User talk:CHANDRAMOHAN .D
ARTIFICIAL BONE IMPLANT
FIELD OF THE INVENTION
The present invention in general relates to an artificial bone implant for its application in bone grafting and to a method of its manufacturing.
More particularly, the present invention relates to an artificial bone implant plate comprising a natural fibre reinforced polymer composite material in a homogenous matrix, the bone implant having improved tensile, flexural and impact strength, is lightweight, allow stiffness, is biocompatible and is adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture.
BACKGROUND OF THE INVENTION
With the increase in accidents, in the modern society that is heavily dependent on industrialization, automation/transportation and hard work, various types of bone fractures have increased. Such fractures are also due to old age bone degeneration; such as it happens in osteoporosis. These eventualities have made bone grafting a very popular surgical procedure for healing various types of wounds/holes in bones.
Hence, bone grafting has gained popularity as a surgical treatment, applied for healing of bone fractures. To be precise, bone grafting involves a surgical procedure by which bone or replacement material is placed into spaces between or around broken bone (fractures) or holes in bones to aid in healing. In the above context various materials and methods have been used for increasing the bone density and the bone volume. The use of autologous bone is the most reliable method and this bone is an efficient implant material. However, a vital drawback is the morbidity at the donor site and the limited availability. On other the use of alloy-implants and xenogeneic bone implants, in lieu of autologous bones is becoming increasingly more dubious as a result of immunological problems and risk of viral contamination. To avoid the application of autologous bones in bone grafting, machinig of ORTHOPAEDIC ALLOY implants, with High Speed Machining have been applied. It offers advantages, but also has its own disadvantages. For example, titanium is currently used as bone replacements, but the implants are simple geometric approximations of the bone shape. Hence, mismatches between real bone and implants are very common. This often causes stress concentrations and premature implant failure. More “conventional” machining of Titanium implants with 5-Axis High Speed Machining, which offers some advantages, also has disadvantages. Mismatches can occur between real bone and implants, often causing stress concentrations and premature implant failure.
Today, most implants are still made out of commercially pure titanium (grades 1 to 4) but, some implant systems (Endopore and NanoTite) are fabricated out of the Ti-6Al-4V alloy. For surgeries and bone transplants, cage materials are used which are known as PLLA and poly-L/D-lactide (PLDLA) material. A mixture of poly-L-lactic acid with 30% of poly-D-lactic acid), which are resorbable and which have an elasticity modulus similar to that of vertebral bone. These resorbable cages reduce the occurrence of stress shielding of the transplant material because, with the resorbing of the cage by the body, the newly formed bone material will gradually be loaded more and more.
However, the applications as detailed in the preceding paragraph do not teach sorting out the problems as explained hereinbefore, in a sacrosanct manner. The use of only a synthetic carrier material (for instance hydroxyapatite) has the drawback that such a carrier material only has osteoconductive properties and has no osteoinductive properties. Cells which are to provide the fusion of the spinal segments will first need to diffuse from the environment into the scaffold or be supplied into the scaffold by new vessel ingrowth. Additionally, the prior art materials as narrated hereinbefore, applied for manufacturing bone implant were not lightweight, did not allow stiffness substantially and were not substantially biocompatible apart from not having substantial flexural, tensile and impact strength. Further, the need of the hour being utilization of renewal resources, such need was also not taken care of in prior art technology. Several prior art patent documents, such as Patent Application No. JP7197400, Patent Application No. CA2168894, patent document WO2009079580, do teach application of renewal resources however, such documents do not teach application of renewal resources for manufacturing bone implants, which are lightweight, allow stiffness, have adequate tensile, flexural, impact strength and ensure biocompatibility and is adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture. Accordingly, there is a long felt need to provide an improved bone implant and a method for its manufacturing whereby the draw backs as aforesaid are substantially taken care of in a sacrosanct manner. In brief, there is a long felt need for designing an artificial bone impact from renewal resources, which ensures that the properties of being lightweight, allowance of stiffness, biocompatibility are taken care of and the bone implant is adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture. There is also a long felt need for an artificial bone implant which has improved tensile, flexural and impact strength.
The present invention meets the above mentioned long felt needs and other associated needs.
Hereinafer in this complete specification at places, for the sake of understanding only and not by way of any limitation bone fractures in humans have been referred. But it should be understood to persons skilled in the art that, the present invention is applicable to all types of bone fractures/holes in human beings and animals, either due to accident or due to osteoporosis or due to some in born disease or subsequent disease or otherwise and is not restricted to humerus bone fractures or femur bone fractures, which are mentioned only for understanding the present invention. Further, hereinafter, the use of the word fracture(s) also includes hole(s) and similar formation(s) as known to happen on bones and the word plate is referred to as the artificial bone implant according to the present invention, in a non-restrictive manner.
