Advances in Bioscience and Biotechnology, 2011, 2, 68-74 ABB
doi:10.4236/abb.2011.22011 Published Online February 2011 (http://www.SciRP.org/journal/abb/).
Published Online February 2011 in SciRes. http://www.scirp.org/journal/ABB
Use of Image processing software in Hip Joint surgery
Rashmi Uddanwadiker
Department of Mechanical Engineering Visvesvaraya National institute of technology
Received 10 January 2011; revised 1 February 2011; accepted 9 February 2011.
ABSTRACT
The scope of this project was to investigate the possi-
bility of application of Image Processing Technique
in the field of Shaft Alignment process. Misalignment
of shaft using image processing software Vision-
builder was calculated. The further purpose of this
project was to check whether the image processing
technique can be used in bone transplant surgery.
The model of the hip was used for the experimenta-
tion purpose. Image processing software Vision-
builder was used to match the profiles of the bone
before implant and bone after implant.
Keywords: Image Processing; Shaft Alignment; Hip
Joint; Bone Transplant
1. INTRODUCTION
Shaft alignment is the positioning of the rotational
centers of two or more shafts such that they are
co-linear when the machines are under normal operat-
ing conditions [1]. On the contrary Shaft Misalignment
as shown in Figure 1 is the condition of two shafts
which are connected but not adequately aligned to
one-another which can cause increased vibration and
loads on the machine parts for which they have not
been designed. The misalignment may directly affect
mechanical reliability. When shafts are misaligned,
harmonic forces are generated; these forces can pro-
duce great stresses on the rotating and stationary com-
ponents.
It further creates dynamic stresses in adjacent com-
ponents causing damage to the assembly.
Life of the bearings is affected by increased forces due
to misalignment [2].
According to the centerlines there are two types of
misalignment: parallel and angular misalignment. In
Parallel Misalignment, the centerlines of both shafts are
parallel but they are offset. Angular Misalignment arises
when the shafts are at an angle to each other as shown in
Figure 2.
Errors of alignment can be caused by parallel mis-
alignment, angular misalignment or a combination of
the two. To check the misalignment a conventional
procedure is using a fast align kit which can measure
and rectify the misalignment.
2. FASTALIGN KIT
Figure 3 shows FASTALIGN kit model FAC-5 and
FAC-5H with AC/DC power supply is used to align the
shafts which are mounted on the fixed machine and
other moving machine. While performing alignment, it
is usual to keep one of the machine (either Driver or
Driven) “undisturbed” or “fixed”. The other machine
will be “shimmed” or “moved”.
The machine which is kept undisturbed is called the
“Fixed Machine or FM” and the machine which is
shimmed or moved is called the “machine to be
shimmed or MTBS”. In the case of motor driven equip-
ment, normally the motor will be MTBS and the driven
equipment will be the FM.
2.1. Principles of Alignment
To achiev e co-axiality, alignment must be done in planes
vertical plane and horizontal plane. The procedure for
vertical plane alignment and horizontal plane alignment
is the same; but, in the vertical plane alig nment, the dial
gauge reading taken at vertical plane will be used and
vice versa. Initially, Vertical plane alignment must be
done as this involves adding and removing of shims.
When the vertical plane alignment is over, alignment
reading are checked to be ‘within limits’ in the vertical
plane then the ‘horizontal plane alignment’ must be
started. The entire procedure is very time consuming and
still may lead to approximate alignment. The perfect
alignment depends on the skill of the operator, mounting
of dial gauge, monitoring the dial gauge accurately etc.
With the help of Vision builder software the precision in
alignment can be obtai ned
Vision Builder is software developed by National In-
struments (NI). With Vision Builder AI, one can easily
configure, benchmark, and deploy a vision system that
addresses vision applications from pattern matching to

