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Project Completion Report
Development and Testing of Customized Joint
Replacement Implants Using Layered Manufacturing
Sponsored by Rajiv Gandhi Science and Technology Commission
Government of Maharashtra
2009-2014
Submitted by
Prof. A. M. Kuthe Principle Investigator
CAD-CAM centre, Mechanical Engineering Department
Visvesvaraya National Institute of Technology
South Ambazari Road,
Nagpur – 440 010
Content
Executive Abstract 3-4
1. Origin of the Project 5-7
a) Need of study
b) Review of work already done
5
6
c) Rational for taking up the project 6
d) Relevance to state priorities 7
e) Objective of the project 7
2. Data Generation 8-13
a) Anatomical data of people from central India 8
b) Data Acquisition 10
3. Implant manufacturing and Testing 14-23
a) Methodology to prepare Physical model using RP 14
b) Generation of 3-D volumetric model 14
c) Construction of RP model 15
d) Fabrication of metallic model 17
e) Software and Hardware 19
i. Mimics& 3-matic 19
ii. AutoCAST 19
iii. Induction furnace 20
iv. Implant testing machine for Static Load 22
v. Fatigue Testing Machine (FTM) 23
4. Case Study 24-32
a) Case Report: Background 24
b) Designing and customisation of MTPJ Implant 25
c) Analysis of design of Implant using FEM 28
d) Surgical Outcome 29
e) Follow ups and X-ray of patient post surgery 30
f) Conclusion 31
5. Deliverables 32-37
a) Website titled “ShalyaTantradnya” 32
b) Ph.D. Thesis 35
c) Technical papers 35
6. Impact & Recognition 38-39
a) Media Scope 38
b) Workshop and Seminars 39
7. Acknowledgment 40-41
Annexure –-I
Annexure –-II
Annexure –-III
Executive Abstract
Visvesvaraya National Institute of Technology (VNIT), institute of national importance,
has established CAD-CAM centre with state of art machineries. Rapid prototyping (RP)
machine in CAD-CAM centre is being used for medical applications in many areas like
building medical models, surgical planning and prostheses design to name a few. Using
rapid prototyping, it is possible to get 3D medical (physical) model directly from CT/MRI
images of body organ. Rapid prototyping is impacting medicine in several important
ways.
At CAD-CAM centre of VNIT, engineers and doctors are working together for handling
highly complicated cases of dislocation, deformities, fractures, tumours etc. in the areas
of orthopaedic, dentistry and oncology including paediatrics. Surgeons can
preoperatively visualise/communicate more details, plan/rehearse the surgical
procedures, reduce surgery time and iterations using the facility at CAD-CAM centre
The project titled “Development and testing of customised joint replacement using
layered manufacturing” was executed during the period 2009-2014 in CAD-CAM centre.
This project was sanctioned by Rajiv Gandhi Science and Technology Commission
Mumbai Govt. of Maharashtra. The technology to fabricate cost effective patient specific
metallic implant using layered manufacturing is developed under this project. The data
collected during the project shows need of customised implants for Indian patient as
design of standard implants are based on the data obtained from population of western
world. In the project report, sample case study of femur is discussed for deciding the
parameters for metallic implant for customisation. The use of layered manufacturing or
rapid prototyping assisted manufacturing helps design engineer and doctors to decide
parameters for customisation of implant and then manufacture the implant. Use of
casting simulation software to get the defect free casting, is also discussed in this
project.
In this project two machines for testing the implant are developed i.e. implant testing
machine for static loading and fatigue testing machine for dynamic loading.
During the project period, some live clinical case studies are also carried out. The case
study of design and development of implant for Metatarsophalangeal joint is discussed
in this project report. The technical papers based on the live clinical cases handled, are
published in reputed journals. The reference of the papers and abstract are included in
this project report.
The technology developed for design and manufacturing the customised metallic
implant is available to doctors and medical researchers through in house developed
website titled “Shalya Tantradnya”. The website is available in public domain and
doctors/surgeons can avail the facility at CAD-CAM centre for design and development
of metallic implant.
During the project period principle investigator delivered invited talk in reputed
institutes viz. IIT Bombay, Sree Chitra Tirunal Institute For Medical Sciences &
Technology Trivendrum, National Institute of Technology Warangal to name a few. The
institute abroad like Harvard-MIT Health Science and Technology Centre Boston USA,
SUNY Downstate Medical Centre & City University New-York USA have also appreciated
development of technology in this project.
The role of medical fraternity in the technology developed in this project is very crucial.
The readiness to use the technology by surgeons and strong backing from the
Government in the form of regulations for use of customised metallic implant will decide
the success of the project in long run.
In summary, this project is perfect amalgamation of engineering and medical science
where in technology is developed to make cost effective customised metallic implant
available in India.
Origin of the Project
a. Need of study
Presently in India, hip replacements and other joint replacements are carried out
using standard sized replacement parts selected from a range provided by
manufacturers, based on anthropometric data of western population. As it do not
replicate the Indian anatomy, possible complication due to this includes infection, blood
clotting, loosening, wear, dislocation, prosthesis breakage and nerve injury. Even the
Indian manufacturers (very limited number) have designed their prosthesis based on the
western standards or by copying the currently western designs. Western countries has
already moved to an era of implant design, that makes a segregation based on gender
but no company has yet taken into account the racial differences that may exist
between western population and Indian population. Although there have been no
specific accurate studies to document the anthropometric differences in Indian and
western population, most surgeons believe that many parameters specifically the neck
shaft angle and the shape of canal definitely varies.
Another non-technical, yet significant problem which is responsible for limited
use of this prosthesis in Indian population is their prohibitive cost. Most of the implants
are imported and hence expensive. Fractures, dealt by orthopedic surgeons,
maxillofacial and neurosurgeons have complex anatomy depending on the nature of
force applied and patients bone strength. Currently available imaging technology often
provides only two-dimensional images in two different planes. Owing to this some vital
details especially with respect to fracture configuration are missed. Use of 3D imaging
software currently used along with CT scan and rapid prototyping (RP) would allow
accurate reproduction of patients’ anatomy and clearly delineate the fracture pattern.
This would help in near accurate preoperative planning. The advantages will include
reduced surgical time, decrease blood loss, more accuracy in fracture reductions and last
but not least eliminated the need of long inventory during surgical procedure. 3D
models design and recreated using RP at Visvesvaraya National Institute of Technology
(VNIT) have been especially useful in achieving above goals while treating patients
suffering from acetabular fracture and complex articular fractures. The above objectives
1
are being handled by designing prosthesis based on normative anthropometric data of
Indian population or individual patient by CAD and RP followed by testing of implant for
its strength.
b. Review of work already done
The R&D initiative in Rapid Manufacturing for a bio-medical application is heavily
emphasized. Earlier studies support the use of a customized, cementless, computed
tomography-generated CAD/CAM (Computer-assisted design/ computer-assisted
manufacturing) prosthesis when preoperative planning indicates that an off-the-shelf
prosthesis cannot provide optimal fit or when excessive bone removal would be
required. Customized femoral componentsis recommended in case of revision surgery
with proximal femoral osteolysis, congenital hip dislocation, excessively large femurs,
grossly abnormal anatomy or when a fracture has occurred below the tip of a femoral
stem.
c. Rational for taking up the project
RP models are currently used in the collaborating hospital for managing trauma cases. It
has shown to reduce surgical timing, decrease blood loss and improve the accuracy.