All through out the specification including the claims, the words “artificial bone implant”, “natural fibres”, “hybrid fibres”, “matrix”, “hardner”, “fractures”, “holes” “plates” are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/Limitation if any, referred to in the specification, is solely by way of example and understanding the present invention.
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide an artificial bone implant from natural fibre reinforced composite material such that the bone implant is adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture.
It is another object of the present invention to provide an artificial bone implant from renewable resources such that the bone implant is lightweight, allow stiffness, is biocompatible.
It is a further object of the present invention to provide an artificial bone implant from natural fibre reinforced composite material, which has substantial tensile, flexural and impact strength.
It is a further object of the present invention to provide an artificial bone implant which is less complicated to design without compromising on its quality standards and efficiency.
It is a further object of the present invention to provide an artificial bone implant which is cost effective and easy to manufacture.
It is a further object of the present invention to provide a method of manufacturing an artificial bone implant from natural fibre reinforced composite material such that, the bone implant is adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture.
How the foregoing objects are achieved will be clear from the following non-limiting exemplary description.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an artificial bone implant for its application in bone grafting, comprising a combination of natural fibres and hybrid fibres reinforced to form a biocompatible composite material in a homogenous matrix, and adapted to be fabricated to form the desired shape and size, said natural fibres having optimum proportions of banana fibre, sisal fibre and roselle fibre and hybrids of said natural fibres, such as herein described.
In accordance with preferred embodiments of the bone implant of the present invention: -said hybrids comprises optimum proportions of sisal fibre and roselle fibre, banana fibre and sisal fibre and banana fibre and roselle fibre;
-said sisal fibre is derived from Agave sisalana, said banana fibre is derived from Musa sapientum and said roselle fibre is derived from Hibiscus sabdariffa;
-said matrix comprises calculated quantity of bio epoxy resin and hardner resin;
-said bone implant is a natural fibre reinforced polymer composite plate material in bio epoxy resin and hardener resin;
-said implant has a coating of calcium phosphate and hydroxyapatite(hybrid) composite for internal and external fixation on fractured bone;
-said implant is adapted to have the desired substantial tensile, flexural and impact strength and is adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture.
The present invention also provides a method for manufacturing an artificial bone implant for its application in bone grafting, said implant comprising a combination of natural fibres and hybrid fibres reinforced homogenously in a matrix to form a biocompatible composite material, and fabricated to form the desired shape and size, said natural fibres having optimum proportions of banana fibre, sisal fibre and roselle fibre and hybrids of said natural fibres, such as herein described, said method involving : a) creating the desired mold; b) applying a releasing agent over a suitable sheet and fitting the same with the inner side of the mold and drying the same; c) adding calculated quantity of matrix material and hardener such as herein described in a suitably cleaned container and stirring the same for a suitable duration so as to create a homogenous mixture; d) adding calculated quantity of said fibers with simultaneous stirring for a suitable duration; e) pouring the mixture so obtained into the mold and ramming mildly for uniform settlement; f) solidifying the mold.
In accordance with preferred embodiments of the method of the present invention:
-said fibres are cleaned in running water, dried in normal shading for 2-3 hours, followed by soaking in a solution comprising 6% NaOH and 80% distilled water, said method of soaking the fibres are carried out at different intervals depending upon the desired strength to be achieved, followed by washing the fibres in running water and drying the same thereafter after each step of soaking;
-said bone implant is a natural fibre reinforced polymer composite material in bio epoxy resin and hardener resin and said step(e) in said method further includes, calculating the predicted thrust force and torque values of said natural fibre reinforced polymer composite material depending upon requirement and comparing said values with the regression model and the scheme delamination factor/zone applying machine vision system.
DETAILED DESCRIPTION OF THE INVENTION
Following describes some preferred embodiments and examples/test results which are purely for the sake of understanding the present invention and not by way of any sort of limitation.
To overcome the disadvantages of prior art, the present invention has developed new material to improve the quality of human life. Owing to the frequent occurrence of bone fractures, the present invention has developed a plate material for fixation on the fractured bone. The novelty of the invention is the natural fiber reinforced composite materials for bone implantation which can be adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture. That apart, the artificial bone implants/plates manufactured from this material, have been found to have improved tensile, flexural and impact strength. These plate materials are lightweight, allow stiffness, and biocompatible with humans/animals. Furthermore, the manufacturing cost is very low having regard to the simple methodology involved. This novelty and the associated technical advancement and economic significance are hitherto not reported.
