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iPod Guides Surgeon, Helps Fix Knee, Hip

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Times of India
29 April 2011
Chennai, India

Orthopaedic surgeon Dr Vijay Bose loves to listen to music on his iPod. Now, he carries it to the operation theatre as a surgical tool.

iPod Guides Surgeon, Helps Fix Knee, Hip Dr Bose, who has replaced several hips and knees, now mounts his iPod into a handheld device as an image-guided navigation system to do the surgery. The application, which takes up less than 3GB space on the iPod, works like a global positioning system (GPS) on mobile phones. The iPod screen displays positioning calculations which change with the patient’s anatomy. It guides the surgeon to position the implant perfectly, with the least error margin.

The application, Dash, developed by Smith & Nephew Inc, works on a similar technology used in computer navigation systems. But computers occupy a lot of space in the theatre and surgeons have to lift their heads to see the screen. "Looking at the computer now and then is not a smooth thing to during a surgery," said Dr Bose. And every time he had to navigate, he would have to seek the assistance of other doctors or technicians.

On April 19, he did a hip resurfacing surgery on a 47-year old US-based basketball coach, Guy Williams, and a knee replacement on a 65-yearold housewife in Chennai, with the hand-held navigation tool. Earlier, Mumbai-based Breach Candy Hospital had done a knee replacement surgery using iPod navigation system.

During the surgery, the iPod loaded with the surgical application is inserted into a special casing mounted on the surgical device held by the doctor. As the surgeon moves his hands within the patient’s joint, a camera placed nearby picks up the images with the help of sensors on the surgical device. The data is transferred to a central processing unit, which transfers the image to the iPod, using a wi-fi connection. The images on the iPod give a visual confirmation for the surgeon and enable a more precise implantation. "There was a greater level of accuracy. The patients are doing well," says Dr Bose.

Replacement surgeries can have a 3-mm margin of error. The challenge is to keep the margins as low as possible. A large error margin could cause complex fractures or dislocations in the patient later. The volumes of replacement surgeries have increased by several folds in the last 10 years across the country and surgeons are expecting many patients to come back for revision surgeries. "These could be because we had been using plastic implants that weren’t strong or because the error margin wasn’t very low. The iPod navigation system helps alignment of the bone joint with a 0.1 mm precision," said Dr Bose.

For the basketball coach Guy Williams, most of these technologies weren’t new. "Some doctors there maybe using similar tools. But the cost of the surgery here is US$ 8000 against the US$ 58,000 there. With my insurance limit, I could not afford the treatment in the US," he said.

Cutting Edge
  1. The total apparatus is made up of a special casing for the iPod as well as a computer system that communicates wirelessly with the Apple device
  2. The computing system also comprises a camera that is equipped with an infrared sensor
  3. The doctor uploads the DASH application onto his iPod
  4. This iPod is fitted inside the specially designed sterile carrier, which has slots for miniature instruments called cutting blocks that the doctor uses during the surgery
  5. Also attached to the carrier are three antennae with reflecting spheres
  6. These three reflecting spheres provide a frame of reference to the infrared sensor on the camera, which tracks each of them to plot the x, y and z axis of each point
  7. The computing system, which communicates with the iPod through Wi-fi, uses a collection of such points to form a composite of the knee
  8. At the time of surgery, the doctor also attaches two spheres, above and below the knee to provide the infrared camera a frame of reference
  9. The 3D composite created by the computer is then relayed back to the iPod to provide the operating surgeon with an image to be used during the procedure
  10. Advanced algorithms in the system also prompt the surgeon with relevant and precise cues during surgery when he/she uses the cutting tools on the carrier thus reducing any chances of error

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