Active participation of medical fraternity is likely to provide a strong impetus towards
converting technology into clinical use. There are bureau service centres in the Western
countries, which accept the scanned data of the bones and other parts of the patients
and deliver the bone implants/ models within stipulated time. The logistic difficulties
and high cost of these centres prevent Indian patients and medical professionals from
availing the services. Research in these areas will offer low cost but high quality services
in hospitals and medical laboratories in India. This will complement the skills of the
medical fraternity to serve their patients better. Due to the low cost of services in India,
we are emerging as a hub offering low cost medical care facilities for the world. At this
juncture, improving the skill sets of Indian medical fraternity with the RP tools will be
more appropriate than ever before.
d. Relevance to State priorities
Through this research the accident victims and patient suffering from bone disorders can
avail the low cost but quality implants in stipulated period. This service can reach in rural
areas as well. The students of medicine and other medical practitioners can get trained
in various relevant areas such as 3D reconstruction, Finite Element Analysis (FEA), etc.
These trainings could be on-the-job type, through seminars and workshops. Indigenous
development of costly imported equipment and special equipment for Indian conditions
will be taken up.
e. Objectives of the project
The aim of the project is to design an affordable implant, which will last at least for 10 to
15 years. This can be done when we address following issues:
1. Recreation of normal biomechanics by designing the customized implants ensuring
best-fit and accurate anthropometric simulation. This is possible by converting CT
(Computer Tomography) scan DICOM (Digital Imaging and Communications in
Medicine) image into CAD file accepted as input to rapid prototyping machine.
2. Ensure the biocompatibility of implants in patients.
3. Reduce the cost of manufacturing the implant by using indigenous technology.
Data Generation The X rays data from individual patient is taken on priority. As the deliverable of the
project is design& development of customised implant, it is thus necessary to decide the
parameter based on which customised implants are manufactured.
a. Anatomical Data of people from central India
Data related to hip joint of the patient is presented here as sample study. In human the
hip joint, formed by the upper end of the femur - the ball and a part of the pelvis called
acetabulum - the socket, referred as ball and socket joint. (Refer Fig.2.1). It is the largest
weight bearing joint in the body and is surrounded by strong ligaments and muscle.
The hip Joint is comprised of the following parts:
• Femur
• Femur Head
• Femur Neck
• Femoral Ligaments
• Acetabulum
• Femoral Head Ligament
Positioning is very important after surgery to reduce stress on the new joint and
displacement of the joint. The new hip will not have the same range of movement of the
original joint, although the patient should eventually be able to return to the previous
level of activity.
Fig. 2.1: Hip Joint Anatomy(Source: Electronic [L])
2
Trauma, bone tumours or arthritis are the main reasons for defects in Femur
bone. During the repair of femur fracture or resection of femur, removal of significant
portion of the femur bone may be required, which can make a patient disabled so the
provision of suitable bone substitute in restoration of the structural functions of the
hard tissue becomes significant.
An arthritic or damaged joint is removed and replaced with an artificial joint
called prosthesis. In case of injury/accident a thighbone called the femur gets fractured
(See Fig.2.2) it may lead to irreparable damage of the hip bone. Due to stress in the neck
part of the femur, it breaks and needs replacement by the implant. The goal is to relieve
the pain in the joint caused by damaged femur. The damaged ball (the upper end of the
femur) is replaced by a metal ball attached to a metal stem fitted into the femur.
Fig. 2.2: Femoral Neck Fracture (Source: Electronic [M])
Horizontal offset (HO), Neck shaft angle (NSA) and femoral head diameter (FHD)
are the parameter for customisation of implant. The self-explanatory Fig. showing HO,
NSA, and FHD is shown below.
Fig. 2.3: Geometrical dimensions of femur bone
b. Data Acquisition
The X-rays data of 296 patients from central India were collected. Out of which 204 and
94 were male and female respectively. Based on this data collection, the extreme values
of HO, FHD and NSA (Gender-wise) are shown in ANNEXURE-I. The statistical analysis of
collected data for men and women is shown in Table 2.1 and 2.2 respectively. The data
demonstrate that, the dimension of HO was marginally more in men (Max=4.6 cm) than
in women (Max=4.5cm) whereas the minimum dimension of HO in men was 2.7 cm and
in women it was 3.0 cm. NSA values (maximum and minimum) are larger in men than
that of in women. However the FHD in men and women were almost equal. The
variations in horizontal offset in male was more than that of female (Male range=1.9,
Female range=1.5). The range difference for NSA in the male and the female is very less
(only 1⁰) whereas the variation for FHD (Male range=1.9, Female range=1.7) was slightly
more in the male than in the female.
