Health Topics » Surgery » Computer Assisted Navigation in Joint Replacement   Login


August 2010
Computer Assisted Navigation in Joint Replacement Surgery
Dr. Hemant Wakankar
Imagine getting stuck in a middle of a desert, with no soul in sight for miles on end. The End? Not necessarily, if you have a satellite phone with you. It can help you communicate and accurately judge your position on earth using the Global Positioning System (GPS). 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.

4 Aims of Surgery
A surgeon attempts four things during a joint replacement surgery, to accurately restore the mechanical alignment of the leg:
  1. Measures the angle of deformity
  2. Assesses the wear of the joint surfaces
  3. Measures the dimensions of damaged or diseased bones
  4. 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 early failure.

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.

Computer guided system is also called navigation, as it guides the surgeon in all the steps of surgery and even points 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. The navigation kit consists of a computer console, touch screen monitor and couple of infrared cameras that track the position of the leg.
  • 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 theatre.
  • 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.
  • During surgery, the anatomical landmarks are registered and data fed to the computer using dedicated instruments with reflective trackers.
  • The 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 millimetre!
  • 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.
7 Computer Assisted Advantages
  1. Restores accurate leg alignment
  2. Increases the survival of the implanted joint
  3. Reduces the risk of complications
  4. No radiation needed during surgery
  5. Constant guidance and monitoring during surgery
  6. Range of motion analyses to achieve maximum function
  7. Minimally invasive surgery, hence decreased blood loss
  8. Decreased hospital stay

Technological Benefits
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, which computer-guided navigation facilitates.
  • In non-obese patients, knee and hip replacement is possible today through a 10-12 cm incision.
  • These techniques have minimised or completely eliminated the damage to the muscles, thereby hastening the post surgery recovery.
  • Patients can stand and walk from the third day onwards after surgery and can be discharged from the hospital as early as fifth day after surgery.
During conventional total knee replacement surgery, a rod is inserted in the cavity of the thigh-bone (femur) to set the alignment of the leg. In computer-guided navigation surgery, the computer sets the alignment axis, and therefore, the rod does not require to be inserted in the thigh-bone. Any potential for the bone marrow and fat reaching the lungs and causing fat embolism, is thereby reduced.

Eat Green Vegetables and Onions Daily
  • It has been found that getting high amounts of the antioxidants lutein and zeaxanthin (found in green veggies like spinach) can help relieve pain in the bones.
  • Onions are a rich source of quercetin, a flavinod with strong anti inflammatory properties.
  • Adding onions to our daily diet is very simple: in salads, curries and even as pickled.
  • Apples, red grapes, and tea are also good sources of quercetin.
Dr.Hemant Wakankar is Consultant – Orthopedician at Jehangir Hospitals, Pune.

 Also See