R. Uddanwadiker / Advances in Bioscience and Biotechnology 2 (2011) 68-74 69
Figure 1. Shaft misalignment.
Figure 2. Types of Misalignments.
Figure 3. Fastalign kit
code reading and presence detection to precision align-
ment and classification.
Additionally, images can be acquired and processed
with any NI frame grabber, Compact Vision System,
Embedded Vision System, Smart Cameras as well as
GigE Vision, IEEE 1394 cameras, and USB DirectShow
cameras
2.2. Shaft Alignment Using Vision Builder VB
In the present research, Vision Builder Software was
used for calculating the misalignment on the shafts. Us-
ing Visionbuilder, linear and angular misalignment be-
tween two shafts was found by a MATLAB program. It
was thereby corrected by taking iterations. The software
gave different parameters about shaft like horizontal
distance between shafts, angle between them etc.
Initially the shafts were covered with white paper and
2 black dots were marked on it. The image of the setup
was captured and imported in Vision Builder. Then the
programme was required to process the image and find
out minute details. The programme consisted of setting
up color range. After processing the image the software
gives values of bo th angu lar an d lin ear misalign ment [3].
Subsequently misalignment was corrected by putting
shims in the setup and the process was repeated in Vi-
sion Builder to check the misalignment.
Figure 4 shows the two shafts with two black dots on
each shaft which was used as an image to be processed
in Vision Builder. Various images were taken of mis-
aligned shaft and after the shaft had been adjusted ac-

R. Uddanwadiker / Advances in Bioscience and Biotechnology 2 (2011) 68-74 70
Figure 4. Experimental setup.
cording to the misalign ment given by the software.
2.3 Observations
Figure 5 (a) and (b) shows the captured image and the
program showing the misalignment. After importing the
image of misaligned shaft in Vision Builder following
results were obtained:
Angle between the two sha ft s = 358.9 6 de grees
Vertical distance (Linear misalignment) = 2.766 mm
After correcting Misalignment:For the correction
shims of value 2 mm in front and 0.5 mm in the back
were used and following results were obtain ed as shown
in Figure 6 (a) and (b):Angle between shafts = 0.3 de-
grees Vertical Distance = 0.088 mm
The principle of Image Processing may be used to
check the misalignment in implants in replacement sur-
geries in bones. Surgeons can use this application in
bone replacement surgeries like hip replacement and
knee replacement. The experiment on a model of ‘total
hip replacement’ was carried out.
3. THE HIP JOINT
The hip joint is the joint between the femur and aceta-
bulum of the pelvis. Its primary function is to support
the weight of the body in both static (e.g. standing) and
dynamic (e.g. walking or runn ing) postures.
3.1. Total Hi p Repl a cement
Hip replacement, is a surgical procedure in which the hip
joint is replaced by a prosthetic implant. Replacing the
hip joint consists of replacing both the acetabulum and
the femoral head. Such joint replacement orthopedic
surgery is conducted to relieve arthritis pain or fix joint
damage as part of hip fracture treatment.
3.2 Alignment Problems in Total Hip Replacement
Surgery
One of the most critic al aspects of a join t replace ment sur-
gery is to ensure proper positioning of the implanted joint.
An incorrectly aligned joint can lead to early wear and
loosening of the joint replacement. Slight misalignment
can lead to eccentric loading causing terrible pain and
discomfort to the patient and failure of the soft tissues
due to excessive loads [4]. In an effort to prevent early
wear and loosening of the artificial joint, surgeons are
constantly searching for ways to ensure that the implant
is properly positioned.
A computer-assisted surgery (CAS) [5] is used to con-
firm proper placement of the joint replacement. The
surgeon can still check with standard referencing in-
struments that the positioning is correct, and the com-
puter can provide confirmation of the placement.
Figure 7 shows the steps used in hip replacement sur-
gery. In orthopedic surgery, there is a well established
relationship between accuracy and outcome. A well
aligned hip resurfacing, hip or knee replacement will
perform better and last longer.
a) Excision of femoral head; b) Reaming of worm out
acetabulum (cup) ; c) Implantation of cup; d) Preparation
of femoral canal; e) Implantation of femoral prosthesis; f)
Implantation of femoral head
3.3. Markers to be Used
In the process some markers were used to locate the po-
sition of the bones. In the present study black dots were
used as markers for simplicity. In actual surgery black
dots cannot be used as markers. So rod type markers on
which LEDs or Colors are fixed were used to detect the
positions of the bones. The ro ds were fixed on the mark-
ers with the help of clips or by biocompatible adhesives.
Markers can also be screwed on the bones but it is not
advisable. In actual surgery optical markers as fluores-
cent color spots can be used as shown in Figure 8.
4. THE ALTERNATIVE METHOD
The system used in CAS that is the special markers,