Table 2.1: Statistical analysis (Gender wise: Male)
(σ=Standard deviation)
Table 2.2: Statistical analysis (Gender wise: Female)
(σ=Standard deviation)
To establish the correlation between the dependent and independent parameters, the
dispersion should be less and the data should be assumed normally distributed. The age
factor was varying from the 35 to 70 years and hence the data was divided according to
the age group. The data collected was stratified into age groups of male and female
subjects to minimise the effect of variations and to get better agreement between
measured and predicted values of all parameters. The mean value of horizontal offset in
male of age group 51-60 was maximum (3.846cm) and in female of the same age group
also it was maximum with 3.815cm. For NSA maximum standard deviation (4.64⁰) was
observed in men of age group 61-70. The mean NSA was marginally lower in women
Statistical analysis of male patients
Measures HO (cm) NSA (⁰) FHD (cm)
Max 4.6 141 5.5
Min 2.7 125 3.6
Mean 3.8 132 4.3
Range 1.9 16 1.9
σ 0.45 3.8 0.40
Statistical analysis of female patients
Measures HO (cm) NSA (⁰) FHD (cm)
Max 4.5 138 5.4
Min 3 123 3.7
Mean 3.8 131 4.3
Range 1.5 15 1.7
σ 0.45 3.8 0.43
than men in all age groups. Femoral head diameter varied in similar way in male and
female with minimum of 3.7 cm and maximum of 5.5 cm (Table 2.3)
Table 2.3: Summary of measured dependent parameters from x-rays
Fig. 2.4 Variation in Neck shaft angle
Parameter Gender Age group No of hip Min Max Mean Standard
Horizontal
offset, HO (cm)
Male 35-50 17 3.0 4.5 3.81 0.45
Male 51-60 15 2.7 4.5 3.84 0.52
Male 61-70 16 3.1 4.6 3.81 0.42
Female 41-50 16 3.0 4.5 3.8 0.47
Female 51-60 13 3.1 4.5 3.81 0.45
Neck shaft
angle, NSA ( 0 )
Male 35-50 17 125 139 131.7 3.70
Male 51-60 15 125 137 131.6 3.41
Male 61-70 16 126 141 131.8 4.64
Female 41-50 16 123 137 131.2 3.89
Female 51-60 13 124 138 131.0 4.00
Femoral head
diameter
FHD (cm)
Male 35-50 17 3.7 5.5 4.33 0.41
Male 51-60 15 3.8 5.2 4.40 0.40
Male 61-70 16 3.6 5.1 4.33 0.41
Female 41-50 16 3.8 5.2 4.34 0.42
Female 51-60 13 3.7 5.4 4.30 0.46
Fig. 2.5 Variation in horizontal offset
Fig. 2.6 Variation in vertical offset
Implant Manufacturing and Testing The sample case study of fabrication of metallic model of femur is discussed in this
chapter
a. Methodology to prepare Physical model using RP
The methodology starts with a patient who has an injured/diseased femur (Fig. 3.1). A
CT scan of the damaged location before the accident is needed which is generally
unavailable. This was overcome by consideration of a mirror image of the corresponding
undamaged bone on the opposite side of the body. It is important to note that in case of
broken femur, bone replacement surgery required while in others conventional
approaches can resort back normal condition. The surgeon will screen the patient and
an acceptable case will be sent to the radiologist to carry out the novel manufacturing
system approach.
Fig. 3.1: Methodology for construction of proposed customised hip prosthesis
Computed tomography was selected as the choice for imaging technique. A CT scan,
performed on the patient (as a part of treatment) at 0° gantry tilt, is acquired using CT
scan to get point data of femur bone. The acquired data in DICOM format is transferred
to the Mimics (Materialise's Interactive Medical Image Control System) software
(Materialise, Leuven, Belgium) in order to reconstruct 3-D model of femur and to
convert DICOM format data into STL (Stereolithography) format.
b. Generation of 3-D volumetric model
The CT scan is processed by the segmentation. The soft tissues & the bone structures
images are separated by selecting the suitable threshold value. After region growing
scan contours are stacked upon each other and the final 3-D model is created.
Segmentation and editing tools enabled to manipulate the data to select bone, soft
tissue, skin etc. Once the area of interest is separated, it is visualised in 3-D and
3
Acquire
CT Data
Generate 3D
Volumetric
Model
Construct
RP Model
in ABS
Material
Preparation
of mould
Casting of
Implants using
Biocompatible
Material
Finishing
of Cast
prosthesis
converted to STL format. The 3-D volumetric model of the femur is shown in Fig. 3.2as
obtained by using Catalyst software.
Fig. 3.2: Creation of geometric modelling using Catalyst software
c. Construction of RP model
Fused Deposition Modelling (FDM) method is selected to fabricate 3-D physical model of
femur bone. The STL data is first pre-processed using Catalyst software supplied by FDM
manufacturer. The major processing steps are slicing, creating supports, and creating
tool-paths. Before building a part, it requires specification of the layer resolution, the
part surface quality, the part interior style, and support style. To build a RP model, layer
resolution, part interior and support style need to be selected. The construction of RP
model on FDM machine is shown in Fig. 3.3.
Fig. 3.3: Layer manufacturing on FDM machine
RP model of femur is extruded using FDM method is shown in Fig. 3.4. The material of
RP model is ABS (Acrylonitrile Butadiene Styrene) P 400 grade and the support
structures of same material is used for overhanging geometries and later removed by
breaking away from the object. ABS parts are sufficiently resistant to heat, chemicals,
and moisture that allows FDM parts to be used for limited to extensive functional
testing, depending upon the application.
Fig. 3.4: RP model of femur
d. Fabrication of Metallic model
Fig. 3.5: Photographs of mould preparation using RP model of femur as pattern
An ABS model of femur is used as a pattern for preparation of mould for sand casting. In
the moulding process sand is compacted around a pattern (RP model of femur) and the
pattern is removed, leaving a mould cavity as the shape of the pattern. A CO2 mould is
prepared to provide strength to the sand and alcohol based graphite paint is applied in
the mould cavity to get good surface finish. Fig. 3.5 and Fig. 3.6isself-explanatory and
shows the detail process of casting.
Fig. 3.6: Graphite painted mould ready for pouring
An induction furnace is used to prepare molten metal of biocompatible material metal.
Molten metal is then poured into the cavity to form the object (Refer Fig. 3.7).
Fig. 3.7: Pouring of Molten Metal
After cooling of cast metal, a very thin layer of femur is finished with abrasive polishing
to remove surface roughness only. Fig.3.8 shows a physical scaled model of metallic
femur.
Fig. 3.8: Cast metallic model of femur
e. Software and Hardware:
The software and hardware procured during the project are described below.
i) Mimics & 3-matic
Mimics software is used to accept CT scan or MRI data as an input for designing
customized implants. The medical data thus obtained will be refined and converted from
DICOM format to .STL format as an acceptable format for the RP machine. 3-matic
software developed by Materialise provides facility to combine CAD tools with pre-
processing (meshing) capabilities. It works on triangulated (STL) files and as such, it is
extremely suitable for organic/freeform 3D data such as the anatomical data resulting
from the segmentation of medical images (from Mimics). Since 3-matic makes it possible
to import CAD data as well as doing reverse engineering of anatomical data, it is a
perfect complement to researcher.
ii) AutoCAST Simulation Software
In order to get defect free casting part simulation of casting process using software is
done. A fully functional version of the AutoCAST-X software is useful for simulating and
improving the casting process by providing a virtual environment for designing the
molds, thereby helping to create optimum mold cavities.
Some important feature of AutoCAST simulation software is as follows:
AutoCAST software is meant for 3D methods design and optimization of casting.
Methods design mainly involves the following:
• Deciding the part orientation and parting line
• Designing cores to produce holes and undercuts
• Select the number of cavities and their layout in mould
• Designing feeder (riser) and feedaid (sleeves, chills, etc.)
• Designing the gating system (sprue, gates, runner, etc)
• Simulating mould filling and casting solidification to predict defect
• Optimizing the methods design to achieve the desired quality
The goal is to achieve the desired casting quality at the minimum cost (higher possible
yield) in the shortest time. Computer aided method and simulation provides the
following benefits:
• Saves foundry resources (material and energy otherwise required for trial)
• Allows early identification of potential problem, useful for improving part design
• Leads to better insight and faster optimization of even complex casting
• Enable comprehensive explanation to clients, and training new engineers.
