90 results found
Jin A, Cobb JP, Hansen U, et al., The effect of long term bisphosphonate therapy on trabecular bone strength and microcrack density, Bone & Joint Research, ISSN: 2046-3758
ObjectivesBisphosphonates (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.
Sukjamsri C, Geraldes D, Gregory T, et al., Micro computed tomography and digital volume correlation techniques to determine micromotion in cementless arthroplasty, World Congress of Biomechanics 2014
Arnold M, Zhao S, Ma S, et al., 2017, Microindentation - a tool for measuring cortical bone stiffness? A systematic review., Bone Joint Res, Vol: 6, Pages: 542-549, ISSN: 2046-3758
OBJECTIVES: Microindentation has the potential to measure the stiffness of an individual patient's bone. Bone stiffness plays a crucial role in the press-fit stability of orthopaedic implants. Arming surgeons with accurate bone stiffness information may reduce surgical complications including periprosthetic fractures. The question addressed with this systematic review is whether microindentation can accurately measure cortical bone stiffness. METHODS: A systematic review of all English language articles using a keyword search was undertaken using Medline, Embase, PubMed, Scopus and Cochrane databases. Studies that only used nanoindentation, cancellous bone or animal tissue were excluded. RESULTS: A total of 1094 abstracts were retrieved and 32 papers were included in the analysis, 20 of which used reference point indentation, and 12 of which used traditional depth-sensing indentation. There are several factors that must be considered when using microindentation, such as tip size, depth and method of analysis. Only two studies validated microindentation against traditional mechanical testing techniques. Both studies used reference point indentation (RPI), with one showing that RPI parameters correlate well with mechanical testing, but the other suggested that they do not. CONCLUSION: Microindentation has been used in various studies to assess bone stiffness, but only two studies with conflicting results compared microindentation with traditional mechanical testing techniques. Further research, including more studies comparing microindentation with other mechanical testing methods, is needed before microindentation can be used reliably to calculate cortical bone stiffness.Cite this article: M. Arnold, S. Zhao, S. Ma, F. Giuliani, U. Hansen, J. P. Cobb, R. L. Abel, O. Boughton. Microindentation - a tool for measuring cortical bone stiffness? A systematic review. Bone Joint Res 2017;6:542-549. DOI: 10.1302/2046-3758.69.BJR-2016-0317.R2.
Boughton OR, Zhao S, Arnold M, et al., 2017, Measuring bone stiffness using microindentation, British Orthopaedic Research Society (BORS) 2016 Conference, Publisher: British Editorial Society of Bone and Joint Surgery, Pages: 31-31, ISSN: 2049-4416
Geraldes DM, Hansen U, Amis AA, 2017, Parametric Analysis of Glenoid Implant Design and Fixation Type, JOURNAL OF ORTHOPAEDIC RESEARCH, Vol: 35, Pages: 775-784, ISSN: 0736-0266
Geraldes DM, Hansen U, Jeffers J, et al., 2017, Stability of small pegs for cementless implant fixation., J Orthop Res
Most glenoid implants rely on large centrally located fixation features to avoid perforation of the glenoid vault in its peripheral regions. Upon revision of such components there may not be enough bone left for the reinsertion of an anatomical prosthesis. Multiple press-fit small pegs would allow for less bone resection and strong anchoring in the stiffer and denser peripheral subchondral bone. This study assessed the fixation characteristics, measured as the push-in (Pin ) and pull-out (Pout ) forces, and spring-back, measured as the elastic displacement immediately after insertion, for five different small press-fitted peg configurations manufactured out of UHMWPE cylinders (5 mm diameter and length). A total of 16 specimens for each configuration were tested in two types of solid bone substitute: Hard (40 PCF, 0.64 g/cm(3) , worst-case scenario of Pin ) and soft (15 PCF, 0.24 g/cm(3) , worst-case scenario of spring-back and Pout ). Two different diametric interference-fits were studied. Geometries with lower stiffness fins (large length to width aspect ratio) were the best performing designs in terms of primary fixation stability. They required the lowest force to fully seat, meaning they are less damaging to the bone during implantation, while providing the highest Pout /Pin ratio, indicating that when implanted they provide the strongest anchoring for the glenoid component. It is highlighted that drilling of chamfered holes could minimize spring-back displacements. These findings are relevant for the design of implants press-fitted pegs because primary fixation has been shown to be an important factor in achieving osseointegration and longevity of secondary fixation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Ma S, Goh EL, Jin A, et al., 2017, Long-term effects of bisphosphonate therapy: perforations, microcracks and mechanical properties, SCIENTIFIC REPORTS, Vol: 7, ISSN: 2045-2322
Ridzwan MIZ, 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., J Orthop Res
Proximal 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. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Chong DYR, Hansen UN, Amis AA, 2016, CEMENTLESS MIS MINI-KEEL PROSTHESIS REDUCES INTERFACE MICROMOTION VERSUS STANDARD STEMMED TIBIAL COMPONENTS, JOURNAL OF MECHANICS IN MEDICINE AND BIOLOGY, Vol: 16, ISSN: 0219-5194
