A Biomechanical Study Natacha Rosa Fernão D Magalhães Ricardo Simões and António Torres Marques Natacha Rosa 3 nd Year Mechanical Engineering PhD Student Enhanced Bone Healing in intramedullary ID: 1048555
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1. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical StudyNatacha Rosa, Fernão D. Magalhães, Ricardo Simões and António Torres Marques
2. Natacha Rosa3nd Year Mechanical Engineering PhD StudentEnhanced Bone Healing in intramedullary nailing through Mechanical Stimulation
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4. Stabilization technique:External fixationTibia diaphysis fractures is the one in which healing is most difficultPlatingwww.synthes.comwww.synthes.comNailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Intramedullary nailingFixation stability and healing
5. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Improvement of intramedullary nailing systemUnderstanding of bone-nail fixation system mechanicsDemandsHow the implant guaranties fracture stability and bone aligment;How it is conducive to bone regenerationBiomechanical stability of the whole boneCompare toFixation stability and healing
6. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study MethodologyMechanicalExperimentationFinite Element Analysis (FEA)VALIDATEEXTENDWhole bone stiffnessvs Bone-intramedullary nail StiffnessInterfragmentary movements
7. 3D ScanNailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study SolidWorksANSYS®MethodologyCortical and trabecular bone structures boundary definition;Solid model construction;Surface preparation;External surface
8. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Methodology: Whole bone systemNeto et al. Rev Hosp Clín. 54, 1999SawBones®Image obtained from: Heiner et al. J Biomech 34, 2001 and adapted with data from SawBones®Heinonen et al. Bone 29, 2001Tencer A. Biomechanics of Fixation and Fractures (Book chapter), 2006
9. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Methodology: Whole bone system
10. 3D ScanNailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study SolidWorksANSYS®MethodologyGrips designCortical and trabecular bone structures boundary definition;Solid model construction;Surface preparation;External surface
11. Dailey et al. Clin Biomech 27, 2009Penzkofer et al. Arch Orthop Trauma Surg 129, 2009Augat et al. J Orthop Trauma 22, 2008“The long axis of each specimen is aligned parallel to the base plate of the machine”Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Methodology: Containers/grips“Tibiae were oriented vertically”Heiner et al. J Biomech 34, 2001Heiner et al. J Biomech 41, 2008“A set of reference axes (bone coordinate system), was marked on the surface of the tibia to help align the bone during experiments and to correlate the experiments with the FE model”Gray et al. Proc Inst Mech Eng 221, 2007Gray et al. J Biomech Eng 130, 2008Vertical axisAnatomical axisMechanical axisSagittal planeCoronal planecYoshioka et al. J Orthop Res 7, 1989Adapted from: Han et al. Knee Surg Sports Traumatol Arthrosc, 2008Tibial mechanical axiscooPickering et al. J Bone Joint Surg, 2012Sagittal planeCoronal planeYoshioka et al. J Orthop Res 7, 1989Tibial plateauDistal tibia
12. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study All loading modes;The same tibia alignment guaranteed in both simulation and mechanical experimentation;Avoid potting bone specimens in cement;Misalignment of bone;Methodology: Containers/grips
13. 3D ScanNailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study SolidWorksANSYS®MethodologyGrips designIntramedullary nail implantation in the boneIntramedullary nail structure drawingCortical and trabecular bone structures boundary definition;Solid model construction;Surface preparation;External surface
14. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Bone-implant complex (BIC) - NailHarmonicExperimental(Hz)Simulation - Ansys®(Hz)Error (%)1st384388.117.62nd432427.35.53rd10571047.16.4Validation through free-free boundary conditionL.A. Medical M596222 AB0366 T nail (inches)Circular ring cross section (inner diameter 5 mm/ 0.197 inches) Stainless steel - AISI 316L ASTM F318
15. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Bone-implant complex (BIC) – Nail implantationwww.aofoundation.orgHan et al. Knee Surg Sports Traumatol Arthrosc, 2008ReamingCreation of the nail entry siteNail insertedNail lockingDiameter: 12.7 mm (0.5 inches)Length: 60 mm (2.36 inches)To accommodate the larger proximal portion in the nailTibial anatomical axis7 cm(2.75 inches)7 cm(2.75 inches)11 mm reaming (0.43 inches) The correct position of the nail was validated by an experienced orthopedic surgeonProximally: 2 screwsDistally: 2 screwsLocking modeNo play between the screw and the bone
16. 3D ScanNailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study SolidWorksANSYS®MethodologyGrips designIntramedullary nail implantation in the boneIntramedullary nail structure drawingCortical and trabecular bone structures boundary definition;Solid model construction;Surface preparation;Finite element analysisExternal surface
17. Intramedullary Nailing Stability in the Bone Healing Process ConceptNature has optimize this process and it would be difficult to intervene in order to improve fracture healingHorn et al. Injury Int J Care Injured 40, 2009There is a tendency to modify the locking option for better stabilityHigh bone-implant stability and instability are detrimental for bone healingImprove treatment method for bone fracture repair by reducing the patient healing timeBailón-Plaza et al. J Biomech 36, 2003Beneficial effects of early loading and adverse effects of delayed loading on bone healingThere is never been determine a quantifiable relationship between the rate of healing and mechanicalComiskey et al. J Biomech 43, 2010
18. Granulation tissue…Woven boneREPAIRREMODELINGLoadWhole boneBICFEPenzkofer et al. (2009)Axial compression in N/μm134001250723 ± 421Torsion (IR) in Nm/deg8.94.50.8 ± 0.14-Point Bending (AT) in Nm2146.251.237 ± 84-Point Bending (LT) in Nm287.0857.637 ± 9Shear (Saggital) in N/mm-294.1131 ± 30Shear (Coronal) in N/mm-309.6164 ± 89Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study Axial compression:Torsion:4-Point Bending (AT):4-Point Bending (LT):Shear (Saggital):Shear (Coronal):11 µmIntact bone214 µm0.36 deg0.58 deg0.12 mm0.12 mm0.32 mm0.36 mm--0.68 mm0.65 mm=1.95% Regression line:Load/moment--deformation/rotation curveEvaluated/validade: Heiner et al. J Biomech 41, 2008Horn et al. (2009)620 ± 240 (CL) 1420 ± 421 (ASL)Fracture location: CentralLoad: 100 NNail diameter: 9 mmFracture gap width: 8 mmConventional nailsResults0.3 – 0.8% Minimal mechanical stimulationBailón-Plaza et al. J Biomech 36, 2003Fritton et al. (2000) Rubin et al. (2001)Goodship et al. (2009)Low-magnitude, high-frequency mechanical signals ability to influence fracture healing
19. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study ConclusionsDifficult to compare studies due to non-standard experimental set-upHigh-frequency low-amplitude interfragmentary micromotion regime applied during early healing recovery phase may be an interesting strategy to enhance the rate and quality of bone repair without risking the disruption of the healing processAn ideal implant stiffness design demands an extensively understanding of the complex relation between the mechanical stimulus (type, magnitude, rate, duration and timing of initiation of loading) and the bone healing processValidation of the finite element model through mechanical experimentation is essential
20. Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study We would like to thank Portuguese Foundation for Science and Technology (FCT) Luso-American Development Foundation (FLAD)and alsoInternational Conference and Expo on Biomechanics and Implant Design for giving the opportunity to present the work developed
21. Thank you for your attention!I welcome your questions, suggestions and comments! Nailing Stability during Tibia Fracture Early Healing Process: A Biomechanical Study