AutoCAST cannot however replace the method engineer. It is only an intelligent
assistant and a virtual foundry, enabling casting engineers to perform their task better
and faster.
iii) Induction Furnace
To melt biocompatible material viz. SS316L, Co-Cr alloy induction furnace is installed in
CAD –CAM centre with the specification of 15 KW solid state power supply unit with DM
water circulating unit and 5 Kg single push out type for melting in Graphite Crucible.
The salient feature of induction furnace is as follows:
• Solid state power supply unit- This unit condition the incoming power suitable to
operate induction furnace. Incoming three phase supply at 50 Hz is converted
into a DC using a three phase rectifier.
• DM water circulation system- De-mineralized water is used for cooling various
components in a closed loop.
• Melting Furnace- Push out type aluminum frame furnace is manufactured with
energy efficient coil. The coil is made out of rectangular cross section electrolytic
grade copper. The gap between two turns of the coil is maintaining using
spacers. The coils are eclectically insulated by a special resign based coating. The
coil is firmly secured to insulating bars equally spaced around the coil periphery.
These bars provide mechanical strength against deformation during maintenance
and normal operation.
Fig. 3.9 Induction furnace at CAD-CAM centre VNIT, Nagpur
iv) Implant Testing Machine For Static Load
Machine setup for studying the hip implants under static loading condition of double
legged stance has been fabricated in house. This setup is helpful for determining the
stress concentration (using load cell and strain gauges) for static loading conditions. This
machine is fabricated as part of M. Tech thesis. Abstract is presented in Annexure II and
thesis will be made available on request.
Fig. 3.10 Implant testing machine for static loading condition
v) Fatigue Testing Machine
The machine for testing the hip implant under dynamic condition for different gait cycle
is fabricated in house. The machine is developed as part of M. Tech thesis. Abstract is
presented in Annexure II and thesis will be made available on request. The modification
in machine is in progress as part of Ph.D. research work.
Fig. 3.11 Fatigue Testing Machine
Case Study Rapid Prototyping Assisted Fabrication of the Customized
Metatarsophalangeal Joint (MTPJ) Implant (SamKu)
a. Case report: background
In this case a 30-years-old male broke the second, third and fourth MTP joint of the left
foot in an accident. The patient was being shown to orthopaedic surgeon; he fitted per-
cutaneous closed 3 k-wires for supporting the broken MTP joint (Fig. 4.1a). The k-wires
increases the incidence of painful stiffness of MTP joints, its use has no advantage
(Watson et al., 1974). But because of improper fixation of the joint the wear and tear
was taking place in the joint and joint surfaces got damaged. It is characterized by pain
as well as reduction in the range of motion, especially dorsiflexion, at the MTPJ, thus
affecting shoe wear, ambulation, and other activities of daily living. The Present case
study is highlighted with the help of following self-explanatory figure and tables.
Fig. (a) Fig. (b)
Fig. 4.1 (a) Radiograph of anterior-posterior view of diseased left foot with k-wires; (b)
radiograph of anterior-posterior view of diseased left foot after removal of k-wires after
weeks
4
Fig. 4.1 (c) Radiograph shows arthritis in 2nd, 3rd, and 4th MTP joint after 10 weeks
b. Designing and customization of MTPJ implant
1. Radiograph
2. 2D Sketching
3. Conversion of 2D sketch into 3D image file
4. Conversion into .STL format
5. Data imported into Catalyst Software of RP
machine
6. Slicing of 3D model
7. Feeding into RP machine
(a)
1. RP machine
2. Layer by layer manufacturing of RP model
3. Mould preparation using RP part
4. Baking of mould
5. Investment casting (using SS316L material)
6. Postprocessing using sandblasting
7. Burr smoothing
8. Rubber wheel cone polish
9. Finished implant
(b)
Table 4.1 (a) Approach of customized implant design; (b) approach of customized
implant manufacturing
Particulars Bone Size (mm)
Metatarsal Second Third
1) Head (radius) 9 8
2) Neck (radius) 2 2
3) Isthmus (radius) 1.5 1.5
4) Length 70 67
Proximal Phalange Second Third
1) Base (radius) 4 3
2) Neck (radius) 2.5 2
3) Isthmus (radius) 1.5 1
4) Length 38 37
Table 4.2 Dimensions of 2nd and 3rd metatarsals and phalanges has taken from
radiograph
(a) (b) (c)
Fig. 4.2 (a), (b), (c) Radiograph showing bone dimensions
Particulars Implant Size (mm)
Metatarsal Second Third
1) Head (radius) 3.9 3.9
2) Neck (radius) 2 2
3) Isthmus (radius) 1 1
4) Length 38 38
Proximal Phalange Second Third
1) Base (cup inner radius) 4 4
2) Neck (radius) 2.10 2.10
3) Isthmus (radius) 0.88 0.88
4) Length 20 20
Table 4.3 Implant dimensions based on the bone size
(a) (b)
Fig.4.3 2D drawing of MTPJ implant (SamKu) (a) metatarsal implant; (b) phalangeal
implant
(a) (b)
Fig.4.4 CAD model in Pro/E wildfire 4.0 (PTC) (a) metatarsal implant; (b) phalange
implant
(a) (b) (c)
Fig.4.5 (a) ABS model of Metatarsal implant developed using RP; (b) ABS model of
Phalange implant developed using RP; (c) Positioning of ABS model of MTPJ implant
(Samku)
(a) (b) (c)
Fig.4.6 Final MTPJ implant (SamKu) of SS316L (a) Metatarsal implant; (b) Phalange
implant; (c) Positioning of MTPJ implant (SamKu) after implantation
c. Analysis of design of implant using FEM
(a) (b)
(b) d)
(e)
Fig.4.7 (a) Loading and boundary conditions; (b) equivalent von mises stress; (c)
equivivalent elastic strain; (d) directional deformation (x-axis); (e) total deformations
d. Surgical outcomes
(a) (b) (c)
(e) (f) (g)
(h) (i)
Fig. 4.8 (a) Preoperative preparation; (b) marking of site; (c) incision and disection; (d)
drilling with the help of drill bit in 3rd metatarsal and phalange; (e) insertion of MTPJ
implant (SamKu) in 3rd metatarsal and phalange; (f) drilling with the help of drill bit in 2nd
metatarsal and phalange; (g) insertion of MTPJ implant (SamKu) in 2nd metatarsal and
phalange; (h) stiching; (i) MTPJ implant (SamKu) after operation
e. Follow-ups and X-Rays of patient post-surgery
(a)
(b)
(c) (d)
(e)
Fig. 9 Follow up after (a) 1 month; (b) 2 months; (c) 6 months; (d) 11 months; (e) 2 years
f. Conclusion
A RP technology has been shown to be a viable method for the pre-surgical planning and
the development of the customized implant. Post-operatively, the MTPJ implant
(SamKu) proved successful and presented no major difficulties. This is being the first
case; the patient is under regular follow up. The post-operative results are
overwhelmingly positive.
