 9° to 61° (18% to 121%) increase in ROM. Conventional THA generated a 52° to 100° (94% to 199%) increase in ROM. Thus, for conventional THA, the capsule function that exerts a limit on ROM is lost. It is restored to some extent by DM-THA, and almost fully restored by hip resurfacing. In positions of low flexion/extension, the posterior capsulotomy provided more normal function than the anterior, possibly because the capsule was shortened during posterior repair. However, in deep flexion positions, the anterior capsulotomy functioned better.ConclusionNative head-size and capsular repair preserves capsular function after arthroplasty. The anterior and posterior approach differentially affect postoperative biomechanical function of the capsular ligaments.
Boughton O, Uemura K, Tamura K, et al., 2019, Gender and Disease Severity Determine Proximal Femoral Morphology in Developmental Dysplasia of the Hip, Journal of Orthopaedic Research, ISSN: 0736-0266
Reznikov N, Boughton O, Ghouse S, et al., 2019, Individual response variations in scaffold-guided bone regeneration are determined by independent strain- and injury-induced mechanisms, Biomaterials, Vol: 194, Pages: 183-194, ISSN: 0142-9612
This study explored the regenerative osteogenic response in the distal femur of sheep using scaffolds having stiffness values within, and above and below, the range of trabecular bone apparent modulus. Scaffolds 3D-printed from stiff titanium and compliant polyamide were implanted into a cylindrical metaphyseal defect 15 × 15 mm. After six weeks, bone ingrowth varied between 7 and 21% of the scaffold pore volume and this was generally inversely proportional to scaffold stiffness. The individual reparative response considerably varied among the animals, which could be divided into weak and strong responders. Notably, bone regeneration specifically within the interior of the scaffold was inversely proportional to scaffold stiffness and was strain-driven in strongly-responding animals. Conversely, bone regeneration at the periphery of the defect was injury-driven and equal in all scaffolds and in all strongly- and weakly-responding animals. The observation of the strain-driven response in some, but not all, animals highlights that scaffold compliance is desirable for triggering host bone regeneration, but scaffold permanence is important for the load-bearing, structural role of the bone-replacing device. Indeed, scaffolds may benefit from being nonresorbable and mechanically reliable for those unforeseeable cases of weakly responding recipients.
Jones GG, Clarke S, Jaere M, et al., 2019, Prothèse unicompartimentaire et désostéotomie pour échec d’ostéotomie tibiale : une alternative chirurgicale à l’arthroplastie totale de genouFailed high tibial osteotomy: A joint preserving alternative to total knee arthroplasty, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 105, Pages: 41-41, ISSN: 1877-0517
High tibial osteotomy is an attractive treatment option for young active patients wishing to return to high level activities. However, it is not considered a long-term solution, with 30% revised at ten years. Currently, the only revision option is a total knee arthroplasty, a procedure that might not deliver the functional level expected by these highly active patients. This paper describes a novel joint preserving approach to HTO revision, using assistive technology, in the form of 3D printed guides, to reverse the osteotomy and simultaneously perform a unicompartmental knee replacement. The indications and planning aims for this procedure are discussed, and the preliminary results in four patients presented. Level of evidence: IV.
Jones GG, Clarke S, Jaere M, et al., 2019, Failed high tibial osteotomy: A joint preserving alternative to total knee arthroplasty, Orthopaedics and Traumatology: Surgery and Research, Vol: 105, Pages: 85-88, ISSN: 1877-0568
High tibial osteotomy is an attractive treatment option for young active patients wishing to return to high-level activities. However, it is not considered a long-term solution, with 30% revised at ten years. Currently, the only revision option is a total knee arthroplasty, a procedure that might not deliver the functional level expected by these highly active patients. This paper describes a novel joint preserving approach to HTO revision, using assistive technology, in the form of 3D printed guides, to reverse the osteotomy and simultaneously perform a unicompartmental knee replacement. The indications and planning aims for this procedure are discussed, and the preliminary results in four patients presented.