The present invention concentrates on the progress of biomaterials in the field of orthopaedics, an effort to utilize the advantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers.
The present invention focuses on the enhanced properties of natural fiber as bone implant. It is a challenge to the creation of better materials for the improvement of quality of life.
The present invention applies natural fiber–reinforced composite as a plate material, which uses pure natural fibers that are rich in medicinal properties like Sisal (Agave sisalana), Banana (Musa sapientum) and Roselle (Hibiscus sabdariffa) fibers.
It focuses on fabrication of natural fiber powdered material (Sisal, Banana and Roselle) reinforced polymer composite [hereinafter referred to as NFRP at places] plate material with bio epoxy resin Grade 3554A and Hardener 3554B, instead of orthopaedics alloys such as titanium, cobalt chrome, stainless steel, and zirconium, this plate material can be used for internal and external fixation on human body for fractured bone.
It utilizes the advantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers.
The variation of mechanical properties such as tensile, flexural, and impact strengths of Sisal and banana (hybrid) at a ratio of 1:1, Roselle and banana (hybrid) at a ratio of 1:1 and Roselle and sisal (hybrid) at a ratio of 1:1 composite at dry and wet conditions were studied.
The experimental results are compared with theoretical results and found to be in good agreement. Also, the present invention advocates the prediction of thrust force and torque of the natural fiber reinforced polymer composite materials, and the values, compared with the Regression model and the Scheme of Delamination factor / zone using machine vision system.
Microstructures of the specimens were scanned by the scanning electron microscope, and composition analyzed by the electron dispersive thermodetector. It has been deciphered that the NFRP composite material coated by calcium phosphate and hydroxyapatite (hybrid) composite can be applied for both internal and external fixation on the human/animal body for fractured bone.
The present invention involves the preparation of the natural fiber reinforced composite material made of Agave sisalana fibers, Musa sapientum fibers and Hibiscus sabdariffal fibers which are used for bone implantation. The composite material is a mixture of Banana fibre reinforced composite, Sisal fibre reinforced composite, Roselle fibre reinforced composite, Sisal & Roselle (hybrid) fibre reinforced composite, Banana & Sisal (hybrid) fibre reinforced composite and Banana & Roselle (hybrid) fibre reinforced composite.
The fibers are cleaned normally in clean running water and dried in normal shading for 2–3 hours and mixed with the solution comprising 6% NaOH and 80% distilled water. The soaking of the fibers is carried out at different time intervals depending on the required strength of the fiber. After completing the soaking process, the fibers are taken out and washed in running water and dried for another 2 hours and then the fibers are taken for the next fabrication process, namely the procasting process.
The natural fiber reinforced polymer composite material according to the present invention coated by calcium phosphate and hydroxyapatite (hybrid) composite has been found to be applicable for both internal and external fixation on the human body for fractured bone.
The benefit of calcium phosphate biomaterials is that the dissolution products can be readily assimilated by the human body. Calcium phosphate is mainly used in filling defects (for example, areas of bone loss such as in tibial plateau fracture), in composite grafts to supplement auto graft, and at sites where compression (rather than tension, bending, or torsion) is the dominant mode of mechanical loading. Variation in the properties of calcium phosphate coatings has an effect on the bone-bonding mechanism and the rate of bone formation. Both the composition and the crystallinity of the calcium phosphate coating are important parameters that determine its bioactivity characteristics.
Hydroxy apatite is a class of calcium phosphate based bioceramic, frequently used as bone graft substitutes owing to its chemical and structural similarity with the natural bone mineral. Its chemical composition is given as Ca10(PO4)6OH)2. The young's modulus of HA ranges between 80-110 (GPa). The elastic modulus of HA is 114 GPa. Fracture toughness is predominant up to 0.7 to 1.2. Biocompatibility is high. Although HA is an excellent bone graft, its inherent low fracture toughness has limited its use in certain orthopaedic application, in particular heavy load bearing implantations.
The reinforced composite, according to the present invention is subjected to various tests such as Moisture Absorption Test, Flexural Test, Tensile Test and Impact Test, the crux of the results whereof are discussed hereinafter
The fabrication process consists of fabricating different composites combinations by using moulding method. The testing process consists of mechanical property testing.
MATERIALS AND METHODS
The matrix material used in this investigation is bio epoxy resin. Roselle, banana and sisal fibers have been used traditionally in high strength ropes in India especially in South India regions.
