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Imagine getting stuck in a middle of a desert with a satellite phone at hand. You can communicate and accurately judge your position on the planet earth with the help of your satellite phone using what is called as global positioning system (GPS). The basic principal in GPS is to track the location of the transmitter that is communicating with the satellites. Satellites triangulate the source of signal to locate the source with pinpoint accuracy. In most major cities abroad, GPS is used in cars for navigation through busy roads. Today, the same principal is assisting the surgeons in various fields to improve the results, and reduce the incidence of complications that can result from technical insufficiencies. The use of navigation technology in the field of Knee and Hip replacement surgery has further helped to improve the results of this already successful surgery. |
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Joint
replacement surgery is a combination of mechanical engineering
and surgical
skills. The most important aspect of knee and hip joint replacement
surgery is to accurately restore the mechanical alignment
of the leg. The surgeon measures the angle of deformity,
assesses the wear of the joint surfaces and measures the
dimensions of damaged or diseased bones, and assesses the
status of the ligaments that give stability to the joint
during surgery. Until now, all this was done by the surgeon
manually, with factor of human error creeping in occasionally.
If any imbalance exists in the placement of the artificial
joint components, these wear out faster and lead to failure
early. Today a well performed total knee replacement with
a good quality prosthesis should last 12 to 15 years or more.
The improvement in the accuracy of prosthesis placement is
expected to improve the results further. Until this technology
became available, the surgeons relied on one’s psychomotor
skills, mechanical instruments and own judgment in the placement
of the artificial joint components.
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 Computer
guided system is also called ‘Navigation’ as
it guides the surgeon in all the steps of surgery and even
point out errors before they are made. It works like the
satellite that detects signals from cars, boats, and other
vehicles equipped with special tracking devices. As the surgeon
moves an instrument within the patient's joint, the infrared
camera, like the GPS satellite, calculates its position,
and then transfers that data to a computer in the operation
theater. The computer then shows the direction and location
of the instrument. The computer navigates the path of instruments
in such a way that the part is fitted in the most optimum
position. It also helps in adjusting the ligament tension
that is very vital to get a stable joint with good range
of motion. It includes a computer console, touch screen monitor
and couple of infrared cameras that track the position of
the leg and the components. During surgery, the anatomical
landmarks are registered and data fed to the computer using
dedicated instruments with reflective trackers. Computer
generates a bone model that guides the surgeon in virtually
all the steps of the surgery. The accuracy of the steps is
improved to 0.5 degree and to one millimeter. Apart from
improving the precision of bone cuts, the computer also helps
in restoring the soft tissue balancing that is critical in
getting the desired good results. |
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The
use of such a technology has certain additional benefits.
Since
the computer guides the accurate bony cuts, the surgical
cut can remain limited with smaller incision and limited
soft tissue dissection. Most of the development in the field
of joint replacement surgery today is in what is called as ‘minimally
invasive surgery’ (MIS). In non obese patients, knee
and hip replacement is possible today through a 10 to 12
centimeter incision. The techniques have evolved that minimize
or completely eliminate the damage to the muscles, thereby
hastening the post surgery recovery. Patients can stand and
walk from third day onwards after surgery and can be discharged
from the hospital as early as fifth day after surgery. Computer
guided navigation assistance further facilitates the minimally
invasive surgery.
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During conventional
total knee replacement surgery, a rod is inserted in the
cavity of the thighbone (femur) to set the alignment of the
leg. In computer guided navigation surgery, the computer
sets the alignment axis and therefore rod does not require
to be inserted in the thighbone. Any potential for the bone
marrow and fat reaching the lungs and cause fat embolism
is thereby reduced.
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The
Advantages of Computer Guided Joint Replacement Surgery
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Computers
have become an integral part of everyday life. Virtually
all aspects of modern lifestyle depend on computers, be it
a washing machine or a modern car. It is therefore no surprise
that computers should come to the assistance of surgeons,
especially in surgeries where precision is required. Over
last decade, extensive research has led to the development
of ‘Navigation’ system for use in many surgical
fields including Joint Replacement Surgery. 
Copyright
2005-06. All rights reserved.Dr. Hemant Wakankar, Pune - India
Contact: 09820254070
E-mail: info@rushi.co.in