Riyiere C, Harman C, Leong A, et al., 2019, Kinematic alignment technique for medial OXFORD UKA: An in-silico study, ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH, Vol: 105, Pages: 63-70, ISSN: 1877-0568
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- Citations: 13
Wang H, Sugand K, Newman S, et al., 2019, Are multiple views superior to a single view when teaching hip surgery? A single-blinded randomized controlled trial of technical skill acquisition, PLoS ONE, Vol: 14, ISSN: 1932-6203
s Metrics Comments Media Coverage Abstract Introduction Materials and methods Results Discussion Conclusion Supporting information References Reader Comments (0) Media Coverage (0) FiguresAbstractPurposeSurgical education videos currently all use a single point of view (POV) with the trainee locked onto a fixed viewpoint, which may not deliver sufficient information for complex procedures. We developed a novel multiple POV video system and evaluated its training outcome compared with traditional single POV.MethodsWe filmed a hip resurfacing procedure performed by an expert attending using 8 cameras in theatre. 30 medical students were randomly and equally allocated to learn the procedure using the multiple POV (experiment group [EG]) versus single POV system (control group [CG]). Participants advanced a pin into the femoral head as demonstrated in the video. We measured the drilling trajectories and compared it with pre-operative plan to evaluate distance of the pin insertion and angular deviations. Two orthopedic attendings expertly evaluated the participants’ performance using a modified global rating scale (GRS). There was a pre-video knowledge test that was repeated post-simulation alongside a Likert-scale questionnaire.ResultsThe angular deviation of the pin in EG was significantly less by 29% compared to CG (p = 0.037), with no significant difference in the entry point’s distance between groups (p = 0.204). The GRS scores for EG were 3.5% higher than CG (p = 0.046). There was a 32% higher overall knowledge test score (p<0.001) and 21% improved Likert-scale questionnaire score (p = 0.002) after video-learning in EG than CG, albeit no significant difference in the knowledge test score before video-learning (p = 0.721).ConclusionThe novel multiple POV provided significant objective and subjective advantages over single POV for acquisition of technical skills in hip surgery.
Doyle R, Boughton O, Plant D, et al., 2019, An in vitro model of impaction during hip arthroplasty, Journal of Biomechanics, Vol: 82, Pages: 220-227, ISSN: 0021-9290
Impaction is required to properly seat press-fit implants and ensure initial implant stability and long term bone ingrowth, however excessive impaction or press-fit presents a high fracture risk in the acetabulum and femur. Current in-vitro impaction testing methods do not replicate the compliance of the soft tissues surrounding the hip, a factor that may be important in fracture and force prediction. This study presents the measurement of compliance of the soft tissues supporting the hip during impaction in operative conditions, and replicates these in vitro. Hip replacements were carried out on 4 full body cadavers while impact force traces and acetabular/femoral displacement were measured. Compliance was then simulated computationally using a Voigt model. These data were subsequently used to inform the design of a representative in-vitro drop rig. Effective masses of 19.7 kg and 12.7 kg, spring stiffnesses of 8.0 kN/m and 4.1 kN/m and dashpot coefficients of 595 N s/m and 322 N s/m were calculated for the acetabular and femoral soft tissues respectively. A good agreement between cadaveric and in-vitro peak displacement and rise time during impact is found. Such an in-vitro setup is of use during laboratory testing, simulation or even surgical training.
Iranpour F, Aframian A, Cobb JP, 2019, Patellofemoral Osteoarthritis: Patellofemoral Arthroplasty, Disorders of the Patellofemoral Joint: Diagnosis and Management, Pages: 129-134, ISBN: 9783030124410
Patellofemoral osteoarthritis is common in older people and those with risk factors including trochlear dysplasia and patellofemoral instability. Patellofemoral arthroplasty (PFA) is indicated in such patients and has the advantage of leaving the remaining structures of the knee intact, including the native tibiofemoral joint surfaces and cruciate ligaments. The design of PFA has evolved from inlay designs to onlay designs which are either symmetrical or asymmetrical, to match the native trochlea. Long-term survival of currently used implants is suboptimal, with the largest series of the most commonly used implant reporting a 10-year survival of 77.3% at 10 years, with most patients being revised for progression of disease. Improvements in our understanding of the indications for PFA together with improvements in the design of instruments and instrumentation have the potential to improve the survival of PFA in the future, allowing more people to benefit from the advantages it confers over total knee arthroplasty (TKA).