Note: On the above work the technical paper is published in RP journal volume 20 no. 4
pages 270-279.
Deliverables
a. Website titled “Shalya Tantradnya”
Shalya Tantradnya word is coined by amalgamating two words from Marathi language
श�य (Shalya) from श�य�व�या (Shalya Vidya) i.e. surgery and तं� (Tandradnya) means
technician or one who practices technology i.e. an engineer. The website (श�यतं�)
Shalya Tantradnya is dedicated to engineers & doctors who work in co-ordination and
serve the society by imbibing latest technical knowledge. The website can be reached on
mec.vnit.ac.in/st or through research (tag) on institute website www.vnit.ac.in. Fig. 5.2
shows information of principal investigator as seen on website. Information about
people associated throughout the execution of project is shown in Fig.5.3. The website
serves as link between CAD CAM centre and doctors. Doctors can utilize the facilities
developed as part of R&D project. Fig. 5.4 shows how doctor can access website for their
benefit.
Fig.5.1 http://mec.vnit.ac.in/st/ home page
5
Fig. 5.2 About Principal Investigator
Fig. 5.3. People associated with project
Fig. 5.4 Helpdesk for doctor
The information about the website is already communicated to around 150 hospitals
and medical colleges.
b. Ph. D Thesis
The Ph. D. thesis titled “A custom bone implantation using rapid prototyping” is
completed during the tenure of project. The data is collected by Tushar Deshmukh
during the project for Ph. D work. Prof. B. Ravi of IIT Bombay has examined the said
work. The said Ph. D thesis will be made available on request. The abstract is presented
in Annexure II.
c. Technical papers *
The list of technical paper published during the project is as follows:
Sr.
No. Title of the paper
Name of the
Journal/conference
Year of
publication
Name of
Authors
International Journals
1
Rapid prototyping assisted
fabrication of the
customized
metatarsophalangeal joint
implant (SamKu): A case
report
Rapid Prototyping
Journal, Volume 20
Number 4,
2014
A. M. Kuthe
Sameer
Raghatate
T. R. Deshmukh
S. W. Dahake
2
Rapid prototyping assisted
fabrication of the
customised
temperomandibular joint
implant : a case report
Rapid Prototyping
Journal,
Vol. 17, No. 5
2011
A. M. Kuthe
T. R. Deshmukh
D. S. Ingole
S. Chawre
V. Bagaria
3
Design and manufacturing of
customized femoral stems
for the Indian population
using rapid manufacturing
Journal of Medical
Engineering and
Technology Vol. 35,
No. 6-7,
Page 308-313
Oct 2011
A. M. Kuthe
T. R. Deshmukh
T. S. Madhugiri
4
Build orientation analysis for
minimum cost determination
in FDM
Journal of Engineering
Manufacturing
Proceed. of The
Institution of Mech.
Engineers, Vol. 225
10 Oct. 2011
A. M. Kuthe
D. S. Ingole
T. R. Deshmukh
K. M. Ashtankar
5
Prediction of femur bone
geometry using
anthropometric data of
Indian population: A
numerical approach
Journal of Medical
Science,
Vol. 10, No. 1
2010
A. M. Kuthe
T. R. Deshmukh
D. S. Ingole
S. B. Thakre
6
Preplanning and simulation
of surgery using rapid
modelling
Journal of Medical
Engineering And
Technology
4th March,
2010
A. M. Kuthe
T. R. Deshmukh
Vaibhav Bagaria
7
Rapid prototyping – a
technology transfer
approach for development
of rapid tooling
Rapid Prototyping
Journal, Emerald ,Vol.
15, Issue 4,
2009.
A. M. Kuthe
D. S. Ingole
A. A. Talankar
S. B. Thakre
8
Use of rapid prototyping and
three-dimensional
reconstruction modeling in
management of complex
International Journal,
Current Orthopaedic
Practice,
June 2009.
A.M. Kuthe
Vaibhav Bagaria
acetabular fracture
Vol.20, Issue 3 Shirish
Deshpande
National Journals
9
Design analysis of
customized femoral stems in
dynamic conditions for the
Indian population: A finite
element approach
Indian Journal of
Biomechanics,
Vol. 3, Issue 1-2
Dec 2012
A. M. Kuthe
G. V. Burele
S. W. Dahake
M. S. Kamble
10
Integrated approach for
fabrication of femur (i.e.
thigh bone) using Rapid
prototyping and casting
Foundry Journal,
Issue 126 Vol. XXI
No.06
Nov/Dec
2009
A. M. Kuthe
T. R. Deshmukh
D. S. Ingole
11
Application of the rapid
prototyping technique to
design a customized
temporomandibular joint
used to treat
temporomandibularankylosis
Indian journal of
Plastic surgery,
Vol 42 Issue 1
Jan/June
2009.
A. M. Kuthe
Vaibhav Bagaria
Suresh Chaware
* The abstract of the technical papers are shown in Annexure-III
Impact & Recognition
a. Media Scope:
During the project period, prominent personalities from society have shown lot of
interest in the R & D work. Newspaper clipping as appeared in Marathi paper
“Maharashtra Times” is shown below. The News refers the name of acting Vice-
chancellor of MUHS Dr. Nilima Kshirsagar.
6
b. Workshop and Seminars
The researchers in the field of technology were informed about the innovative work
carried out during the project period. Number of workshop & seminar were organised in
the CAD-CAM centre during the period. The Fig. below shows the front page of
proceeding of BIE 2013 “Workshop on Biologically Inspired Engineering” where in
Prof. Subhrata Saha Director of Biomedical Engineering Program, SUNY Downstate
Medical Centre, Brooklyn New York USA presented the keynote lecture.
7
Acknowledgment
It is a matter of great satisfaction and pleasure to present this project completion report
on “Development and Testing of customized joint replacement Implants Using Layered
Manufacturing”, sponsored by ‘Rajiv Gandhi Science and Technology Commission
(RGSTC)’, Government of Maharashtra, under the Scheme ‘Assistance for S and T
application’ (2009-2014). On the very outset of this project completion report; I would
like to extend my sincere & heartfelt obligation towards all the personages of RGSTC
Dr. Anil Kakodkar, Dr. Arun Sapre, Dr. P. D. Mujumdar and Dr. P. Dolas who have helped
me in this endeavour. Without their active guidance, help, cooperation &
encouragement, I would not have made headway in the project.
I express my earnest gratefulness to our institute directors during project period
Dr. S. S. Gokhale (2005-2009), Dr. C. S. Moghe (2010-2011), Dr. S. S. Gokhale (2011-
2012), Dr. Shreenivas Rao (2012-2013), Dr. Narendra Chaudhary (2013 – till date),
whose support has been an important factor for the success in entire project.