R. Uddanwadiker / Advances in Bioscience and Biotechnology 2 (2011) 68-74 71
(a)
(b)
Figure 5. (a). Snapshot of the result given by VB on the misaligned shaft; (b). Picture showing the programme and the vertical mis-
alignment.
whole program and device is very costly- about 70 lakhs,
and since this techno logy is not manufactured in India it
has to be imported from Outside India (one of the
manufacturers is Brain Lab, Germany). Thus, the sur-
gery cost is high which common people cannot afford.
So the new method will give a cheaper solution for the
bone transplant surgery which will be available in India.
VisionBuilder Software is used for calculating the

R. Uddanwadiker / Advances in Bioscience and Biotechnology 2 (2011) 68-74 72
(a)
(b)
Figure 6. (a). Snapshot of the program after aligning shaft; (b). Snapshot of program showing vertical distance.
misalignment on the shafts and removing it. Using Vi-
sionbuilder linear and angular misalignment between
two shafts is found by a specific programme. Then it is
corrected by taking iterations. The software gives dif-
ferent parameters about shaft like horizontal distance
between shafts, angle between them etc.
4.1. Hip Replacement Using Vision Builder
Here a method for precisely positioning the bones using
camera, orthopedic markers and Visionbuilder software

R. Uddanwadiker / Advances in Bioscience and Biotechnology 2 (2011) 68-74 73
(a) (b) (c)
(d) (e) (f)
Figure 7. Steps of hip replacement surgery.
Figure 8. Markers used in actual surgery.
has been provided. The markers are observed by a cam-
era in different planes which can give accurate image of
the bone positions. Markers have fluorescent color mark
on it which can be detected by a camera as shown in
Figure 8. The images are fed into the computer having
Visionbuilder so ftware.
It receives and processes the image giving the meas-
ures of required parameters. Then the various parameters
obtained for different images before as in Figure 9 and
after the placement of the implant as shown in Figure 10
are compared. Thus, it can be confirmed that the bone is
perfectly placed and positioned accurately.
4.2. Experimentation
Four points are marked on the model of hip and femur
bone. Two points on the pelvis that is hip bone and two
on the femur bone. The images of the points are taken in
horizontal, vertical and angled planes. The points
marked on the bones are of black color as the color of
bones is white. In actual surgery the points can be
marked by fluorescent color as there is blood and flesh.
The markers, projected out from bone were used. Thus
the actual points were in different plane than the actual
plane of the bone.
The image was processed in the Visionbuilder. The
different parameters obtained are
 Distance between the points on femur bone
 Distance between the poin ts on pelvis bone
Distance between one point on femur bone and the
point on pelvis bone.
The angle between the lines formed by the points on
pelvis and the points on femur.
Then the model of implant was placed in the position.
The images of the implant were taken in three planes.
The same parameters were obtained for this setup.
The profile was matched by changing the positions of
implant slightly.
4.3. The program in Vision Builder for Hip
Replacement
Visionbuilder is a menu driven software. The following
steps were taken to generate the program:
The image was selected
Then the area of interest was created.
Points which are to be analyzed are detected by using
intensity range. We used RGB image. The intensity
range was given 0–0 . As our objects are blac k.
Then the geometric distance and angle was found out

R. Uddanwadiker / Advances in Bioscience and Biotechnology 2 (2011) 68-74 74
Figure 9. Hip bone and femur bone.
Figure 10. Model of implant of the femur bone.
using geometry command.
Then the control commands were set so that the dis-
tances and angles are in the given range using calculator
command.
The images were run in loop and according to the
range set, the program gave the image which gives the
results close to the original profile.
5. RESULTS
As measured from the Front view the results are pre-
sented in the Table 1.
Thus it can be concluded that the Software used for
alignment of shaft can be used for alignment of bones
also and can make the surgery cost effective and lead to
successful treatment of the patient.
REFERENCES
[1] John Piotrowski (1995) Shaft Alignment Handbook.
ISBN: 1574447211, 592-594
[2] Victor Wowk (2000) Specifying Shaft Alignment. Ap-
plied Technology Publications, 191(4), 659-675.
[3] Masanori Idesawa (1993) High Precision image position
sensing methods suitable for 3-D measurement. Optics
and Lasers in Engineering, 10( 3-4), 191-204
[4] Mark T.(2001) Precision bone alignment. United state
patents US 5249581.
[5] H. Bäthis et.al.(2003) Alignment in total knee arthro-
plasty :A Comparison Of Computer-Assisted Surgery
With The Conventional Technique Journal of Bone and
Joint Surgery 86-B(5), 682-687.