1.Home_Screen_small

ACL-X

The Smartphone App
for ACL Surgery

1.Home_Screen_small

ACL-X

The Smartphone App
for ACL Surgery

Developed for knee surgeons
performing ACL reconstruction

This App was developed for knee surgeons performing anterior cruciate ligament (ACL) reconstruction and using intraoperative fluoroscopy to increase precision of bone tunnel placement. By means of supporting lines that you can overlay virtually over the X-ray photograph in the app, the app can calculate the relative distance of the target point for the k-wire for a femoral or tibial surgery.

ACL-X App
ACL-X App

Scientific reference and App in use: The ideal position for bone tunnel placement

In the medical literature, femoral measurement of a radiographic image is known as quadrant method by Bernard and Hertel. It may help knee surgeons identify the ideal position for bone tunnel placement during ACL reconstruction.

The femoral measurement step by step

The femoral measurement
step by step

The app will display relative ratio of your target point in reference to the outlines of bone of the femoral condyles. The numbers in % relate to the relative distance of the target point off the most posterior and proximal border of the condyles.

The app will display relative ratio of your target point in reference to the outlines of bone of the femoral condyles. The numbers in % relate to the relative distance of the target point off the most posterior and proximal border of the condyles.

  • Preperation

    Preperation

    During the operative procedure, place a guide wire (or the top of an microfracure awl) into the center of the femoral insertion area using your standard operative set up. Alternatively you may advance the the k-wire in the center of the projected bone tunnel forward penetrating the skin on the lateral side of the femur so the the end of the wire is flush with the femoral cortex of the insertion.
  • Take a picture

    Take a picture

    Aquire a fluoroscopic image of the knee in a strong lateral plane (both condyles have to overlap perfectly). Start the measuring process in the app and take a picture of the fluoroscopic image from the monitor or a print-out of the image. If you are not happy with the picture you can “redo” the picture. In case that the photo is satisfactory press “use phote”.
  • 1. Blumensaat Line

    1. Blumensaat Line

    Touch the screen with two fingers (e.g. index and middle finger) to establish a line. By moving and turning your fingers you can move the line in a way that it perfecty overlies the Blumensaat-line (BS-Line) representing the roof of the interkondylar notch in the femur. (do not use only one finger as no line will be displayed in that case.)
  • 2. Posterior Condyle Line

    2. Posterior Condyle Line

    Now by touching the screen with only one finger, a blue line is displayed being perpendicular (90° angle) to the former BS-line. Move the line to the most posterior aspect of the femoral condyle.
  • 3. Anteriore Condyle Line

    3. Anteriore Condyle Line

    Using the tip of your finger, establish and position another line in the same manner as before located at the most anterior aspect of the femoral condyle.
  • 4. Distal Condyle Line

    4. Distal Condyle Line

    Using the tip of your finger, establish and position another line parallel to Blumensaat line (BS-line) outlining the most distal aspect of the femoral condyle (this line being a tangent to the circle line of the condylar bone).
  • 5. Target point

    5. Target point

    Using a finger tip, a bullseye is placed over the target point on the femur (e.g. end of the k-wire). The placement is facilitated by an extension of the touchpoint to the bullseye.
  • Measurement

    Measurement

    The app will display the relative ratio of your target point in reference to the outlines of the bone of the femoral condyles. The measurement values relate to the relative distance of the target point of the most posterior and proximal border of the condyles.

The femoral measurement step by step

The app will display relative ratio of your target point in reference to the outlines of bone of the femoral condyles. The numbers in % relate to the relative distance of the target point off the most posterior and proximal border of the condyles.

  • Preperation

    Preperation

    During the operative procedure, place a guide wire (or the top of an microfracure awl) into the center of the femoral insertion area using your standard operative set up. Alternatively you may advance the the k-wire in the center of the projected bone tunnel forward penetrating the skin on the lateral side of the femur so the the end of the wire is flush with the femoral cortex of the insertion.
  • Take a picture

    Take a picture

    Aquire a fluoroscopic image of the knee in a strong lateral plane (both condyles have to overlap perfectly). Start the measuring process in the app and take a picture of the fluoroscopic image from the monitor or a print-out of the image. If you are not happy with the picture you can “redo” the picture. In case that the photo is satisfactory press “use phote”.
  • 1. Blumensaat Line

    1. Blumensaat Line

    Touch the screen with two fingers (e.g. index and middle finger) to establish a line. By moving and turning your fingers you can move the line in a way that it perfecty overlies the Blumensaat-line (BS-Line) representing the roof of the interkondylar notch in the femur. (do not use only one finger as no line will be displayed in that case.)
  • 2. Posterior Condyle Line

    2. Posterior Condyle Line

    Now by touching the screen with only one finger, a blue line is displayed being perpendicular (90° angle) to the former BS-line. Move the line to the most posterior aspect of the femoral condyle.
  • 3. Anteriore Condyle Line

    3. Anteriore Condyle Line

    Using the tip of your finger, establish and position another line in the same manner as before located at the most anterior aspect of the femoral condyle.
  • 4. Distal Condyle Line

    4. Distal Condyle Line

    Using the tip of your finger, establish and position another line parallel to Blumensaat line (BS-line) outlining the most distal aspect of the femoral condyle (this line being a tangent to the circle line of the condylar bone).
  • 5. Target point

    5. Target point

    Using a finger tip, a bullseye is placed over the target point on the femur (e.g. end of the k-wire). The placement is facilitated by an extension of the touchpoint to the bullseye.
  • Measurement

    Measurement

    The app will display the relative ratio of your target point in reference to the outlines of the bone of the femoral condyles. The measurement values relate to the relative distance of the target point of the most posterior and proximal border of the condyles.

ACL-X

ACL-X

Available on the App Store now.
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