1) Chemical Treatment of said natural fibers The fibers are powdered. Then the fibers are cleaned normally in clean running water and dried. A glass beaker is taken and 6% NaOH is added and 80% of distilled water is added and a solution is made. After adequate drying of the fibers in normal shading for 2 to 3 hours, the fibers are taken and soaked in the prepared NaOH solution. Soaking is carried out for different time intervals depending upon the strength of fiber required. In this study, the fibers are soaked in the solution for three hours. After the fibers are taken out and washed in running water, these are dried for another 2 hours. The fibers are then taken for the next fabrication process namely the Procasting process.
2) Advantages of chemical treatment Chemical treatment with NaOH removes moisture content from the fibers thereby increasing its strength. Also, chemical treatment enhances the flexural rigidity of the fibers. Last, this treatment clears all the impurities that are adjoining the fiber material and also stabilizes the molecular orientation.
Moisture Absorption Test Procedure
Tensile, flexural and impact specimens as per ASTM standards were cut from the fabricated plate. Edges of the samples were sealed with polyester resin and subjected to moisture absorption. The composite specimens to be used for moisture absorption test were first dried in an air oven at 50 ◦C. Then these conditioned composite specimens were immersed in distilled water at 30 ◦C for about 5 days. At regular intervals, the specimens were removed from water and wiped with filter paper to remove surface water and weighed using a digital balance of 0.01mg resolution. The samples were immersed in water to permit the continuation of sorption until saturation limit was reached. The weighing was done within 30 s, in order to avoid any errors due to evaporation. The test was carried out according to ASTM D570 to find out the swelling of specimen. After 5 days, the test specimens were again taken out of the water bath and weighed.
Mechanical testing:
After moisture absorption tests, the tensile strength of the composites were measured with a universal testing machine in accordance with the ASTM D638 procedure at a crosshead speed of 2mm/min. Flexural tests were performed on the same machine, using the 3-point bending fixture according to ASTMD790 with the cross-head speed of 2 mm/min. In the impact test, the strength of the samples was measured using an Izod impact test machine. All test samples were notched. The procedure used for impact testing was ISO 180. The test specimen was supported as a vertical cantilever beam and broken by a single swing of a pendulum.
Finite Element Analysis
Analysis package using for Stress Analysis on Humeral Shaft along with plate: ANSYS 11.0. Computerized tomography scanning image [CT scan] of humerus bone in .stl file was converted in to .iges file and then imported to ANSYS for the stress analysis on humeral shaft with plate and without plate.
MANUAL CALCULATION
The project case is mainly for youngsters during the bike riding. The weight of the person was assumed to be around 60 kg. Assumption made Initial velocity of Vehicle V1 is 60kmph, Final velocity of Vehicle V2 is zero Mass of human body=60kg External diameter of bone [D] = 22 mm Internal diameter [d] = 11 mm Bending Stress on Solid Shaft:
σьmax = (32×Mmax) / (3.14×d³)
Bending Stress on Hollow Shaft
σь max = 32× Mmax ×D / 3.14 [D4 -d4]
σьmax –Maximum bending stress in N/mm2 Mmax - Maximum bending moment in N mm
ACCELERATION
a = (V2- V1) / ∆ t
Where
V1 – initial velocity
V2 – final velocity
∆ t – change in time
Then the deceleration is 16.66m/sec2
According to Newton’s Second Law:
Force (F) = m a
So, Force F= 1000N
Stress for Bone with Plate (Roselle and sisal (hybrid)) Weight of the plate: Volume of screw = Area×thickness×No of holes on plate = Π×r2×t×n = 226.08mm³ Volume of the plate =l×w×t =150×10×4.5 =6750mm3 Net volume = vol. of plate – vol. of screw
= 6976.08mm³
Weight of the plate per meter length = 0.000182N/mm
Conclusion
An artificial bone model was fabricated using ABS (Acrylonitrile Butadyine Styrene) by Rapid Prototyping Technology. This technique helps to analyze the actual bone structure and plate fixation can be done more accurately. Due to RP technologies doctors and especially surgeons are privileged to do some things which previous generations could only have imagined. However this is just a little step ahead. There are many unsolved medical problems and many expectations from RP in this field. Development in speed, cost, accuracy, materials (especially biomaterials) and tight collaboration between surgeons and engineers is necessary and so are constant improvements from RP vendors. This will help RP technologies to give their maximum in such an important field like medicine and new technologies can not only improve and replace conventional methods; they also offer the chance for new types of products and developing procedures. The stress analysis of humerus bone and fixation of plate for the fractured bone has been carried out with stainless steel, cobalt chrome, titanium, zirconium, Roselle and sisal (hybrid), Sisal and banana (hybrid) and Roselle and banana (hybrid). After plate fixation on humerus bone, the stress induced on the bone with plate and without plate is calculated both manually and using ANSYS software. In this research Sisal and Roselle fiber particle reinforced composite plate materials Thermal Heat transfer coefficient has been calculated manually and CFD, both the results are found to be good in agreement.
