Patient Information
Vedant Kulkarni:
Hi. My name is Vedant Kulkarni, and I'm a Pediatric Orthopedic Surgeon at Shriners Hospitals for Children in Northern California. I'd like to get started with a demonstration of how to use the HipScreen app on your Android device. After you open the HipScreen app, select the third tab to open the migration percentage ruler. The first step is to load an X-ray onto the ruler. You can do this by selecting the camera icon to take a photo of an X-ray. To reduce any concerns of health privacy, if you take a photo of an X-ray within the HipScreen app, it is not saved to your device. If you have already taken a photo of your child's X-ray or your X-ray outside of the HipScreen app and have it saved on your device, you can also use the photos button to load the photo onto the app. Let's start by taking a photo of a pelvis X-ray. You can take the X-ray picture in landscape mode or in portrait mode.
Let's take a picture of this AP pelvis X-ray, by pressing the camera icon. I'll then press the check to select this X-ray for interpretation. Once it displays, the next step will be to rotate the X-ray so that it is leveled. Press the rotate button, and a new menu will appear. Notice that there are multiple gray horizontal lines across the screen. You'll use these lines to level the pelvis using one of the four landmarks we taught you in a previous tutorial. Let's use the triradiate cartilage, our top choice for landmark to level the pelvis in this example. Watch as I pan and zoom the image so that the landmark is more visible.
I'll then use the CCW button to rotate the image counterclockwise, and the CW button to rotate the image clockwise. I will do this until the horizontal line goes through the same part of the triradiate cartilage on both hips, although I won't use it in this example. You can press the 90 degree button to rotate the image a complete 90 degrees. This can be helpful if you start off in landscape mode or portrait mode, and want to switch to the other. Now that I'm satisfied with the rotation, I'll press the done button, and the orientation of the pelvis x\X-ray is locked. The next step is to activate the ruler overlay so that we can measure the migration percentage of each hip. When I press the ruler button, a ruler overlay will appear. Notice that as I zoom in on the image, the overlay size does not change.
This allows us to fit the X-ray to the ruler, allowing for quick measurement of the migration percentage without moving the lines on the screen. Also, notice that the ruler has two sides. We'll use the left half for the hip on the left half of the screen to start. Pan and zoom the image until the white line touches the lateral aspect of the femoral head, and the black line touches the medial aspect of the femoral head. One trick is to turn the ruler overlay on and off, so that you can make sure that you have the proper landmarks.
Once this is done, the femoral head is divided into 10% increments by vertical lines. The white line is the starting point for your measurement. Starting at the white vertical line, each gray line is a 10% increment of the femoral head. Notice that the third line is actually red. To measure the migration percentage, start at the white line and count which vertical line intersects the lateral edge of the acetabulum. In this case, it is the sixth vertical line from the starting white line, so 60% of the femoral head is lateral to the edge of the acetabulum. The migration percentage is 60%. If the edge of the acetabulum falls between two gray lines, you can still estimate the migration percentage to the nearest percent.
Now, notice the edge of the acetabulum is inside the red box. If the lateral edge of the acetabulum is within the red box, the migration percentage must be 30% or greater, and a referral to a pediatric orthopedic surgery specialty center for continued hip surveillance management is indicated. Let's go to the right hip now. We'll repeat the same steps on the right half of the ruler.
I will move the image and adjust it so that the medial aspect of the femoral head touches the black line, and the lateral aspect of the femoral head touches the white line. I'll again turn the ruler overlay on and off, to make sure the landmarks are appropriately positioned. Now that the femoral head is appropriately positioned, notice that the third vertical line from the starting white line touches the edge of the acetabulum. It's the red line. So the migration percentage is 30%.
You'll find more resources on www.hipscreen.org. Thanks so much.