Maillot C, Leong A, Harman C, et al., 2019, Poor relationship between frontal tibiofemoral and trochlear anatomic parameters: Implications for designing a trochlea for kinematic alignment, KNEE, Vol: 26, Pages: 106-114, ISSN: 0968-0160
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- Citations: 7
Logishetty K, Western L, Morgan R, et al., 2018, Can an Augmented Reality Headset Improve Accuracy of Acetabular Cup Orientation in Simulated THA? A Randomized Trial., Clin Orthop Relat Res
BACKGROUND: Accurate implant orientation reduces wear and increases stability in arthroplasty but is a technically demanding skill. Augmented reality (AR) headsets overlay digital information on top of the real world. We have developed an enhanced AR headset capable of tracking bony anatomy in relation to an implant, but it has not yet been assessed for its suitability as a training tool for implant orientation. QUESTIONS/PURPOSES: (1) In the setting of simulated THA performed by novices, does an AR headset improve the accuracy of acetabular component positioning compared with hands-on training by an expert surgeon? (2) What are trainees' perceptions of the AR headset in terms of realism of the task, acceptability of the technology, and its potential role for surgical training? METHODS: Twenty-four study participants (medical students in their final year of school, who were applying to surgery residency programs, and who had no prior arthroplasty experience) participated in a randomized simulation trial using an AR headset and a simulated THA. Participants were randomized to two groups completing four once-weekly sessions of baseline assessment, training, and reassessment. One group trained using AR (with live holographic orientation feedback) and the other received one-on-one training from a hip arthroplasty surgeon. Demographics and baseline performance in orienting an acetabular implant to six patient-specific values on the phantom pelvis were collected before training and were comparable. The orientation error in degrees between the planned and achieved orientations was measured and was not different between groups with the numbers available (surgeon group mean error ± SD 16° ± 7° versus AR 14° ± 7°; p = 0.22). Participants trained by AR also completed a validated posttraining questionnaire evaluating their experiences. RESULTS: During the four training sessions, participants using AR-guidance had smaller mean (± SD) e
Jones GG, Logishetty K, Clarke S, et al., 2018, Do patient-specific instruments (PSI) for UKA allow non-expert surgeons to achieve the same saw cut accuracy as expert surgeons?, Archives of Orthopaedic and Trauma Surgery, Vol: 138, Pages: 1601-1608, ISSN: 0936-8051
INTRODUCTION: High-volume unicompartmental knee arthroplasty (UKA) surgeons have lower revision rates, in part due to improved intra-operative component alignment. This study set out to determine whether PSI might allow non-expert surgeons to achieve the same level of accuracy as expert surgeons. MATERIALS AND METHODS: Thirty-four surgical trainees with no prior experience of UKA, and four high-volume UKA surgeons were asked to perform the tibial saw cuts for a medial UKA in a sawbone model using both conventional and patient-specific instrumentation (PSI) with the aim of achieving a specified pre-operative plan. Half the participants in each group started with conventional instrumentation, and half with PSI. CT scans of the 76 cut sawbones were then segmented and reliably orientated in space, before saw cut position in the sagittal, coronal and axial planes was measured, and compared to the pre-operative plan. RESULTS: The compound error (absolute error in the coronal, sagittal and axial planes combined) for experts using conventional instruments was significantly less than that of the trainees (11.6°±4.0° v 7.7° ±2.3º, p = 0.029). PSI improved trainee accuracy to the same level as experts using conventional instruments (compound error 5.5° ±3.4º v 7.7° ±2.3º, p = 0.396) and patient-specific instruments (compound error 5.5° ±3.4º v 7.3° ±4.1º, p = 0.3). PSI did not improve the accuracy of high-volume surgeons (p = 0.3). CONCLUSIONS: In a sawbone model, PSI allowed inexperienced surgeons to achieve more accurate saw cuts, equivalent to expert surgeons, and thus has the potential to reduce revision rates. The next test will be to determine whether these results can be replicated in a clinical trial.