The materials used in this project are: 1) Banana fibre reinforced composite 2) Sisal fibre reinforced composite 3) Roselle fibre reinforced composite 4) Sisal & Roselle (hybrid) fibre reinforced composite 5) Banana & Sisal (hybrid) fibre reinforced composite 6) Banana & Roselle (hybrid) fibre reinforced composite
The selection of natural fibre strength, for manufacturing the bone implant preferably involves, calculating the predicted thrust force and torque values of said natural fibre reinforced polymer composite material depending upon requirement and comparing said values with the regression model and the scheme delamination factor/zone applying machine vision system.
As stated hereinbefore, to establish the improved traits of the composite material according to the present invention, being applied as an artificial bone implant experiments were carried out, results whereof have been discussed hereinbefore. Now, as discussed before, artificial bone model applied in the experiments is fabricated using ABS (Acrylonitrile Butadyine Styrene) by Rapid Prototyping Technology.
Hereinafter, for the sake of perspicuity only, the said Rapid Prototyping Technology( hereinafter referred to at places as RPT) is further elaborated. It presents in a non-restrictive manner the procedure for making a model of humerus bone using rapid prototyping technologies [RPT] and it is to be understood that other similar methodologies can also be applied, for establishing the uniqueness of the present invention. The methodology involves, using data obtained from CT images combined with digital CAD and rapid prototyping model for surgical planning and this new application enables the surgeon to choose the proper configuration and location of internal fixation of plate on humerus bone during orthopaedic surgery.
OVERVIEW Rapid Prototyping Technology (RPT), Solid Freeform Fabrication (SFF) or Layer Manufacturing encompasses a group of production processes. Unlike conventional production processes, which work in a subtractive manner (removing material from a raw block of material giving the final shape of the part), the RPT process builds up parts layer by layer.
The basic steps are the same for all technologies in RP: 1. Design: Create a 3D CAD solid model of the design 2. Converting: Convert the CAD model to STL format 3. Pre-Process: Slice the STL file into thin cross-sectional layers (generated by a dedicated Software) 4. Building process: Construct the model one layer atop another 5. Post-Process: Clean and finish the model
The CAD representation should be done using a 3D solid modeler. These CAD data are derived either from the design process or from a 3D measuring device’s point cloud or from computer tomography (CT). Most 3D solid modelers offer an interface to the STL file format that is used as input into the RP machines. The RP software packages slice the 3D model into layers; add support structures where necessary and the actual production can start. Rapid is a bit misleading for the actual manufacturing part of the procedure, as the part production will take hours and days rather than minutes as for the conventional process. What is really rapid is the fast start of the process as the part can be manufactured nearly without any additional programming tasks. Depending on the actual RP process used, more or less time consuming procedures are necessary for cleaning and in some cases post curing the finished parts. In addition to prototypes, RP techniques can also be used to make tooling (Rapid Tooling) and even production-quality parts (Rapid Manufacturing). For small production runs and complicated objects, rapid prototyping maybe the optimal manufacturing process available. Although RPT started with plastic materials, today there is a big choice of metallic and ceramic materials available for almost every major RP process.
RP technologies are applied here , in the experiments hereinbefore, as a multi- discipline area in the field of orthopaedics. Using RP in medicine is a quite complex task which implies a multidisciplinary approach and very good knowledge of engineering as well as medicine; it also demands many human resources and tight collaboration between doctors and engineers. After years of development rapid prototyping technologies are now being applied in medicine for manufacturing dimensionally accurate human anatomy models from high resolution medical image data. The procedure for making humerus bone model using RP technologies is also discussed.
As stated before, the present invention encompasses an effort to utilize the advantages offered by renewable resources for the development of Biocomposite materials based on biopolymers and natural fibers. It focuses mechanical and material properties of natural fibers that are used for bone grafting substitutes which is now becoming a great challenge for biomedical engineers. The prime object of the present invention is the preparation of the natural fiber reinforced composite material made of Agave sisalana fibers, Musa sapientum fibers and Hibiscus sabdariffal fibers which are used for bone implantation.