I also wish to thank Dean (R&C) Dr. O. J. Kakade and Dr. Suryawanshi who have always
supported me and accepted my work whole heartedly and been my inspiration.
I am grateful to all the Heads of the Mechanical Department during project viz. Dr. P. M.
Padole, Dr. A. Chatterji, Dr. I. K. Chopde and Dr. S. B. Thombre for their continuous and
unconditional support in my journey to complete this project in such a fruitful manner.
I take this opportunity to owe my thanks to Dr. Kishor Asthankar, Dr. Yogesh Puri and all
my faculty members and staff of mechanical engineering department for their
encouragement and able guidance at every stage of this report. I thank all the research
associates, assistance for their sincere work which led the project on success path.
I express my gratitude to all doctors Dr. G. M. Taori, Dr. Vaibhav Baparia, Dr. Suresh
Chavare and Dr. Sirish Deshpande (Central India Institute of Medical Science (CIIMS),
Nagpur) Dr. Datarkar (Datarkar Hospital, Nagpur) and Dr. Sameer Raghtate (Raghtate
Hospital, Nagpur) who have helped me by providing not only the facilities to carryout
clinical case studies but also a critical approach in order to make it a success.
I would also like to acknowledge with much appreciation the crucial role of Ph. D
Scholars viz. Mr. Tushar Deshmukh, Mr. Dilip Ingole, Mr. Baiju Tharakan, M. Tech and
B. Tech students during the tenure of the project without which it would have been just
a trance.
I am obliged to Mr. R. Dixit, Mr. Pendam, Mr. Vinod Mandurkar and Mr. Bhaskar
Rasekar the office staff at Mechanical Department, VNIT, Nagpur for their valuable
support.
I specially thank Mr. Ashutosh Bagde and Miss. Shraddha Jaiswal for the efforts in
compilation of this project report.
Any omission in this brief acknowledgement does not mean lack of gratitude.
Dr. A. M. Kuthe
Principal Investigator
Annexure-I
(X-rays showing extreme values of HO, FHD
and NSA (Gender-wise))
X-rays showing extreme values of HO, FHD and NSA (Gender-wise)
Patient’s age: 55M
Weight: 72 Kg
Height: 169 cm
Parameters measured:
HO: 2.7 cm FHD: 5.2 cm NSA: 135°
Patient’s age: 47M
Weight: 80 Kg
Height: 179 cm
Parameters measured:
FHD: 3.7cm HO: 4.4 cm NSA: 132°
Patient’s age: 71M
Weight: 68 Kg
Height: 163 cm
Parameters measured:
HO: 4.6 cm FHD: 4.9 cm NSA: 133°
Patient’s age: 42M
Weight: 67 Kg
Height: 163cm
Parameters measured:
FHD: 5.5 cm HO: 3.7 cm NSA: 131°
136 165
175 116
Patient’s age: 41M
Weight: 80 Kg
Height: 181 cm
Parameters measured:
NSA: 125° HO: 3.9 cm FHD: 3.9 cm
Patient’s age: 45F
Weight: 57 Kg
Height: 150 cm
Parameters measured:
HO: 3.0 cm FHD: 3.9 cm NSA: 136°
Patient’s age: 66M
Weight: 82 Kg
Height: 176 cm
Parameters measured:
NSA: 141° HO: 3.1 cm FHD: 4.2 cm
Patient’s age: 52F
Weight: 62 Kg
Height: 161 cm
Parameters measured:
HO: 4.5 cm FHD: 3.7 cm NSA: 124°
13 44
11 20
Patient’s age: 52F
Weight: 62 Kg
Height: 161 cm
Parameters measured:
FHD: 3.7 cm HO: 4.5 cm NSA: 124°
Patient’s age: 41F
Weight: 56 Kg
Height: 157 cm
Parameters measured:
NSA: 123° HO: 4.5 cm FHD: 4.2 cm
Patient’s age: 57F
Weight: 47 Kg
Height: 149 cm
Parameters measured:
FHD: 5.4 cm HO: 4.3 cm NSA: 130°
Patient’s age: 57F
Weight: 52 Kg
Height: 159 cm
Parameters measured:
NSA: 136° HO: 3.1 cm FHD: 4.1 cm
2 38
44 33
Annexure-II(Abstracts of Ph. D & M. Tech thesis)
Ph. D Thesis (2010)
A Customized Bone Implantation Using Rapid Prototyping
Tushar Ramkrishna Deshmukh
Abstract
The development of the prototypes has passed through the phases; mainly manual
prototyping, virtual or soft prototyping and rapid prototyping (RP). It is an important and
essential part of the product development. The most important thing about RP is that,
the parts are built in one step, directly from geometric model of the part to be
manufactured. Fused Deposition Modeling (FDM) creates 3- dimensional functional
prototypes from P400 grade acrylonitrile butadiene styrene resin. It was recognized
quite early that rapid prototyping could bring great improvements to the fields of
prosthetics and implantation. The ability to create free form surface and hidden features
makes RP an ideal technology for medical implants. The research work aims to study the
medical application of RP and related issue by identifying problems related to present
implants. The work is accomplished by fabricating a metallic model of femur using RP
and casting techniques. The other application of RP as a pre-planning tool in case of
complex surgeries is also successfully explored. The medical application of RP is
explained with the help of case study of temporomandibular joint applying RP in
designing and fabricating customized implant. The application finite element analysis as
an optimization tool in deciding optimum size of the implant is also carried out. The
study of anthropometric parameters for documenting variations in femur geometry and
formulating mathematical model for prediction of femur geometry as a baseline for
selection of medical implants is also investigated. Conclusions are drawn and these can
be tested further and refined by future research work. It is interesting to note that, the
technology has shown enormous potential in eliminating the tedious and time
consuming steps of traditional prostheses fabrication.
M. Tech Thesis (2013)
Fatigue and Fracture Analysis of Hip Joint Implant during Gait Cycle
Apar Bhatnagar
Abstract
This project describes a simple approach to the fatigue and fracture testing of hip joint
implant during gait cycle. A fatigue testing machine for the implant is designed as a part
of project and performance of material is characterized by an S-N curve. Fatigue testing
of hip implant used to determine the endurance properties by simulating the dynamic
loading of the implant during gait cycle. A customized implant is used during testing
whose data is collected from the previous records and is patterned with the help of
rapid prototyping machine after which the final component can be casted for testing.
The practical difficulties with fatigue testing are twofold:
Firstly, any specimen must be subjected to a large number of loading, and due to the
statistical scatter in the data a large number of samples must be tested with certain
frequency, since low frequency loading may take considerable time to reach the desired
cycle of interest.