Rivière C, Dhaif F, Shah H, et al., 2018, Kinematic alignment of current TKA implants does not restore the native trochlear anatomy, Revue de Chirurgie Orthopedique et Traumatologique, Vol: 104, Pages: 673-685, ISSN: 1877-0517
Rivière C, Dhaif F, Shah H, et al., 2018, Kinematic alignment of current TKA implants does not restore the native trochlear anatomy, Orthopaedics and Traumatology: Surgery and Research, Vol: 104, Pages: 983-995, ISSN: 1877-0568
INTRODUCTION: Preserving constitutional patellofemoral anatomy, and thus producing physiological patellofemoral kinematics, could prevent patellofemoral complications and improve clinical outcomes after kinematically aligned TKA (KA TKA). Our study aims 1) to compare the native and prosthetic trochleae (planned or implanted), and 2) to estimate the safety of implanting a larger Persona® femoral component size matching the proximal lateral trochlea facet height (flange area) in order to reduce the native articular surfaces understuffing generated by the prosthetic KA trochlea. METHODS: Persona® femoral component 3D model was virtually kinematically aligned on 3D bone-cartilage models of healthy knees by using a conventional KA technique (group 1, 36 models, planned KA TKA) or an alternative KA technique (AT KA TKA) aiming to match the proximal (flange area) lateral facet height (10 models, planned AT KA TKA). Also, 13 postoperative bone-implant (KA Persona®) models were co-registered to the same coordinate geometry as their preoperative bone-cartilage models (group 2 - implanted KA TKA). In-house analysis software was used to compare native and prosthetic trochlea articular surfaces and medio-lateral implant overhangs for every group. RESULTS: The planned and performed prosthetic trochleae were similar and valgus oriented (6.1° and 8.5°, respectively), substantially proximally understuffed compared to the native trochlea. The AT KA TKAs shows a high rate of native trochlea surface overstuffing (70%, 90%, and 100% for lateral facet, groove, medial facet) and mediolateral implant overhang (60%). There was no overstuffing with conventional KA TKAs having their anterior femoral cut flush. CONCLUSION: We found that with both the planned and implanted femoral components, the KA Persona® trochlea was more valgus oriented and understuffed compared to the native trochlear anatomy. In addition, restoring the lateral trochlea facet height by increasing t
Ma S, Goh EL, Karunaratne A, et al., 2018, The Effects of Bisphosphonate at the Nanoscale: Effects on Bone Collagen, Mineral Strain and Collagen-Mineral Interaction, Annual Meeting of the American-Society-for-Bone-and-Mineral-Research, Publisher: WILEY, Pages: 410-411, ISSN: 0884-0431
Aqil A, Patel S, Wiik A, et al., 2018, Patient-specific guides improve hip arthroplasty surgical accuracy, COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING, Vol: 21, Pages: 579-584, ISSN: 1025-5842
Zhao 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
Zhao 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: 2046-3758
Objectives: 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.
Wiik 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: 1590-9921
BACKGROUND: 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.
Boughton OR, Ma S, Zhao S, et al., 2018, Measuring bone stiffness using spherical indentation, PLoS ONE, Vol: 13, ISSN: 1932-6203
ObjectivesBone 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
Jones GG, Clarke S, Jaere M, et al., 2018, 3D printing and unicompartmental knee arthroplasty, EFORT Open Reviews, Vol: 3, Pages: 248-253, ISSN: 2058-5241
In 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.
Jones GG, Jaere M, Clarke S, et al., 2018, 3D printing and high tibial osteotomy, EFORT Open Reviews, Vol: 3, Pages: 254-259, ISSN: 2058-5241
High 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.
Logishetty K, Western L, Morgan R, et al., 2018, Augmented reality for arthroplasty training - a randomised controlled trial of simulator-based training for acetabular cup orientation skills, Clinical Orthopaedics and Related Research, ISSN: 0009-921X
Background: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
Riviere 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
Riviere 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
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Riviere 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
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