PROBLEM IDENTIFICATION Trauma is a major cause of death and disability in both developed and developing countries. The World Health Organization (WHO) predicts that by the year 2020, trauma will be the leading cause of years of life lost for both developed and developing nations. Now a days Trauma is mainly due to increase in population as well as increase in transportation. Due to that there is an increase in accidents that causes bone fracture of human body. Most of the bone fractures in day-to-day life occur in the humerus and femur bones. Machining of ORTHOPAEDIC ALLOY implants, with High Speed Machining, offers advantages, but also has its own disadvantages Titanium is currently used as bone replacements, but the implants are simple geometric approximations of the bone shape. Hence forth there are more chances of mismatches to occur between real bone and implants, which often causes stress concentrations and premature implant failure. More “conventional” machining of Titanium implants with 5-Axis High Speed Machining, which offers some advantages, but also has disadvantages. Mismatches can occur between real bone and implants often causing stress concentrations and premature implant failure.
Fused deposition modeling (FDM) The FDM process works as follows: First, a 3D solid model exported to the FDM QuicksliceTM software using the (STL) format. The concept is that an ABS filament is fed through a heating element, which heats it to a semi-molten state. The filament is then fed through a nozzle and deposited onto the partially constructed part. Since the material is extruded in a semi-molten state, the newly deposited material fuses with adjacent material that has already been deposited. The head then moves around in the x–y plane and deposits material according to the part geometry. The platform holding the part then moves vertically downwards in the z-plane to begin depositing a new layer on top of the previous one. After a period of time, the head will have deposited a full physical representation of the original CAD file of the humerus bone.
Materials There are varieties of materials which can be used for medical applications of RP. The material should be selected depends on the purpose of made model (planning procedures, implants, prostheses, surgical tools, tissue scaffold …), demanded properties of material for concrete application and the possibilities of the chosen RP technique. Materials must show biological compatibility.
RP medical materials include: • Photosensitive resins for medical application (STL); • Metals (stainless steel, titanium alloys, Cobalt Chromium alloys, other); • Advanced bioceramic materials (Alumnia, Zirconia, Calcium phosphate- based Bio-ceramics, porous ceramics) for LOM; • Polycaprolactone (PCL) scaffolds, polymer-ceramic composite scaffold made of Polypropylene-tricalcium phosphate (PP-TCP). PCL and PCL-hydroxyapatite (HA) for FDM, PLGA, starch-based polymer for 3DP, polyetheretherketone-hydroxyapatite (PEEK-HA), PCL scaffolds in tissue engineering for (SLS); • Bone cement: new calcium phosphate powder binders (mixture of tetra calcium phosphate (TTCP) and beta – tricalcium phosphate (TCP)), Polimethyl methacrylate (PMMA) material, other polymer calcium phosphate cement composites for bone substitutes and implants; • Many other biocompatible materials.
Acrylonitrile Butadiene Styrene (ABS): Acrylonitrile Butadiene Styrene, chemical formula: ((C8H8• C4H6•C3H3N) n) is a common thermoplastic used to make light, rigid, molded products. ABS plastic ground down to an average diameter of less than 1 micrometer is used as the colorant in some tattoo inks. It is a copolymer made by polymerizing styrene and Acrylonitrile in the presence of polybutadiene. The proportions can vary from 15 to 35% Acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene. The result is a long chain of polybutadiene criss-crossed with shorter chains of poly (styrene-co-Acrylonitrile). The nitrile groups from neighboring chains, being polar, attract each other and bind the chains together, making ABS stronger than pure polystyrene. The most important mechanical properties of ABS are resistance and toughness.
APPLICATIONS OF RAPID PROTOTYPING IN ORTHOPAEDICS Production of prototypes for medical modeling (orthopaedics) in general can be classified into two broad categories based on manufacturing process route and type of data available, i.e. designed data and scanned/digitized data. Designed data is data that is created according to a person's idea on computer aided design (CAD) system. For this type of data, the designer has total control to modify, adjust and manipulate his design ideas to serve the functional purpose of his design. Producing models with this type of data is very straightforward and no further data treatment is required. CAD solid model can be directly converted to STL format for use in subsequent rapid prototyping process.
Scanner or digitizer is normally used to capture structures that exist in physical form, either dead or living things, and using surface modeler software, three-dimensional CAD representation is created. For this type of data, the user has limited capability to modify and manipulate the geometry and further processing is required before they can be readily used by rapid prototyping system. For example, further data treatment is needed for Scanned data from computed tomography (CT) and Magnetic resonance imaging (MRI) scanners which capture soft and hard tissue information based on density threshold value. The undesired soft tissue data is removed before it is sent to rapid prototyping machine for fabrication.
Segregating soft tissue data and leaving only hard tissue (i.e. humerus bone) structure can be carried out by applying certain range of density threshold value. This procedure can be a daunting task for complex structure and one has to repeat the procedure many times until satisfactory result is achieved. There are a number of commercial software’s such as MIMICS, and Go-build which translate this data to the format required by RP systems. In reverse engineering method, point cloud data for an existing object is captured using coordinate measuring machine or laser digital surface scanner and using surface modeler, this raw data is processed to form three-dimensional model of the object in CAD system.