Fatigue is the progressive and localized structure damage that occurs when a material is
subjected to cyclic loading and unloading. When the loads are above a certain threshold,
microscopic crack will begin to form at the surface and eventually a crack will reach a
critical size and the structure will suddenly fracture.
Fracture is so developed on the hip implant will detected with the help of non-
destructive testing method i.e. either by liquid penetrant testing or by ultrasonic testing
methods
M. Tech Thesis (2011)
Evaluation & measurement of stresses in customized femur implant in double
legged stance position
Dheeraj Shankarrao Bhiogade
Abstract
The main purpose in this project is to offer a choice for customized prosthesis or implant
which is purely design and developed for particular patient, this project gives them
flexibility for selection of best implant which gives an optimal fit and avoiding of re-
surgery. The customized implant data is collected from old records or X rays, CT scan,
MRI scan which helping to generate geometric model using Unigapies NX, CATIA,
implant manufacturing and experiment i.e. physical testing.
Simulate actual situation with experimental setup. Develop finite element modelling
procedure of current available hip prostheses Analysis of standard and customized
implant in static loading using ANSYS. For a different combination of joint reaction forces
(JRF). Project includes design, modelling and development of experimental setup for
femur bone and its implant. For validation of customize implant. The value of the neck
shaft angle were 5-6° more in Indian population, material used to manufactured
implants is stainless steel 316L.
The finite element analysis is validating with the help of experimental analysis, this
thesis included the detail procedure of analysis and experiment. This thesis chapter no.8
can be use as a manual for experimentation purpose.
This tensile work offer to an Indian surgeon, from this project the customized implant
manufacturing will start in India itself. In this thesis there were four software used, NX-6,
Pro-E, ANSYS &AutoCAST-X.
Annexure-III (Abstracts of technical paper published)
1. Rapid prototyping-assisted fabrication of the customized metatarsophalangeal
joint implant (SamKu) A case report
Abstract
Purpose– The main purpose of this paper is to report the
successful treatment modality for patients suffering from
arthritis of the metatarsophalangeal joint (MTPJ) of the foot
which otherwise could not be treated through traditional
surgeries.
Design/methodology/approach– The unique capabilities of the
computer-aided design and the rapid prototyping (RP)
technology are used to develop the customized MTPJ implant (SamKu).
Findings– This approach shows good results in the fabrication of the MTPJ implant.
Postoperatively, the patient experienced normalcy in the movement of the MTPJ of the
foot.
Practical implications– Advanced technologies made it possible to fabricate the
customized MTPJ implant (SamKu). The advantage of this approach is that the physical
RP model assisted in designing the final metallic implant. It also helped in the surgical
planning and the rehearsals.
Originality/value– This case report illustrates the benefits of imaging/computer-aided
manufacturing/RP to develop the customized implant and serve those patients who
could not be treated in the traditional way. This is a pioneered attempt toward
implementation of a customized implant for patients suffering from arthritis of the
MTPJ.
Keywords: Rapid prototyping, Custom implant, Computer-aided modeling, Medical
treatment, SamKu
Paper type: Research paper
2. Rapid prototyping assisted fabrication of the customised temperomandibular
joint implant : a case report
Abstract
Purpose - The purpose of this paper was to find a successful
treatment modality {or patients suffering from
temporomandibular joint (TMl) ankylosis who could not be
treated through traditional surgeries.
Design/methodology/approach - This work integrated the
unique capabilities of the imaging technique, the rapid
prototyping (RP) technology and the advanced
manufacturing technique to develop the customised TMJ implant. The patient
specific TMJ implant was fabricated using the computed tomography scanned data
and the fused deposition modeling of RP for the TMJ surgery.
Findings - This approach showed good results in fabrication of the TMJ implant.
Postoperatively, the patient experienced normalcy in the jaw movements.
Practical implications - Advanced technologies helped to fabricate the customised
TMJ implant. The advantage of this approach is that the physical RP model assisted
in designing the final metallic implant. lt also helped in the surgical planning and
the rehearsals.
Originality/value - This case report illustrates the bene{its of imaging/computer-
aided design/computer-aided manufacturing/RP to develop the customised implant
and serve those patients who could not be treated in the traditional way.
Keywords: Computer aided modelling, Rapid prototyping, Custom implant Medical
treatment, Surgery
Paper type: Case study
2. Design and manufacturing of customized femoral stems for the Indian population
using rapid manufacturing
Abstract
Joint replacement surgeries in India primarily involve the use of
conventional implants, also referred to as ‘standard implants’.
There has been a little awareness about the possibility of using
customised implants for such surgeries. Although standard
implants from various biomedical companies are easily available
in the Indian market, they are expensive and rarely conform to
patient’s anatomy. Studies in the past have shown that there
are anatomical variations in the hip joint for different ethnic backgrounds and
geographical locations.
This article evaluates the feasibility of using custom-manufactured hip implants and
presents a comparison between the former and standard implant from stress reduction
point of view.
Two CAD models of femoral stems – one from standard sized hip implant available in the
market and other from customised hip implant designed as per parameters from a
radiograph (specific to the patient’s anatomy) – are used for evaluation. Finite element
analysis was carried out for a double-legged stance.The comparative study indicated
lesser stresses in head and neck region of the customised femoral stems than the
standard implant.
The study suggests design feasibility of customised implants for the Indian population
owing to reduction in stresses in the implant.
Keywords: Customised hip implants, Finite element, Femoral stems, CAD, Indian
population, Rapid manufacturing
3. Build orientation analysis for minimum cost determination in FDM
Abstract
The main idea behind this paper is to highlight efforts made to improve the application
potential of the fused deposition modelling (FDM) process by
producing the rapid prototyping parts at minimum cost. Build
orientation analysis for prismatic, curved boundary, and complex-
shaped parts is carried out. The mathematical model is
formulated to estimate the total cost of part preparation in FDM.
Optimal part build orientation and the values of parameters
resulting in the minimum total cost of parts preparation are
identified. The parts produced by the FDM rapid prototyping process are considered for
build orientation analysis. The concept can be extended for parts produced with any
layered manufacturing process. This is the first attempt to deal with diversified types of
part geometries and formulate a universal cost model applicable for all types of parts to
determine minimum cost in FDM.
Keywords: Rapid Prototyping, FDM, Build Orientation, Optimization
4. Prediction of femur bone geometry using anthropometric data of Indian
population: A numerical approach
Abstract
The development and validation of a generic model to get
preliminary idea about various components of geometry of the
femur using mathematical method was presented. The synthesis
of the generic model requires the following steps: acquisition of
anthropometric data of the patients; x-ray images of hip joint of
the patients; measurement of various components of the femur;
creation of model using mathematical method; validation of the
model. From the results it was apparent that, the geometry of the femur can be
obtained through anthropometric data using mathematical approach. The results
showed that, the correlation obtained in the age group of 51-60 (M) was better than
other age groups of the same category. There was no significant difference between the
correlation obtained in male and female categories. The measured values and values
obtained through mathematical models showed good correlation. The generic models
were validated by comparing observed values with the calculated values and the
agreement found was qualitative.