Geraldes D, Hansen U, Jeffers J, et al., 2016, Interference fit optimisation for small press-fitted pegs, International Society for Technology in Arthroplasty 2015, Publisher: BRITISH EDITORIAL SOCIETY OF BONE & JOINT SURGERY, Pages: 150-150, ISSN: 2049-4416
Ma S, Goh EL, Patel B, et al., 2016, Are the cracks starting to appear in bisphosphonate therapy?, British Orthopaedic Research Society (BORS) 2016 Conference, Publisher: British Editorial Society of Bone and Joint Surgery, Pages: 53-53, ISSN: 2049-4416
Tempelaere C, Pierrart J, Lefèvre-Colau M-M, et al., 2016, Dynamic Three-Dimensional Shoulder Mri during Active Motion for Investigation of Rotator Cuff Diseases, PLOS ONE, Vol: 11, Pages: e0158563-e0158563
Geraldes D, Hansen U, Amis A, 2015, Parametric analysis of glenoid implant design, European Society of Biomechanics 2015
Geraldes D, Hansen U, Amis A, 2015, Parametric analysis of glenoid implant design, International Society of Biomechanics 2015
Simpson RL, Nazhat SN, Blaker JJ, et al., 2015, A comparative study of the effects of different bioactive fillers in PLGA matrix composites and their suitability as bone substitute materials: A thermo-mechanical and in vitro investigation., Journal of the Mechanical Behavior of Biomedical Materials, Vol: 50, Pages: 277-289, ISSN: 1751-6161
Bone substitute composite materials with poly(L-lactide-co-glycolide) (PLGA) matrices and four different bioactive fillers: CaCO3, hydroxyapatite (HA), 45S5 Bioglass(®) (45S5 BG), and ICIE4 bioactive glass (a lower sodium glass than 45S5 BG) were produced via melt blending, extrusion and moulding. The viscoelastic, mechanical and thermal properties, and the molecular weight of the matrix were measured. Thermogravimetric analysis evaluated the effect of filler composition on the thermal degradation of the matrix. Bioactive glasses caused premature degradation of the matrix during processing, whereas CaCO3 or HA did not. All composites, except those with 45S5 BG, had similar mechanical strength and were stiffer than PLGA alone in compression, whilst all had a lower tensile strength. Dynamic mechanical analysis demonstrated an increased storage modulus (E') in the composites (other than the 45S5 BG filled PLGA). The effect of water uptake and early degradation was investigated by short-term in vitro aging in simulated body fluid, which indicated enhanced water uptake over the neat polymer; bioactive glass had the greatest water uptake, causing matrix plasticization. These results enable a direct comparison between bioactive filler type in poly(α-hydroxyester) composites, and have implications when selecting a composite material for eventual application in bone substitution.
Sukjamsri C, Geraldes DM, Gregory T, et al., 2015, Digital volume correlation and micro-CT: An in-vitro technique for measuring full-field interface micromotion around polyethylene implants, JOURNAL OF BIOMECHANICS, Vol: 48, Pages: 3447-3454, ISSN: 0021-9290
Tuncer M, Patel R, Cobb JP, et al., 2015, Variable bone mineral density reductions post-unicompartmental knee arthroplasty, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 23, Pages: 2230-2236, ISSN: 0942-2056
Geraldes D, Hansen U, Amis A, 2014, A framework for parametric analysis of glenoid implant design, MECBioengineering 2014
Geraldes D, Hansen U, Jeffers J, et al., 2014, A framework for parametric analysis of glenoid implant design, International Society for Technology in Arthroplasty 2014
Gregory T, Hansen U, Khanna M, et al., 2014, A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty, ACTA ORTHOPAEDICA, Vol: 85, Pages: 91-96, ISSN: 1745-3674
Tuncer M, Hansen UN, Amis AA, 2014, Prediction of structural failure of tibial bone models under physiological loads: Effect of CT density-modulus relationships, MEDICAL ENGINEERING & PHYSICS, Vol: 36, Pages: 991-997, ISSN: 1350-4533
Geraldes D, Sukjamsri C, Gregory T, et al., 2013, A study of micromotion in cementless arthroplasty using digital volume correlation technique, Tomography for Scientific Advancement Symposium 2013
Gregory TM, Sankey A, Augereau B, et al., 2013, Accuracy of Glenoid Component Placement in Total Shoulder Arthroplasty and Its Effect on Clinical and Radiological Outcome in a Retrospective, Longitudinal, Monocentric Open Study, PLOS ONE, Vol: 8, ISSN: 1932-6203
Tuncer M, Cobb JP, Hansen UN, et al., 2013, Validation of multiple subject-specific finite element models of unicompartmental knee replacement, MEDICAL ENGINEERING & PHYSICS, Vol: 35, Pages: 1457-1464, ISSN: 1350-4533
Gregory T, Hansen U, Emery R, et al., 2012, Total shoulder arthroplasty does not correct the orientation of the eroded glenoid, ACTA ORTHOPAEDICA, Vol: 83, Pages: 529-535, ISSN: 1745-3674
Chong DYR, Hansen UN, Amis AA, 2011, THE INFLUENCE OF TIBIAL PROSTHESIS DESIGN FEATURES ON STRESSES RELATED TO ASEPTIC LOOSENING AND STRESS SHIELDING, JOURNAL OF MECHANICS IN MEDICINE AND BIOLOGY, Vol: 11, Pages: 55-72, ISSN: 0219-5194
Chong DYR, Hansen UN, van der Venne R, et al., 2011, The influence of tibial component fixation techniques on resorption of supporting bone stock after total knee replacement, JOURNAL OF BIOMECHANICS, Vol: 44, Pages: 948-954, ISSN: 0021-9290
Chong DYR, Hansen UN, Amis AA, 2010, Analysis of bone-prosthesis interface micromotion for cementless tibial prosthesis fixation and the influence of loading conditions, JOURNAL OF BIOMECHANICS, Vol: 43, Pages: 1074-1080, ISSN: 0021-9290
Junaid S, Gupta S, Sanghavi S, et al., 2010, Failure mechanism of the all-polyethylene glenoid implant, JOURNAL OF BIOMECHANICS, Vol: 43, Pages: 714-719, ISSN: 0021-9290
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