Data acquisition The morphological data of the humerus bone was collected using the above mentioned CTscanner. A 3D data set was acquired producing 119 sagittal slices with a slice thickness of 1 mm. The reconstructed CT data was transferred to a CD and loaded into the MIMICS software.
Software The humerus scanning data and model STL manipulation were processed using MIMICS and MAGICS RP Software.The modeling software is a general purpose segmentation programme for grey value images. This software can generate both the frontal and lateral view from the CT scans . From CT data 3D model of humerus bone has been created. RP made a real copy of the bone . The real copy was used for planning of orthopedic surgery especially choice of implant type, implant position and application procedure.
Planning and explaining complex surgical operations
This is very important role of RP technologies in medicine which enable pre-surgery planning. The use of 3D model of humerus bone helps the surgeon to plan and perform complex surgical procedures and simulations and gives him an opportunity to study the bone structures of the patient before the surgery, to increase surgical precision, to reduce time of procedures and risk during surgery as well as costs (thus making surgery more efficient). The possibility to mark different structures in different colors (due to segmentation technique) in a 3D physical model can be very useful for surgery planning and better understanding of the problem as well as for teaching purpose.
Teaching purposes RP models can be used as teaching aids for students in the classroom as well as for researchers. These models can be made in many colors and provide a better illustration of anatomy, allow viewing of internal structures and much better understanding of some problems or procedures which should be taken in concrete case. They are also used as teaching simulators.
PROCEDURAL STEPS FOLLOWED TO MAKE A MOLD BY INDIRECT TOOLING
Determine the approximate volume of plaster needed. Volume = length x width x height for rectangles. Prepare the proper amount of plaster and water to be mixed Cold water will give increased expansion (possibly making mold removal difficult) and slower setting time. Warm water will give less expansion and faster setting without problems. Prepare the molds or forms. Before begin mixing, arrange the containers for clean-up, molds or forms, and a container or cardboard box to dispose of excess plaster before it hardens in the bucket. Plaster releases well from leather-hard clay. For other materials, “size” the mold with mold soap (available from Ceramics suppliers) or several layers of a water-soluble release like Oil Soap (actually water-soluble). Using an oil-based releases like Vaseline will release, but the oils can block the mold pores and decrease absorbency of the mold. Mix by hand for 2-6 minutes or with a paddle for 1-2 minutes. It is recommended mixing with a paddle for several minutes and doing the last minute by hand. The plaster has begin to set, and a faint trail could be seen by the finger drag across the surface of the plaster. Tap the bucket several times to bring trapped bubbles of air to the surface. Plaster was set and ready to pour. Pour plaster slowly to avoid air bubbles or splashing. Tap the container or jiggle the table gently to release bubbles. Pour excess plaster on RP pattern of Humerus Bone. Pouring too early will allow the water in the plaster to degrade the mold soap and may cause release problems. Pouring too late may result in uneven plaster pours; it sets and reaches maximum expansion in about 20 minutes, then contracts slightly. It is a good idea, to wait at least an hour before taking molds apart to get two mold of (2 half of dies) the above process has been repeated. Clean up the mold Use a metal rib or Surform to round sharp edges. Molds should be dry before using. or the mold will become soft and chalky, and it will crumble easily. Make molds on a level, smooth surface (formica, marble, glass, linoleum). Use mold soap or Oil Soap to size the item to be cast and the inside of the cottle. Porous items has been sized several times.
A very important aspect according to the present invention is choosing the correct combination of natural and hybrid fibres. This is effected by calculating the values depending upon the prediction of thrust force and torque of the composite material, and comparing the values, with the regression model and the scheme of delamination factor zone using machine vision system
DELAMINATION
The advantage of the composite materials over conventional materials is that they possess high specific strength, stiffness, and fatigue characteristics, which enable structural design to be more versatile. Owing to the inhomogeneous and anisotropy nature of composite materials, their machining behavior differs in many respects from metal machining. In recent years, customer requirements have put greater emphasis on product development, with new challenges to manufacturers, such as machining techniques. Machining of composite materials requires the need for better understanding of cutting process with regard to accuracy and efficiency. Though near net shape process have gained a lot of attention, more intricate products need secondary machining to achieve the required accuracy. Drilling is the most frequently used secondary operation for fiber-reinforced materials.