Keywords: Modelling, Fumul, Nemerical Method, bone , geometry.
5. Preplanning and simulation of surgery using rapid modelling.
Abstract
Rapid prototyping (RP) is increasingly being used for solution of
many problems associated with biomedical engineering. RP
quickly delivers prototypes that are constructed in an additive,
layer-by-layer process driven by three-dimensional computer
aided design (CAD) data. The aim of this work was to
demonstrate that surgery for acetabulum fracture can be
significantly facilitated through the use of a method based on
advanced imaging techniques and the RP technique. A case of
complex acetabulum fracture was reported, and application of computed tomography
(CT) images, CAD and RP were explored. Modelling of the fractured part helped in
preplanning and simulating the surgery and saved surgery time. The method allowed
feedback action at most steps of the surgery process, thus permitting an important time
saving during surgery.
Keywords: Imaging, Rapid prototyping, Acetabulum
6. Rapid prototyping – a technology transfer approach for development of rapid
tooling
Abstract
Purpose – The purpose of this paper is to apply rapid prototyping
(RP) philosophy as a technology transferin industries to take its
time and cost-effective advantages for development of rapid
tooling (RT).
Design/methodology/approach – Experimentations are
performed for development of RT for sand casting, investment
casting and plastic moulding applications.
Findings – This paper reports the procedures developed for manufacture of production
tooling using RP. A cost/benefit model is developed to justify implementation of RP as a
technology transfer in industries.
Research limitations/implications – The examples are limited to parts build by fused
deposition modelling RP process. However, the concepts experimented may be applied
for other RP processes.
Practical implications – RP has proved to be a cost-effective and time-efficient approach
for development of RT, thereby ensuring possibility for technology transfer in casting as
well as plastic industries.
Originality/value – This is the pioneer attempt towards quantifying RP benefits, in view
of technology transfer. This paper presents original case studies and findings on the
basis of experimentations performed in foundries.
Keywords: Rapid prototyping, Machine tools, Cost-benefit analysis
Paper type: Case study
7. Use of rapid prototyping and three-dimensional reconstruction modelling in
management of complex acetabular fracture
Abstract
Background:-The production of a copy of the fracture or a
deformity in a bone with a complex geometry can be one of the
important applications of the integration between two modern
computer-based technologies, reverse engineering (RE) and
rapid prototyping (RP).
Methods-This article reviews recent development in this field and present a case series
about the use of medical CT/MRI scanning, three-dimensional reconstruction,
anatomical modeling, computer-aided design, RP and computer-aided implantation in
treating a complex fracture of acetabulums, calcaneum, and medial condyle of femur
(Hoffa's fracture).
Conclusion-The use of RP technology helped us to understand the fracture
configuration and to achieve near anatomical reduction. With this we believe, this
technology will reduce the surgical time as was observed in our cases. This
consequently, will lower the requirement of an anesthetic dosage and decrease the
intraoperative blood loss.In summary, the merging of computational analysis, modeling,
designing, and fabrication will serve as important means to treat conditions and
fractures around joints, spine, acetabulum, and craniofacial region.
8. Design analysis of customized femoral stems in dynamic conditions for the Indian
population: A finite element approach
Abstract
The use of conventional implants also called as standard
implants are common in joint replacement surgeries in India.
The awareness of the concept of customized implant has been
found very less. Although standard implants from various
biomedical companies are easily available in the Indian market,
they are expensive and rarely conform to patient’s anatomy.
Past anthropometric studies have proved that people from
different ethnic background and belonging to geographical locations exhibit anatomical
variations. Every human being is unique in terms of skeletal geometry. This article
evaluates the feasibility of using custom-made hip implants and presents comparisons
between the former and standard implant from stress reduction point of view by using
finite element approach. Two CAD models of femoral stems - one from standard sized
hip implant available in the market and other from the customized hip implant designed
as per parameters from the radiograph (specific as per patients anatomy) – are used for
the evaluation. In this paper a dynamic model of the human femur during the gait cycle
was developed. Finite element analysis was carried out for different activities like slow
walk, normal walk, fast walk, upstair, downstair, standing up, standing down, standing
on 2-1-2 legs, knee bend, and, jogging. The comparative study indicated lesser stresses
in head and neck region of the customized femoral stems than the standard implant.
The study suggests design feasibility of customized implants for the Indian population
owing to reduction in stresses in the implant.
Keywords :Customized hip implant, CAD, finite element analysis, modelling, dynamic
conditions
9. Integrated approach for fabrication of femur (i.e. thigh bone) using Rapid
prototyping and casting
Abstract
Casting is a conventional method of fabrication of complex
components, and rapid prototyping is an advanced technique used
for producing physical models. The aim of this work was to find the
feasibility and suitability of rapid prototyping and casting
technologies to work together for medical applications. The
primary concern is the to reproduce implant of external design
similar to human bone, which has to meet dimensional
requirements. This paper illustrates the novel approach of fabrication of femur with the
help of experimental investigations.
10. Application of the rapid prototyping technique to design a customized
temporomandibular joint used to treat temporomandibularankylosis
Abstract
Anthropometric variations in humans make it difficult to replace
a temporomandibular joint (TMJ), successfully using a standard
“one-size-fits-all” prosthesis. The case report presents a unique
concept of total TMJ replacement with customized and modified
TMJ prosthesis, which is cost-effective and provides the best fit
for the patient. The process involved in designing and
modifications over the existing prosthesis are also described. A 12-year- old female who
presented for treatment of left unilateral TMJ ankylosis underwent the surgery for total
TMJ replacement. A three-dimensional computed tomography (CT) scan suggested
features of bony ankylosis of left TMJ. CT images were converted to a sterolithographic
model using CAD software and a rapid prototyping machine. A process of rapid
manufacturing was then used to manufacture the customized prosthesis. Postoperative
recovery was uneventful, with an improvement in mouth opening of 3.5 cm and painless
jaw movements. Three years postsurgery, the patient is pain-free, has a mouth opening
of about 4.0 cm and enjoys a normal diet. The postoperative radiographs concur with
the excellent clinical results. The use of CAD/CAM technique to design the custom-made
prosthesis, using orthopaedically proven structural materials, significantly improves the
predictability and success rates of TMJ replacement surgery.
Keywords: Ankylosis, CAD, Rapid prototyping, Temporomandibular joint, Total joint
replacement
CAD-CAM Centre, Mechanical Engineering Department
Visvesvaraya National Institute of Technology South Ambazari Road,Nagpur – 440 010
Website:-www.vnit.ac.in