Induced delamination occurs both at the entry and exit planes of the work piece. These delaminations could be correlated to the thrust force during the approach and exit of the drill. Delamination is one of the major concerns in drilling holes in composite materials. To understand the effects of the process parameters on delamination, numerous experiments have to be performed and analyzed mathematical models have to be built on the same. Modeling of the formation of delamination is highly complex and expensive. Hence, statistical approaches are widely used over the conventional mathematical models.
Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for joining fractured bone by means of plate material in the field of orthopedics.
NON-LIMITING ADVANTAGES OF THE INVENTION
1. The invention of natural fiber reinforced composite material is of light weight, allows stiffness and is biocompatible with humans.
2. The invention of natural fiber reinforced composite material is used for internal and external fixation on human body for fractured bone.
3. The usage of this invention of natural fiber reinforced composite material helps persons who need implants, to adapt to nature-feel implants and have a more pleasant life.
4. The invention of natural fiber reinforced composite material with chemical treatment of NaOH removes the moisture content from the fibers, thereby increasing their strength.
5. The chemical treatment of the composite material also enhances the rigidity of the fibers.
6. The chemical treatment of the composite material also clears all the impurities in the fiber material and also stabilizes the molecular orientation.
7. These natural fibers are used as a suitable reinforcing material to satisfy the environmental and they are now fastly emerging as a potential alternative for orthopaedics alloys.
From the foregoing description, with particular reference to the test results and the accompanying drawings, it will be clear to persons skilled in the art that the objects of the present invention are fulfilled by the present invention.
The present invention has been described with reference to preferred embodiments experimental results and drawings, purely for the sake of the understanding the invention and not by way of any limitation and the present invention includes all legitimate developments within the scope of what has been described hereinbefore and claimed in the appended claims.
WE CLAIM:
1. An artificial bone implant for its application in bone grafting, comprising a combination of natural fibres and hybrid fibres reinforced to form a biocompatible composite material in a homogenous matrix, and adapted to be fabricated to form the desired shape and size, said natural fibres having optimum proportions of banana fibre, sisal fibre and roselle fibre and hybrids of said natural fibres, such as herein described.
2. The artificial bone implant as claimed in claim 1 wherein said hybrids comprise optimum proportions of sisal fibre and roselle fibre, banana fibre and sisal fibre and banana fibre and roselle fibre.
3. The artificial bone implant as claimed in claim 2 wherein said sisal fibre is derived from Agave sisalana, said banana fibre is derived from Musa sapientum and said roselle fibre is derived from Hibiscus sabdariffa.
4. The artificial bone implant as claimed in claim 1 wherein said matrix comprises calculated quantity of bio epoxy resin and hardner resin.
5. The artificial bone implant as claimed in any preceding claim wherein said bone implant is a natural fibre reinforced polymer composite plate material in bio epoxy resin and hardener resin.
6. The artificial bone implant as claimed in claim 5 wherein said implant has a coating of calcium phosphate and hydroxyapatite (hybrid) composite for internal and external fixation on fractured bone.
7. The artificial bone implant as claimed in any preceding claim wherein said implant is adapted to have the desired substantial tensile, flexural and impact strength and is adapted to be fabricated and designed precisely, for perfect fitting on the desired location in a bone fracture.
8. A method for manufacturing an artificial bone implant for its application in bone grafting, said implant comprising a combination of natural fibres and hybrid fibres reinforced homogenously in a matrix to form a biocompatible composite material, and fabricated to form the desired shape and size, said natural fibres having optimum proportions of banana fibre, sisal fibre and roselle fibre and hybrids of said natural fibres, such as herein described, said method involving : a) creating the desired mold; b) applying a releasing agent over a suitable sheet and fitting the same with the inner side of the mold and drying the same; c) adding calculated quantity of matrix material and hardener such as herein described in a suitably cleaned container and stirring the same for a suitable duration so as to create a homogenous mixture; d) adding calculated quantity of said fibers with simultaneous stirring for a suitable duration; e) pouring the mixture so obtained into the mold and ramming mildly for uniform settlement; f) solidifying the mold.
9. The method as claimed in claim 8 wherein prior to said step (d), said fibres are cleaned in running water, dried in normal shading for 2-3 hours, followed by soaking in a solution comprising 6% NaOH and 80% distilled water, said method of soaking the fibres are carried out at different intervals depending upon the desired strength to be achieved, followed by washing the fibres in running water and drying the same thereafter after each step of soaking.
10. The method as claimed in claim 8 wherein said bone implant is a natural fibre reinforced polymer composite material in bio epoxy resin and hardener resin and said step (e) in said method further includes, calculating the predicted thrust force and torque values of said natural fibre reinforced polymer composite material depending upon requirement and comparing said values with the regression model and the scheme delamination factor/zone, applying machine vision system.
